Control effects and economic evaluation of pumpkin leaf extract on caterpillars of the small cabbage butterfly

Abstract

SUMMARYThe control effect of Cucurbita ficifolia (pumpkin) leaf acetone extract on caterpillars of the small cabbage butterfly Pieris rapae Linnaeus (Lepidoptera: Pieridae) was observed in laboratory and field experiments from 1 March 2006 to 30 May 2007. The mechanism of the action by which pumpkin leaf extract (PLE) controls small cabbage caterpillars was examined for feeding restraint, and the values for 0·50 feeding restraint concentration (FC50) and 0·95 feeding restraint concentration (FC95) after 12 and 24 h were estimated. The results showed that the absolute anti-feeding activity for fourth instar caterpillars after 12 h was 0·65 and after 24 h was 0·56, while relative anti-feeding activity was 0·57 after 12 h and 0·59 after 24 h. Field experimental results indicated that the leaf protection effects increased up to day 7, while the feeding control effects remained constant. Comparison of the profits from pest management using indigenous pesticides, biological pesticides and chemical pesticides and without pest management suggested that there are currently economic benefits associated with the use of indigenous pesticides, such as PLE.