BIBLIOGRAPHY PERALTA, JEAN SALVATERA. APRIL...
BIBLIOGRAPHY
PERALTA, JEAN SALVATERA. APRIL 2007. Seasonal Abundance and Natural
Enemy of Bemesia tabaci Gennadius (Hemiptera : Aleyrodidae). Benguet State University, La
Trinidad, Benguet.
Adviser: Bonie S. Ligat Sr., MSc
ABSTRACT
The study was conducted at the Balili Experimental Area and Swamp Area, La Trinidad,
Benguet from July 2006 to January 2007 to monitor the population of Bemesia tabaci Gennadius
during the wet and dry season, to determine the effect of rainfall, relative humidity, and
temperature on the population of B. tabaci, to know the natural enemies of B. tabaci, and to
know the host plants of B. tabaci.
Population of Bemesia tabaci Gennadius during the wet season was lower than during the
dry season. The population of the adult during wet season was 124 and 542 during dry season.
The nymph was 125 during wet season and 361 during dry season. The population of pupae
during wet season was 92 and 270 during dry season.
A unit rise on the intensity of rain, the average population of adult B. tabaci was reduced
to 4.08, 2.64 for the nymph and 1.74 for the pupae. Likewise, a unit increase in temperature
increased the average population of the adult by 6.55, 3.99 for the nymph and 2.97 for the pupae.
The natural enemy of B. tabaci was the predatory mites, Amblyseious sp.
The host plants of B. tabaci were Brassica oleracea, Brassica sinensis, Phaseolus
vulgaris, Apium graveolens, Pisum sativum, Capsicum annum L., Lycopersicon esculentum,
Smalanthus sonchifolius, Helianthus anus Linn., genus Fragaria, Nicotiana tabacum, Rorippa
indica L., Cardimine hirsute L., Solanum nigrum L., Cuphea carthaginensis Jacquin, Galinsoga
parviflora Cav., genus Chrysanthemum.
TABLE OF CONTENTS
Page
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
RESULTS AND DISCUSSION
Population of Bemesia tabaci Gennadius
during the Wet and Dry Season. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
Relationship of Population of Bemesia
tabaci Gennadius During the Wet and
Dry Season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
Natural Enemy of Bemesia tabaci . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
Host Plants of Bemesia tabaci Gennadius
and the Population of the Insect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
INTRODUCTION
Whitefly, Bemisia tabaci Gennadius, common name for any member of a family
of plant-feeding insects that resemble tiny moths. They are not actually true flies; they
have piercing-sucking mouthparts and are related to aphids, cicadas, and jumping plant
lice. Whitefly is under family Aleyrodidae, suborder Sternorrhyncha and order
Hemiptera.
B. tabaci occur in groups on the underside of leaves. The adults of most species
are similar in appearance and are shaped like tiny moths. Most are less than about 2mm
(0.08 inch) long. The body is usually yellowish, but they appear white because of a mealy
wax that covers the wings and body. Females lay tiny, oblong eggs on the underside of
the leaves. Eggs hatch into barely visible, yellowish oblong nymphs known as the
“crawlers”. After hatching, “crawlers” soon pierce the host plant with their needle like
mouthparts and remain settled on the plant until adulthood. The semitransparent nymphs
become flattened and oval after the first moult, or shedding off of skin. They are covered
with a waxy secretion and look like tiny scale insects. They have an unusually modified
form of metamorphosis, in that the immature stages begin life as mobile individuals, but
soon attached to the plant and the stage before the adult is called a pupa, though it is not
at all the same as the true pupal stage in holometabolous insects (Hunter et al., 1996).
B. tabaci is one of the most destructive pests that damage almost all kinds of
plants. They are damaging plants by sucking the flowing sap or phloem of the plants.
High populations of these insects may cause leaves to yellow, shrivel and drop
prematurely. The excess sap or honeydew excreted by nymphs collect dusts that leads to
Seasonal Abundance and Natural Enemy of Bemesia tabaci Gennadius (Hemiptera :
Aleyrodidae). PERALTA, JEAN SALVATERA. APRIL 2007
2
growth of sooty molds and attracts ants. Like many other species in the aphid and cicada
order, white flies can transmit viruses to plants.
Managing pest could either be done in such ways: these were chemical control,
biological control and cultural control. The use of beneficial insects was the most
preferred one. By using biological control, leads to no chemical toxicity in the
surroundings. Thus, the study shows on the use of natural enemies that could reduce the
population of the pest and the factors that contributes in the reduction of population. In
such matters, this study could help students as for their research works and an additional
knowledge to them.
The objectives of the study were to monitor the population of Bemesia tabaci
Gennadius during the wet and dry season, to determine the effect of rainfall, relative
humidity, and temperature on the population of B. tabaci, to know the natural enemies of
B. tabaci, and to know the host plants of B. tabaci.
The study was conducted at the Balili Experimental Area and Swamp Area, La
Trinidad, Benguet from July 2006 to January 2007.
3
REVIEW OF LITERATURE
Life stages, description and characteristics of Bemesia tabaci Gennadius. The
eggs are pale yellow oval, 0.3 mm in length, and are laid on the underside of the leaves.
The egg hatches within 4 to 12 days. The larvae are yellowish that has fine thin wax
covering their abdomen so they are hardly be seen. The first instar larvae are called
“crawlers”. The pupa is elliptical and opaque, deep yellow in color. The adults are small,
about 1mm long and slightly with wings covered with white waxy bloom. The larva and
adult suck plant juices (Colting et al., 2003).
