BIBLIOGRAPHY AMADO, MARY JEAN T. APRIL...
BIBLIOGRAPHY
AMADO, MARY JEAN T. APRIL 2011. Distribution of Entomopathogenic Nematodes
(EPNs) in Vegetable and Strawberry Growing Areas in Mountain Province. Benguet State
University, La Trinidad, Benguet.
Adviser: Luciana M. Villanueva, PhD.
ABSTRACT
A survey was conducted in five vegetable and strawberry growing municipalities of Mt.
Province from January to March 2011 to determine the presence of entomopathogenic nematodes
(EPNs) and how they are affected by soil pH, texture and crops.
Result showed that 19 out of 32 sites were positive for EPNs. Sabangan showed the
highest recovery frequency of 46.15% followed by Besao and Bauko with 24.44% and 22.73%,
respectively. Bontoc with only one site has 15.38% recovery frequency while Sagada has the
least with 10.81%. Although soil pH and texture did not significantly affect the presence of
EPNs in 5 municipalities surveyed, it was noted that higher number of EPNs was detected in
areas with pH ranging from 4.00-5.99. The least number was collected in areas with soil pH
ranging from 3.00-3.99, 6.00-6.99, and 7.00-7.99. On the other hand, most of the positive
samples were collected in silt loam with 89.47% followed by loam with 7.89% and the least was
sandy loam soil with 2.63%. Conversely, the presence of EPNs was significantly influenced by
crops. The frequency of occurrence of EPNs was highest in soil samples from potato 42.86%
followed by cabbage and pepper, with 11.63% and 10%, respectively.
Results of the investigation indicate that the presence of EPNs is dependent on soil pH,
soil texture and crops planted. However, these findings need to be verified.
TABLE OF CONTENTS
Page
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .
i
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
REVIEW OF LETIRATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Life Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Mutualistic Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
Behavioral Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
Efficacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
MATERIALS AND METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
Geography and Collection of Soil Samples . . . . . . . . . . . . . . . . . . . . .
6
Isolation of EPNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
Determination of Soil Ph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Soil Texture Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Data Gathered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
RESULTS AND DISCUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
Effect of Soil pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Effect of Soil Texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
Effect of Crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
SUMMARY, CONCLUSION AND RECOMMENDATION . . . . . . . . . . . .
22
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
1
INTRODUCTION
Nematodes are a diverse group of invertebrates abundant as parasites or free
living forms in soil, fresh water, and marine environments. Barker (1998) stated that there
are more than 15,000 described species that represent only a small portion of the total
members in Phylum Nematoda. The soil is particularly rich habitat for nematodes with
about 26% described genera inhabiting soil as bacterivores, fungivores, omnivores,
predators or plant parasites. Added to this are soil dwelling stages of insect parasites
referred to as entomopathogenic nematodes (EPNs) (Wharton, 1986).
Entomopathogenic nematode (EPNs) are extra ordinarily lethal to many important
soil insect pests, yet they are safe to plants and animals. Unlike chemicals, nematode
applications do not require mask or other safety equipment, re entry time, residues;
ground water contamination; chemical trespass and pollution are not issues. Thus
development of EPN technology will be a great help for researchers and vegetable
growers to produce good quality and safe food for consumers
Recognizing the hazards of pesticides to man and the environment, many
countries in the world is considering biological control agents such as entomopathogenic
nematodes (EPNs) as the best alternative to chemical control of plant diseases and pests
(Souto et al., 2004).
The study was conducted to determine the presence of entomopathogenic
nematodes (EPNs) in vegetable and strawberry growing areas in Mt. Province and how
they are affected with soil texture, pH and crops.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
2
REVIEW OF LITERATURE
Entomopathogenic nematodes have been known since the 17th century but it was
only in the 1930’s that serious consideration was given to using nematodes to control
insect (Nickle, 1984). This nematode has been found infecting grubs of the Japanese
beetle, Popilla japonica, at the Travis stock Golf course near Haddon field, New Jersey.
Entomopathogenic nematodes are adapted to most climatic conditions in hot,
temperate and cold zones, distributed from lowlands to high alpine altitudes. S.
carpocapsae and S.feltiae are widely distributed in temperate regions. H.bacteriphora is
common in regions with continental and Mediterranean climates, and H.indica is found
throughout much of the tropics and subtropics (Steiner, 1996).
Currently, there are two genera which contain the most important species of
entomopathogenic nematodes; Steinernema and Heterorhabditis (Lewis, 2000). Species
in these genera have a global distribution. They exhibit differences in host range,
infectivity and environmental tolerances (Hominick et al., 1996). Most entomopathogenic
nematodes described belong to the genus Steinernema, a total of 24 species have been
isolated, and four species have been commercialized; S.carpocapsae, S. feltiae,
S.riobravis and S.capterisci. Of the Heterorhabditis species H.bacteriophora and
H.megidis have been commercialized (Booth, 2000).
Life Cycle
Steinernematids are similar to heterorhabditids in general life cycle and gross
morphology (Wouts, 1984). The major difference between the two families is in the
reproductive strategies. Steinernematids are amphimictic, they require a male and female
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
3
infective juvenile to invade an insect host to produce progeny. In the case of
heterorhabditid, adults resulting from the infective juveniles are hermaphrodites;
therefore only one juvenile is needed to enter the host for progeny production (Hazir et
al., 2003).
The infective stage of entomopathogenic nematodes (third-stage dauer juveniles)
seeks and invades larvae of soil dwelling insect species (Klein, 1990). They enter the
insect host through natural body openings, the mouth, anus, or respiratory inlets
(spiracles) and then penetrate into the blood cavity from the gut (Poinar 1990).
Heterorhabditis penetrates through chinks in the insects interskeletal membranes by
scratching away with special tooth (Bedding and Molyneux, 1982). They release
bacterium through anus for steinernematids and through mouth by hetrorhabditids
(Poinar, 1966). The toxins produced by the developing nematodes (Burman, 1982) and
bacteria cause septicemia and kill the insect host within 24-48 hours after infection
(Akhurst and Boemere, 1990).
Insects use anti bacteial protiens and phagocytosis followed by nodule formation
to counteract the bacterial cells. It may also encapsulate nematodes followed by
melanization. However, in some cases, nematodes overcome the insect’s defense and
successfully infect its host. This is in relation to the nematodes surface coat proteins that
suppresses the host immune response (Wang, 1998). Moreover, the invading nematodes
immuno –inhibiting factors that destroy the antibacterial factors produced by the insect
and allow the mutualistic bacteria to produce insecticidal toxins that rapidly kill the host
(Bowen et al., 1998)
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
4
Mutualistic Bacteria
Steinernema and Heterorhabditis are associated with mutualistic bacteria
Xenorhabdus and Photorhabdus respectively. Xenorhabdus and Photorhabdus are motile
gram negative, facultative, none spore forming, anaerobic rods in the family
Enterobacteriaceae. These symbiotic bacteria are vectored in the insect’s hemocoel by the
nematode infective juvenile (Forst et al., 1996). The difference that occur between the 2
bacterial genera is, most Photorhabdus spp. are luminescent and catalase positive, where
as Xenorhabdus spp. have no luminescence and are catalase negative (Hazir et al., 2003)
Behavioral Ecology
EPNs employ different foraging strategies to locate and infect hosts. The
intermediate foraging strategist (S. riobrave and S.feltiae) infects insect that occur just
below the soil surface, such as prepupae of lepidopterous insects, fungus gnats, or weevil
larvae. The sit and wait strategist or ambushers (S. carpocapsae) are characterized by low
motility which search at or near the soil surface. They infect mobile host species such as
codling moth, cutworms and mole crickets. At the other extreme, foraging strategy or
cruiser (S. glaseri and H.bacteriophora) are characterized by high motility and are
distributed throughout the soil profile. They infect sedentary host such as scarab and
lepidopterous prepupae and pupae (Hazir et al., 2003).
Various biotic and abiotic factors can influence the successful use of
entomopathogenic nematodes as biological control agent. The persistence of EPNs in
natural areas depends on the dauer larvae’s ability to disperse and persist until it can
locate a suitable host. Extrinsic factors such as temperature, soil moisture, soil texture,
pH, and UV radiation affect their dispersal and persistence. Furtheremore, many soil
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
5
dwelling nematodes have evolved behaviors resulting in reduced host finding attachment
and penetration by infective juveniles. Some nematodes that have been isolated from host
cadavers in the field have restricted host range (e.g. S. kushidari and S.scarabaei are
adapted to scarab larvae (Stock and Koppenhoefer, 2003). S. scapteresci is adapted to
mole cricket and poorly infect other insects (Grewal, 1993). Among the biotic factors
(natural enemies) are bacteria, fungi, mites, predatory nematodes, tardigrades and
collembolans. Mites appear to be especially voracious nematode feeders (Walter, 1987).
Efficacy
Several studies have shown effectiveness of entomopathogenic nematodes in
recent years. EPNs have been applied successfully against soil inhabiting insects (as soil
application) as well as above-ground insects (foliar spray) in cryptic habitat (Shapiro -
Ilan et al., 2006.) In a golf course ecosystem, the application of Heterorhabditis
bacteroiphora, an introduced nematode, significantly reduced the abundance, species
richness, maturity and diversity of the nematode community (Somaseker et al., 2002).
Further laboratory test showed that S. carpocapsae alone infected more than 250 insect
species from over 75 families in 11 0rders (Poinar, 1983).
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
6
MATERIALS AND METHODS
Soil samples were collected from strawberry and vegetable growing areas in Mt.
Province and further laboratory study was done at STVRDC laboratory, Benguet State
University La Trinidad, Benguet from January to April 2011.
A. Geography and Collection of Soil Samples
Mt. Province is known to be the Philippines biggest and highest chain of
mountains. The province is bounded on the north by Kalinga, on the south by Benguet
and Ifugao, on the east by Isabela, and on the west by Ilocos sur and Abra. Mt. Province
is politically subdivided into 10 municipalities and 144 barangays. It has a total land area
of 209,733 hectares, 23% is classified as alienable and disposable, and 77% as forest
lands. Mt. Province is characterized by towering peaks and sharp ridges on its central and
western part while the eastern portion features gently sloping and rolling foothills. The
Province falls on type III climate category that is characterized by uneven distribution of
rains throughout the year and this cover the eastern part of the province.
