Bioactivities of orange peel extracts against the larvae of Spodoptera litura Fab. and Spodoptera exigua Hüb.

The effects of peel ethanol extracts from Citrus unshiu on the larvae of Spodoptera litura Fab. and Spodoptera exigua Hub. were preliminarily investigated in laboratory by measuring antifeedant index, body weight gains and mortality of the larvae after their feeding on the cabbage leaves coated with the extract. The results indicated that the cabbage leaf consumption and body weight gains were both reduced, and the larval mortality was increased after the larvae had fed on the leaves coated with the extract. The higher the concentration, the more obvious the effect on the pests was. The larval mortality of S. exigua was higher than that of S. litura at the same extract concentration. Both the median inhibitory concentration (IC_(50)) and the median antifeedant concentration (AFC_(50)) in the non-choice test for S. exigua were lower than those for S. litura. However, the AFC_(50) in the choice test was higher for S. exigua than for S. litura. The overall results indicated that the bioactivities of peel ethanol extract from Citrus unshiu against S. exigua are better than against S. litura.