INTEGRATED PEST MANAGEMENT ~.. )- GRAIN AND VEGETABLE COWPEA Vigna unguiculata (L.) Walp.

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1 - d$> ~$! ~~ :J; ~ INTEGRATED PEST MANAGEMENT ~.. )- GRAIN AND VEGETABLE COWPEA Vigna unguiculata (L.) Walp. BY SUjAG. THESIS SUBMITfED IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE DEGREE OF DOCTOR OF PHILOSOPHY FACULTY OF AGRICULTURE KERALA AGRICULUTURAL UNIVERSITY DEPARTMENT OF AGRICULTURAL ENTOMOLOGY COLLEGE OF AGRICULTURE, VELLAYANI THIRUV ANANTHAPURAM

2 CERTIFICATE Certified that this thesis entitled "Integrated pest management in grain and vegetable cowpea Vigna unguiculata (L.) Walp." is a record of research work done independently by Mrs. Suja G. under my guidance and supervision and that it has not previously formed the basis for the award of any degree, fellowship or associateship to her. ~ Vellayani, Dr. S. NASEEMA BEEVI (Chair person, Advisory committee) Associate Professor, Department of Entomology, College of Agriculture, Vellayani.

3 ABSTRACT The research on "Integrated Pest Management in 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 gram 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 DAS and Pod borers, Pod bugs and A. craccivora at 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).

4 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 DAS and 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 251.8:1:6.74 and 914:1:50.28 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

5 j density. The turning rate increased with increase in hunger level, but searching speed decreased with increase in hunger level. The fitstand second instar grubs remained on the undersurface of cowpea leaves while the third and fourth instar moved towards the terminal shoot. The fitstinstar 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 LCsovalue (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

6 4 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 I% wherever fungal disease is prevalent. Clean cultivation. Treating the seeds with rhizobium g ha-ibefore sowing. Monitoring the fields for incidence of pests / population of natural enemies especially at DAS for A. craccivora, epilachna beetles and pod borers and DAS for pod bugs.

7 . 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 sexmacu/atus Harmonia octomacu/ata and maggots of I scutellare. Need based application of Fusarium 106 spores mr! 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

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