Abstract
Studies were undertaken to identify pigeonpea, Cajanus cajan (L.) Millspaugh and the wild relative of pigeonpea, Cajanus scarabaeoides (L.) (accession ICPW 125,) genotypes that are hospitable to the pod borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larval parasitoid, Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) for the management of this pest in pigeonpea based cropping systems. Percentage parasitization of the H. armigera larvae by the C. chlorideae females was greater under no-choice conditions than under multi-choice conditions because of forced parasitization under no-choice conditions. Lowest parasitization was recorded on the wild relative, ICPW 125, which may be due to long nonglandular hairs and low survival of H. armigera larvae. Parasitization of H. armigera larvae was greater under no-choice, dual-choice and/or multi-choice conditions on ICPL 87, ICPL 87119 and ICPL 87091, which are susceptible to H. armigera, than on the pod borer-resistant genotypes ICPL 332WR, ICPL 84060 and ICPB 2042; while survival and development of the parasitoid was better on H. armigera larvae fed on ICPL 87, ICPL 87119, LRG 41, ICP 7035 and ICPL 87091 than on ICPL 332WR, ICPL 84060, ICPB 2042 and ICPW 125. The genotypes ICPL 87, ICPL 87119, LRG 42 and ICPL 87091 that are hospitable to C. chloridae, are better suited for use in integrated pest management to minimize the losses due to H. armigera in pigeonpea.
Highlights
Pigeonpea is one of the major pulses grown in the semi-arid tropics between 30°N and 30°S, covering about 50 countries in Asia, Africa and the Americas
Effectiveness of C. chlorideae in parasitization of H. armigera larvae on different genotypes of pigonpea No-choice conditions Under no-choice cage conditions, there were significant differences in larval parasitization on different pigeonpea genotypes, and highest parasitization was recorded on ICPL 87 (61.74%), followed by ICPL 87119 (52.55%), ICPL 87091 and (41.39%) (Figure 1)
Least larval parasitization was observed on the pigeonpea wild relative, C. scarabaeoides accession ICPW 125 (2.00%), probably because of the presence of long hairs and/or chemicals that may be repellent to the adult wasps, and the possible adverse effects of secondary metabolites in this accession on the parasitoid survival and development
Summary
Pigeonpea is one of the major pulses grown in the semi-arid tropics between 30°N and 30°S, covering about 50 countries in Asia, Africa and the Americas. It is damaged by more than 200 species of insects, of which Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is the most important pest in the semi-arid tropics (Reed et al 1989; Sharma 2005). Helicoverpa armigera has a wide host range, and feeds on more than 250 crop species. It has developed very high levels of resistance to conventional insecticides, including synthetic pyrethroids (Kranthi et al 2002). Helicoverpa armigera is a polyphagous pest (Bilapate 1984; Firempong and Twine 1986), damaging a wide range
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