Toxic Effect of Garlic Extracts on the Eggs of Aedes aegypti (Diptera: Culicidae): A Scanning Electron Microscopic Study

Abstract

The surface features of the eggs of Aedes aegypti (L.) and the effect of garlic extracts on their hatching were studied by scanning electron microscopy. The exochorion and endochorion layers of the eggshells display an essentially pentagonal reticulation. The exochorion meshwork exhibits large and small papillae interconnected by horizontal struts. At higher magnification, the large papillae show aeropyles on their rough surface. Eggs hatched in deionized water undergo complete fracture near the anterior poles producing free shell caps. In contrast, eggs placed in 6% reconstituted Kyolic garlic extract are only partially fractured, display attached shell caps, and the larvae remain trapped within the shells. In the natural garlic bulb extract, the eggs show no fracture lines in their shells. No larvae were observed either alive or dead in the garlic extracts, suggesting the embryos were disabled before they could escape from their eggshells as viable larvae. It is concluded that aqueous extracts of garlic inhibit hatching of Aedes eggs. Thus, compounds in garlic may be beneficial in the control of mosquitoes.