The Effects of Extracts of Lantana camara (L.) and Azadirachta indica (A. Juss) on the Population Dynamics of Plutella xylostella, Brevicoryne brassicae and Hellula undalis on Cabbage

摘要

The effects of ethanolic extract of neem, Azadirachta indica (Meliaceae), seeds and petroleum ether extract of Lantana camara leaves (Verbenaceae) on the populations of three cabbage pests, Plutella xylostella , Brevicoryne brassicae and Hellula undalis were studied. The study was conducted between January and April 2008. Extracts of the two plants were sprayed on cabbage plants to control these pests. A standard synthetic chemical insecticide (Mektin) was used as reference product. The experiment was conducted in a randomized complete block design and each treatment was replicated four times. The effects of plant extracts on the population dynamics of the pests’ species, the level of infestation and yield were assessed. Significantly more of the pests infested the control plants than the treated plants ( P < 0.01). The mean weight of cabbage heads on the sprayed plots was significantly heavier than that of the control unsprayed plots. The use of A. indica seeds and L. camara leaf extracts increased yield by 37.05% and 25.80%, respectively. Spraying the cabbage plants with the plant extracts significantly reduced the numbers of pests compared with the control plants. The use of these plant extracts can be incorporated into an overall control programme of these pests.