Selection for tolerance in Callosobruchus maculatus to sub-lethal doses of essential oils of Eugenia aromatica and Piper guineense

Abstract

Selection for tolerance to sub-lethal doses of essential oils of Piper guineense and Eugenia aromatica in population of Callosobruchus maculatus adult and effect of the selection bioassay on egg and larval stages was achieved through exposure to oil vapour (0.05ml, 0.1ml and 0.2ml) under laboratory conditions of 28 ± 3 oC and 65% ± 5% relative humidity. The populations exposed to the oil vapour were termed “selected population” while the unexposed populations were termed “unselected population”. All stages of the insect were monitored for four generations. The results show that adult individuals of the beetle exposed to essential oils for four generations showed no significant increase in percentage survival between the different generations. However, there was significant increase in the numbers of adult emergence from one generation to the next in C. maculatus selected as eggs and larvae, irrespective of the sub-lethal dose of the essential oils of P. guineense and E. aromatica respectively.