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Efficacy of lemongrass essential oil and citral in controlling Callosobruchus maculatus (Coleoptera: Chrysomelidae), a post-harvest cowpea insect pest

de Souza Alves, Marcela, Campos, Ivana Mello, de Mello Conde de Brito, Diego, Cardoso, Cristiane Martins, Pontes, Emerson Guedes, de Souza, Marco Andre Alves
Crop protection 2019
Callosobruchus maculatus, Chrysomelidae, Cymbopogon citratus, Vigna unguiculata, acetylcholinesterase, biotransformation, citral, cowpeas, crop production, enzyme activity, essential oils, females, fumigants, grains, insect pests, lipid composition, males, mortality, oogenesis, oviposition, sexual behavior, storage pests, storage time, toxicity, triacylglycerols
The cowpea weevil, Callosobruchus maculatus (F.), is a storage pest that mainly infects cowpea (Vigna unguiculata (L.) Walp), spending part of its life cycle inside the grains. Depending on the region, the decrease in cowpea production by cowpea weevils can exceed 70% during a six-month storage period. This study investigated the fumigant effect of lemongrass essential oil (Cymbopogon citratus (DC.) Stapf.) and citral on the reproductive cycle, sexual behaviour, lipid composition and the enzymatic activity of biotransformation enzymes in cowpea weevils. Mortality (61.43%, 85.00%), oviposition (4.00%, 29.51%) and emergence (10.32%, 1.51%) were observed for lemongrass essential oil and citral treatments, respectively. Exposure to lemongrass essential oil led to changes in behavior for both sexes, decrease in triacylglycerol content of virgin and mated females, and reduction of the activities of acetylcholinesterase (females and males) and β-esterase (females). These changes may affect the survival, energy resource transfer during oogenesis and oviposition, which are likely mechanisms involved with essential oil toxicity.