Distribution and abundance. According to Colting et al., (2003), this pest is
distributed throughout the Cordillera and abundant during dry season.
Natural enemies. The aphinilid wasp, lacewings, spiders, staphinilid beetles and
some fungi are the enemies of this pest (Colting et al., 2003). In addition, Kruger (2006)
mentioned a number of natural enemies that attack B. tabaci which includes parasitic
wasps, predatory mites, beetles and fungi. Some of them have used successfully in
biological control.
Damage of this pest. The greatest potential threat from the tobacco whitefly is that
it can transmit more than 60 plant viruses including tomato yellow leaf curl, lettuce
infectious yellows and squash leaf curl. Direct damage by the feeding of adults and
nymphs are unlikely to be seen unless infestation is severe. Detection of the pest
therefore relies mainly on seeing adults and immature stages. However, if infestation is
severe, damage can occur in the form of sticky honeydew and associated with sooty
4
molds, chlorotic spots and leaf yellowing. Physiological disorders such as leaf silvering
of cucurbits and fruit distortion of tomatoes may also be included (Anon., 1996).
Parasitization of the host. The immature parasitoids develop within the whitefly
host, eventually consuming the entire host, except the integument. The immature
parasitoid pupates within the integument of the host and the adult parasitoid emerges
through a round hole (Anon., 1981).
Host plants of Bemesia tabaci Gennadius. This is widely polyphagous, feeding on
over 500 species of plants in 74 families. Its hosts include vegetable, field and ornamental
crops. Of the important vegetable crops in Florida, this is a major peat of tomato,
peppers, squash, cucumber, beans, eggplant, watermelon and cabbage. The Florida-
grown field crops of potato, peanut, soybean and cotton are heavily attacked by Bemesia.
The ornamental host plants of Bemesia are too numerous to list, but include poinsettia,
hibiscus, and chrysanthemum (Anon., 1981). Also, Achterberg in 1999 added that the
hosts are almost exclusively angiosperma, mostly woody dicots. Such preference could
be a reflection of their tropical distribution
Spread of Bemesia tabaci Gennadius. It has been reported from all except
Antarctica. Over 900 host plants have been recorded for this pest and it reportedly
transmits 111 virus species. It is believed that B. tabaci has been spread throughout the
world through the transport of plant products that were infested with whiteflies. Once
established, B. tabaci quickly spreads and through its feeding habits the transmission of
the disease, it carries causes destruction to crops around the world. B. tabaci is believed
to be a species complex, with a number of recognized biotypes and two described extant
cryptic species (Anon., 2000).
5
MATERIALS AND METHODS
Materials
The materials that were used in this study were as follows: bean seeds (Bean Pole
Blue Lake variety), grab hoe, sticks, watering can, a quadrant made out of transparent
plastic measuring three square centimeters, water, markers, masking tape, bond papers,
thread, magnifying lens, pair of scissors, CP 10 plastic containers, tissue papers,
dissecting microscope, and listing materials such as pen and paper.
Methods
Land preparation. An area of 100 m2 were cleaned and prepared. Ten plots were
hilled up and holes about 2 cm deep were made in each plot.
Planting. The seeds were planted with the planting distance of 8 cm with three
seeds in each hole. The variety of bean seeds planted was the Bean Pole Blue Lake. After
the seeds were planted, application of fertilizer (chicken dung) was done. The fertilizer
was placed at the center of the plot.
Data gathering. The gathering of data started when the plants had already leaves
and it was attacked by B. tabaci. Ten plants per plot were chosen as samples. The number
of B. tabaci adult, nymph, and pupa, were counted. B. tabaci that was found on the
quadrant was counted. Twenty sample leaves that contain eggs were collected and it is
brought to the laboratory for the observation on how the predator attacks B. tabaci.
Data gathering and sample collection outside the study area. This was done from
the field near the Balili Mites Predatory Rearing House running to the swamp areas going
6
to Km.5 and back to the laboratory house. Plants that were attacked by B. tabaci and the
population of this insect were listed. The data collection was done once a month.
Proving the presence of adult predators by sweeping B. tabaci. Sweeping was
done ten times on the host plants that had a higher population. The collected specimens
were put on the CP 10 plastic containers.
Collection of leaves for proving natural enemies. Twenty sample leaves,
measuring three cm², that contain eggs, nymph and pupae of B. tabaci were collected.
The specimens were put on the CP 10 plastic containers. Specimens were reared until
such predators were observed.
Rainfall intensity, relative humidity and temperature. The rainfall intensity,
relative humidity and temperature were taken at the PAG-ASA (Philippine Atmospheric,
Geophysical and Astronomical Services Administration) – BSU.
Hosts plants. Plants that were infested with this pest including the population
count on the adult, nymph and pupae were listed.
The data gathered were:
1. Population of B. tabaci. The population of adult, nymph and pupae counted in
the leaves subjected to transparent plastic quadrant measuring 3 cm² were counted and
noted
2. Host plants. The plants that were infested with B. tabaci during the conduct of
the study was also noted.
3. Natural enemies of B. tabaci. These were the predators that were associated
with B. tabaci.
7
4. Rainfall intensity, relative humidity and temperature. The intensity of rain,
relative humidity and temperature during the conduct of the study was taken at the BSU-
PAG-ASA.
8
RESULTS AND DISCUSSION
Population of Bemesia tabaci Gennadius
During the Wet and Dry Season
The months of July, August, September and October were the wet season and the
months of November, December and January were the dry season.
