INSECTICIDAL EFFECTS OF ESSENTIAL OILS OBTAINED FROM SIX PLANTS AGAINST CALLOSOBRUCHUS MACULATUS (F.) (COLEOPTERA: BRUCHIDAE), A PEST OF COWPEA (VIGNA UNGUICULATA) (L.)

Abstract

Callosobruchus maculatus (F.), cowpea seed beetle (Coleoptera: Bruchidae) is one of the most serious pests of cowpea (the black-eyed pea) grains, worldwide. In this study, essential oils of Artemisia dracunculus L., Artemisia santonicum L., Artemisia spicigera C. Koch, Origanum onites L., Satureja thymbra L. and Thymus sipyleus Boiss. were tested for their insecticidal activities against three day-old adults of C. maculatus at 25 +/- 2 degrees C, 65 +/- 5 % r.h. in dark conditions, at different exposure times (12, 24, 48 and 72 h), and doses (5, 7.5 and 10 mu l). It was found that there were the mortalities in all exposure doses and durations. The percentage mortality of adults of C. maculatus increased with increasing the concentration of different oils and exposure times. Minimum mortality rate in C. maculatus adults (16.6%) was recorded at 12 h with 5 mu l essential oil of O. onites, while the peak mortality was registered as 100%, at 72 h with 10 mu l essential oil of A. dracunculus. Additionally, LD25, LD50 and LD90 values of each essential oil were estimated for C. maculatus. Results suggested that the essential oils from the tested plants could be used as potential control agents against C. maculatus adults in stored cowpea (the black-eyed pea) protection.