Histological effects of essential oils, their monoterpenoids and insect growth regulators on midgut, integument of larvae and ovaries of khapra beetle, Trogoderma granarium everts

Abstract

Trogoderma granarium is one of the world’s most feared stored-product pests. This study has been conducted to evaluate the histological effects of caraway essential oil and its major monoterpenoid, carvone as well as pyriproxyfen, a juvenile hormone analogue on T. granarium treated as 4th instar larvae. Severe effects were found in the midgut of 4th instar larvae treated with 0.5 mL diluted caraway oil, 2 mL diluted carvone for 2 days. The mid gut and ovarioles of female adults resulted from 4th instar larvae of T. granarium treated with the same concentrations showed also characteristic variations. The histological changes in the midgut and integument of 4th instar larvae treated with 0.05 mL pyriproxyfen for 5 days as well as midgut, integument of delayed 6th instar larvae and ovarioles of female resulted from these treatments after 20 days showed great destruction.