As shown in Table 1, during wet season, the population of Bemesia tabaci
Gennadius adult was 124, 125 for the nymph and 92 for the pupae. During dry season,
the population of adult was 542, 361 for the nymph and 270 for the pupae.
The population of adult, nymph and pupae during the wet season was lower than
during dry season as indicated in Appendix Graph 1. The decrease in population during
wet season could be due to the high intensity of rain. The increase in population during
dry season was due to the increase in temperature.
Table 1. Total Population of Bemesia tabaci Gennadius in wet (July to October) and dry
season (November to January)
SEASON
POPULATION
ADULT
NYMPH
PUPAE
Wet Season
124
125
92
Dry season
542
361
270
9
Relationship of Population of Bemesia tabaci
Gennadius During the Wet and Dry Season
Table 2 shows the effect of meteorological factors on the population densities of
B. tabaci. During wet season, a unit increase on the intensity of rainfall resulted for the
decreased in population of B. tabaci. The population decreases as the rainfall intensity
rises. Likewise, there was an increased in the population of B. tabaci as the rainfall
intensity declines.
For every unit increase on the intensity of rain there was a decrease in the
population of adult by a number of 4.08 and an addition of 6.55 for every unit increase in
temperature. For the nymph, a number of 2.64 was reduced and an addition of 3.99. A
unit increased in rainfall intensity makes the population of pupa to reduce by a number of
1.74 and the addition by a number of 2.1 for pupa for every rise in temperature.
For every rise in the intensity of rainfall to about 3.74 mm, there was a
corresponding decreased on the population of adult to 418, 236 to nymph and 178 to the
pupae of B. tabaci as presented in Table 3. On the other hand, should there be a rise in
temperature by 2.45ºC, the population of adult increased to 418, 236 for the nymph and
178 for the pupae.
Natural Enemy of Bemesia tabaci
The predator of B. tabaci found during the conduct of the study was the predatory
mites, Amblyseious sp. The predator predates by sucking the sap or juice of the prey. The
predatory stages were the nymph and the adult. The predator attacks the eggs, nymphs
and pupae of B. tabaci.
10
Table 2. Effect of meteorological factors on the population densities of Bemesia tabaci
Gennadius
STAGES OF B.
RAINFALL
RELATIVE
TEMPERATURE
tabaci G.
INTENSITY (mm)
HUMIDITY (%)
(ºC)
(POPULATION)
Effect
T-value
Effect
T-value
Effect
T-value
Adult (666)
-4.08
-2.08*
0.31
1.65 n.s.
6.55
2.36**
Nymph (486)
-2.64
-2.43*
0.18
1.73 n.s.
3.99
2.59**
Pupae (362)
-1.74
-1.85 n.s.
0.15
1.63 n.s.
2.91
2.19**
Legend: n.s. – not significant
* - significant
** - highly significant
Table 3. Relationship on the change of intensity of rain and temperature to the population
of adult, nymph, and pupa of B. tabaci
STAGES
RAINFALL POPULATION TEMPERATURE POPULATION
INTENSITY
Change
Change
Change
Change
Adult
Initial 1.13
542
21.60
124
3.74
418
2.45
418
Final 4.87
124
24.05
542
Nymph Initial 1.13
361
21.60
361
3.74
236
2.45
236
Final 4.87
125
24.05
125
Pupa
Initial 1.13
270
21.60
270
3.74
178
2.45
178
Final 4.87
92
24.05
92
11
Host Plants of Bemesia tabaci Gennadius
and the Population of the Insect
Table 4 shows the host plants and the population of B. tabaci. The highest
population of adult was six on eggplant and the lowest was one on celery, sweet pea,
strawberry, kutkutsarita, yellow cress, parparsik and macbride. For the nymph, the lowest
was two on kutkutsarita and yellow cress, while the highest was 11 on tomato. As for the
population of pupae, the lowest was zero on garden pea, eggplant and strawberry, and the
highest was six on chrysanthemum. The egg, nymph and pupae of B. tabaci were found
mostly on the lower leaves of the plants.
12
Table 4. Host plants and the population of Bemesia tabaci
HOST PLANTS (SCIENTIFIC NAME)
POPULATION
TOTAL
Adult
Nymph
Pupae
Broccoli (Brassica oleracea)
3
8
3
14
Cabbage (Brassica sinensis)
4
7
2
13
Chinese cabbage
2
9
4
15
Pechay
3
5
1
9
Snap beans (Phaseolus vulgaris)
4
10
3
17
Celery (Apium graveolens)
1
3
4
8
Garden pea (Pisum sativum)
1
6
0
7
Bell/Sweet pepper (Capsicum annum L.)
2
7
2
11
Tomato (Lycopersicon esculentum)
3
11
5
19
Yacon (Smalanthus sonchifolius)
4
5
2
11
Sunflower (Helianthus anus Linn.)
2
7
3
12
Eggplant (Solanum melongena)
6
7
0
13
Strawberry (genus Fragaria)
1
4
0
5
Tobacco (Nicotiana tabacum)
5
3
4
12
Kutkutsarita
1
2
2
5
Yellow cress (Rorippa indica l.)
1
2
0
3
Parparsik (Cardimine hirsute L.)
1
4
1
6
Amti (Solanum nigrum L.)
2
3
3
8
Macbride (Cuphea carthaginensis Jacquin)
1
3
1
5
Galinsoga (Galinsoga parviflora Cav.)
