Studies on Insect Pests and Diseases of Chayote, Sechium Edule (Swartz.) in Kenya
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The chayote, Sechium edule Sw., belongs to the family Cucurbitaceae. All parts of the plant can be utilized including the fruit, seed, tuberous roots and young shoots. Yields of up to 1,500 fruits per plant have been recorded. A study was conducted to investigate the pests that attack this crop. Mature plants were observed for pest damage, punctured and wounded fruits were harvested, placed in plastic containers and observed daily for larval and subsequent pupal development. The pupae were harvested using forceps, placed in plastic vials and observed daily for adult emergence. The emerged adults were identified, sexed and counted. Data was analysed using SAS. The leaves were infested by sap sucking pests; thrips, Spider mites Tetranychus ludeni, Cotton aphid Aphis gossypii, White flies Bemisia tabaci, brown bugs, leaf feeders; Spodoptera species and coleopteran. The fruits were infested by fruit flies Dacus bivittatus andD. ciliatus and two unidentified dipteran species. An average of seven fruit flies was collected from each fruit. Fruit flies significantly reduced fruit yields and marketability; causing fruit rot and deformation. The wounds caused by insects provided entry points for fungal pathogens. Fruit fly larvae that came into contact with the fungus died. But those that developed within the fruit and only came to the surface for pupation were able to pupate and emerge as adults. Only one gregarious larval-pupal parasitoid, Oomyzus species (Hymenoptera: Eulophidae) was recorded from one cocoon of fruit fly, from where sixteen adults emerged comprising offive females and eleven males. The main disease was powdery mildew which. led to the drying •of the leaves. The results demonstrate that that S. edule is attacked by a wide- variety of pests. More research is .needed to develop an effective IPM programme and to support adoption ofthe vegetable to improve in slums and semi arid areas.