A semi-synthetic chickpea flour based diet for long-term maintenance of laboratory culture of Helicoverpa armigera

Artificial rearing of insects in the laboratory is a pre-requisite for undertaking studies on insecticide/biopesticide bioassays, and evaluation of germplasm, segregating breeding material, mapping populations, and transgenic plants for resistance to insects. For successful rearing of insects in the laboratory, there is need for standardizing a semi-synthetic diet that supports survival and development of the insect for several generations. We tested different semi-‘synthetic diets for rearing the legume pod borer, Helicoverpa armigera for two generations under laboratory conditions. All the semi-synthetic diets tested supported the growth and development of H. armigera up to adult emergence, but there were significant differences in survival and development and fecundity on different diets. The highest larval survival was observed in the wheatgerm based diet in first (97.5%) and second generation (93.5%), followed by chickpea based modified diet (93.75% survival in both the generations). The lowest larval weights (270.7 and 283.7 mg) were recorded in the tapioca granules diet in 1^st and 2^nd generation, respectively. The adult emergence ranged from 68.7 to 83.3%, and 60.4 to 81.2% in the 1^st and 2^nd generation, respectively. Least fecundity was observed in the tapioca granules based diet (422 and 603 eggs per female) in both the generations, but the differences were not significant. Complete or partial replacement of agar-agar with tapioca granules was not suitable for use in artificial diets. The results indicated that modified chickpea flour based diet was quite appropriate for rearing H. armigera under laboratory conditions.