A survey was undertaken from February to March 2011 to assess the distribution
of EPNs in vegetable and strawberry growing areas in Bauko, Sabangan, Bontoc, Besao,
and Sagada, Mt. Province.
Soil samples were collected from nine (9) vegetable sampling sites in Bauko, five
in Sabangan, one in Bontoc, twelve in Sagada and nine in Besao (Figures 1- 5), A total
of 174 samples were collected from the 5 municipalities. About 0.5 kg comprising five to
10 sub-samples were collected randomly per area. The samples were placed on properly
labeled plastic bags and were brought to the laboratory for nematode isolation.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
7
A
A
B
C
D
D
Figure 1. Sampling sites in Bauko, Mt. Province: (A) Buga, Mt. Data, (B) Sintu proper, (C)
Sintu, (D) Monamon
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
8
A
B
Figure 2. Sampling sites in Sabangan, Mt. Province: (A) Pengew, (B) Capinitan
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
9
A
B
Figure 3. Sampling sites in Lanao, Bontoc, Mt. Province: (A) site 1, (B) site 2
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
10
A
A
B
B
C
D
Figure 4. Sampling sites in Sagada, Mt. Province: (A) Nalabasan, Poblacion, (B)
Madongo, (C) Petaad, Ambasing, (D) Legleg, Ambasing
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
11
A
A
B
B
C
D
Figure 5. Sampling sites in Besao, Mt. Province: (A) Amdakig, (B) Banao, (C) Lake
Danum, (D) Suquib
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
12
B. Isolation of EPNs
Entomopathogenic nematodes (EPNs) were isolated from soil by using lesser wax
moth, Achroia grisella larvae as bait (Figure 6). About 250 g of soil was placed in each
improvised baiting container. To provide aeration and at the same time prevent the escape
of wax moth larvae, wire mesh was provided in the plastic cover of the baiting container
(Figure 7). Around 10 larvae were placed per container to serve as bait for the nematodes.
After 2-3 days, the larval cadavers were retrieved from the soil and washed with distilled
water and arranged in a petri plate lined with moist filter paper. The infected insect was
examined under a dissecting microscope for the presence of EPNs.
Figure 6. Lesser wax moth (Achroia
Figure 7. Plastic containers with soil
grisella) larvae used as bait
samples collected from
different municipalities in
Mt. Mountain Province
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
13
D. Determination of soil pH
About 30 g of soil samples were air dried in the laboratory for 3 days. Grinding of
soil samples was done using mortar and pestle prior to pH determination which was done
after calibrating the pH meter (Figure 8).
Figure 8. Determination of soil pH using a pH meter
E. Soil texture classification
Following the procedure of Robinson (2005), soil classification was done. About
50 cc of soil taken from samples collected was moistened with 10 ml water to determine
if it will form a ball (Figure 8). The soil was squeezed in the palm of the hand and
depending on the form that it would create; soil texture was determined.
Sand- Soil either does not form a ball or forms a ball but easily breaks when
bounced at the palm.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
14
Loam- Soil can be formed into a ball and a ribbon less than 2.5 cm.
Clay- Soil can be formed into a ball and a ribbon more than 2.5 cm.
Data Gathered
1. Presence of EPNs
2. Soil pH
3. Soil Texture
Figure 9. Classification of soil texture by feel method
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
P = 0.029
15
RESULTS AND DISCUSSION
Table 1 shows the abundance and recovery frequency of EPNs in vegetable and
strawberry growing areas in Mt. Province. EPNs were recovered from 38 samples out of
174 soil samples collected (21.84%) and 19 positive sites out of 32 sites sampled
(59.38%). Although not significantly different, the highest recovery was recorded in
Sabangan, followed by Besao, Bauko, Bontoc, and Sagada with 46.15, 24.44, 22.73,
15.38 and 10.81%, respectively. In terms of EPN abundance, Bontoc with only 1 site that
grows vegetables gave 100% followed by Besao (85.71%), Sabangan (80.00%), Bauko
(62.50%) and Sagada (27.27%).
Effect of Soil pH
The effect of soil pH on the recovery frequency of EPNs in five municipalities of
Mt. Province is shown in Table 2. Although not significantly different as shown by
Pearson’s chi-square test, most of the EPNs were recovered from pH-4.00-5.99. This is
true in all the municipalities surveyed. In very acidic soil (pH 3.00-3.99), EPNs were
only detected in Sabangan, while at pH range of 6.00-6.99, they were found only in
Bauko. In highly alkaline soil (7.00-7.99), the EPNs were only recovered in Besao.
Results of the study confirmed the findings of Rosa et al., (2000) that most of the EPNs
were recovered from soil with pH below 6.00. On the other hand, according to Herrera et
al (2007) soil pH does not significantly affect occurrence of EPNs although they are
easily isolated from pH range of 5.01 to 8.0.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
16
Table 1. Abundance and recovery frequency of entomopathogenic nematodes (EPNs) in
strawberry and vegetable growing areas/municipalities in Mountain Province
TOTAL
POSITIV
NO. OF
ABUN-
SOIL
E SOIL
RECOVERY
MUNICI-
TOTAL POSITIV DANCE SAMPLE SAMPLE
FREQUENC
PALITIES SITES
E SITES
(%)a
S
S
Y (%)b
Sabangan
5
4
80.00
13
6
46.15
Bauko
8
5
62.50
66
15
22.73
Bontoc
1
1
100.00
13
2
15.38
Sagada
11
3
27.27
37
4
10.81
Besao
7
6
85.71
45
11
24.44
GRAND
TOTAL
32
19
59.38
174
38
21.84
a (Number of positive sites/ number of total sites) x 100
b (Number of positive samples /number of total samples) x 100
Table 2. Recovery frequency (%) of positive soil samples for EPN by soil pH in
vegetable and strawberry growing areas in Mt. Province per municipality
MUNICIPALITIES
pH RANGE
Sabangan
Bauko
Bontoc
Sagada
Besao
3.00 - 3.99
6.69
-
-
-
-
4.00 - 4.99
15.38
3.03
7.69
10.81
20.00
5.00 - 5.99
23.07
16.66
7.69
-
2.00
6.00 - 6.99
-
3.03
-
-
-
7.00 - 7.99
-
-
-
-
1.00
Total No. of Samples
13
66
13
45
37
Positive Soil Samples (%)
46.15
22.72
15.38
24.44
10.81
Effect of Soil Texture
The effect of soil texture on the incidence of EPNs by municipality is shown in
Table 3. Statistical analysis showed that except for Bauko (P=0.029), the presence of
EPN was not significantly affected by soil texture. However, in most of the
municipalities surveyed, the EPNs were mostly detected from silt loam and loam except
for EPNs collected from Bontoc which were recovered from sandy loam soil.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
17
Regardless of municipality, soil texture has no significant effect on the occurrence
of EPNs (Table 4). However, most of the positive samples were noted from silt loam
followed by loam and sandy loam with 89.47, 7.89 and 2.63 % recovery frequency,
respectively.
Our results are similar to the findings of Mracek et al., (2004) and Rosa et al.,
(2000) that EPNs were mostly recovered from light soils such as silt loam and sandy
loam except for S. kraussei which can tolerate both silt/clay organic soils. According to
Mraceket et al., (2005) heavy soils decrease the nematode mobility which could be the
reason why no EPNs were recovered from clay loam to heavy clay in all the sampling
sites (Figure 10).
Table 3. Number and recovery frequency (%) of positive soil samples collected from
vegetable and strawberry growing areas in Mt. Province as influenced by soil
texture
NUMBER OF POSITIVE
RECOVERY
SOIL TEXTURE
SOIL SAMPLES
FREQUENCY*
Sand
-
-
Sandy loam
1
2.63
Silt loam
34
89.47
Loam
3
7.89
Clay loam
-
-
Light clay
-
-
Heavy clay
-
-
GRAND TOTAL
38
100
* (number of positive soil samples/ total number of positive soil samples) x 100
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
18
Sabangan
Bauko
20
) 20
) 15
15
10
10
5
5
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
0
R
e
c
o
v
e
r
y
f
r
e
q
e
n
c
y
(
%
Sand Loamy Silt Loam
Clay Light Heavy
Sand Loamy Silt Loam Clay Light Heavy
sand loam
loam
clay
clay
sand loam
loam
clay
clay
Soil texture
Soil texture
Bontoc
) 20
15
10
5
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Sand Loamy Silt
Loam
Clay Light Heavy
sand
loam
loam
clay
clay
Soil texture
Sagada
Besao
)20
) 20
15
15
10
10
5
5
0
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Sand Loamy Silt
Loam
Clay
Light Heavy
sand
loam
loam
clay
clay
Sand Loamy Silt Loam Clay Light Heavy
sand loam
loam
clay
clay
Soil texture
Soil texture
Figure 10. Influence of soil texture on the distribution of positive samples in vegetable
and strawberry growing areas in Mt. Province (a) Sabangan, (b) Bauko, (c)
Bontoc, (d) Sagada and (e) Besao
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
19
Table 4. Recovery frequency (%) of positive soil samples for EPNs in vegetable and
strawberry growing areas in Mt. Province per municipality as influenced by soil
texture
MUNICIPALITIES
SOIL TEXTURE
Sabangan
Bauko
Bontoc
Sagada
Besao
Sand
-
-
-
-
-
Sandy loam
-
-
2.63
-
-
Silt loam
13.16
39.47
2.63
10.53
23.68
Loam
2.63
-
-
-
5.26
Clay loam
-
-
-
-
-
Light clay
-
-
-
-
-
Heavy clay
-
-
-
-
-
Total No. of Samples
6
15
2
4
11
Recovery Frequency (%)
15.79
39.47
5.26
10.53
28.95
Effect of Crops
Figure 11 shows the effect of crops on the recovery frequency of EPNs in
different municipalities of Mt. Province. Apparently, crops did not significantly influence
the recovery frequency of EPNs in Sabangan. However, in Bauko, significantly higher
EPN recovery was recorded in potato, followed by garden pea and cabbage. In Bontoc,
EPNs were only detected in beans and banana while in Sagada they were detected only in
cabbage, beans and pepper. Similar to Bauko, the highest recovery of EPNs in Besao was
recorded in potato, followed by pechay, cabbage and corn. Surprisingly, no EPN was
recovered in strawberry areas in Sagada and Besao. This could be due to the fact that
strawberry was newly introduced in these two municipalities and therefore the population
of insect pests associated with strawberry which are the hosts of EPNs is still very low.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
20
Sabangan
Bauko
)
) 20
(
% 20
15
15
10
f
r
e
q
u
e
n
c
y
10
5
5
R
e
c
o
v
e
r
f
r
e
q
u
e
n
c
y
(
%
R
e
c
o
v
e
r
y
0
0
Crops
Crops
)
20
Bontoc
15
10
5
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Crops
Sagada
)
Besao
) 20
20
18
15
16
14
12
10
108
5
6
4
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
2
0
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Crops
Crops
Figure 11. Recovery frequency of positive samples for EPN by crops in vegetable and
strawberry growing areas in Mt. Province, (a) Sabangan, (b) Bauko, (c)
Bontoc, (d) Sagada and (e) Besao
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
21
On the other hand, regardless of municipality, positive samples for EPNs were
significantly affected by crops (Figure 12). The highest recovery frequency was obtained
from potato with 47.37%, followed by cabbage (13.16 %), garden pea and beans
(7.89%), chinese cabbage and pechay (5.26 %), and carrots, banana, peper, zuccini, and
broccoli (2.63 %). According to Garcia del Pino and Palomo (1996a) and Mracek and
Webster (1993) habitat preference is related to insect host distribution. Since farmers
have been planting potato,cabbage garden pea and beans for quite a long time , the insect
pests associated with these crops have already increased their populations ; thus favoring
the growth and development of their associated EPNs .
