PhD

The research on "Integrated Pest Management m grain and vegetable
cowpea, Vigna unguiculata (L.) Walp." was carried out in the college of
Agriculture, Vellayani and Onattukara Regional Agricultural Research Station,
Kayamkulam to evolve a suitable integrated management strategy against the major
pests attacking grain cowpea.
A survey was conducted to monitor the incidence of major pests of cowpea,
their associated natural enemies and the plant protection measures adopted among
the 90 farmers m the three major grain cowpea growmg areas
viz. Thiruvananthapuram, Alappuzha and Palakkad districts. The major pests
recorded in the survey were Aphis craccivora Koch. Ophiomyia phaseoli Tryon and
Liriomyza trifolii Burgess at 20-25 DAS and Pod borers, Pod bugs and
A. craccivora at 55-60 DAS. -Among the natural enemies observed, Coccinella
transversalis F. was the predominant one in Palakkad district, whereas
Menochilus sexmaculatus F. and Micraspis sp. dominated in Alappuzha and
Thiruvananthapuram districts.
The peak population of A. craccivora and percentage infestation by pod
borers were observed at peak flowering and pod formation stage (59 DAS), whereas
the pod bug population was maximum at pod maturity stage (68 DAS).

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The population of predators was also observed to be maximum at 59 DAS. The
A. craccivora population and the percentage of pod borer damage were higher in the
unprotected cowpea fields compared to that in the nearby farmer's fields. A similar
trend was observed in the case of predators also.
The plant protection measures were adopted by 82.2 and 74.1 percent of the
farmers at 20-25 DAS and 55-60 DAS, respectively. Synthetic insecticides were
used by majority of the farmers, of which the organophosphates took the major
share. Most of the farmers used contact insecticides rather than systemic, at both the
stages of the survey. Majority of the farmers used the recommended dose of
insecticides while the volume of spray fluid used was below the recommended one.
Most of the cowpea growing farmers in Thiruvananthapuram district gained
information on plant protection measures through mass media and neighboring
farmers, whereas in Alappuzha and Palakkad districts the main source of
information was from the ScientistlUniversity and seminars, respectively.
Among the major predators, coccinellids were found to be the most efficient
one since both the grubs and adults were predaceous in nature and present in cowpea
fields in all the seasons. The maximum feeding potential was observed for
C. transversalis with a mean total consumption of 251.8±6.74 and 914±50.28
A. craccivora by a single grub and adult, respectively.
In the study on the predatory behaviour of coccinellids revealed that the
searching speed and turning rate were found to be increasing with increase in prey

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density. The turning rate increased with increase in hunger level, but searching
speed decreased with increase in hunger level. The first and second instar grubs
remained on the undersurface of cowpea leaves while the third and fourth instar
moved towards the terminal shoot. The first instar grubs were cannibalistic on their
own unfertile eggs, the second instar fed on the nymphs of aphids and third and
fourth instar fed voraciously on adult and nymphs of aphids. Adult females were
more efficient than males in recognizing, attacking and consuming aphids.
The bioassay using bio rational insecticides indicated that neem oil was
having the highest LCso value (least toxicity) and safety index to both the third instar
grubs and adults of C. transversalis and M sexmaculatus, followed by Nimbecidine.
Among the synthetic insecticides, chlorpyriphos was having the highest safety index
on the third instar grubs and adults of C. transversalis and M sexmaculatus.
From the pest management trial conducted for two seasons (January to May
2000 and 2001), two treatments viz., neem kernel suspension 5% + mechanical
+ cultural control and chlorpyriphos 0.05% + mechanical + cultural control were
found to be the promising ones in terms of their effectiveness against major pests,
safety to natural enemies, highest per hectare yield, highest marginal benefit: cost
ratio and the very low level of terminal residues (below MRL).
Evaluation studies in storage also indicated no damage in the grains obtained
from the treatments received chlorpyriphos 0.05% followed by NKS 5% up to fIve

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months of storage. No significant variation in weight loss was observed among the
various treatments.
The technologies emerged superior in various experiments along with the
already proven techniques was tested in farmers' fields in 3 locations through their
participation, in comparison with farmers practice to work out an IPM strategy.
The mean population and extent of damage by all the pests in IPM plots were
significantly low compared to farmer's practices. The population of natural enemies
though not significant, in all the stages, was high compared to those in farmer's
practices. The IPM treatments were superior in terms of yield and benefit: cost ratio
also.
Thus, an IPM strategy against major pests of cowpea could be developed as
• Burning of trash before sowing
• Selecting healthy seeds
• Soil drenching with Bordeaux mixture 1 % wherever fungal disease is
prevalent
• Clean cultivation
• Treating the seeds with rhizobium culture @ 250-375 g ha-1 before sowing
• Monitoring the fields for incidence of pests / population of natural enemies
especially at 52-59 DAS for A. craccivora, epilachna beetles and pod borers
and 60- 68 DAS for pod bugs.

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• Adopt mechanical methods of pest control such as application of dry leaf ash
at 10 DAS, keeping yellow sticky trap / yellow pan tray and collection and
destruction of infested leaves, flower buds and pods and sweeping and
destruction of the pests.
• Collection and release of potential natural enemies viz., grubs and adults of
C. transversalis, M sexmaculatus Harmonia octomaculata and maggots of
I scutellare
• Need based application of Fusarium pallidoroseum @7x 106 spores ml'
specifically for the management of A. craccivora
• Need based application of neem kernel suspension (NKS) 5% or
chlorpyriphos 0.05% during 45 DAS in the case of moderate incidence of
A. craccivora, epilachna beetles and pod borers and a second spray using
NKS 5% at 60 DAS if needed against pod borers and pod bugs