BIBLIOGRAPHY TIBAO, MARLON Y. APRIL 2012....
BIBLIOGRAPHY
TIBAO, MARLON Y. APRIL 2012. Insect Pests Succesion of Organically
Grown Pechay ( Brassica chinensis Linnaeus). Benguet State University, La Trinidad,
Benguet.
Adviser: Maria Ana C. Tanyag, MSc.
ABSTRACT
The study was conducted at Balili Experimental Station, Benguet State University,
La Trinidad, Benguet from July to September 2011 to identify the insect pests of pechay,
determine the total number of insect pests of the growth stages of the crop, and to record
the characteristic damage of the insect pests.
Insect pests observed associated with pechay are the Phyllotreta spp. (Fam.
Chrysomelidae), Pieres rapae (Fam. Pieridae), Trichoplusia ni and Spodoptera litura
(Fam. Noctuidae), Liriomyza huidobrensis (Fam. Agromyzidae), Plutella xylostella (Fam.
Plutellidae), and Myzus persicae (Fam. Aphididae).
The highest insect pest population was observed in the vegetative stage with a total
number of 1,410, while the lowest population of insect pests was recorded in the seedling
stage with a total number of 416. The seeding stage ranked second to the vegetative stage
with a total number of 1,057 insect pests, followed by a total number of 588 insect pests
observed in the flowering stage.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Flea beetles were found to be the most abundant insect pest in all the growth stages
of pechay with a total number of 2,196, followed by leafminers with a total number of 594.
Cabbage butterflies, with a total number of 438, ranked third in abundance followed by 85
cutworms. Diamondback moth was the lowest in number of 81.
The feeding of flea beetles on pechay shows a characteristic damage of shot holes
on the leaves, flowers, stem and pods. The cabbage looper and cutworm inflict rugged
holes on the leaves, while the leafminer adult causes punctures on the leaves. Cuts starting
from the leaf margins are inflicted by cabbage butterflies. Diamondback moth causes
irregular patches on the leaves while yellowish dots are characteristic damage due to
aphids.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
RESULTS AND DISCUSSION
Identification of Insect Pests of
Associated with Pechay
The insect pests observed and collected from the families of Chrysomelidae (flea
beetle), Pieridae (cabbage butterfly), Noctuidae (cutworms and cabbage looopers),
Agromyzidae (leafminers), Plutellidae (diamondback moths), and Aphididae (aphids) are
presented in Table 1. With the observed list of insect pests, the diamondback moth and the
cabbage butterfly as cited by Esguirra (1961) are found on all the growth stages of pechay.
ORDER: Coleoptera
FAMILY: Chrysomelidae
SCIENTIFIC NAME: Phyllotreta
spp.
LOCAL NAME: Timel, Flea
beetle
COMMON NAME: Flea beetle
Figure 1. Flea beetle chewing on the petals. ( 15x)
ORDER: Lepidoptera
FAMILY: Pieridae
SCIENTIFIC NAME: Pieres
rapae (Linnaeus)
LOCAL NAME: Cabbage
butterfly, Bigis
COMMON NAME: Cabbage
butterfly ,
Figure 2. Cabbage butterfly larva chewing on
leaves (10x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
ORDER: Lepidoptera
FAMILY: Noctuidae
SCIENTIFIC NAME:
Spodoptera litura (Fabricius)
LOCAL NAME: Cutworm, Bigis
COMMON NAME: Cutworm
Figure 3. Cutworm chewing on leaves (15x)
ORDER: Lepidoptera
FAMILY: Noctuidae
SCIENTIFIC
NAME:
Trichoplusia ni (Hubner)
LOCAL NAME: Looper, Bigis
COMMON NAME: Looper
Figure 4. Cabbage looper walking on the leaf (5x)
ORDER: Diptera
FAMILY: Agromyzidae
SCIENTIFIC NAME: Liriomyza
huidobrensis (Blanchard)
LOCAL NAME: Leafminer
COMMON NAME: Leafminer
Figure 5. Leafminer larva brought out from the
leaf (400x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
ORDER: Lepidoptera
FAMILY: Plutellidae
SCIENTIFIC NAME: Plutella
xylostella (Linnaeus)
LOCAL NAME: Diamondback
moth, Tarsan, Bigis
COMMON NAME:
Diamondback moth
Figure 6. Diamondback moth larva chewing on the
leaves (10x)
ORDER: Hemiptera
FAMILY: Aphididae
SCIENTIFIC NAME: Myzus
persicae (Zulser)
LOCAL NAME: Aphids
COMMON NAME: Aphids
Figure 7. Aphid sucking on plant leaf (10x)
Table 1. Insect pests associated with pechay
FAMILIES OF INSECT
COMMON NAME
SCIENTIFIC NAME
PEST
Chrysomelidae
Flea beetle
Phyllotreta spp.
