Studies On The Effects Of Non-crucifer Vegetables Extracts On Pieris Rapae And Its Natural Enemies

Based on the co-evolution between chemical defence of plant and behavior of phytophgous insects, the interference control effects of alcohol extracts of several kinds of non-crucifer vegetables on Pieris rapae and the effects of them on predatory enemy communities in cabbage field were studied in this paper. The main results were as follows:1 The interference control effects of alcohol extracts of non-crucifer vegetables on Pieris rapaeThe research results showed that the extracts of the nine non-crucifer vegetables including Crassocephalum crepidioides, Spinacia oleracea, Folium allii tuberose, Allium cepa , Allium sativum , Apium graveolens, Coriandrum sativum, Capsicum annuum and Lycopersicon esculentum, had significant effects of repelling adults and deterring egg laying, their interference control indices were 0.3768, 0.4586, 0.5404, 0.3778, 0.3681, 0.3461, 0.3434, 0.3403 and 0.3492 respectively. The interference control effects of causing death by toxicity on egg and small larva of Pieris rapae were lower than the effects of repelling adults and deterring egg laying. The interference indices of population control of the nine non-crucifer vegetables on Pieris rapae were 0.0965, 0.1289, 0.3880, 0.1810, 0.1166, 0.1477, 0.1955, 0.1608 and 0.5570 respectively . It meant that their control effects on Pieris rapae reached 90.35%, 87.11%, 61.20%, 81.90%, 88.34%, 85.23%, 80.45%, 83.92% and 94.43% respectively.2 The effects of alcohol extracts of non-crucifer vegetables on predatory enemy communities in cabbage fieldThe research results showed that effects of crowndaisy chrysanthemum had relatively low effect on predatory enemy community in cabbage fields . The characteristic indices, including total individual , richness, evenness and diversity of the predatory enemy community in treated plot declined slightly as compared with those in check plot . The extract of garlic had certain effect on predatory enemy community in cabbage fields and the community characteristic indices of total individual , richness, evenness and diversity declined evidently as compared with those in check plot.3 The effects of alcohol extracts of non-crucifer vegetables on the ratio of number of natural enemies to that of insect pests in cabbage fieldsThe research results showed that the ratio of number of natural enemies to that of insect pests in cabbage fields after spraying extracts of crowndaisy chrysanthemum and garlic was always higher than that of check plot. It meant that using the extracts of the tow non-crucifer vegetables above to control Pieris rapae was beneficial to protect and enhance the natural control effects of natural enemies on insect pests in cabbage fields .