A survey of some insect pests of cultivated vegetables in three selected irrigation areas along Jakara River, Kano, Nigeria

Abstract

The survey aimed at identifying insect pests that attack vegetables grown in three irrigation areas along Jakara River in Kano, Nigeria. The areas were Kwarin gogau, Nomansland and Kwakwaci. Two methods of trapping the insects were employed, namely hand capture for wingless insects as well as hand net for flying insects. Morphological identification of insects was done using taxonomic keys, hand lens as well as light microscope for checking fine structures. Quadrant was used to determine the frequency of occurrence of insect pest on different vegetable plants at different sites, which was used in computing insect pest density. Six vegetable types were found to be predominantly cultivated in the irrigation sites. These included Lactuca sativa (Lettuce), Brassica oleracea (Cabbage), Amaranthus spp (Spinach), Lycopersicum esculentum (Tomato), Abelmoschus esculentus (Okra), and Allium cepa (Onion). The highest insect pest density of 66.7 pest/m 2 was obtained at Kwakwachi area, where Aphid was found only in that site. Caterpillar (Lepidoptera) and Leaf beetles (Coleoptera) were the only pests found in all the three irrigation sampling sites, while Bug (Hemiptera), Aphid (Homoptera) and Thrips (Thysanoptera) were found at Kwakwaci irrigation site. Amaranthus (spinach) was found to be attacked by all the insect pests identified (which include representatives from seven orders), with exception of Thrips (Thysanoptera). There was significant difference between number of insects per sites (P<0.05). There was also significant difference between average frequencies of insect pest per sites (P< 0.05).