2
3
1
6
Chrysanthemum (genus Chrysanthemum)
3
8
6
17
13
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary
The study was conducted at the Balili Experimental Area, La Trinidad, Benguet
from July 2006 to January 2007 to monitor the population of Bemesia tabaci Gennadius
during the wet and dry season, to determine the effect of rainfall, relative humidity, and
temperature on the population of B. tabaci, to know the natural enemies of B. tabaci, and
to know the host plants of B. tabaci.
In the study, the population of B. tabaci was lower during the wet season than
during the dry season. For every unit increase in intensity of rain, B. tabaci population
was reduced by a number of 4.8 on adult, 2.64 on nymph and 1.74 on pupae. A number
of 6.55, 3.99 and 2.91 was added to the population of adult, nymph and pupa as there was
a unit rise in temperature. On the other hand, relative humidity does not affect the change
in population of the B. tabaci. The observed predator of B. tabaci was the predatory
mites, Amblyseious sp. This predator was feeding by sucking the sap of the prey. The
predatory stages were the nymph and adult. There were 21 species listed as host of B.
tabaci. To mention a few, they were cabbage, broccoli and pechay.
Conclusion
Bemesia tabaci Gennadius was abundant during the dry season. The population of
B. tabaci was affected by rainfall intensity and temperature, but not relative humidity. As
the intensity of rain goes higher, the population becomes lower, and as the temperature
rises, the population also increases. Chemical control of B. tabaci was not the only
14
control that could be used. B. tabaci could be managed by the use of natural enemies.
One natural enemy recorded was the predatory mite. B. tabaci has 21 host plants making
them very difficult to control.
Recommendation
It is recommended that further study should be done including the possibility of
conducting under greenhouse condition to know the other factors that may affect the
population of the insect.
15
LITERATURE CITED
ACHTERBERG, K. V. 1991. The Insects of Australia (2nd ed. Vol. 1). Division of
Entomology Commonwealth Science and Industrial Research Organization.
Melbourne University Press. P. 452.
ANONYMOUS. 1981. Silver leaf whitefly. Retrieved September 1, 2006 from
http://creatures.ifas.ufl.edu/veg/leaf/silverleaf_whitefly.htm#desc.
ANONYMOUS. 1996. Pest of plants. Retrieved September 1, 2006 from
http://www.defra.gov.uk/planth/pestpics/qic6.htm.
ANONYMOUS. 2000. Whitefly ecology. Retrieved September 1, 2006 from
http://www.issg.org/database/species/ecology.asp?si=106&fr=1.
COLTING, L. M., B. S. LIGAT, L. G. LINIO, J. P. PEREZ, J. PABLO. 2003.
Compendium of Insect Pest and Weeds Associated with Crops in Cordillera.
Department of Agric., Cordillera Highland Agricultural Resources (CHARM)
Project and BSU. P. 23.
HUNTER, W. B., E. HIEBERT, S.E. WEBB and J.E. POLSTON. 1996. Precibarial and
cibarial chemosensilla in the whitefly, B. tabaci. International Journal of Insect
Morphology and Embryology. Vol. 25: 295-304. Retrieved February 14, 2006
from http://en.wikipedia.org/wiki/whitefly.
KRUGER, K. 2006. General information on whiteflies. Retrieved September 1, 2006
from http://www.rietkka@plant2. agric.za.
16
APPENDICES
Appendix Graph 1. Population of adult, nymph and pupae B. tabaci during the wet & dry
season
100
90
Nymph
Adult
80
Pupae
70
60
50
P
o
p
u
l
a
t
i
o
n
s
40
30
20
10
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
17
Appendix Graph 2. Rainfall intensity and population of adult B. tabaci
100
50
Population
90
45
Rainfal Intensity
(mm)
80
40
70
35 )m
60
30 ty (m
50
25
o
p
u
l
a
t
i
o
n
P
a
i
n
f
a
l
I
n
t
e
n
si
40
20 R
30
15
20
10
10
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
18
Appendix Graph 3. Rainfall intensity and population of nymph B. tabaci
60
50
Population
45
50
Rainfal Intensity (mm)
40
35
40
)
m
30 ty (m
30
25
o
p
u
l
a
t
i
o
n
P
a
i
n
f
a
l
I
n
t
e
n
si
20 R
20
15
10
10
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
19
Appendix Graph 4. Rainfall intensity and population of pupae B. tabaci
45
50
45
40
40
35
35
30
)
Population
m
Rainfal Intensity (mm)
30 ty (m
25
25
o
p
u
l
a
t
i
o
n
P 20
a
i
n
f
a
l
I
n
t
e
n
si
20 R
15
15
10
10
5
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
20
Appendix Graph 5. Temperature and population of adult B. tabaci
100
30
Population
90
Temperature (%)
25
80
70
20
)
60
50
15
o
p
u
l
a
t
i
o
n
p
e
r
a
t
u
r
e
(
%
P
T
e
m
40
10
30
20
5
10
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
21
Appendix Graph 6. Temperature and population of nymph B. tabaci
60
30
Population
Temperature (%)
50
25
40
20
)
30
15
o
p
u
l
a
t
i
o
n
p
e
r
a
t
u
r
e
(
%
P
T
e
m
20
10
10
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
22
Appendix Graph 7. Temperature and population of pupae B. tabaci
45
30
Population
40
Temperature (%)
25
35
30
20
)
25
15
o
p
u
l
a
t
i
o
n
p
e
r
a
t
u
r
e
(
%
P 20
T
e
m
15
10
10
5
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
PERALTA, JEAN SALVATERA. APRIL 2007. Seasonal Abundance and Natural
Enemy of Bemesia tabaci Gennadius (Hemiptera : Aleyrodidae). Benguet State University, La
Trinidad, Benguet.
