Evaluation of vegetable oil as oviposition deterrents for the management of pink bollworm, Pectinophora gossypiella (Saunders) in cotton

Oviposition deterrents are the info-chemicals that modifies the behavior of conspecific female insects either to settle on the treated surface or to lay eggs thereafter, reducing intra-specific competition. Drawing from our prior research, it has been established that the fatty acids (Oleic and linoleic acid) found in vegetable oils exhibit properties of oviposition deterrence. The present study was designed to investigate the oviposition deterrent activity of vegetable oils against pink bollworm. Six different vegetable oils, namely groundnut, sunflower, soybean, rice bran, safflower and sesame containing oleic and linoleic acid as major fatty acids were selected and evaluated under laboratory and field conditions. Under laboratory conditions, oils were tested at concentrations ranging from 0.5 to 3.0%, with methanol as control. Cotton twigs with squares served as the oviposition substrate and the total number of eggs laid by the moth was counted and compared to control. The results demonstrated a significant reduction in number of eggs laid as evident from the avoidance index (AI) and percent effective deterrence (PED) values of vegetable oil treatments. Descending order of oviposition deterrent efficacy as revealed from AI and PED values, groundnut (AI = 0.74, PED = 84.40%) > soybean (0.67, 79.87%) > sesame (0.65, 78.59%) > sunflower (0.59, 74.09%) > rice bran (0.57, 71.93%) > safflower (0.55, 71.09%). Our findings were further validated through field studies conducted during 2019–2020 and 2020–2021, confirming effectiveness of the selected vegetable oils in reducing the boll damage. Study demonstrates the promising oviposition deterrent effect of vegetable oils against Pectinophora gossypiella and hold great potential as an eco-friendly component in integrated pest management program of cotton.