Effect of thymol on reproductive biology of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

The objective of this study was to determine the possibilities for use of thymol, a common compound in essential oils of Thymus and Origanum plants, as an alternative biopesticidal compound to control Helicoverpa armigera. Thymol was applied to Helicoverpa armigera larvae topically and also administered orally at sublethal levels to determine the effects on their reproduction and development. Thymol did affect egg development and oviposition was reduced by 9.42 and 38.86% under two different applications, respectively. Growth inhibition was also observed and 6.7% of insects were dead as larvae, 42.4% as pupae and 6.6% as pupal-adult intermediates. The present studies clearly indicate that thymol used at sublethal levels can alternatively control bollworms by altering reproductive mechanisms.