Adviser: Bonie S. Ligat Sr., MSc
ABSTRACT
The study was conducted at the Balili Experimental Area and Swamp Area, La Trinidad,
Benguet from July 2006 to January 2007 to monitor the population of Bemesia tabaci Gennadius
during the wet and dry season, to determine the effect of rainfall, relative humidity, and
temperature on the population of B. tabaci, to know the natural enemies of B. tabaci, and to
know the host plants of B. tabaci.
Population of Bemesia tabaci Gennadius during the wet season was lower than during the
dry season. The population of the adult during wet season was 124 and 542 during dry season.
The nymph was 125 during wet season and 361 during dry season. The population of pupae
during wet season was 92 and 270 during dry season.
A unit rise on the intensity of rain, the average population of adult B. tabaci was reduced
to 4.08, 2.64 for the nymph and 1.74 for the pupae. Likewise, a unit increase in temperature
increased the average population of the adult by 6.55, 3.99 for the nymph and 2.97 for the pupae.
The natural enemy of B. tabaci was the predatory mites, Amblyseious sp.
The host plants of B. tabaci were Brassica oleracea, Brassica sinensis, Phaseolus
vulgaris, Apium graveolens, Pisum sativum, Capsicum annum L., Lycopersicon esculentum,
Smalanthus sonchifolius, Helianthus anus Linn., genus Fragaria, Nicotiana tabacum, Rorippa
indica L., Cardimine hirsute L., Solanum nigrum L., Cuphea carthaginensis Jacquin, Galinsoga
parviflora Cav., genus Chrysanthemum.
TABLE OF CONTENTS
Page
Bibliography. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
MATERIALS AND METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
RESULTS AND DISCUSSION
Population of Bemesia tabaci Gennadius
during the Wet and Dry Season. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
Relationship of Population of Bemesia
tabaci Gennadius During the Wet and
Dry Season . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
Natural Enemy of Bemesia tabaci . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9
Host Plants of Bemesia tabaci Gennadius
and the Population of the Insect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
INTRODUCTION
Whitefly, Bemisia tabaci Gennadius, common name for any member of a family
of plant-feeding insects that resemble tiny moths. They are not actually true flies; they
have piercing-sucking mouthparts and are related to aphids, cicadas, and jumping plant
lice. Whitefly is under family Aleyrodidae, suborder Sternorrhyncha and order
Hemiptera.
B. tabaci occur in groups on the underside of leaves. The adults of most species
are similar in appearance and are shaped like tiny moths. Most are less than about 2mm
(0.08 inch) long. The body is usually yellowish, but they appear white because of a mealy
wax that covers the wings and body. Females lay tiny, oblong eggs on the underside of
the leaves. Eggs hatch into barely visible, yellowish oblong nymphs known as the
“crawlers”. After hatching, “crawlers” soon pierce the host plant with their needle like
mouthparts and remain settled on the plant until adulthood. The semitransparent nymphs
become flattened and oval after the first moult, or shedding off of skin. They are covered
with a waxy secretion and look like tiny scale insects. They have an unusually modified
form of metamorphosis, in that the immature stages begin life as mobile individuals, but
soon attached to the plant and the stage before the adult is called a pupa, though it is not
at all the same as the true pupal stage in holometabolous insects (Hunter et al., 1996).
B. tabaci is one of the most destructive pests that damage almost all kinds of
plants. They are damaging plants by sucking the flowing sap or phloem of the plants.
High populations of these insects may cause leaves to yellow, shrivel and drop
prematurely. The excess sap or honeydew excreted by nymphs collect dusts that leads to
Seasonal Abundance and Natural Enemy of Bemesia tabaci Gennadius (Hemiptera :
Aleyrodidae). PERALTA, JEAN SALVATERA. APRIL 2007
2
growth of sooty molds and attracts ants. Like many other species in the aphid and cicada
order, white flies can transmit viruses to plants.
Managing pest could either be done in such ways: these were chemical control,
biological control and cultural control. The use of beneficial insects was the most
preferred one. By using biological control, leads to no chemical toxicity in the
surroundings. Thus, the study shows on the use of natural enemies that could reduce the
population of the pest and the factors that contributes in the reduction of population. In
such matters, this study could help students as for their research works and an additional
knowledge to them.
The objectives of the study were to monitor the population of Bemesia tabaci
Gennadius during the wet and dry season, to determine the effect of rainfall, relative
humidity, and temperature on the population of B. tabaci, to know the natural enemies of
B. tabaci, and to know the host plants of B. tabaci.
The study was conducted at the Balili Experimental Area and Swamp Area, La
Trinidad, Benguet from July 2006 to January 2007.
3
REVIEW OF LITERATURE
Life stages, description and characteristics of Bemesia tabaci Gennadius. The
eggs are pale yellow oval, 0.3 mm in length, and are laid on the underside of the leaves.
The egg hatches within 4 to 12 days. The larvae are yellowish that has fine thin wax
covering their abdomen so they are hardly be seen. The first instar larvae are called
“crawlers”. The pupa is elliptical and opaque, deep yellow in color. The adults are small,
about 1mm long and slightly with wings covered with white waxy bloom. The larva and
adult suck plant juices (Colting et al., 2003).
Distribution and abundance. According to Colting et al., (2003), this pest is
distributed throughout the Cordillera and abundant during dry season.
