Mechanism of Resistance in Wild Gossypium Species to Helicoverpa armigera (Hubner)

Eight species of wild Gossypium viz., Gossypium anomalum, G. raimondii. G. harknessii, G. arboretum, G. palmari, G. davidsonii, G. armourianum and G. stocksii and the susceptible controls MCU 9 and TCHB 213 were evaluated to determine the mechanism of resistance to Hericoverpa armigera (Hubner). None of the wild species was preferred for oviposition both under choice and no choice tests. The lowest number of eggs was laid on G. harknessii, G. raimondii, G. stocksii and the largest on MCU 9 and TCHB 213. Trichome density did not show linear relationship with oviposition. G. raimondii, G. anomalum, G. davidsonii, G. armourianum and G. stocksii were least preferred for feeding by H. armigera larvae and adversely affected the larval survival, weight gain, pupation weight and size of the pupae, adult emergence and sex ratio exhibiting antibiotic effect on the growth and development of H. armigera. Tannin, gossypol and total phenols in the leaves and fruiting bodies of wild species were negatively correlated with weight, survival of larvae and pupation of H.armigera.