Toxicity , histopathological and ultrastructural effects of Artemisia herba alba ectract in the midgut of culex quinquefasciatus larvae (Diptera: culicidae) [electronic resource].

Includes reference.

Crude ethanolic extract from Artemisia herba alba"was tested against the .:r instar larvae of Culex quinquefasciatus .The larvae were exposed to serial concentrations (2.75 ,2.50,2.25, 2.00, 1.50 & /.00 mgll ).The plant extract showed marked effects on larval mortality. Sequental observations using light and electron microscopes on effects of the LCso value were made on gastric ceaca and midgut epithelial cells .Exposure times 6, /2 , 24 and 48 hours were tested. The toxic effect ofthe extracts have a wide range ofaffecting degrees in the alimentary canal. The main alterations observed in gastric caecae and midgut were partial or total cell destruction, high cytoplasmatic vacuolization, disruption of rough endoplasmic reticulum ,cell hypertrophy and the epithelium did not maintain its monolayer appearance. At longer exposure period, the midgut epithelium cellsfrom treated larvae appeared more elongate and swollen than cells observedfrom control larvae. The microvilli was degenerated. After 48 hours the changes were more obivous, with the apical region of the cell bulging into the gut lumen.The cells contained large cytoplasmic spaces ,cellular damage had increased ,with cells ruptured at the apical surface and leakage ofcytoplasmic materials into the gut lumen. Observation oftissues sections from larvae treatedfor different exposure times revealed a wide and clear variations in the degree ofdamage occured. The present study provides a quite clear evidence regarding the mode of action of the A. herba alba extract used as bioinsecticidal for controlling mosquito larvae.

Summary in Arabic.

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