Effects of neem kernel extracts (Azadirachta indica) on insect and mite pests in greenhouses
1998
Hiiesaar, K. | Kuusik, A. | Luik, A. | Metspalu, L. (Estonian Agricultural University, Tartu (Estonia). Dept. of Plant Protection)
The direct toxicity of 0,1 per cent water solutions of azadirachtin was studied at different developmental stages of twospotted spider mite, Tetranychus urticae, in larvae of cucumber aphid, Aphis gossypii, and tobacco thrips, Thrips tabaci. A strong ovicidal effect on the eggs of T.urticae was revealed: the azadirachtin water solutions of 0,5 per cent and 0,1 per cent resulted in the failures of embryonic development in 85,5 per cent and 24,6 per cent respectively. In the first instar larvae of spider mite the water solutions of 0,5 per cent and 0,1 per cent caused the mortality of 70,4 per cent and 15,1 per cent respectively. The adults and the second instar larvae of T.tabaci exhibited high susceptibility to used preparations, 0,5 per cent water emulsion has mortal effect on 89,9 per cent of individuals. The larvae of A. gossypii were yet active during first two days after treatments with both water solution but on the 5th day after treatments with 0,5 per cent and 0,1 per cent solutions 74,1 per cent and 31,4 per cent of larvae were killed respectively. From the recent results it may be concluded that the direct toxic effect of azadirachtin has since been underestimated as far as this botanical insecticide is commonly known and regarded as the specific insect growth regulator
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