Effect of Weed Management on Insect Pest Population on Cotton (Gossypium Hirsutum L.) At Werer, Ethiopia

Presence of weeds within-crop field modifies microclimate For example, changes in canopy parameters influenced by the presence of weeds can enhance or hinder arthropod fitness within the crop field. Nyambo (1988) reported that in Tanzania, Cleome sp. was an alternative host for the bollworm (Helicoverpa armigera) and assisted in the biological control of the pest in two ways; firstly, by providing a source of insects which were not pesticide resistant, having escaped the spray applied to the cotton crop and also in supporting a more diverse parasitoid population. It was confirmed that parasitism of H. armigera was greater on the weed than on cotton In Sudan, eradication of Abutilon spp. and Solanum dubium L. is encouraged by legislation as part of the management programme for cotton pests. Malvaceous shrubs are often preferred over cotton as a food source for Earias spp. and they migrate to nearby cotton crops only in drier areas where natural vegetation is sparse