50
) 40
30
20
10
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Crops
Figure 12. Recovery frequency (%) of positive soil samples for EPNs as
influenced by crops
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
22
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary
A survey was conducted in five vegetable and strawberry growing municipalities
of Mt. Province from January to March 2011 to determine the distribution of
entomopathogenic nematodes (EPNs) and how they are influenced by soil pH, texture
and vegetation. Soil samples were brought to the STVRDC Laboratory, Benguet State
University, La Trinidad, Benguet for nematode and soil analyses.
EPNs were recovered from 38 samples out of 174 soil samples collected
(21.84%) and 19 out of 32 sites sampled (59.38%). Although not significantly different,
the highest recovery frequency was recorded in Sabangan followed by Besao, Bauko,
Bontoc and Sagada with 46.15%, 24.44%, 22.73%, 15.38% and 10.81%, respectively.
Regardless of municipality, most of the EPNs were detected in pH ranging from
4.00- 5.99. On the other hand, higher number of positive samples were collected from
silt loam (89.47%), followed by loam (7.89%) and sandy loam (2.63%) soil. No EPNs
were recovered from clay loam, light clay and heavy clay loam.
The presence of EPNs was also influenced by crops. The highest recovery was
obtained from potato with 47.37% followed by cabbage (13.16%), garden pa and beans
(7.89%), Chinese cabbage and pechay (5.26), and carrots, banana, pepper, zucchini and
broccoli (2.63%).
The present study reported for the first time the occurrence of EPNs in Mt.
Province.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
23
Conclusion
Results of the investigation showed that soil pH, soil texture and crops
influenced the recovery frequency of EPNs. Slightly acidic and silty loam soil favored the
growth and development of most vegetables including potato. Higher recovery frequency
of EPNs in the above mentioned pH range and soil texture could also be related to the
insect or nematode populations feeding on these crops which serve as host for EPNs.
Recommendation
Additional surveys are recommended taking into account other factors like soil
moisture, temperature, season including altitude.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
24
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Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
27
APPENDICES
Appendix Table 1. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Bauko, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL pH
TEXTURE
OF EPNs
1
Monamon
radish
4.67
Silt loam
-
2
Monamon
carrots
5.69
Silt loam
-
3
Monamon
radish
4.94
Silt loam
-
4
Monamon
potato
4.77
Silt loam
-
5
Monamon
carrot
5.51
Silt loam
+
6
Monamon
radish
5.95
Silt loam
-
7
Monamon
radish
6.79
Loam
-
8
Monamon
carrots
4.84
Loam
-
9
Monamon
potato
5.34
Silt loam
+
10
Monamon
potato
5.66
Silt loam
+
11
Monamon, site 1 potato
5.34
Silt loam
+
12
Monamon
cabbage
5.91
Silt loam
-
13
Monamon
radish
5.31
Loam
-
14
Monamon
cabbage
5.56
Loam
-
15
Monamon
radish
6.69
Loam
-
16
Monamon
potato
5.13
Silt loam
-
17
Monamon
potato
5.76
Silt loam
-
18
Monamon
potato
5.5
Silt loam
+
19
Monamon
potato
5.45
Silt loam
+
20
Monamon
potato
5.66
Silt loam
-
21
Sinto
cabbage
6.26
Silt loam
-
22
Sinto
cabbage
6.07
Silt loam
+
23
Sinto
garden pea
5.48
Silt loam
-
24
Sinto
garden pea
6.41
Silt loam
+
25
Sinto Proper
garden pea
4.71
Silt loam
+
26
Sinto proper
potato
5.56
Loam
-
27
Sinto proper
potato
6.00
Silt loam
-
28
Sinto Proper
potato
5.67
Silt loam
+
29
Sinto Proper
potato
5.96
Silt loam
-
30
Sinto Proper
potato
5.94
Silt loam
-
31
Sinto proper
potato
5.83
Silt loam
+
32
Sinto proper
cabbage
6.02
Silt loam
-
33
Sinto proper
cabbage
5.93
Loam
-
34
Buga Sinto
potato
4.47
Silt loam
+
35
Buga Sinto
potato
5.84
Silt loam
-
36
Buga Sinto
potato
5.49
Silt loam
+
37
Buga Sinto
corn
7.02
Silt loam
-
38
Buga Sinto
potato
5.89
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
28
Appendix Table 1. Continued…
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY CROP
SOIL pH
TEXTURE
OF EPNs
39
Sadsadan
beans
5.36
Silt loam
-
40
Sadsadan
beans
4.37
Loam
-
41
Sadsadan
beans
6.02
Silt loam
-
42
Sadsadan
potato
5.24
Silt loam
-
43
Sadsadan
garden pea
6.26
Silt loam
-
44
Sadsadan
potato
5.08
Silt loam
-
45
Sadsadan
potato
4.79
Silt loam
-
46
Sadsadan
potato
4.86
Silt loam
-
47
Sadsadan
cabbage
5.05
Silt loam
-
48
Mabaay
garden pea
4.66
Silt loam
-
49
Mabaay
garden pea
4.78
Loam
-
50
Mabaay
potato
5.48
Loam
-
51
Mabaay
camote
5.70
Silt loam
-
52
Mabaay
garden pea
4.59
Silt loam
-
53
Mabaay
garden pea
4.83
Loam
-
54
Mabaay
carrots
5.73
Silt loam
-
55
Mabaay
camote
5.49
Silt loam
-
56
Mabaay
carrots
5.52
Silt loam
-
57
Mabaay
camote
5.63
Silt loam
-
58
Mabaay
garden pea
4.84
Loam
-
59
Mabaay
garden pea
4.68
Silt loam
-
60
Mabaay
garden pea
5.42
Silt loam
-
61
Baayan
chinese cabbage
5.09
Silt loam
+
62
Baayan
chinese cabbage
5.37
Silt loam
+
63
Leseb
cabbage
3.77
Silt loam
-
64
Leseb
cabage
4.39
Silt loam
-
65
Leseb
cabbage
4.69
Silt loam
-
66
Leseb
cabbage
4.64
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
29
Appendix Table 1a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Bauko, Mountain Province)
SOIL pH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
1
0
1
4 (4.00-4.99)
16
2
18
5 (5.00-5.99)
26
11
37
6 (6.00-6.99)
7
2
9
7 (7.00-7.99)
1
0
1
Total
51
15
66
Pearson chi2 (4) = 3.0056 Pr = 0.557; X2(.05,4)= 9.48
NS- not significant
Appendix Table 1b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Bauko, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
13
0
13
Silt loam
38
15
53
Total
51
15
66
Pearson chi2 (4) = 4.7614 Pr = 0.029; X2(.05,4)= 3.841
S-significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
30
Appendix Table 2. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Sabangan, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL PH
TEXTURE
OF EPNs
1
Sabangan
Zucini
3.49
Silt loam
+
2
Sabangan
Zucini
5.67
Silt loam
-
3
Capinitan
Cabbage
4.08
Silt loam
+
4
Capinitan
Cabbage
4.03
Silt loam
+
5
Capinitan
Cabbage
5.19
Silt loam
-
6
Busa Capinitan
Potato
5.10
Loam
-
7
Busa Capinitan
Broccoli
5.90
Silt loam
-
8
Busa Capinitan
Potato
5.10
Silt loam
+
9
Busa Capinitan
Broccoli
5.95
Silt loam
+
10
Busa Capinitan
Potato
5.45
Silt loam
-
11
Kamatagan
Beans
5.28
Loam
+
12
Kamatagan
Zucini
6.28
Loam
-
13
Pengew Sabangan Zucini
3.63
Silt loam
-
Appendix Table 2a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil Ph (Sabangan, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
1
1
2
4 (4.00-4.99)
0
2
2
5 (5.00-5.99)
5
3
8
6 (6.00-6.99)
1
0
1
Total
6
7
13
Pearson chi2 (4) = 3.4435 Pr = 0.328; X2(.05,3)= 7.815
NS- not significant
Appendix Table 2b. Pearson Chi-Square Test Analysis of independence for EPN
presence and soil texture (Sabangan, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
2
1
3
Silt loam
5
5
10
Total
7
6
13
Pearson chi2 (4) = 0.2579 Pr = 0.612; X2(.05,1)= 3.841
S-significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
31
Appendix Table 3. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Bontoc, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY CROP
SOIL pH
TEXTURE
OF EPNs
1
Lanao
Eggplant
5.66
Silt loam
-
2
Lanao
Onion
4.605
Sandy loam
-
3
Lanao
Tomato
4.935
Sandy loam
-
4
Lanao
Petchay
3.775
Sandy loam
-
5
Lanao
Camote
4.4
Silt loam
-
6
Lanao
Beans S
4.205
Silt loam
+
7
Lanao
Petchay
5.46