Pieridae
Cabbage butterfly
Pieres rapae
Noctuidae
Cutworm
Spodoptera litura
Cabbage looper
Trichoplusia ni
Agromyzidae
Leafminer
Liriomyza huidobrensis
Plutellidae
Diamondback moth
Plutella xylostella
Aphididae
Aphid
Myzus persicae
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Total Number of Insect Pests of
the Growth Stages of Pechay
The number of insect pests found in the four growth stages of pechay was presented
in Table 2.
Insect pests of the seedling stage showed the lowest number of 416 from among all
the growth stages of pechay. The insect pests during this stage were the flea beetles (Figure
1) found to have the highest number of 214, followed by adult leafminer with a total
number of 169. Cutworms (Figure 3) ranked third with a total number of 19, while cabbage
butterflies (Figure 2) with a number of 12 ranked fourth. The lowest number is found in
aphids (Figure 7) with only two counts. It was only in this stage that aphids were observed.
Solang (2005) cited that when adult flea beetles emerge in large number, they can quickly
devastate the seedling of the host plant.
The vegetative stage recorded the highest number of insect pests which is 1,410.
This is because of the longer days of exposure of the crop to the environment (23 days).
Flea beetles, adult leafminers, cabbage butterflies, and cutworms were observed to increase
in number from the seedling stage. The highest number is found in flea beetles 749,
followed by the adult leafminers 288. The third highest count of 237 is observed in cabbage
butterflies while cutworms showed a number of 57, hence ranked fourth. It is in this stage
that 32 cabbage loopers (Figure 4), 31 leafminer larvae (Figure 5), and 16 diamondback
moths (Figure 6) were observed.
The result corroborated the study of Wakit (1980) that the population of flea beetles
was observed to increase as the crop matured due to increasing leaf surface area. However,
the great infestation occurred during the vegetative stage of the plant. The result was also
supported by Lumas-e (1981) that the population of leaf miner was observed three weeks
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
after emergence. When the plants were four weeks after emergence, they increased
abruptly.
The total number of all insect pests of the flowering stage was observed to have
decreased 588, compared to the total number of insect pests during vegetative stage. The
highest number was found in flea beetles 451, followed by the cabbage butterflies with a
count of 66. Leafminer larvae ranked third with a count of 27, looper ranked fourth with a
count of 15, followed by the diamondback moth 12, which ranked sixth. The last is the
cutworm with a number of six. This is because of the shorter period of the plants exposure
to the environment (10 days), and the occurrence of typhoons and daily rainfalls which
makes the insects immobile.
The result was again supported by Lumas-e (1981) on her study that the population
of the leafminers decreased at the fifth week after emergence. She added that heavy
drenching rain will wash off many of the weaker insect species.
The seeding stage showed the second highest 1,057 of all the growth stages of
pechay. This is due to the number of days the crop was exposed to the environment (20
days). The population of all insect pests increased except for the cut worms which
decreased in number. The flea beetles were found to have the highest number 782, followed
by the cabbage butterflies with a total number of 123. Ranked third are the leafminer larvae
and diamondback moth with a population of 53, while the fourth are the cabbage loopers
with a total number of 28. The adult leafminer (Figure 8) has a total number of 15 which
ranked fifth, followed by cutworm which decreased with a population of six.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Figure 8. Adult leafminer scratching its ovipositor
on the leaves (40x)
Table 2. Total number of insect pests of the different growth stages of pechay
Growth
Flea Cabbage Looper Cutworm
Leafminer
DBM
Aphid
Total
Stages
beetle butterfly
adult larvae
Seedling
214
12
0
19
169
0
0
2
416
Vegetative
749
237
32
57
288
31
16
0
1410
Flowering
451
66
15
6
11
27
12
0
588
Seeding
782
123
28
3
15
53
53
0
1057
Total
2196
438
75
85
483
111
81
2
3471
800
750
700
650
Flea Beetle
600
550
Cabbage butterfly
500
Looper
450
400
Cutworm
350
Leafminer (adult)
otal population 300
T 250
Leafminer (larvae)
200
DBM
150
100
Aphid
50
0
Seedling
Vegetative Flowering
seeding
Growth Stages
Figure 9. Insect pests population of the growth stages of pechay
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Characteristic Damage Inflicted by the
Insect Pests of Pechay on the Parts of the Plant
Table 3 shows the characteristic damage of the insect pests of pechay on the
parts of the plant.
