Lethal and sublethal effects of essential oils from Eucalyptus camaldulensis and Heracleum persicum against the adults of Callosobruchus maculatus.

ABSTRACT

The cowpea weevil, Callosobruchus maculatus F. (Coleoptera Bruchidae), is an important pest of stored cowpea, Vigna ungiculata (L.) Walpers (Fabales Fabaceae), with ample distribution in tropical and subtropical regions. Many plant essential oils have a broad-spectrum activity against pest insects, and these oils traditionally have been used in the protection of stored products. In this study, the lethal and sublethal effects of essential oils from Eucalyptus camaldulensis Dehnh. (Myrtales Myrtaceae) and Heracleum persicum Desf. (Apiales Apiaceae) were evaluated on the adults of C. maculatus at 26 ± 1° C, 70 ± 5% RH, and a photoperiod of 168 LD. The LC50 values of E. camaldulensis and H. persicum were 56.7 and 219.4 µL/L air after 12 hr and 26.1 and 136.4 µL/L air after 24 hr of exposure, respectively. The LT50 values of E. camaldulensis and H.persicum were 6.3 and 10.9 hr, respectively. The results showed that low lethal concentration (LC20) of essential oils negatively affected the longevity, fecundity, and fertility of female adults. The sex ratio of C. maculatus offspring was not significantly affected by essential oils. Therefore, these essential oils can be suggested for controlling C. maculatus in storage systems. The introduction of essential oils into storage systems could potentially decrease seed losses.