Sandy loam
-
8
Lanao
Petchay
5.195
Sandy loam
-
9
Lanao
Petchay
5.42
Sandy loam
-
10
Lanao
Petchay
4.15
Silt loam
-
11
Lanao
Camote
5.375
Sandy loam
-
12
Lanao
Beans
4.565
Sandy loam
-
13
Lanao
Banana
5.8
Sandy loam
+
Appendix Table 3a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Bontoc, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
1
0
1
4 (4.00-4.99)
5
1
6
5 (5.00-5.99)
5
1
6
Total
11
2
13
Pearson chi2 (4) = 0.1970 Pr = 0.906; X2(.05,2)= 5.991
NS- not significant
Appendix Table 3b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Bontoc, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
8
1
9
Silt loam
3
1
4
Total
11
2
13
Pearson chi2 (4) = 0.4104 Pr = 0.522; X2(.05,2)= 3.841
NS-not significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
32
Appendix Table 4. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Sagada, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL pH
TEXTURE
OF EPNs
1
Sagada
Cabbage
4.49
Silt loam
-
2
Sagada
Onion
5.15
Silt loam
-
3
Dugo Sagada
Banana
5.04
Silt loam
-
4
Batnong
Cabbage
4.68
Silt loam
-
5
Liang Sagada
Pepper
5.17
Silt loam
-
6
Liang Sagada
Pepper
4.96
Silt loam
+
7
Engan
Beans
4.17
Silt loam
-
8
Engan
Beans
4.58
Silt loam
-
9
Nalabasan Sagada
Cabbage
4.86
Loam
-
10
Nalabasan Sagada
Cabbage
4.80
Loam
-
11
Nalabasan Sagada
camote
4.59
Silt loam
-
12
Bayuan
Cabbage
3.90
Silt loam
-
13
Bayuan
Petchay
4.67
Silt loam
-
14
Bayuan
Cabbage
4.23
Silt loam
-
15
Bayuan
Cabbage
1.88
Silt loam
-
16
Malba,Bayuan
Pepper
4.84
Silt loam
-
17
Malba,Bayuan
Cabbage
4.14
Silt loam
-
18
Malba,Bayuan
Pepper
4.06
Silt loam
-
19
Tobeng
Cabbage
4.70
Silt loam
+
20
Tobeng tegyab
Cabbage
4.09
Silt loam
-
21
Madongo
Beans
4.03
Silt loam
+
22
Madongo
Beans
4.42
Silt loam
-
23
Madongo
Cabbage
4.45
Silt loam
-
24
Madongo
Beans
4.28
Silt loam
-
25
Madongo
Beans
4.34
Silt loam
-
26
Madongo
Cabbage
4.19
Silt loam
+
27
Madongo
Cabbage
4.33
Silt loam
-
28
Petaad Ambasing
Pepper
3.97
Silt loam
-
29
Petaad Ambasing
Strawberry
4.15
Silt loam
-
30
Petaad Ambasing
Strawberry
4.22
Silt loam
-
31
Petaad Ambasing
Strawberry
4.25
Silt loam
-
32
Legleg Ambasing
Tomato
5.37
Silt loam
-
33
Legleg Ambasing
Beans
3.94
Silt loam
-
34
Legleg Ambasing
Eggplant
4.24
Silt loam
-
35
Legleg Ambasing
Chinese cabbage
5.53
Loam
-
36
Legleg Ambasing
Pepper
4.41
Silt loam
-
37
Ambasing
Beans
4.25
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
33
Appendix Table 4a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Sagada, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
1 (1.00-1.99)
1
0
1
3 (3.00-3.99)
3
0
3
4 (4.00-4.99)
24
4
28
5 (5.00-5.99)
5
0
5
Total
33
4
37
Pearson chi2 (4) = 1.4416 Pr = 0.696; X2(.05, 3) = 7.815
S-significant
Appendix Table 4b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Sagada, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
3
0
3
Silt loam
30
4
34
Total
33
4
37
Pearson chi2 (4) = 0.3957 Pr = 0.529; X2(.05, 1) = 3.841
NS- not significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
34
Appendix Table 5. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Besao, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL pH
TEXTURE OF EPNS
1
Besao proper
Beans
6.43
Loam
-
2
Besao proper
Beans
5.14
Silt loam
-
3
Banao
Potato
4.97
Silt loam
-
4
Banao
Beans
4.51
Silt loam
-
5
Banao, site 3
Potato
5.48
Silt loam
-
6
Banao
Strawberry
4.15
Silt loam
-
7
Banao, site 3
Potato
4.84
Silt loam
+
8
Banao, site 3
Potato
5.00
Silt loam
-
9
Banao
Potato
5.44
Silt loam
-
10
Banao
Citrus
5.56
Loam
-
11
Banao, site 3
Potato
4.65
Silt loam
+
12
Banao, site 3
Potato
5.12
Silt loam
-
13
Banao, site 2
Potato
4.57
Silt loam
-
14
Banao, site 2
Cabbage
4.00
Silt loam
-
15
Banao, site 2
Potato
4.35
Silt loam
+
16
Banao, site 2
Potato
4.36
Silt loam
-
17
Banao, site 2
Potato
4.50
Silt loam
+
18
Banao, site 2
Cabbage
3.9
Silt loam
-
19
Banao, site 2
Potato
4.36
Silt loam
+
20
Banao, site 2
Cabbage
4.46
Silt loam
+
21
Banao, site 2
Cabbage
4.52
Silt loam
-
22
Banao, site 2
Cabbage
3.97
Silt loam
-
23
Banao, site 2
Cabbage
4.33
Silt loam
-
24
Banao
Potato
4.66
Silt loam
+
25
Banao, site 1
Cabbage
4.86
Silt loam
-
26
Banao, site 1
Petchay
5.71
Loam
+
27
Banao, site 1
Cabbage
4.99
Silt loam
-
28
Banao
Cabbage
5.61
Silt loam
-
29
Banao, site 1
Petchay
5.22
Silt loam
-
30
Amdakig, site 3 Cabbage
4.31
Silt loam
-
31
Amdakig, site 3 Potato
4.75
Silt loam
+
32
Amdakig, site 3 Cabbage
4.85
Silt loam
-
33
Banguitan
Beans
6.94
Loam
-
34
Banguitan
Garden pea
7.23
Loam
+
35
Suquib
Pepper
5.77
Silt loam
-
36
Suquib
Cabbage
5.03
Silt loam
-
37
Suquib
Pepper
5.36
Silt loam
-
38
Suquib
Pepper
5.70
Silt loam
-
39
Suquib
Petchay
4.48
Silt loam
+
40
Suquib
Camote
5.67
Silt loam
-
41
Suquib
Cabbage
4.68
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
35
Appendix Table 1. Continued…
SAMPLE
AVERAGE SOIL
PRESENCE
#
LOCALITY CROP
SOIL pH
TEXTURE
OF EPNs
42
Suquib
Cabbage
5.31
Silt loam
-
43
Suquib
Cabbage
4.73
Silt loam
-
44
Suquib
Cabbage
4.51
Silt loam
-
45
Suquib
Pepper
5.31
Silt loam
-
Appendix Table 5a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Besao, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
2
0
2
4 (4.00-4.99)
15
9
24
5 (5.00-5.99)
15
1
16
6 (6.00-6.99)
2
0
2
7 (7.00-7.99)
0
1
1
Total
11
15
45
Pearson chi2 (4) = 9.4677 Pr = 0.050; X2(.05,3)= 9.48
S-significant
Appendix Table 5b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Besao, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
3
2
5
Silt loam
31
9
40
Total
34
1
45
Pearson chi2 (4) = 0.7370 Pr = 0.391; X2(.05, 1) = 3.841
NS- not significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
36
Appendix Table 6. T-test for equivalence of EPN presence and soil ph
VARIABLE OBSER-
MEAN
STD.
STD.
95%
INTERVA
VATION
ERR
DEV.
CONF.
L
(-)
5
5.312
2.548094 5.69771 -1.762644 12.38664
2
(+)
5
4.522
2.190145 4.89731
1.558817
10.60282
3
Combined
10
4.917
1.589377 5.02605
1.32158
8.51242
Difference
0.789999 3.359988
-
8.568691
9
6988691
Diff=mean (epn_) – mean (epn) t=0.2351 t (.05, 8) = 1.860
Ho: diff=0 Satterthwaite’s degrees of freedom=7.82343
NS-Not significant
Appendix Table 7. T-test for equivalence of EPN presence and soil texture
VARIABLE OBSER- MEAN STD. STD.
95%
INTERVAL
VATIO
ERR
DEV.
CONF.
N
(-)
7
11.65286 8.502528 22.49557 -1.762644
12.38664
(+)
7
3.118572 2.747365 7.268844 -1.558817
10.60282
Combined
14
7.385714 4.452583 16.66004
1.32158
8.51242
Difference 8.53428
8.935378
-10.93
8.568691
6
Diff=mean (var2) – mean (var3) t=0.9551 t (.05, 12) = 1.782
Ho: ff=0 degrees of freedom=12
NS- Not significant
Appendix Table 8. T-test for equivalence of EPN presence and crops
VARIABLE OBSER-
MEAN
STD.
STD.
95%
INTERVA
VATIO
ERR
DEV.
CONF.
L
N
(-)
12
5.41
1.826214 6.326191
1.39053
9.42947
(+)
12
1.77
0.776657 2.690421 0.0605882
3.579412
6
Combined
24
3.59
1.042005 5.10476
1.434449
5.745551
Difference
3.64
1.984504
-
7.755609
0.4756086
Diff=mean (var2) – mean (var3) t=1.8342 t (05, 12) = 1.717
Significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
AMADO, MARY JEAN T. APRIL 2011. Distribution of Entomopathogenic Nematodes
(EPNs) in Vegetable and Strawberry Growing Areas in Mountain Province. Benguet State
University, La Trinidad, Benguet.
Adviser: Luciana M. Villanueva, PhD.
ABSTRACT
A survey was conducted in five vegetable and strawberry growing municipalities of Mt.
Province from January to March 2011 to determine the presence of entomopathogenic nematodes
(EPNs) and how they are affected by soil pH, texture and crops.
