Plants as a Source of Biopesticides for Pest Control: A New Perspective

Abstract

Rhizome extract of "C" and seed extract of "N" were tested in the laboratory for their effects on feeding, development, mortality, reproduction and oviposition of Crocidolomia pavonana (Fabricus) (Lepidoptera; Pyrallidae) on broccoli. Antifeedant activity of "C" and "N" biopesticides were tested against fourth instar C. pavonana larvae in leaf-disc choice and no-choice tests. The results show that under the choice condition, the treatment with 1% and 1.25% "C" biopesticide for 24h or 48h, reduced feeding by the test larvae on broccoli leaves by more than 90%. Under the same condition, reduction in feeding after 24h caused by treatment with 0.12% and 0.2% "N" biopesticide was recorded as 86.7% and 95.8% respectively. In the no-choice test, the treatment with 1% and 1.25% "C" biopesticide reduced feeding by 61.8% and 74.2% respectively after 24h and by 70.6% and 77.7% after 48H. Under no-choice conditions "N" biopesticide at concentrations from 0.025% to 0.2% was not effective in deterring the test larvae from feeding on treated leaves. In the testing to evaluate the effects of test biopesticides on reproduction and longevity of C. pavonana, fourth instar larvae were offered treated leaves for 48 h, then their development was followed until adult emergence. The duration of fourth instar and pupal period of the survivors, as well as the fecundity and longevity of the resulting adults, were recorded. Oviposition-deterring activity on C. pavonana of "C" and "D" biopesticides was tested against gravid females of C. pavonana (5-8 days post emergence) on broccoli seedlings in choice and no-choice tests.