Insecticidal and Antifeedant Efficacy of Jatropha oil extract against the Desert Locust, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae)

摘要

Jatropha curcas (physic nut) is a drought-resistant multipurpose shrub or a small tree belonging to the Family Euphorbiaceae. Jatropha seed oil concentrations of 5%, 10%, 15% and 20% were tested for biological activity against the third nymphal instar of the desert locust, S. gregaria. All tested concentrations caused significant (p< 0.05) mortality in the experimental insects ranged from 22.4% to 59.2% after 7 days of application. The LD50 values for treated nymphs at 48, 72, and 96 hrs. were 3.12%, 6.57% and 9.85% respectively. Oil concentration of 10% has resulted in a delay of the development time from the 5th to 6th nymphal instar by 5 days, where treated nymphs had completed development in 16.50 days compared with only 11.33 days in the untreated control group and 12.00 days in the group treated with hexane. The same concentration (10%) also significantly reduced the per cent of egg hatch. The concentration of 5% caused a significant, 50% more, antifeedant effect on the treated nymphs as compared to the untreated control group.