Result showed that 19 out of 32 sites were positive for EPNs. Sabangan showed the
highest recovery frequency of 46.15% followed by Besao and Bauko with 24.44% and 22.73%,
respectively. Bontoc with only one site has 15.38% recovery frequency while Sagada has the
least with 10.81%. Although soil pH and texture did not significantly affect the presence of
EPNs in 5 municipalities surveyed, it was noted that higher number of EPNs was detected in
areas with pH ranging from 4.00-5.99. The least number was collected in areas with soil pH
ranging from 3.00-3.99, 6.00-6.99, and 7.00-7.99. On the other hand, most of the positive
samples were collected in silt loam with 89.47% followed by loam with 7.89% and the least was
sandy loam soil with 2.63%. Conversely, the presence of EPNs was significantly influenced by
crops. The frequency of occurrence of EPNs was highest in soil samples from potato 42.86%
followed by cabbage and pepper, with 11.63% and 10%, respectively.
Results of the investigation indicate that the presence of EPNs is dependent on soil pH,
soil texture and crops planted. However, these findings need to be verified.
TABLE OF CONTENTS
Page
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .
i
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
REVIEW OF LETIRATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Life Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Mutualistic Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
Behavioral Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
Efficacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
MATERIALS AND METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
Geography and Collection of Soil Samples . . . . . . . . . . . . . . . . . . . . .
6
Isolation of EPNs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
Determination of Soil Ph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Soil Texture Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Data Gathered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
RESULTS AND DISCUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
Effect of Soil pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Effect of Soil Texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
Effect of Crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
SUMMARY, CONCLUSION AND RECOMMENDATION . . . . . . . . . . . .
22
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
1
INTRODUCTION
Nematodes are a diverse group of invertebrates abundant as parasites or free
living forms in soil, fresh water, and marine environments. Barker (1998) stated that there
are more than 15,000 described species that represent only a small portion of the total
members in Phylum Nematoda. The soil is particularly rich habitat for nematodes with
about 26% described genera inhabiting soil as bacterivores, fungivores, omnivores,
predators or plant parasites. Added to this are soil dwelling stages of insect parasites
referred to as entomopathogenic nematodes (EPNs) (Wharton, 1986).
Entomopathogenic nematode (EPNs) are extra ordinarily lethal to many important
soil insect pests, yet they are safe to plants and animals. Unlike chemicals, nematode
applications do not require mask or other safety equipment, re entry time, residues;
ground water contamination; chemical trespass and pollution are not issues. Thus
development of EPN technology will be a great help for researchers and vegetable
growers to produce good quality and safe food for consumers
Recognizing the hazards of pesticides to man and the environment, many
countries in the world is considering biological control agents such as entomopathogenic
nematodes (EPNs) as the best alternative to chemical control of plant diseases and pests
(Souto et al., 2004).
The study was conducted to determine the presence of entomopathogenic
nematodes (EPNs) in vegetable and strawberry growing areas in Mt. Province and how
they are affected with soil texture, pH and crops.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
2
REVIEW OF LITERATURE
Entomopathogenic nematodes have been known since the 17th century but it was
only in the 1930’s that serious consideration was given to using nematodes to control
insect (Nickle, 1984). This nematode has been found infecting grubs of the Japanese
beetle, Popilla japonica, at the Travis stock Golf course near Haddon field, New Jersey.
Entomopathogenic nematodes are adapted to most climatic conditions in hot,
temperate and cold zones, distributed from lowlands to high alpine altitudes. S.
carpocapsae and S.feltiae are widely distributed in temperate regions. H.bacteriphora is
common in regions with continental and Mediterranean climates, and H.indica is found
throughout much of the tropics and subtropics (Steiner, 1996).
Currently, there are two genera which contain the most important species of
entomopathogenic nematodes; Steinernema and Heterorhabditis (Lewis, 2000). Species
in these genera have a global distribution. They exhibit differences in host range,
infectivity and environmental tolerances (Hominick et al., 1996). Most entomopathogenic
nematodes described belong to the genus Steinernema, a total of 24 species have been
isolated, and four species have been commercialized; S.carpocapsae, S. feltiae,
S.riobravis and S.capterisci. Of the Heterorhabditis species H.bacteriophora and
H.megidis have been commercialized (Booth, 2000).
Life Cycle
Steinernematids are similar to heterorhabditids in general life cycle and gross
morphology (Wouts, 1984). The major difference between the two families is in the
reproductive strategies. Steinernematids are amphimictic, they require a male and female
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
3
infective juvenile to invade an insect host to produce progeny. In the case of
heterorhabditid, adults resulting from the infective juveniles are hermaphrodites;
therefore only one juvenile is needed to enter the host for progeny production (Hazir et
al., 2003).
The infective stage of entomopathogenic nematodes (third-stage dauer juveniles)
seeks and invades larvae of soil dwelling insect species (Klein, 1990). They enter the
insect host through natural body openings, the mouth, anus, or respiratory inlets
(spiracles) and then penetrate into the blood cavity from the gut (Poinar 1990).
Heterorhabditis penetrates through chinks in the insects interskeletal membranes by
scratching away with special tooth (Bedding and Molyneux, 1982). They release
bacterium through anus for steinernematids and through mouth by hetrorhabditids
(Poinar, 1966). The toxins produced by the developing nematodes (Burman, 1982) and
bacteria cause septicemia and kill the insect host within 24-48 hours after infection
(Akhurst and Boemere, 1990).
Insects use anti bacteial protiens and phagocytosis followed by nodule formation
to counteract the bacterial cells. It may also encapsulate nematodes followed by
melanization. However, in some cases, nematodes overcome the insect’s defense and
successfully infect its host. This is in relation to the nematodes surface coat proteins that
suppresses the host immune response (Wang, 1998). Moreover, the invading nematodes
immuno –inhibiting factors that destroy the antibacterial factors produced by the insect
and allow the mutualistic bacteria to produce insecticidal toxins that rapidly kill the host
(Bowen et al., 1998)
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
4
Mutualistic Bacteria
Steinernema and Heterorhabditis are associated with mutualistic bacteria
Xenorhabdus and Photorhabdus respectively. Xenorhabdus and Photorhabdus are motile
gram negative, facultative, none spore forming, anaerobic rods in the family
Enterobacteriaceae. These symbiotic bacteria are vectored in the insect’s hemocoel by the
nematode infective juvenile (Forst et al., 1996). The difference that occur between the 2
bacterial genera is, most Photorhabdus spp. are luminescent and catalase positive, where
as Xenorhabdus spp. have no luminescence and are catalase negative (Hazir et al., 2003)
Behavioral Ecology
EPNs employ different foraging strategies to locate and infect hosts. The
intermediate foraging strategist (S. riobrave and S.feltiae) infects insect that occur just
below the soil surface, such as prepupae of lepidopterous insects, fungus gnats, or weevil
larvae. The sit and wait strategist or ambushers (S. carpocapsae) are characterized by low
motility which search at or near the soil surface. They infect mobile host species such as
codling moth, cutworms and mole crickets. At the other extreme, foraging strategy or
cruiser (S. glaseri and H.bacteriophora) are characterized by high motility and are
distributed throughout the soil profile. They infect sedentary host such as scarab and
lepidopterous prepupae and pupae (Hazir et al., 2003).
Various biotic and abiotic factors can influence the successful use of
entomopathogenic nematodes as biological control agent. The persistence of EPNs in
natural areas depends on the dauer larvae’s ability to disperse and persist until it can
locate a suitable host. Extrinsic factors such as temperature, soil moisture, soil texture,
pH, and UV radiation affect their dispersal and persistence. Furtheremore, many soil
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
5
dwelling nematodes have evolved behaviors resulting in reduced host finding attachment
and penetration by infective juveniles. Some nematodes that have been isolated from host
cadavers in the field have restricted host range (e.g. S. kushidari and S.scarabaei are
adapted to scarab larvae (Stock and Koppenhoefer, 2003). S. scapteresci is adapted to
mole cricket and poorly infect other insects (Grewal, 1993). Among the biotic factors
(natural enemies) are bacteria, fungi, mites, predatory nematodes, tardigrades and
collembolans. Mites appear to be especially voracious nematode feeders (Walter, 1987).
Efficacy
Several studies have shown effectiveness of entomopathogenic nematodes in
recent years. EPNs have been applied successfully against soil inhabiting insects (as soil
application) as well as above-ground insects (foliar spray) in cryptic habitat (Shapiro -
Ilan et al., 2006.) In a golf course ecosystem, the application of Heterorhabditis
bacteroiphora, an introduced nematode, significantly reduced the abundance, species
richness, maturity and diversity of the nematode community (Somaseker et al., 2002).
Further laboratory test showed that S. carpocapsae alone infected more than 250 insect
species from over 75 families in 11 0rders (Poinar, 1983).
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
6
MATERIALS AND METHODS
Soil samples were collected from strawberry and vegetable growing areas in Mt.
Province and further laboratory study was done at STVRDC laboratory, Benguet State
University La Trinidad, Benguet from January to April 2011.
A. Geography and Collection of Soil Samples
Mt. Province is known to be the Philippines biggest and highest chain of
mountains. The province is bounded on the north by Kalinga, on the south by Benguet
and Ifugao, on the east by Isabela, and on the west by Ilocos sur and Abra. Mt. Province
is politically subdivided into 10 municipalities and 144 barangays. It has a total land area
of 209,733 hectares, 23% is classified as alienable and disposable, and 77% as forest
lands. Mt. Province is characterized by towering peaks and sharp ridges on its central and
western part while the eastern portion features gently sloping and rolling foothills. The
Province falls on type III climate category that is characterized by uneven distribution of
rains throughout the year and this cover the eastern part of the province.
A survey was undertaken from February to March 2011 to assess the distribution
of EPNs in vegetable and strawberry growing areas in Bauko, Sabangan, Bontoc, Besao,
and Sagada, Mt. Province.