Natural enemies. The aphinilid wasp, lacewings, spiders, staphinilid beetles and
some fungi are the enemies of this pest (Colting et al., 2003). In addition, Kruger (2006)
mentioned a number of natural enemies that attack B. tabaci which includes parasitic
wasps, predatory mites, beetles and fungi. Some of them have used successfully in
biological control.
Damage of this pest. The greatest potential threat from the tobacco whitefly is that
it can transmit more than 60 plant viruses including tomato yellow leaf curl, lettuce
infectious yellows and squash leaf curl. Direct damage by the feeding of adults and
nymphs are unlikely to be seen unless infestation is severe. Detection of the pest
therefore relies mainly on seeing adults and immature stages. However, if infestation is
severe, damage can occur in the form of sticky honeydew and associated with sooty
4
molds, chlorotic spots and leaf yellowing. Physiological disorders such as leaf silvering
of cucurbits and fruit distortion of tomatoes may also be included (Anon., 1996).
Parasitization of the host. The immature parasitoids develop within the whitefly
host, eventually consuming the entire host, except the integument. The immature
parasitoid pupates within the integument of the host and the adult parasitoid emerges
through a round hole (Anon., 1981).
Host plants of Bemesia tabaci Gennadius. This is widely polyphagous, feeding on
over 500 species of plants in 74 families. Its hosts include vegetable, field and ornamental
crops. Of the important vegetable crops in Florida, this is a major peat of tomato,
peppers, squash, cucumber, beans, eggplant, watermelon and cabbage. The Florida-
grown field crops of potato, peanut, soybean and cotton are heavily attacked by Bemesia.
The ornamental host plants of Bemesia are too numerous to list, but include poinsettia,
hibiscus, and chrysanthemum (Anon., 1981). Also, Achterberg in 1999 added that the
hosts are almost exclusively angiosperma, mostly woody dicots. Such preference could
be a reflection of their tropical distribution
Spread of Bemesia tabaci Gennadius. It has been reported from all except
Antarctica. Over 900 host plants have been recorded for this pest and it reportedly
transmits 111 virus species. It is believed that B. tabaci has been spread throughout the
world through the transport of plant products that were infested with whiteflies. Once
established, B. tabaci quickly spreads and through its feeding habits the transmission of
the disease, it carries causes destruction to crops around the world. B. tabaci is believed
to be a species complex, with a number of recognized biotypes and two described extant
cryptic species (Anon., 2000).
5
MATERIALS AND METHODS
Materials
The materials that were used in this study were as follows: bean seeds (Bean Pole
Blue Lake variety), grab hoe, sticks, watering can, a quadrant made out of transparent
plastic measuring three square centimeters, water, markers, masking tape, bond papers,
thread, magnifying lens, pair of scissors, CP 10 plastic containers, tissue papers,
dissecting microscope, and listing materials such as pen and paper.
Methods
Land preparation. An area of 100 m2 were cleaned and prepared. Ten plots were
hilled up and holes about 2 cm deep were made in each plot.
Planting. The seeds were planted with the planting distance of 8 cm with three
seeds in each hole. The variety of bean seeds planted was the Bean Pole Blue Lake. After
the seeds were planted, application of fertilizer (chicken dung) was done. The fertilizer
was placed at the center of the plot.
Data gathering. The gathering of data started when the plants had already leaves
and it was attacked by B. tabaci. Ten plants per plot were chosen as samples. The number
of B. tabaci adult, nymph, and pupa, were counted. B. tabaci that was found on the
quadrant was counted. Twenty sample leaves that contain eggs were collected and it is
brought to the laboratory for the observation on how the predator attacks B. tabaci.
Data gathering and sample collection outside the study area. This was done from
the field near the Balili Mites Predatory Rearing House running to the swamp areas going
6
to Km.5 and back to the laboratory house. Plants that were attacked by B. tabaci and the
population of this insect were listed. The data collection was done once a month.
Proving the presence of adult predators by sweeping B. tabaci. Sweeping was
done ten times on the host plants that had a higher population. The collected specimens
were put on the CP 10 plastic containers.
Collection of leaves for proving natural enemies. Twenty sample leaves,
measuring three cm², that contain eggs, nymph and pupae of B. tabaci were collected.
The specimens were put on the CP 10 plastic containers. Specimens were reared until
such predators were observed.
Rainfall intensity, relative humidity and temperature. The rainfall intensity,
relative humidity and temperature were taken at the PAG-ASA (Philippine Atmospheric,
Geophysical and Astronomical Services Administration) – BSU.
Hosts plants. Plants that were infested with this pest including the population
count on the adult, nymph and pupae were listed.
The data gathered were:
1. Population of B. tabaci. The population of adult, nymph and pupae counted in
the leaves subjected to transparent plastic quadrant measuring 3 cm² were counted and
noted
2. Host plants. The plants that were infested with B. tabaci during the conduct of
the study was also noted.
3. Natural enemies of B. tabaci. These were the predators that were associated
with B. tabaci.
7
4. Rainfall intensity, relative humidity and temperature. The intensity of rain,
relative humidity and temperature during the conduct of the study was taken at the BSU-
PAG-ASA.
8
RESULTS AND DISCUSSION
Population of Bemesia tabaci Gennadius
During the Wet and Dry Season
The months of July, August, September and October were the wet season and the
months of November, December and January were the dry season.
As shown in Table 1, during wet season, the population of Bemesia tabaci
Gennadius adult was 124, 125 for the nymph and 92 for the pupae. During dry season,
the population of adult was 542, 361 for the nymph and 270 for the pupae.
