Histological effects of some essential oils combination on different tissues of the black cut worm larvae Agrotis ipsilon (Hufn.)

Abstract

Plant essential oils and terpenes may be used as a spray or as a bait feeding trap for controlling A ipsilon as an alternative means of chemical pesticides in IPM programs. Oil combination promotes their effect and decrease insect buildup resistance because it contains many different terpenes, which have different modes of action. The combination of LC₅₀ concentration of Garlic oil at (0.030%) and Mint oil (0.160%) in one artificial diet for the 3^rd larval instar of A.ipsilon cleared great changes have been detected by light microscope in different larval tissues compared with the untreated control larvae. No pathological changes were detected on the fore gut, salivary gland or malpighian tubules, most of the histopathological changes were mostly localized in the mid gut, hind gut, fat body, integument and trachea. Different cells of the mid gut exhibited a swelling, appearance and microvilli showed complete disorders in many areas, increasing in goblet cells secretion with rupture of basement membrane, many vacuolation occurred in the cell cytoplasm. Tracheal tubes become narrow; Muscle fiber showed relaxation and disintegration of the fibrils, hind gut showed lyses in the intima layer, disintegration of some of the epithelial cells. Vacuolization of the fat bodies occurred. Detachment of the cuticle from epidermis in some areas. This article is the first record on the histopathological effects of the combination of natural essential oils (Garlic+ Mint) as a bio-insecticide on different tissues of A. ipsilon larvae and the data may contribute to a knowledge of the mode of action of this combination used as a bio-insecticide against the larvae of this insect pest. So the results suggested that the   combination of the natural plant essential oils of garlic with mint in one spray solution may be used in IPM program against A. ipsilon larvae.