Flea beetles are found at the leaves, stem, flowers and pods. Possessing chewing
mouth parts, they chew the different parts of the plant resulting to shot holes on the leaves
(Figure 10), stem (Figure11), flowers (Figure 12) and pods (Figure 13).The result
corroborated the study of Wakit (1980) that flea beetles brought damage by chewing on
the foliage of the plants at early stage of growth development. Leaves that are attacked by
these insect pests showed holes.
Figure 10 a. Shot holes on the seedlings
Figure 10 b. Shot holes on the leaves
caused by flea beetle (5x)
caused by flea beetle (5x)
Figure 11. Shot holes on stem caused by
Figure 12. Shot holes on petals caused by
flea beetle (15x)
flea beetles (5x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Figure 13. Shot holes on pod caused by
flea beetles (5x)
Cabbage butterflies, with chewing mouth parts, feed on the crops that result to a cut
that usually starts from the leaf margin (Figure 14). The observation revealed the study of
Davidson and Pears in1996 that the larvae of the cabbage butterfly feed mostly on the lower
surface of the leaves. They form a hole that usually unites into irregular shapes and sizes
in the leaves.
Figure 14. Cut on the leaves starting from
the leafmargin caused by
cabbage butterfly larva (5x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
On the other hand, cabbage loopers (Figure 15) and cutworms (Figure 16) feed on
the crop by chewing the leaves that result to rugged holes. This result revealed the study of
Gacadan (1997) that the damaged leaves had larger irregular holes brought about by
chewing activity of the looper larvae. On the other hand, Mula (2003) said that young
larvae of cutworms make holes on the leaves. Removal of entire leaf blade is caused by the
cutworm during the early stage of the plant (Figure 17).
Figure 15. Irregular holes caused by
Figure 16. Rugged hole on leaf blade due
cabbage looper (5x)
to
a cutworm (5x)
Figure 17. Removed part of leaves caused by cutworm (5x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Irregular patches on the leaves were caused by diamondback moth feeding
(Figure18). These results corroborated the study of Amolang (2000) that diamondback
moth larvae chew the leaves making irregular small and big holes on the leaves. It was also
found out by Wakit (1980) that the larval stage is the most injurious. The larvae attacked
the crop by chewing the tissue of the lower side of the leaves. The attacked leaves were
characterized by presence of small irregular holes.
Figure 18. Irregular patches on the leaves
caused by diamondback
moth larva (5x)
Whitish bloches and winding trail (Figure19) on the leaves were also due to the
leafminer larvae. They feed on the plant by chewing the tissues of the plant. This was
supported by Colting et al. (2003) by saying that the larva makes serpentine and curled
mines on the leaves. This was elaborated by Pyenson (1977) that the basic or primitive type
of mouth part is the chewing type which permits its possessor to bite off or chew on, or
into, external part of a plant or to tunnel its way to some part of the plant. Likewise, the
leafminer adult also contributes to the damage of the plant. The adult leafminer scratches
its ovipositor causing punctures on the leaves (Figure 20). The result corroborate the study
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
of Ligligen (2003) that adult female leafminer uses its ovipositor to make punctures on the
leaves.
Figure 19. Whitish blotch mined by
Figure 20. Punctures on leaf scratched by
leafminer larva (5x)
leafminer adult (5x)
Among the insect pests of pechay that was identified in the study, aphids were the only
insect pest with piercing-sucking mouth parts. When it fed on the plants, it resulted to
yellowish dots on the leaves due to sap extraction. The result agrees with Wakit (1980) that
aphids attacked cabbage crop by sucking the sap. As observed, attacked leaves were
characterized by presence of yellowish dots.
