Efficacy of helicoverpa armigera (Hubner) on conventional and genetically modified cotton from Dhule district

Abstract

The study deals with efficacy of cotton bollworms, Helicoverpa armigera (Hubner), on conventional, and Genetically Modified (GM) (Bollgard® and Bollgard® II) cottons plants, (Gossypium hirsutum L.) from Dhule District. This study was carried out in field as well as laboratory experiments. The neonate larvae of Helicoverpa armigera were placed on the selected components of cotton squares and flowers of conventional, and Genetically Modified (GM) cotton varieties. As the result we found that the survival of Helicoverpa armigera was greater on flower anthers and square anthers than on other floral parts for each cotton cultivar. The survival of Helicoverpa armigera was found lowest on all Genetically Modified (GM) cotton plant s (Bollgard®) floral structures. On Bollgard® cotton plants, more larvae were recovered from white flowers and bolls. To quantify injury from bollworms on Genetically Modified (Bollgard® and Bollgard® II) cottons plants, first instar larvae were placed in white flowers of conventional, Bollgard®, and Bollgard® II cottons plants. Bollworms damaged proximately two and three times more fruiting forms on conventional cotton plants than on Bollgard® and Bollgard® II cotton plants, respectively. To evaluate the influence of alternate hosts on bollworm sensitivity to conventional and Bollgard® cottons plants, host colonies were established on field grain sorghum, Sorghum bicolor (Moench); corn, Zea mays L.; soybean, Glycine max (Merrill); conventional cotton plants; and meridic diet. For the evaluation of larval behavior on Bollgard® cotton plant, first instar of Helicoverpa armigera were placed on terminals of non-flowering and flowering cotton plants. Larvae were recovered lower on Bollgard® cotton plants than on conventional cotton plants. Larvae remained near the terminals of conventional cotton plants feeding onterminal foliage and squares. In the present study, we found that the field corn and grain sorghum was the best hosts for bollworm, Helicoverpa armigera than the cotton plants.