Effect of essential oil of colocynth, Citrullus colocynthis and spearmint, Mentha spicata against the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae)

Abstract

Khapra beetle Trogoderma granarium is considered to be the most severe primary pests, affected both the quality and quantity of wheat during storage. Therefore, khapra beetle is a serious problem in developing and developed countries. A laboratory study was performed to evaluate the influence of the essential oil rate of spearmint Mentha spicata and colocynth Citrullus colocynthis against khapra beetle T. granarium to determine the mortality rate of egg, larvae, pupa, and adults. Throughout the experiment, increasing the doses of essential oil of spearmint resulted in the highest rate of mortality of the khapra beetle egg, larvae, and pupa compared with increasing the rate of essential oil of colocynth. Thus, a linear relationship was found between the mortality rate of khapra egg, larvae, and pupa with the essential oil rate of spearmint. The highest mortality rate of adults (94%) was obtained by applying 50 µL of spearmint. In contrast, the highest concentrations (40 and 50 µL) of essential oil of colocynth showed the lowest mortality rate of khapra beetle adults. This study suggested that the essential oil of spearmint could be utilized as potential control agents for stored-product insects in wheat.