Mechanism of Resistance in Wild Gossypium species to Helicoverpa armigera (Hübner)
Mar 7, 2019
Eight wild species of Gossypium were evaluated to determine the mechanism of resistance to Helicoverpa armigera (Hübner). Wild species, viz. Gossypium anomalum, G. raimondii, G. harknessii, G. arboreum, G. palmari, G. davidsonii, G. armourianum and G. stocksii and the susceptible control MCU 9 and TCHB 213 were included in the study. Oviposition studies revealed that none of the wild species was preferred for oviposition both under free choice and no choice test. The lowest number of eggs was laid on G. harknessii, G. raimondii, G. stocksii and the largest 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.