Actions of azadirachtin, a plant allelochemical, against insects

✍ Scribed by Jennifer Mordue Luntz, A.; Simmonds, Monique S. J.; Ley, Steven V.; Blaney, Walter M.; Mordue, William; Nasiruddin, Munira; Nisbet, Alasdair J.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 249 KB
• Volume: 54
• Category: Article
• ISSN: 1526-498X
• DOI: 10.1002/(sici)1096-9063(1998110)54:3<277::aid-ps801>3.0.co;2-i

✦ Synopsis

Investigations of the antifeedant mode of action of azadirachtin and four synthetic analogues, 22,23-dihydroazadirachtin, 3-tigloylazadirachtol, 11methoxydihydroazadirachtin and 22,23-bromoethoxydihydroazadirachtin have revealed that both polyphagous and oligophagous insects are behaviourally responsive to azadirachtin, with the most responsive species being able to di †erentiate extremely small changes in the parent molecule. In Lepidoptera the antifeedant response is correlated also with increased neural activity of the chemoreceptors. When locusts are treated on crop plants, the antifeedant and physiological actions of azadirachtin and analogues work in concert and result in feeding deterrence, growth and moulting aberrations and mortality with the same order of potency as for antifeedancy. SpeciÐc binding studies using [3H]dihydroazadirachtin carried out on locust testes and Spodoptera Sf9 cells have shown that the competitive binding of the di †erent analogues of azadirachtin to these binding sites occurs in a similar order of potency to that found with antifeedant and IGR bioassays. This suggests a causal link between speciÐc binding to membrane proteins and the ability of the molecule to exert biological e †ects.