Table 3. Characteristic damage inflicted by the insect pests
of pechay on parts of the plant
CHARACTERISTIC DAMAGE
INSECT PESTS
Leaves
Stems
Flowers
Pods
Flea beetle
Shot holes
Shot holes
Shot holes
Shot holes
Cabbage butterfly
Cuts usually starts
from the margin
Cabbage looper
Rugged holes
Cutworm
Rugged holes
Diamondback moth
Irregular patches
and holes
Leafminer (larvae)
Winding trail
Leafminer (adult)
Punctures
Aphids
Curled leaves
Yellowish dots
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
SUMMARY, CONCLUSION AND RECOMMENDATION
The study was conducted at the Experimental Station, Benguet State University, La
Trinidad, Benguet from July to September 2011.
The study aimed to identify the insect pests of pechay, determine the total number
of insect pests of the growth stages of the crop, and to record the characteristic damage of
the insect pests.
Identified insect pests of pechay are from the family Chrysomellidae, Pieridae,
Noctuidae, Agromyzidae, Plutellidae, and Aphididae.
The total number of insect pests in the seeding stage of pechay is 416. The
vegetative stage had the highest number of insect pests which is 1,410. There are 1,057
insect pests in the flowering stage and the seeding stage had 588 insect pests.
The characteristic damage of flea beetle is shot holes on the leaves, flowers, stems
and pods. The cabbage looper and cutworm larvae chew on the underneath and surface of
the leaf causing rugged holes on the leaf blade, while the leafminer adult punctures on the
leaves scratching its ovipositor. The leafminer larvae damage the leaf by chewing plant
tissues which result to large whitish blotches, block end area and white winding trail
through in the anterior surface of the leaf. The diamondback moth larvae chew the leaves
which cause irregular patches on the leaves, and the aphids suck the plant sap which results
to curling and yellowish dots on leaves,
Conclusion and Recommendation
The insect pests of pechay which are the flea beetles, cabbage butterflies, cutworms,
cabbage loopers, leafminers, diamondback moths, and aphids occurred in all the growth
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
stages of pechay. It is in the vegetative stage where the insect population is highest, while
the lowest population is observed in the seeding stage.
A further study of the seasonal abundance of flea beetles, cabbage butterflies and
leafminers including the management practices for each insect pest could be conducted.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
LITERATURE CITED
AMOLANG, E.S. 2000. Insects Pest Associated with Harvested Crucifers, Cucurbits and
Solanaceous Crops. BS Thesis. BSU, La Trinidad Benguet. P.8.
BALSINA, A.D.2007. Population Abundance of Aphids (Lipasis erysimi) on Cabbage. BS
Thesis. BSU, La Trinidad Benguet. P.1.
COLTING, L.M, B.S. LIGAT, LIRIO, J.C, PEREZ, J. P. PABLO. 2003. Compendium of
Insect Pests and Weeds Associated with Crops in the Cordillera. Cordillera
Highland Agricultural Resource Management (CHARM) project: Cor. Sto.Tomas
Rd. Marcos Highway, Baguio Dairy Farm, Baguio City and Benguet State
University, La Trinidad Benguet.Pp.5, 10, 14.
DA-CAR. 2000. Department of Agriculture Cordillera Administrative Region Field Unit,
BP Complex Guisad 2600 BaguioCity.
DAVIDSON, P. P. and C.J. PEARS. 1996. Insect Pests of Farm Garden and Orchard. John
Wily. New York. P. 325.
ESGUIRRA M. 1961. Insect Pest of Vegetables. University of the Philippines. Department
of Agriculture Communications and Cooperative with the Department of
Entomology. P.1.
GACADAN, E.D. 1997. Biology of Simi-looper; Trichupusia ni Hubner, Lipedoptera;
Noctuidae Infesting Cruciferous Crops. BS Thesis. BSU, La Trinidad Benguet. Pp.
7-9.
KNODEL, J.J. 2002.Biology and Integrated Pest Management in Canola.North Dakota
University. P.1234
LIGLIGEN, A.B. 2003. Life Cycle of Leafminer Liriomyza huidobrensis Blanchard,
(Ditera; Agromyzidae) on Selected Crops. BS Thesis. BSU, La Trinidad Benguet.