Soil samples were collected from nine (9) vegetable sampling sites in Bauko, five
in Sabangan, one in Bontoc, twelve in Sagada and nine in Besao (Figures 1- 5), A total
of 174 samples were collected from the 5 municipalities. About 0.5 kg comprising five to
10 sub-samples were collected randomly per area. The samples were placed on properly
labeled plastic bags and were brought to the laboratory for nematode isolation.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
7
A
A
B
C
D
D
Figure 1. Sampling sites in Bauko, Mt. Province: (A) Buga, Mt. Data, (B) Sintu proper, (C)
Sintu, (D) Monamon
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
8
A
B
Figure 2. Sampling sites in Sabangan, Mt. Province: (A) Pengew, (B) Capinitan
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
9
A
B
Figure 3. Sampling sites in Lanao, Bontoc, Mt. Province: (A) site 1, (B) site 2
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
10
A
A
B
B
C
D
Figure 4. Sampling sites in Sagada, Mt. Province: (A) Nalabasan, Poblacion, (B)
Madongo, (C) Petaad, Ambasing, (D) Legleg, Ambasing
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
11
A
A
B
B
C
D
Figure 5. Sampling sites in Besao, Mt. Province: (A) Amdakig, (B) Banao, (C) Lake
Danum, (D) Suquib
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
12
B. Isolation of EPNs
Entomopathogenic nematodes (EPNs) were isolated from soil by using lesser wax
moth, Achroia grisella larvae as bait (Figure 6). About 250 g of soil was placed in each
improvised baiting container. To provide aeration and at the same time prevent the escape
of wax moth larvae, wire mesh was provided in the plastic cover of the baiting container
(Figure 7). Around 10 larvae were placed per container to serve as bait for the nematodes.
After 2-3 days, the larval cadavers were retrieved from the soil and washed with distilled
water and arranged in a petri plate lined with moist filter paper. The infected insect was
examined under a dissecting microscope for the presence of EPNs.
Figure 6. Lesser wax moth (Achroia
Figure 7. Plastic containers with soil
grisella) larvae used as bait
samples collected from
different municipalities in
Mt. Mountain Province
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
13
D. Determination of soil pH
About 30 g of soil samples were air dried in the laboratory for 3 days. Grinding of
soil samples was done using mortar and pestle prior to pH determination which was done
after calibrating the pH meter (Figure 8).
Figure 8. Determination of soil pH using a pH meter
E. Soil texture classification
Following the procedure of Robinson (2005), soil classification was done. About
50 cc of soil taken from samples collected was moistened with 10 ml water to determine
if it will form a ball (Figure 8). The soil was squeezed in the palm of the hand and
depending on the form that it would create; soil texture was determined.
Sand- Soil either does not form a ball or forms a ball but easily breaks when
bounced at the palm.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
14
Loam- Soil can be formed into a ball and a ribbon less than 2.5 cm.
Clay- Soil can be formed into a ball and a ribbon more than 2.5 cm.
Data Gathered
1. Presence of EPNs
2. Soil pH
3. Soil Texture
Figure 9. Classification of soil texture by feel method
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
P = 0.029
15
RESULTS AND DISCUSSION
Table 1 shows the abundance and recovery frequency of EPNs in vegetable and
strawberry growing areas in Mt. Province. EPNs were recovered from 38 samples out of
174 soil samples collected (21.84%) and 19 positive sites out of 32 sites sampled
(59.38%). Although not significantly different, the highest recovery was recorded in
Sabangan, followed by Besao, Bauko, Bontoc, and Sagada with 46.15, 24.44, 22.73,
15.38 and 10.81%, respectively. In terms of EPN abundance, Bontoc with only 1 site that
grows vegetables gave 100% followed by Besao (85.71%), Sabangan (80.00%), Bauko
(62.50%) and Sagada (27.27%).
Effect of Soil pH
The effect of soil pH on the recovery frequency of EPNs in five municipalities of
Mt. Province is shown in Table 2. Although not significantly different as shown by
Pearson’s chi-square test, most of the EPNs were recovered from pH-4.00-5.99. This is
true in all the municipalities surveyed. In very acidic soil (pH 3.00-3.99), EPNs were
only detected in Sabangan, while at pH range of 6.00-6.99, they were found only in
Bauko. In highly alkaline soil (7.00-7.99), the EPNs were only recovered in Besao.
Results of the study confirmed the findings of Rosa et al., (2000) that most of the EPNs
were recovered from soil with pH below 6.00. On the other hand, according to Herrera et
al (2007) soil pH does not significantly affect occurrence of EPNs although they are
easily isolated from pH range of 5.01 to 8.0.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
16
Table 1. Abundance and recovery frequency of entomopathogenic nematodes (EPNs) in
strawberry and vegetable growing areas/municipalities in Mountain Province
TOTAL
POSITIV
NO. OF
ABUN-
SOIL
E SOIL
RECOVERY
MUNICI-
TOTAL POSITIV DANCE SAMPLE SAMPLE
FREQUENC
PALITIES SITES
E SITES
(%)a
S
S
Y (%)b
Sabangan
5
4
80.00
13
6
46.15
Bauko
8
5
62.50
66
15
22.73
Bontoc
1
1
100.00
13
2
15.38
Sagada
11
3
27.27
37
4
10.81
Besao
7
6
85.71
45
11
24.44
GRAND
TOTAL
32
19
59.38
174
38
21.84
a (Number of positive sites/ number of total sites) x 100
b (Number of positive samples /number of total samples) x 100
Table 2. Recovery frequency (%) of positive soil samples for EPN by soil pH in
vegetable and strawberry growing areas in Mt. Province per municipality
MUNICIPALITIES
pH RANGE
Sabangan
Bauko
Bontoc
Sagada
Besao
3.00 - 3.99
6.69
-
-
-
-
4.00 - 4.99
15.38
3.03
7.69
10.81
20.00
5.00 - 5.99
23.07
16.66
7.69
-
2.00
6.00 - 6.99
-
3.03
-
-
-
7.00 - 7.99
-
-
-
-
1.00
Total No. of Samples
13
66
13
45
37
Positive Soil Samples (%)
46.15
22.72
15.38
24.44
10.81
Effect of Soil Texture
The effect of soil texture on the incidence of EPNs by municipality is shown in
Table 3. Statistical analysis showed that except for Bauko (P=0.029), the presence of
EPN was not significantly affected by soil texture. However, in most of the
municipalities surveyed, the EPNs were mostly detected from silt loam and loam except
for EPNs collected from Bontoc which were recovered from sandy loam soil.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
17
Regardless of municipality, soil texture has no significant effect on the occurrence
of EPNs (Table 4). However, most of the positive samples were noted from silt loam
followed by loam and sandy loam with 89.47, 7.89 and 2.63 % recovery frequency,
respectively.
Our results are similar to the findings of Mracek et al., (2004) and Rosa et al.,
(2000) that EPNs were mostly recovered from light soils such as silt loam and sandy
loam except for S. kraussei which can tolerate both silt/clay organic soils. According to
Mraceket et al., (2005) heavy soils decrease the nematode mobility which could be the
reason why no EPNs were recovered from clay loam to heavy clay in all the sampling
sites (Figure 10).
Table 3. Number and recovery frequency (%) of positive soil samples collected from
vegetable and strawberry growing areas in Mt. Province as influenced by soil
texture
NUMBER OF POSITIVE
RECOVERY
SOIL TEXTURE
SOIL SAMPLES
FREQUENCY*
Sand
-
-
Sandy loam
1
2.63
Silt loam
34
89.47
Loam
3
7.89
Clay loam
-
-
Light clay
-
-
Heavy clay
-
-
GRAND TOTAL
38
100
* (number of positive soil samples/ total number of positive soil samples) x 100
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
18
Sabangan
Bauko
20
) 20
) 15
15
10
10
5
5
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
0
R
e
c
o
v
e
r
y
f
r
e
q
e
n
c
y
(
%
Sand Loamy Silt Loam
Clay Light Heavy
Sand Loamy Silt Loam Clay Light Heavy
sand loam
loam
clay
clay
sand loam
loam
clay
clay
Soil texture
Soil texture
Bontoc
) 20
15
10
5
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Sand Loamy Silt
Loam
Clay Light Heavy
sand
loam
loam
clay
clay
Soil texture
Sagada
Besao
)20
) 20
15
15
10
10
5
5
0
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Sand Loamy Silt
Loam
Clay
Light Heavy
sand
loam
loam
clay
clay
Sand Loamy Silt Loam Clay Light Heavy
sand loam
loam
clay
clay
Soil texture
Soil texture
Figure 10. Influence of soil texture on the distribution of positive samples in vegetable
and strawberry growing areas in Mt. Province (a) Sabangan, (b) Bauko, (c)
Bontoc, (d) Sagada and (e) Besao
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
19
Table 4. Recovery frequency (%) of positive soil samples for EPNs in vegetable and
strawberry growing areas in Mt. Province per municipality as influenced by soil
texture
MUNICIPALITIES
SOIL TEXTURE
Sabangan
Bauko
Bontoc
Sagada
Besao
Sand
-
-
-
-
-
Sandy loam
-
-
2.63
-
-
Silt loam
13.16
39.47
2.63
10.53
23.68
Loam
2.63
-
-
-
5.26
Clay loam
-
-
-
-
-
Light clay
-
-
-
-
-
Heavy clay
-
-
-
-
-
Total No. of Samples
6
15
2
4
11
Recovery Frequency (%)
15.79
39.47
5.26
10.53
28.95
Effect of Crops
Figure 11 shows the effect of crops on the recovery frequency of EPNs in
different municipalities of Mt. Province. Apparently, crops did not significantly influence
the recovery frequency of EPNs in Sabangan. However, in Bauko, significantly higher
EPN recovery was recorded in potato, followed by garden pea and cabbage. In Bontoc,
EPNs were only detected in beans and banana while in Sagada they were detected only in
cabbage, beans and pepper. Similar to Bauko, the highest recovery of EPNs in Besao was
recorded in potato, followed by pechay, cabbage and corn. Surprisingly, no EPN was
recovered in strawberry areas in Sagada and Besao. This could be due to the fact that
strawberry was newly introduced in these two municipalities and therefore the population
of insect pests associated with strawberry which are the hosts of EPNs is still very low.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
20
Sabangan
Bauko
)
) 20
(
% 20
15
15
10
f
r
e
q
u
e
n
c
y
10
5
5
R
e
c
o
v
e
r
f
r
e
q
u
e
n
c
y
(
%
R
e
c
o
v
e
r
y
0
0
Crops
Crops
)
20
Bontoc
15
10
5
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Crops
Sagada
)
Besao
) 20
20
18
15
16
14
12
10
108
5
6
4
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
2
0
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Crops
Crops
Figure 11. Recovery frequency of positive samples for EPN by crops in vegetable and
strawberry growing areas in Mt. Province, (a) Sabangan, (b) Bauko, (c)
Bontoc, (d) Sagada and (e) Besao
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
21
On the other hand, regardless of municipality, positive samples for EPNs were
significantly affected by crops (Figure 12). The highest recovery frequency was obtained
from potato with 47.37%, followed by cabbage (13.16 %), garden pea and beans
(7.89%), chinese cabbage and pechay (5.26 %), and carrots, banana, peper, zuccini, and
broccoli (2.63 %). According to Garcia del Pino and Palomo (1996a) and Mracek and
Webster (1993) habitat preference is related to insect host distribution. Since farmers
have been planting potato,cabbage garden pea and beans for quite a long time , the insect
pests associated with these crops have already increased their populations ; thus favoring
the growth and development of their associated EPNs .
