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 caused by tick infestations that reduce the productivity of their livestock. To diminish these losses, natural products (eco-friendly) for ectoparasite control with lower chance of improvement of resistance are required. This study aimed to examine the effect of different concentrations (0.5, 1.5, 2.5, and 4%) of Allium sativum (Garlic) extract on the viability of eggs laid by Argaspersicus 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. Applying different concentrations (100, 200, 400, 500, and 600 ppm) of garlic extract on the eggs resulted in the percentage of unhatched eggs increasing significantly as garlic concentrations also increased.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 include: the 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 that garlic extract affected A. persicus oogenesis by interfering with the formation of yolk granules and egg shells. Our results suggest that garlicextract causes partial blockage of the vitellogenesis and other aspects of oogenesis as indicated by disrupted synthesis of yolk protein in the newly formed oocytes.