Title: Laboratory trials on the effects of neem oil and neem-seed based extracts against the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae)
Abstract: Using the spider mite Tetranychus urticae Koch, it was demonstrated that neem oil and other neem-seed extracts are toxic to the mites when applied as foliage or contact spray. Neem seed kernel extracts (NSKE) prepared with pentane were considerably more toxic than cold-pressed neem oil, commercial neem oil and AZT extract. LD50 values of topically applied extracts were calculated as 1.33%, 1.86%, 2.06% and 3.86% for pentane extract, commercial neem oil, cold-pressed neem oil and AZT-extract, respectively. Furthermore, pentane extract and cold-pressed neem oil reduced the fecundity of the mites on treated plants and the survival of nymphs hatched from treated eggs. Application of pentane extract or neem oil in sublethal concentrations caused growth disrupting effects on the nymphal stages and ovicidal effects. Nonpolar components of the oil and pentane extract were more effective than the polar components. Quantification of the insecticidal substance azadirachtin in the extracts revealed that this compound is not the most active principle against spider mites
Publication Year: 1992
Publication Date: 1992-01-01
Language: en
Type: article
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Cited By Count: 7
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