Effects of a neem extract on blood feeding, oviposition and oocyte ultrastructure in Anopheles stephensi Liston (Diptera: Culicidae)

Secondary metabolites of the neem tree ( Azadirachta indica A. Juss., Meliaceae) exhibit a wide range of biological activities in insects. However, few studies have addressed the effects of neem extracts or compounds in arthropods of medical importance. In this study, a laboratory strain of Anophele...

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Bibliographic Details
Published in:Tissue & cell 2006-12, Vol.38 (6), p.361-371
Main Authors: Lucantoni, L., Giusti, F., Cristofaro, M., Pasqualini, L., Esposito, F., Lupetti, P., Habluetzel, A.
Format: Article
Language:English
Subjects:
Animals
Anopheles
Anopheles - drug effects
Anopheles - physiology
Anopheles - ultrastructure
Anopheles stephensi
Anti-feeding
Arthropoda
Azadirachta - chemistry
Azadirachta indica
Azadirachtin
Blood
Culicidae
Diptera
Feeding Behavior - drug effects
Female
Insecticides - pharmacology
Limonins - pharmacology
Meliaceae
Microscopy, Electron, Transmission
Neem
Oocytes - drug effects
Oocytes - ultrastructure
Oviposition
Oviposition - drug effects
Plant Extracts - pharmacology
Ultrastructure
Vitellogenesis
Vitellogenesis - drug effects
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Summary:Secondary metabolites of the neem tree ( Azadirachta indica A. Juss., Meliaceae) exhibit a wide range of biological activities in insects. However, few studies have addressed the effects of neem extracts or compounds in arthropods of medical importance. In this study, a laboratory strain of Anopheles stephensi was used to assess the effects of a commercial formulation (Neem Azal ® (NA)), containing azadirachtin A at 34%, on blood feeding, oviposition and oocyte ultrastructure. Oral administration of Neem Azal ® to A. stephensi females through artificial blood meals did impair blood intake and oviposition in a concentration dependent manner. Similar results were obtained on females, which had consumed Neem Azal ® in sucrose solution before taking a blood meal of plain blood. Neem treated females displayed a delay in oocyte development in both the phase of vitellogenesis and the phase of choriogenesis. The ultrastructural studies on ovaries from Neem Azal ® treated females revealed distinct structural modifications indicative of: (i) a complete block of oogenesis, (ii) impairment of vitellogenesis and vitelline envelope formation, (iii) a severe degeneration of follicle cells. In agreement with results obtained in other insects, this study indicates that Neem Azal ® impairs hormone control of oogenesis and exerts a cytotoxic effect on both follicular cells and oocytes of the Asian malaria vector A. stephensi.
ISSN:0040-8166
1532-3072
DOI:10.1016/j.tice.2006.08.005