Field evaluation of Helicoverpa armigera nucleopolyhedrovirus formulationsfor control of the chickpea pod-borer, H-armigera (Hubn.), on chickpea (Cicer arietinum var. Shoba) in southern India

Treatment of chickpea with HearNPV(1) at 1.5 x 10(12) p.i.b. per ha was as effective, or better at controlling Helicoverpa armigera larvae, and increa sing yield relative to control, than either a standard chemical insecticide , endosulfan, or Bacillus thuringiensis, in two successive years. Currently high virus production costs make the viral treatments uncompetitive compar ed with the chemical treatment, but more economic than B. thuringiensis tre atments. Several formulations of virus were tested, including an emulsifiab le concentrate, a ULV suspension and a microencapsulated preparation, but n one were consistently more effective than a filtered but un-purified aqueou s suspension of HearNPV. Yield and pod damage correlated with mid and late season number of medium-sized and large larvae. Persistence of all treatmen ts, including endosulfan and B. thuringiensis was short, and six treatments were necessary to provide adequate crop protection. HearNPV was the slowes t-acting of the three control agents, with average survival times (AST) of 5.5 days, compared with 3.2 and 4.3 days for larvae fed leaves treated with B. thuringiensis and endosulfan, respectively. Marginal rates of return we re not very sensitive to product costs. Further research should focus on fo rmulations designed to prolong virus persistence, and socio-economic studie s to design the optimal implementation route for this technology. Supply, c ost and quality control issues need to be addressed. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.