Evaluation of Some Selected Local Phytoextracts Against Wheat Aphid Schizaphis graminum Rondani (Hemiptera: Aphididae) under Laboratory and Field Conditions

Abstract

| Plant-derived insecticides have been focused for biorational pest management because these are relatively quickly biodegradable, cost-effective, less persistent and exhibit low mammalian toxicity than synthetic pesticides. This study assessed the toxicity potential of seven local plant species ( i.e. parthenium Parthenium hysterophorus L., eucalyptus Eucalyptus camaldulensis Dehnh., milkweed Calotropis gigantean (L.) Dryand., bakain Melia azedarach L., neem Azadirachta indica A. Juss., tobacco Nicotiana tabacum L. and thorn apple Datura stramonium L.) against wheat aphid ( Schizaphis graminum Rondani) under laboratory and field conditions. Using foliar spray method, toxicity bioassay was conducted with three different concentrations ( i.e. 250, 500 and 1000 ppm) of methanolic plant extracts under controlled laboratory conditions, while three different concentrations (25, 50 and 75 g/L) of each botanical extract was tested in the field trial. Results showed a significant mortality and suppression of S. graminum individuals at 72 h after treatment in the laboratory and at 10 th day post-treatment in the field. In laboratory bioassay, maximum aphid mortality was caused by the extracts of D. stramonium (92%), A. indica (84%), N. tabacum (78%) and M. azedarach (70%) at 72 h post-treatment at their highest concentration (1000 ppm). Results of field trial showed significant aphid mortality by D . stramonium (78%), A. indica (72%), N. tabacum (68%) and M. azedarach (62%) extracts noted for their highest concentration (75 g/L) at 10 th day after treatment. Based on overall results of the study, the extracts of D. stramonium , A. indica , N. tabacum and M. azedarach are recommended to be considered for biorational management of S. graminum .