Larvicidal, Histopathological and Ultra-structure Studies of Matricharia chamomella Extracts Against the Rift Valley Fever Mosquito Culex quinquefasciatus (Culicidae: Diptera)

摘要

The present study was carried out to establish the larvicidal properties and histopathological effect of Matricharia chamomella plant extract on third larval instar of the Culex quinquefasciatus , the mosquito vector of Rift valley fever in Saudi Arabia using stock solution from King Saud University. Results of log-probit analysis( at 95% confidence level ) revealed that LC50 and LC90 values gradually decreased with the exposure periods ( 24 and 48 h) .This study shows that the larvicidal action of the M. chamomella plant extract is positively correlated to the concentration tested. The histopathological changes caused by LC50 have been investigated using light and an electron microscope. Observations were revealed over time (24 and 48 h). The most noticeable effect is the increasing damage to the larvae mid-gut epithelium, including cell vacuolization and rupture of the epithelial walls, microvillus damage and the epithelium cell contents passing into the mid-gut lumen. This article is the first report of the toxicity and histopathological effects of the M. chamomella as a bioinsecticide in the mid-gut of Cx. quinquefasciatus larvae. These results indicate that the tested extract may affect delayed larval development.