Fecundity and fertility inhibition effects of some plant essential oils and their major components against Acanthoscelides obtectus Say (Coleoptera: Bruchidae)

Fecundity (egg production) and fertility (egg hatchability/progeny production) are important components of both sexual and asexual reproduction of insects. Some plant essential oils (EOs) are reported to be active inhibitors against various insect pests by reducing or completely hindering their fecundity and fertility. The present study was carried out to determine the inhibitory effects of three plant EOs [eucalyptus (Eucalyptus camaldulensisDehn.), peppermint (Mentha piperitaL.) and anise (Pimpinella anisumL.)] and their major components (1,8-cineole, L-menthol and trans-anethole, respectively) on egg-laying and progeny production of bean weevil,Acanthoscelides obtectusSay (Coleoptera: Bruchidae), which is an economically important pest of common bean,Phaseolus vulgarisL. (Fabaceae), in tropical and subtropical regions. The EOs were extracted by hydro-distillation, and their chemical composition was determined by gas chromatography-mass spectrometry. The oils and components were bio-assayed via fumigation against the pest by exposing newly emerged virgin females and young males to the median lethal concentration (LC50) of each material for 10 h. After the exposure, the surviving individuals were mated in the following combinations; treated females x treated males (TF x TM), untreated females x treated males (UF x TM), treated females x untreated males (TF x UM), untreated females x untreated males (UF x UM). According to the results, the highest fecundity inhibition was observed in TF x TM with 86.05%, 71.9% and 55.72% for anise, eucalyptus and peppermint oils, respectively. In addition, the highest progeny production inhibition was seen in the TF x TM combination with 93.3%, 68.0% and 44.9% after exposing to eucalyptus, anise and peppermint oils, respectively. Overall the results showed that the exposure of newly emerged adults by the median lethal concentration of EOs and their major components negatively affected the egg-laying and progeny production of bean weevil. These results may also pioneer new approaches in insect pest control of stored products.