Fatty acids for insect species remain constant: A case study of pink bollworm, Pectinophora gossypiella (Saunders)

Abstract

Pink bollworm, Pectinophora gossypiella (Saunders) originates from South Asia and has spread across major cotton-growing regions. The pest is considered to be the most destructive and of economic concern across the globe. In India, the pest has developed resistance to dual Bt toxins and its concealed feeding nature makes the target sites almost inaccessible for the insecticide. In view of this issue, there is need to identify a suitable alternative for its management. In this context, semiochemicals serve as one of the best eco-friendly options. These chemical substances or mixtures broadcast messages for the purpose of communication. Semiochemicals may be released from eggs, faecal pellets, tarsal segments, scales, anal tufts and/or any insect components that reduce the intra/interspecific competition for shared resources such as food, mating, oviposition site etc. Accurate identification of the semiochemical compounds and their proportion in natural blends that arouse a strong behavioural response in insects, requires a thorough knowledge. Therefore in the present study, we tried to explore the chemicals present in eggs, faecal pellets and whole-body wash extracts of mated female. Seven compounds were identified from a methanolic extract of faecal-pellet samples, namely hexadecanoic acid, 9,12-octadecadienoic acid, 9-octadecenoic acid and their methyl esters along with methyl stearate. However, only four methyl-esterified forms were found in common in eggs and female body wash extract. This clearly shows that the compounds remain constant and conserved for the species but the role of these compounds needs to be demonstrated.