Insecticidal toxin complex from Photorhabdus Luminscens and its histopathological effects on the midgut of the sand fly Phlebotomus papatasi

Abstract

The susceptibility of sand fly Phlebotomus papatasi to the Photorhabdus luminescens toxin complex was investigated. We evaluated the activity of Photorhabdus luminescens toxin complex with three concentrations (toxin complex, 1:2 and 1:4 diluted toxin) per each cup contain ten larvae of sand fly. Five plastic cups were set up for each treatment dose and incubated at 24 0C in the dark. Toxicity was varied according to the concentration and period of exposure. We investigated the effect of the LC50 on midgut of 3rd larval instar of P. papatasi, causing serious damage to the epithelial columnar cells. Electron microscop observations revealed, by time 12, 24, 36, 48, 72, 96, 144,166, 192 and 216h, increasing damages of the larvae midgut epithelium. Histological data suggested that the primary site of action of the toxin is the midgut.