Pp. 3, 7.
LUMAS-E, E.F. 1981. Ecological Succession on Insect Pest of Lettuce. BS Thesis.
Mountain State Agricultural College, La Trinidad Benguet. Pp. 7-8.
METCALF, C.L. 1962. Destructive and Useful Insects. United States of America. McGraw
Hill Company Inc. Pp. 596-602.
MULA, R.P. 2003. A Compendium of Insect Pests, Disease, and Weeds of Vegetables.
Caraballio and Southern Cordillera Agricultural Development (CASCADE)
Program. Bayumbong 3700 Nueva Viscaya. Pp.2-8.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
PARKER, B.L., N.S. TALEKAR, and M. SKINNER. 2001. Insect Pest of Selected
Vegetable in Tropical and Sub Tropical in Asia. (Publication 2001) p.1-2.
PYENSON, L.L. 1977. Fundamentals of Entomology and Plant Pathology. Westport
Connecticut. AVI Publishing Company Inc. P. 6.
ROSS.H.H., C.H. ROSS and J.R. ROSS. 1982. A Textbook of Entomology. 4th ed. John
Wiley and Sons. New York, Chester. Brisbane and Singapore. P. 501.
SOLANG, G. 2005. Life Cycle of Stripped Flea Beetle Associated with Pechay and Their
Response to Toxicity of Insecticide. Thesis. BSU, La Trinidad Benguet. Pp. 4-5.
WAKIT, T.P. 1980. Study on Abundance of Pests of Chinese Cabbage. BS theses.
Mountain State Agricultural College. La Trinidad Benguet. P.8.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
TIBAO, MARLON Y. APRIL 2012. Insect Pests Succesion of Organically
Grown Pechay ( Brassica chinensis Linnaeus). Benguet State University, La Trinidad,
Benguet.
Adviser: Maria Ana C. Tanyag, MSc.
ABSTRACT
The study was conducted at Balili Experimental Station, Benguet State University,
La Trinidad, Benguet from July to September 2011 to identify the insect pests of pechay,
determine the total number of insect pests of the growth stages of the crop, and to record
the characteristic damage of the insect pests.
Insect pests observed associated with pechay are the Phyllotreta spp. (Fam.
Chrysomelidae), Pieres rapae (Fam. Pieridae), Trichoplusia ni and Spodoptera litura
(Fam. Noctuidae), Liriomyza huidobrensis (Fam. Agromyzidae), Plutella xylostella (Fam.
Plutellidae), and Myzus persicae (Fam. Aphididae).
The highest insect pest population was observed in the vegetative stage with a total
number of 1,410, while the lowest population of insect pests was recorded in the seedling
stage with a total number of 416. The seeding stage ranked second to the vegetative stage
with a total number of 1,057 insect pests, followed by a total number of 588 insect pests
observed in the flowering stage.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Flea beetles were found to be the most abundant insect pest in all the growth stages
of pechay with a total number of 2,196, followed by leafminers with a total number of 594.
Cabbage butterflies, with a total number of 438, ranked third in abundance followed by 85
cutworms. Diamondback moth was the lowest in number of 81.
The feeding of flea beetles on pechay shows a characteristic damage of shot holes
on the leaves, flowers, stem and pods. The cabbage looper and cutworm inflict rugged
holes on the leaves, while the leafminer adult causes punctures on the leaves. Cuts starting
from the leaf margins are inflicted by cabbage butterflies. Diamondback moth causes
irregular patches on the leaves while yellowish dots are characteristic damage due to
aphids.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
RESULTS AND DISCUSSION
Identification of Insect Pests of
Associated with Pechay
The insect pests observed and collected from the families of Chrysomelidae (flea
beetle), Pieridae (cabbage butterfly), Noctuidae (cutworms and cabbage looopers),
Agromyzidae (leafminers), Plutellidae (diamondback moths), and Aphididae (aphids) are
presented in Table 1. With the observed list of insect pests, the diamondback moth and the
cabbage butterfly as cited by Esguirra (1961) are found on all the growth stages of pechay.