The population of adult, nymph and pupae during the wet season was lower than
during dry season as indicated in Appendix Graph 1. The decrease in population during
wet season could be due to the high intensity of rain. The increase in population during
dry season was due to the increase in temperature.
Table 1. Total Population of Bemesia tabaci Gennadius in wet (July to October) and dry
season (November to January)
SEASON
POPULATION
ADULT
NYMPH
PUPAE
Wet Season
124
125
92
Dry season
542
361
270
9
Relationship of Population of Bemesia tabaci
Gennadius During the Wet and Dry Season
Table 2 shows the effect of meteorological factors on the population densities of
B. tabaci. During wet season, a unit increase on the intensity of rainfall resulted for the
decreased in population of B. tabaci. The population decreases as the rainfall intensity
rises. Likewise, there was an increased in the population of B. tabaci as the rainfall
intensity declines.
For every unit increase on the intensity of rain there was a decrease in the
population of adult by a number of 4.08 and an addition of 6.55 for every unit increase in
temperature. For the nymph, a number of 2.64 was reduced and an addition of 3.99. A
unit increased in rainfall intensity makes the population of pupa to reduce by a number of
1.74 and the addition by a number of 2.1 for pupa for every rise in temperature.
For every rise in the intensity of rainfall to about 3.74 mm, there was a
corresponding decreased on the population of adult to 418, 236 to nymph and 178 to the
pupae of B. tabaci as presented in Table 3. On the other hand, should there be a rise in
temperature by 2.45ºC, the population of adult increased to 418, 236 for the nymph and
178 for the pupae.
Natural Enemy of Bemesia tabaci
The predator of B. tabaci found during the conduct of the study was the predatory
mites, Amblyseious sp. The predator predates by sucking the sap or juice of the prey. The
predatory stages were the nymph and the adult. The predator attacks the eggs, nymphs
and pupae of B. tabaci.
10
Table 2. Effect of meteorological factors on the population densities of Bemesia tabaci
Gennadius
STAGES OF B.
RAINFALL
RELATIVE
TEMPERATURE
tabaci G.
INTENSITY (mm)
HUMIDITY (%)
(ºC)
(POPULATION)
Effect
T-value
Effect
T-value
Effect
T-value
Adult (666)
-4.08
-2.08*
0.31
1.65 n.s.
6.55
2.36**
Nymph (486)
-2.64
-2.43*
0.18
1.73 n.s.
3.99
2.59**
Pupae (362)
-1.74
-1.85 n.s.
0.15
1.63 n.s.
2.91
2.19**
Legend: n.s. – not significant
* - significant
** - highly significant
Table 3. Relationship on the change of intensity of rain and temperature to the population
of adult, nymph, and pupa of B. tabaci
STAGES
RAINFALL POPULATION TEMPERATURE POPULATION
INTENSITY
Change
Change
Change
Change
Adult
Initial 1.13
542
21.60
124
3.74
418
2.45
418
Final 4.87
124
24.05
542
Nymph Initial 1.13
361
21.60
361
3.74
236
2.45
236
Final 4.87
125
24.05
125
Pupa
Initial 1.13
270
21.60
270
3.74
178
2.45
178
Final 4.87
92
24.05
92
11
Host Plants of Bemesia tabaci Gennadius
and the Population of the Insect
Table 4 shows the host plants and the population of B. tabaci. The highest
population of adult was six on eggplant and the lowest was one on celery, sweet pea,
strawberry, kutkutsarita, yellow cress, parparsik and macbride. For the nymph, the lowest
was two on kutkutsarita and yellow cress, while the highest was 11 on tomato. As for the
population of pupae, the lowest was zero on garden pea, eggplant and strawberry, and the
highest was six on chrysanthemum. The egg, nymph and pupae of B. tabaci were found
mostly on the lower leaves of the plants.
12
Table 4. Host plants and the population of Bemesia tabaci
HOST PLANTS (SCIENTIFIC NAME)
POPULATION
TOTAL
Adult
Nymph
Pupae
Broccoli (Brassica oleracea)
3
8
3
14
Cabbage (Brassica sinensis)
4
7
2
13
Chinese cabbage
2
9
4
15
Pechay
3
5
1
9
Snap beans (Phaseolus vulgaris)
4
10
3
17
Celery (Apium graveolens)
1
3
4
8
Garden pea (Pisum sativum)
1
6
0
7
Bell/Sweet pepper (Capsicum annum L.)
2
7
2
11
Tomato (Lycopersicon esculentum)
3
11
5
19
Yacon (Smalanthus sonchifolius)
4
5
2
11
Sunflower (Helianthus anus Linn.)
2
7
3
12
Eggplant (Solanum melongena)
6
7
0
13
Strawberry (genus Fragaria)
1
4
0
5
Tobacco (Nicotiana tabacum)
5
3
4
12
Kutkutsarita
1
2
2
5
Yellow cress (Rorippa indica l.)
1
2
0
3
Parparsik (Cardimine hirsute L.)
1
4
1
6
Amti (Solanum nigrum L.)
2
3
3
8
Macbride (Cuphea carthaginensis Jacquin)
1
3
1
5
Galinsoga (Galinsoga parviflora Cav.)
2
3
1
6
Chrysanthemum (genus Chrysanthemum)
3
8
6
17
13
SUMMARY, CONCLUSION AND RECOMMENDATION
Summary
The study was conducted at the Balili Experimental Area, La Trinidad, Benguet
from July 2006 to January 2007 to monitor the population of Bemesia tabaci Gennadius
during the wet and dry season, to determine the effect of rainfall, relative humidity, and
temperature on the population of B. tabaci, to know the natural enemies of B. tabaci, and
to know the host plants of B. tabaci.
