Bruchid Infestation of Cowpea Varieties in the Field
Cowpea is one of the most widely grown leguminous crops in Africa: in Kenya it occupies over 66,000 ha and Coast Province ranks second to Eastern Province with about 5200 ha. It is an important food item consumed both as a vegetable and as a grain. Unfortunately, it suffers from both preharvest and postharvest infestations which accounts for serious losses of the crop. With the introduction to Kenya of improved varieties from IITA, Nigeria, such losses would be increased due to varying susceptibility in different pest ecosystems. The objective of this study therefore was to observe the infestation of the IITA varieties and compare them with local cowpea varieties collected from different parts of Kenya. The work was conducted at C.A.R.S., Mtwapa from 1979 to 1981 inclusive. From the study, five different bruchid species were identified as infesting cowpea varieties in the field. These were Collosobruchus rhodensienus; C. phaseoli; C. chinensis; Bruchidius atrolineatus; and C. analis; in order of decreasing abundance. Over 50% of the bruchids found in the field were C. rhodensienus while Zabrotes spp. and C. maculatus (F) were never encountered in the field. Although the IITA materials were introduced because of their yield potential, it was found that some of them were as susceptible to preharvest bruchid attack as the locally available materials. The short rains season had more bruchid infestations than the long rain season. There were also fewer eggs on pods of local varieties and fewer bruchids emerging from seeds of local as compared to IITA varieties. The results however were not significantly different. Further work should be done to establish the complex of bruchids found in stored cowpea varieties, the losses caused and control measures applicable to reduce damage.
Key WordsBruchids Collosobruchus cowpea preharvest infestation postharvest infestation
Unable to display preview. Download preview PDF.
- Gokhale V. G. and Srivastava B. K. (1975) Ovipositional behaviour of C. maculatus, Coleoptera, bruchids, part L Distribution of eggs and relative ovipositional preference on several leguminous seeds. Indian J. Ent. 37, 122–128.Google Scholar
- Hinton H. E. and Corbet A. S. (1972) Common insect pests of stored food products. British Museums, Economic series No. 15.Google Scholar
- Oyunuga V. A. (1967) Agriculture in Nigeria, An Introduction. FAO, Rome, Italy.Google Scholar
- Sellchop J. P. F. (1962) Cowpea, Vigna unguiculata (L.) (Walp). Fld Crop Abstr. 15, 259–266.Google Scholar
- Southgate B. J. (1978) The importance of bruchids as pests of grain legumes, their distribution and control. In Pests of Grain Legumes: Ecology and Control (Edited by Singh S. R., Van Enden H. F. and Taylor T. A.) pp. 219–229. Academic Press, London.Google Scholar
- Statistical Abstracts (1978), Central Bureau of Statistics, Ministry of Economic Planning and Community Affairs.Google Scholar