ORDER: Coleoptera
FAMILY: Chrysomelidae
SCIENTIFIC NAME: Phyllotreta
spp.
LOCAL NAME: Timel, Flea
beetle
COMMON NAME: Flea beetle
Figure 1. Flea beetle chewing on the petals. ( 15x)
ORDER: Lepidoptera
FAMILY: Pieridae
SCIENTIFIC NAME: Pieres
rapae (Linnaeus)
LOCAL NAME: Cabbage
butterfly, Bigis
COMMON NAME: Cabbage
butterfly ,
Figure 2. Cabbage butterfly larva chewing on
leaves (10x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
ORDER: Lepidoptera
FAMILY: Noctuidae
SCIENTIFIC NAME:
Spodoptera litura (Fabricius)
LOCAL NAME: Cutworm, Bigis
COMMON NAME: Cutworm
Figure 3. Cutworm chewing on leaves (15x)
ORDER: Lepidoptera
FAMILY: Noctuidae
SCIENTIFIC
NAME:
Trichoplusia ni (Hubner)
LOCAL NAME: Looper, Bigis
COMMON NAME: Looper
Figure 4. Cabbage looper walking on the leaf (5x)
ORDER: Diptera
FAMILY: Agromyzidae
SCIENTIFIC NAME: Liriomyza
huidobrensis (Blanchard)
LOCAL NAME: Leafminer
COMMON NAME: Leafminer
Figure 5. Leafminer larva brought out from the
leaf (400x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
ORDER: Lepidoptera
FAMILY: Plutellidae
SCIENTIFIC NAME: Plutella
xylostella (Linnaeus)
LOCAL NAME: Diamondback
moth, Tarsan, Bigis
COMMON NAME:
Diamondback moth
Figure 6. Diamondback moth larva chewing on the
leaves (10x)
ORDER: Hemiptera
FAMILY: Aphididae
SCIENTIFIC NAME: Myzus
persicae (Zulser)
LOCAL NAME: Aphids
COMMON NAME: Aphids
Figure 7. Aphid sucking on plant leaf (10x)
Table 1. Insect pests associated with pechay
FAMILIES OF INSECT
COMMON NAME
SCIENTIFIC NAME
PEST
Chrysomelidae
Flea beetle
Phyllotreta spp.
Pieridae
Cabbage butterfly
Pieres rapae
Noctuidae
Cutworm
Spodoptera litura
Cabbage looper
Trichoplusia ni
Agromyzidae
Leafminer
Liriomyza huidobrensis
Plutellidae
Diamondback moth
Plutella xylostella
Aphididae
Aphid
Myzus persicae
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Total Number of Insect Pests of
the Growth Stages of Pechay
The number of insect pests found in the four growth stages of pechay was presented
in Table 2.
Insect pests of the seedling stage showed the lowest number of 416 from among all
the growth stages of pechay. The insect pests during this stage were the flea beetles (Figure
1) found to have the highest number of 214, followed by adult leafminer with a total
number of 169. Cutworms (Figure 3) ranked third with a total number of 19, while cabbage
butterflies (Figure 2) with a number of 12 ranked fourth. The lowest number is found in
aphids (Figure 7) with only two counts. It was only in this stage that aphids were observed.
Solang (2005) cited that when adult flea beetles emerge in large number, they can quickly
devastate the seedling of the host plant.
The vegetative stage recorded the highest number of insect pests which is 1,410.
This is because of the longer days of exposure of the crop to the environment (23 days).
Flea beetles, adult leafminers, cabbage butterflies, and cutworms were observed to increase
in number from the seedling stage. The highest number is found in flea beetles 749,
followed by the adult leafminers 288. The third highest count of 237 is observed in cabbage
butterflies while cutworms showed a number of 57, hence ranked fourth. It is in this stage
that 32 cabbage loopers (Figure 4), 31 leafminer larvae (Figure 5), and 16 diamondback
moths (Figure 6) were observed.
The result corroborated the study of Wakit (1980) that the population of flea beetles
was observed to increase as the crop matured due to increasing leaf surface area. However,
the great infestation occurred during the vegetative stage of the plant. The result was also
supported by Lumas-e (1981) that the population of leaf miner was observed three weeks
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after emergence. When the plants were four weeks after emergence, they increased
abruptly.