50
) 40
30
20
10
R
e
c
o
v
e
r
y
f
r
e
q
u
e
n
c
y
(
%
0
Crops
Figure 12. Recovery frequency (%) of positive soil samples for EPNs as
influenced by crops
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
22
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary
A survey was conducted in five vegetable and strawberry growing municipalities
of Mt. Province from January to March 2011 to determine the distribution of
entomopathogenic nematodes (EPNs) and how they are influenced by soil pH, texture
and vegetation. Soil samples were brought to the STVRDC Laboratory, Benguet State
University, La Trinidad, Benguet for nematode and soil analyses.
EPNs were recovered from 38 samples out of 174 soil samples collected
(21.84%) and 19 out of 32 sites sampled (59.38%). Although not significantly different,
the highest recovery frequency was recorded in Sabangan followed by Besao, Bauko,
Bontoc and Sagada with 46.15%, 24.44%, 22.73%, 15.38% and 10.81%, respectively.
Regardless of municipality, most of the EPNs were detected in pH ranging from
4.00- 5.99. On the other hand, higher number of positive samples were collected from
silt loam (89.47%), followed by loam (7.89%) and sandy loam (2.63%) soil. No EPNs
were recovered from clay loam, light clay and heavy clay loam.
The presence of EPNs was also influenced by crops. The highest recovery was
obtained from potato with 47.37% followed by cabbage (13.16%), garden pa and beans
(7.89%), Chinese cabbage and pechay (5.26), and carrots, banana, pepper, zucchini and
broccoli (2.63%).
The present study reported for the first time the occurrence of EPNs in Mt.
Province.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
23
Conclusion
Results of the investigation showed that soil pH, soil texture and crops
influenced the recovery frequency of EPNs. Slightly acidic and silty loam soil favored the
growth and development of most vegetables including potato. Higher recovery frequency
of EPNs in the above mentioned pH range and soil texture could also be related to the
insect or nematode populations feeding on these crops which serve as host for EPNs.
Recommendation
Additional surveys are recommended taking into account other factors like soil
moisture, temperature, season including altitude.
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
24
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Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
27
APPENDICES
Appendix Table 1. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Bauko, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL pH
TEXTURE
OF EPNs
1
Monamon
radish
4.67
Silt loam
-
2
Monamon
carrots
5.69
Silt loam
-
3
Monamon
radish
4.94
Silt loam
-
4
Monamon
potato
4.77
Silt loam
-
5
Monamon
carrot
5.51
Silt loam
+
6
Monamon
radish
5.95
Silt loam
-
7
Monamon
radish
6.79
Loam
-
8
Monamon
carrots
4.84
Loam
-
9
Monamon
potato
5.34
Silt loam
+
10
Monamon
potato
5.66
Silt loam
+
11
Monamon, site 1 potato
5.34
Silt loam
+
12
Monamon
cabbage
5.91
Silt loam
-
13
Monamon
radish
5.31
Loam
-
14
Monamon
cabbage
5.56
Loam
-
15
Monamon
radish
6.69
Loam
-
16
Monamon
potato
5.13
Silt loam
-
17
Monamon
potato
5.76
Silt loam
-
18
Monamon
potato
5.5
Silt loam
+
19
Monamon
potato
5.45
Silt loam
+
20
Monamon
potato
5.66
Silt loam
-
21
Sinto
cabbage
6.26
Silt loam
-
22
Sinto
cabbage
6.07
Silt loam
+
23
Sinto
garden pea
5.48
Silt loam
-
24
Sinto
garden pea
6.41
Silt loam
+
25
Sinto Proper
garden pea
4.71
Silt loam
+
26
Sinto proper
potato
5.56
Loam
-
27
Sinto proper
potato
6.00
Silt loam
-
28
Sinto Proper
potato
5.67
Silt loam
+
29
Sinto Proper
potato
5.96
Silt loam
-
30
Sinto Proper
potato
5.94
Silt loam
-
31
Sinto proper
potato
5.83
Silt loam
+
32
Sinto proper
cabbage
6.02
Silt loam
-
33
Sinto proper
cabbage
5.93
Loam
-
34
Buga Sinto
potato
4.47
Silt loam
+
35
Buga Sinto
potato
5.84
Silt loam
-
36
Buga Sinto
potato
5.49
Silt loam
+
37
Buga Sinto
corn
7.02
Silt loam
-
38
Buga Sinto
potato
5.89
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
28
Appendix Table 1. Continued…
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY CROP
SOIL pH
TEXTURE
OF EPNs
39
Sadsadan
beans
5.36
Silt loam
-
40
Sadsadan
beans
4.37
Loam
-
41
Sadsadan
beans
6.02
Silt loam
-
42
Sadsadan
potato
5.24
Silt loam
-
43
Sadsadan
garden pea
6.26
Silt loam
-
44
Sadsadan
potato
5.08
Silt loam
-
45
Sadsadan
potato
4.79
Silt loam
-
46
Sadsadan
potato
4.86
Silt loam
-
47
Sadsadan
cabbage
5.05
Silt loam
-
48
Mabaay
garden pea
4.66
Silt loam
-
49
Mabaay
garden pea
4.78
Loam
-
50
Mabaay
potato
5.48
Loam
-
51
Mabaay
camote
5.70
Silt loam
-
52
Mabaay
garden pea
4.59
Silt loam
-
53
Mabaay
garden pea
4.83
Loam
-
54
Mabaay
carrots
5.73
Silt loam
-
55
Mabaay
camote
5.49
Silt loam
-
56
Mabaay
carrots
5.52
Silt loam
-
57
Mabaay
camote
5.63
Silt loam
-
58
Mabaay
garden pea
4.84
Loam
-
59
Mabaay
garden pea
4.68
Silt loam
-
60
Mabaay
garden pea
5.42
Silt loam
-
61
Baayan
chinese cabbage
5.09
Silt loam
+
62
Baayan
chinese cabbage
5.37
Silt loam
+
63
Leseb
cabbage
3.77
Silt loam
-
64
Leseb
cabage
4.39
Silt loam
-
65
Leseb
cabbage
4.69
Silt loam
-
66
Leseb
cabbage
4.64
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
29
Appendix Table 1a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Bauko, Mountain Province)
SOIL pH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
1
0
1
4 (4.00-4.99)
16
2
18
5 (5.00-5.99)
26
11
37
6 (6.00-6.99)
7
2
9
7 (7.00-7.99)
1
0
1
Total
51
15
66
Pearson chi2 (4) = 3.0056 Pr = 0.557; X2(.05,4)= 9.48
NS- not significant
Appendix Table 1b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Bauko, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
13
0
13
Silt loam
38
15
53
Total
51
15
66
Pearson chi2 (4) = 4.7614 Pr = 0.029; X2(.05,4)= 3.841
S-significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
30
Appendix Table 2. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Sabangan, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL PH
TEXTURE
OF EPNs
1
Sabangan
Zucini
3.49
Silt loam
+
2
Sabangan
Zucini
5.67
Silt loam
-
3
Capinitan
Cabbage
4.08
Silt loam
+
4
Capinitan
Cabbage
4.03
Silt loam
+
5
Capinitan
Cabbage
5.19
Silt loam
-
6
Busa Capinitan
Potato
5.10
Loam
-
7
Busa Capinitan
Broccoli
5.90
Silt loam
-
8
Busa Capinitan
Potato
5.10
Silt loam
+
9
Busa Capinitan
Broccoli
5.95
Silt loam
+
10
Busa Capinitan
Potato
5.45
Silt loam
-
11
Kamatagan
Beans
5.28
Loam
+
12
Kamatagan
Zucini
6.28
Loam
-
13
Pengew Sabangan Zucini
3.63
Silt loam
-
Appendix Table 2a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil Ph (Sabangan, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
1
1
2
4 (4.00-4.99)
0
2
2
5 (5.00-5.99)
5
3
8
6 (6.00-6.99)
1
0
1
Total
6
7
13
Pearson chi2 (4) = 3.4435 Pr = 0.328; X2(.05,3)= 7.815
NS- not significant
Appendix Table 2b. Pearson Chi-Square Test Analysis of independence for EPN
presence and soil texture (Sabangan, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
2
1
3
Silt loam
5
5
10
Total
7
6
13
Pearson chi2 (4) = 0.2579 Pr = 0.612; X2(.05,1)= 3.841
S-significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
31
Appendix Table 3. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Bontoc, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY CROP
SOIL pH
TEXTURE
OF EPNs
1
Lanao
Eggplant
5.66
Silt loam
-
2
Lanao
Onion
4.605
Sandy loam
-
3
Lanao
Tomato
4.935
Sandy loam
-
4
Lanao
Petchay
3.775
Sandy loam
-
5
Lanao
Camote
4.4
Silt loam
-
6
Lanao
Beans S
4.205
Silt loam
+
7
Lanao
Petchay
5.46
Sandy loam
-
8
Lanao
Petchay
5.195
Sandy loam