In the study, the population of B. tabaci was lower during the wet season than
during the dry season. For every unit increase in intensity of rain, B. tabaci population
was reduced by a number of 4.8 on adult, 2.64 on nymph and 1.74 on pupae. A number
of 6.55, 3.99 and 2.91 was added to the population of adult, nymph and pupa as there was
a unit rise in temperature. On the other hand, relative humidity does not affect the change
in population of the B. tabaci. The observed predator of B. tabaci was the predatory
mites, Amblyseious sp. This predator was feeding by sucking the sap of the prey. The
predatory stages were the nymph and adult. There were 21 species listed as host of B.
tabaci. To mention a few, they were cabbage, broccoli and pechay.
Conclusion
Bemesia tabaci Gennadius was abundant during the dry season. The population of
B. tabaci was affected by rainfall intensity and temperature, but not relative humidity. As
the intensity of rain goes higher, the population becomes lower, and as the temperature
rises, the population also increases. Chemical control of B. tabaci was not the only
14
control that could be used. B. tabaci could be managed by the use of natural enemies.
One natural enemy recorded was the predatory mite. B. tabaci has 21 host plants making
them very difficult to control.
Recommendation
It is recommended that further study should be done including the possibility of
conducting under greenhouse condition to know the other factors that may affect the
population of the insect.
15
LITERATURE CITED
ACHTERBERG, K. V. 1991. The Insects of Australia (2nd ed. Vol. 1). Division of
Entomology Commonwealth Science and Industrial Research Organization.
Melbourne University Press. P. 452.
ANONYMOUS. 1981. Silver leaf whitefly. Retrieved September 1, 2006 from
http://creatures.ifas.ufl.edu/veg/leaf/silverleaf_whitefly.htm#desc.
ANONYMOUS. 1996. Pest of plants. Retrieved September 1, 2006 from
http://www.defra.gov.uk/planth/pestpics/qic6.htm.
ANONYMOUS. 2000. Whitefly ecology. Retrieved September 1, 2006 from
http://www.issg.org/database/species/ecology.asp?si=106&fr=1.
COLTING, L. M., B. S. LIGAT, L. G. LINIO, J. P. PEREZ, J. PABLO. 2003.
Compendium of Insect Pest and Weeds Associated with Crops in Cordillera.
Department of Agric., Cordillera Highland Agricultural Resources (CHARM)
Project and BSU. P. 23.
HUNTER, W. B., E. HIEBERT, S.E. WEBB and J.E. POLSTON. 1996. Precibarial and
cibarial chemosensilla in the whitefly, B. tabaci. International Journal of Insect
Morphology and Embryology. Vol. 25: 295-304. Retrieved February 14, 2006
from http://en.wikipedia.org/wiki/whitefly.
KRUGER, K. 2006. General information on whiteflies. Retrieved September 1, 2006
from http://www.rietkka@plant2. agric.za.
16
APPENDICES
Appendix Graph 1. Population of adult, nymph and pupae B. tabaci during the wet & dry
season
100
90
Nymph
Adult
80
Pupae
70
60
50
P
o
p
u
l
a
t
i
o
n
s
40
30
20
10
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
17
Appendix Graph 2. Rainfall intensity and population of adult B. tabaci
100
50
Population
90
45
Rainfal Intensity
(mm)
80
40
70
35 )m
60
30 ty (m
50
25
o
p
u
l
a
t
i
o
n
P
a
i
n
f
a
l
I
n
t
e
n
si
40
20 R
30
15
20
10
10
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
18
Appendix Graph 3. Rainfall intensity and population of nymph B. tabaci
60
50
Population
45
50
Rainfal Intensity (mm)
40
35
40
)
m
30 ty (m
30
25
o
p
u
l
a
t
i
o
n
P
a
i
n
f
a
l
I
n
t
e
n
si
20 R
20
15
10
10
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
19
Appendix Graph 4. Rainfall intensity and population of pupae B. tabaci
45
50
45
40
40
35
35
30
)
Population
m
Rainfal Intensity (mm)
30 ty (m
25
25
o
p
u
l
a
t
i
o
n
P 20
a
i
n
f
a
l
I
n
t
e
n
si
20 R
15
15
10
10
5
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
20
Appendix Graph 5. Temperature and population of adult B. tabaci
100
30
Population
90
Temperature (%)
25
80
70
20
)
60
50
15
o
p
u
l
a
t
i
o
n
p
e
r
a
t
u
r
e
(
%
P
T
e
m
40
10
30
20
5
10
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
21
Appendix Graph 6. Temperature and population of nymph B. tabaci
60
30
Population
Temperature (%)
50
25
40
20
)
30
15
o
p
u
l
a
t
i
o
n
p
e
r
a
t
u
r
e
(
%
P
T
e
m
20
10
10
5
0
0
4 11 18 25 1 8 15 22 29 2 9 16 23 30 7 14 21 28 5 12 19 26 2 9 16 23 30 6
July Aug. Sept. Oct. Nov. Dec. Jan.
WET
DRY
SEASONS
22
Appendix Graph 7. Temperature and population of pupae B. tabaci
45
30
Population
40
Temperature (%)
25
35
30
20
)
25
15
o
p
u
l
a
t
i
o
n
p
e
r
a
t
u
r
e
(
%
P 20
T
e
m
15
10
10
5
5
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Document Outline
- BIBLIOGRAPHY
- TABLE OF CONTENTS
- INTRODUCTION