The total number of all insect pests of the flowering stage was observed to have
decreased 588, compared to the total number of insect pests during vegetative stage. The
highest number was found in flea beetles 451, followed by the cabbage butterflies with a
count of 66. Leafminer larvae ranked third with a count of 27, looper ranked fourth with a
count of 15, followed by the diamondback moth 12, which ranked sixth. The last is the
cutworm with a number of six. This is because of the shorter period of the plants exposure
to the environment (10 days), and the occurrence of typhoons and daily rainfalls which
makes the insects immobile.
The result was again supported by Lumas-e (1981) on her study that the population
of the leafminers decreased at the fifth week after emergence. She added that heavy
drenching rain will wash off many of the weaker insect species.
The seeding stage showed the second highest 1,057 of all the growth stages of
pechay. This is due to the number of days the crop was exposed to the environment (20
days). The population of all insect pests increased except for the cut worms which
decreased in number. The flea beetles were found to have the highest number 782, followed
by the cabbage butterflies with a total number of 123. Ranked third are the leafminer larvae
and diamondback moth with a population of 53, while the fourth are the cabbage loopers
with a total number of 28. The adult leafminer (Figure 8) has a total number of 15 which
ranked fifth, followed by cutworm which decreased with a population of six.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
Figure 8. Adult leafminer scratching its ovipositor
on the leaves (40x)
Table 2. Total number of insect pests of the different growth stages of pechay
Growth
Flea Cabbage Looper Cutworm
Leafminer
DBM
Aphid
Total
Stages
beetle butterfly
adult larvae
Seedling
214
12
0
19
169
0
0
2
416
Vegetative
749
237
32
57
288
31
16
0
1410
Flowering
451
66
15
6
11
27
12
0
588
Seeding
782
123
28
3
15
53
53
0
1057
Total
2196
438
75
85
483
111
81
2
3471
800
750
700
650
Flea Beetle
600
550
Cabbage butterfly
500
Looper
450
400
Cutworm
350
Leafminer (adult)
otal population 300
T 250
Leafminer (larvae)
200
DBM
150
100
Aphid
50
0
Seedling
Vegetative Flowering
seeding
Growth Stages
Figure 9. Insect pests population of the growth stages of pechay
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Characteristic Damage Inflicted by the
Insect Pests of Pechay on the Parts of the Plant
Table 3 shows the characteristic damage of the insect pests of pechay on the
parts of the plant.
Flea beetles are found at the leaves, stem, flowers and pods. Possessing chewing
mouth parts, they chew the different parts of the plant resulting to shot holes on the leaves
(Figure 10), stem (Figure11), flowers (Figure 12) and pods (Figure 13).The result
corroborated the study of Wakit (1980) that flea beetles brought damage by chewing on
the foliage of the plants at early stage of growth development. Leaves that are attacked by
these insect pests showed holes.
Figure 10 a. Shot holes on the seedlings
Figure 10 b. Shot holes on the leaves
caused by flea beetle (5x)
caused by flea beetle (5x)
Figure 11. Shot holes on stem caused by
Figure 12. Shot holes on petals caused by
flea beetle (15x)
flea beetles (5x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
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Figure 13. Shot holes on pod caused by
flea beetles (5x)
Cabbage butterflies, with chewing mouth parts, feed on the crops that result to a cut
that usually starts from the leaf margin (Figure 14). The observation revealed the study of
Davidson and Pears in1996 that the larvae of the cabbage butterfly feed mostly on the lower
surface of the leaves. They form a hole that usually unites into irregular shapes and sizes
in the leaves.
Figure 14. Cut on the leaves starting from
the leafmargin caused by
cabbage butterfly larva (5x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
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On the other hand, cabbage loopers (Figure 15) and cutworms (Figure 16) feed on
the crop by chewing the leaves that result to rugged holes. This result revealed the study of
Gacadan (1997) that the damaged leaves had larger irregular holes brought about by
chewing activity of the looper larvae. On the other hand, Mula (2003) said that young
larvae of cutworms make holes on the leaves. Removal of entire leaf blade is caused by the
cutworm during the early stage of the plant (Figure 17).
