Eggs viability and Histological Changes in Ovary of Argas (Persicargas) persicus (Acari: Argasidae) after Treatment with Allium sativum Extract.

Abstract

Agriculturists in developing countries are suffering from many diseases that reduce the productivity of their livestock caused by tick infestations. To diminish these losses, natural products (eco-friendly) for ectoparasite control with lower chance of improvement of resistance are required. This study aimed to study the effect of different concentrations (0.5, 1.5, 2.5, and 4%) of Allium sativum (Garlic) extract on viability of eggs laid by Argas persicus females and their ovaries development. It was found that, the number of eggs laid by treated females were significantly (P<0.05) decreased than those laid by normal females. There is a significant inverse relationship between the treatment concentration of garlic extract and the percentage of hatched eggs. Direct application on eggs with different concentrations (100, 200, 400, 500, and 600 ppm) of garlic extract resulted in significant increase in the percentage of unhatched eggs as the concentrations increase. The average diameters of oocytes in treated females were decreased by 61% from the normal oocytes average diameter and the ovary appeared studded with previtellogenic primary oocytes. Histological changes observed in the treated ovaries included: presence of vacuolization; alteration of oocyte morphology, which changed from rounded to elongate, disorganization of the yolk granules, and deformation of the chorion. These results demonstrate the action of garlic extract on A. persicus oogenesis which interfered with the formation of yolk granules and egg shell. Our results suggests that garlic extract causes partial blockage of the vitellogenesis and other aspects of oogenesis as indicated by disrupted synthesis of yolk protein in the newly formed oocytes.