-
9
Lanao
Petchay
5.42
Sandy loam
-
10
Lanao
Petchay
4.15
Silt loam
-
11
Lanao
Camote
5.375
Sandy loam
-
12
Lanao
Beans
4.565
Sandy loam
-
13
Lanao
Banana
5.8
Sandy loam
+
Appendix Table 3a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Bontoc, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
1
0
1
4 (4.00-4.99)
5
1
6
5 (5.00-5.99)
5
1
6
Total
11
2
13
Pearson chi2 (4) = 0.1970 Pr = 0.906; X2(.05,2)= 5.991
NS- not significant
Appendix Table 3b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Bontoc, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
8
1
9
Silt loam
3
1
4
Total
11
2
13
Pearson chi2 (4) = 0.4104 Pr = 0.522; X2(.05,2)= 3.841
NS-not significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
32
Appendix Table 4. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Sagada, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL pH
TEXTURE
OF EPNs
1
Sagada
Cabbage
4.49
Silt loam
-
2
Sagada
Onion
5.15
Silt loam
-
3
Dugo Sagada
Banana
5.04
Silt loam
-
4
Batnong
Cabbage
4.68
Silt loam
-
5
Liang Sagada
Pepper
5.17
Silt loam
-
6
Liang Sagada
Pepper
4.96
Silt loam
+
7
Engan
Beans
4.17
Silt loam
-
8
Engan
Beans
4.58
Silt loam
-
9
Nalabasan Sagada
Cabbage
4.86
Loam
-
10
Nalabasan Sagada
Cabbage
4.80
Loam
-
11
Nalabasan Sagada
camote
4.59
Silt loam
-
12
Bayuan
Cabbage
3.90
Silt loam
-
13
Bayuan
Petchay
4.67
Silt loam
-
14
Bayuan
Cabbage
4.23
Silt loam
-
15
Bayuan
Cabbage
1.88
Silt loam
-
16
Malba,Bayuan
Pepper
4.84
Silt loam
-
17
Malba,Bayuan
Cabbage
4.14
Silt loam
-
18
Malba,Bayuan
Pepper
4.06
Silt loam
-
19
Tobeng
Cabbage
4.70
Silt loam
+
20
Tobeng tegyab
Cabbage
4.09
Silt loam
-
21
Madongo
Beans
4.03
Silt loam
+
22
Madongo
Beans
4.42
Silt loam
-
23
Madongo
Cabbage
4.45
Silt loam
-
24
Madongo
Beans
4.28
Silt loam
-
25
Madongo
Beans
4.34
Silt loam
-
26
Madongo
Cabbage
4.19
Silt loam
+
27
Madongo
Cabbage
4.33
Silt loam
-
28
Petaad Ambasing
Pepper
3.97
Silt loam
-
29
Petaad Ambasing
Strawberry
4.15
Silt loam
-
30
Petaad Ambasing
Strawberry
4.22
Silt loam
-
31
Petaad Ambasing
Strawberry
4.25
Silt loam
-
32
Legleg Ambasing
Tomato
5.37
Silt loam
-
33
Legleg Ambasing
Beans
3.94
Silt loam
-
34
Legleg Ambasing
Eggplant
4.24
Silt loam
-
35
Legleg Ambasing
Chinese cabbage
5.53
Loam
-
36
Legleg Ambasing
Pepper
4.41
Silt loam
-
37
Ambasing
Beans
4.25
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
33
Appendix Table 4a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Sagada, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
1 (1.00-1.99)
1
0
1
3 (3.00-3.99)
3
0
3
4 (4.00-4.99)
24
4
28
5 (5.00-5.99)
5
0
5
Total
33
4
37
Pearson chi2 (4) = 1.4416 Pr = 0.696; X2(.05, 3) = 7.815
S-significant
Appendix Table 4b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Sagada, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
3
0
3
Silt loam
30
4
34
Total
33
4
37
Pearson chi2 (4) = 0.3957 Pr = 0.529; X2(.05, 1) = 3.841
NS- not significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
34
Appendix Table 5. Locality, crop, pH, soil texture and presence of EPN in soil samples
collected from Besao, Mountain Province
SAMPLE
AVERAGE
SOIL
PRESENCE
#
LOCALITY
CROP
SOIL pH
TEXTURE OF EPNS
1
Besao proper
Beans
6.43
Loam
-
2
Besao proper
Beans
5.14
Silt loam
-
3
Banao
Potato
4.97
Silt loam
-
4
Banao
Beans
4.51
Silt loam
-
5
Banao, site 3
Potato
5.48
Silt loam
-
6
Banao
Strawberry
4.15
Silt loam
-
7
Banao, site 3
Potato
4.84
Silt loam
+
8
Banao, site 3
Potato
5.00
Silt loam
-
9
Banao
Potato
5.44
Silt loam
-
10
Banao
Citrus
5.56
Loam
-
11
Banao, site 3
Potato
4.65
Silt loam
+
12
Banao, site 3
Potato
5.12
Silt loam
-
13
Banao, site 2
Potato
4.57
Silt loam
-
14
Banao, site 2
Cabbage
4.00
Silt loam
-
15
Banao, site 2
Potato
4.35
Silt loam
+
16
Banao, site 2
Potato
4.36
Silt loam
-
17
Banao, site 2
Potato
4.50
Silt loam
+
18
Banao, site 2
Cabbage
3.9
Silt loam
-
19
Banao, site 2
Potato
4.36
Silt loam
+
20
Banao, site 2
Cabbage
4.46
Silt loam
+
21
Banao, site 2
Cabbage
4.52
Silt loam
-
22
Banao, site 2
Cabbage
3.97
Silt loam
-
23
Banao, site 2
Cabbage
4.33
Silt loam
-
24
Banao
Potato
4.66
Silt loam
+
25
Banao, site 1
Cabbage
4.86
Silt loam
-
26
Banao, site 1
Petchay
5.71
Loam
+
27
Banao, site 1
Cabbage
4.99
Silt loam
-
28
Banao
Cabbage
5.61
Silt loam
-
29
Banao, site 1
Petchay
5.22
Silt loam
-
30
Amdakig, site 3 Cabbage
4.31
Silt loam
-
31
Amdakig, site 3 Potato
4.75
Silt loam
+
32
Amdakig, site 3 Cabbage
4.85
Silt loam
-
33
Banguitan
Beans
6.94
Loam
-
34
Banguitan
Garden pea
7.23
Loam
+
35
Suquib
Pepper
5.77
Silt loam
-
36
Suquib
Cabbage
5.03
Silt loam
-
37
Suquib
Pepper
5.36
Silt loam
-
38
Suquib
Pepper
5.70
Silt loam
-
39
Suquib
Petchay
4.48
Silt loam
+
40
Suquib
Camote
5.67
Silt loam
-
41
Suquib
Cabbage
4.68
Silt loam
-
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
35
Appendix Table 1. Continued…
SAMPLE
AVERAGE SOIL
PRESENCE
#
LOCALITY CROP
SOIL pH
TEXTURE
OF EPNs
42
Suquib
Cabbage
5.31
Silt loam
-
43
Suquib
Cabbage
4.73
Silt loam
-
44
Suquib
Cabbage
4.51
Silt loam
-
45
Suquib
Pepper
5.31
Silt loam
-
Appendix Table 5a. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil pH (Besao, Mountain Province)
SOIL PH
PRESENCE OF EPNs
TOTAL
(-)
(+)
3 (3.00-3.99)
2
0
2
4 (4.00-4.99)
15
9
24
5 (5.00-5.99)
15
1
16
6 (6.00-6.99)
2
0
2
7 (7.00-7.99)
0
1
1
Total
11
15
45
Pearson chi2 (4) = 9.4677 Pr = 0.050; X2(.05,3)= 9.48
S-significant
Appendix Table 5b. Pearson Chi-Square Test Analysis of Independence for EPN
presence and soil texture (Besao, Mountain Province)
SOIL TEXTURE
PRESENCE OF EPNs
TOTAL
(-)
(+)
Loam
3
2
5
Silt loam
31
9
40
Total
34
1
45
Pearson chi2 (4) = 0.7370 Pr = 0.391; X2(.05, 1) = 3.841
NS- not significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
36
Appendix Table 6. T-test for equivalence of EPN presence and soil ph
VARIABLE OBSER-
MEAN
STD.
STD.
95%
INTERVA
VATION
ERR
DEV.
CONF.
L
(-)
5
5.312
2.548094 5.69771 -1.762644 12.38664
2
(+)
5
4.522
2.190145 4.89731
1.558817
10.60282
3
Combined
10
4.917
1.589377 5.02605
1.32158
8.51242
Difference
0.789999 3.359988
-
8.568691
9
6988691
Diff=mean (epn_) – mean (epn) t=0.2351 t (.05, 8) = 1.860
Ho: diff=0 Satterthwaite’s degrees of freedom=7.82343
NS-Not significant
Appendix Table 7. T-test for equivalence of EPN presence and soil texture
VARIABLE OBSER- MEAN STD. STD.
95%
INTERVAL
VATIO
ERR
DEV.
CONF.
N
(-)
7
11.65286 8.502528 22.49557 -1.762644
12.38664
(+)
7
3.118572 2.747365 7.268844 -1.558817
10.60282
Combined
14
7.385714 4.452583 16.66004
1.32158
8.51242
Difference 8.53428
8.935378
-10.93
8.568691
6
Diff=mean (var2) – mean (var3) t=0.9551 t (.05, 12) = 1.782
Ho: ff=0 degrees of freedom=12
NS- Not significant
Appendix Table 8. T-test for equivalence of EPN presence and crops
VARIABLE OBSER-
MEAN
STD.
STD.
95%
INTERVA
VATIO
ERR
DEV.
CONF.
L
N
(-)
12
5.41
1.826214 6.326191
1.39053
9.42947
(+)
12
1.77
0.776657 2.690421 0.0605882
3.579412
6
Combined
24
3.59
1.042005 5.10476
1.434449
5.745551
Difference
3.64
1.984504
-
7.755609
0.4756086
Diff=mean (var2) – mean (var3) t=1.8342 t (05, 12) = 1.717
Significant
Distribution of Entomopathogenic Nematodes (EPNs) in Vegetable and Strawberry
Growing Areas in Mountain Province. AMADO, MARY JEAN T. APRIL 2011
Document Outline
- Distribution of Entomopathogenic Nematodes(EPNs) in Vegetable and Strawberry Growing Areas in Mountain Province
- BIBLIOGRAPHY
- TABLE OF CONTENTS
- INTRODUCTION
- REVIEW OF LITERATURE
- MATERIALS AND METHODS
- RESULTS AND DISCUSSION
- SUMMARY, CONCLUSION AND RECOMMENDATION
- LITERATURE CITED
- APPENDICES