Figure 15. Irregular holes caused by
Figure 16. Rugged hole on leaf blade due
cabbage looper (5x)
to
a cutworm (5x)
Figure 17. Removed part of leaves caused by cutworm (5x)
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
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Irregular patches on the leaves were caused by diamondback moth feeding
(Figure18). These results corroborated the study of Amolang (2000) that diamondback
moth larvae chew the leaves making irregular small and big holes on the leaves. It was also
found out by Wakit (1980) that the larval stage is the most injurious. The larvae attacked
the crop by chewing the tissue of the lower side of the leaves. The attacked leaves were
characterized by presence of small irregular holes.
Figure 18. Irregular patches on the leaves
caused by diamondback
moth larva (5x)
Whitish bloches and winding trail (Figure19) on the leaves were also due to the
leafminer larvae. They feed on the plant by chewing the tissues of the plant. This was
supported by Colting et al. (2003) by saying that the larva makes serpentine and curled
mines on the leaves. This was elaborated by Pyenson (1977) that the basic or primitive type
of mouth part is the chewing type which permits its possessor to bite off or chew on, or
into, external part of a plant or to tunnel its way to some part of the plant. Likewise, the
leafminer adult also contributes to the damage of the plant. The adult leafminer scratches
its ovipositor causing punctures on the leaves (Figure 20). The result corroborate the study
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
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of Ligligen (2003) that adult female leafminer uses its ovipositor to make punctures on the
leaves.
Figure 19. Whitish blotch mined by
Figure 20. Punctures on leaf scratched by
leafminer larva (5x)
leafminer adult (5x)
Among the insect pests of pechay that was identified in the study, aphids were the only
insect pest with piercing-sucking mouth parts. When it fed on the plants, it resulted to
yellowish dots on the leaves due to sap extraction. The result agrees with Wakit (1980) that
aphids attacked cabbage crop by sucking the sap. As observed, attacked leaves were
characterized by presence of yellowish dots.
Table 3. Characteristic damage inflicted by the insect pests
of pechay on parts of the plant
CHARACTERISTIC DAMAGE
INSECT PESTS
Leaves
Stems
Flowers
Pods
Flea beetle
Shot holes
Shot holes
Shot holes
Shot holes
Cabbage butterfly
Cuts usually starts
from the margin
Cabbage looper
Rugged holes
Cutworm
Rugged holes
Diamondback moth
Irregular patches
and holes
Leafminer (larvae)
Winding trail
Leafminer (adult)
Punctures
Aphids
Curled leaves
Yellowish dots
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SUMMARY, CONCLUSION AND RECOMMENDATION
The study was conducted at the Experimental Station, Benguet State University, La
Trinidad, Benguet from July to September 2011.
The study aimed to identify the insect pests of pechay, determine the total number
of insect pests of the growth stages of the crop, and to record the characteristic damage of
the insect pests.
Identified insect pests of pechay are from the family Chrysomellidae, Pieridae,
Noctuidae, Agromyzidae, Plutellidae, and Aphididae.
The total number of insect pests in the seeding stage of pechay is 416. The
vegetative stage had the highest number of insect pests which is 1,410. There are 1,057
insect pests in the flowering stage and the seeding stage had 588 insect pests.
The characteristic damage of flea beetle is shot holes on the leaves, flowers, stems
and pods. The cabbage looper and cutworm larvae chew on the underneath and surface of
the leaf causing rugged holes on the leaf blade, while the leafminer adult punctures on the
leaves scratching its ovipositor. The leafminer larvae damage the leaf by chewing plant
tissues which result to large whitish blotches, block end area and white winding trail
through in the anterior surface of the leaf. The diamondback moth larvae chew the leaves
which cause irregular patches on the leaves, and the aphids suck the plant sap which results
to curling and yellowish dots on leaves,
Conclusion and Recommendation
The insect pests of pechay which are the flea beetles, cabbage butterflies, cutworms,
cabbage loopers, leafminers, diamondback moths, and aphids occurred in all the growth
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
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stages of pechay. It is in the vegetative stage where the insect population is highest, while
the lowest population is observed in the seeding stage.
A further study of the seasonal abundance of flea beetles, cabbage butterflies and
leafminers including the management practices for each insect pest could be conducted.
Insect Pests Succesion of Organically Grown Pechay ( Brassica chinensis Linnaeus)|
TIBAO, MARLON Y. APRIL 2012
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