Abstract
The cotton bollworm, Heliothis armigera Hübner, is the most important insect pest of cotton in Western Tanzania and attacks a wide range of food crops grown in the cotton areas including wild host plants. A study to investigate the role of natural enemies in regulating the larvae populations of the pest in the mixed cropping system typical of Western Tanzania was done. The populations and larvae mortality factors were assessed on maize, sorghum, cotton, chickpea, tomato and Cleome sp. Diseases (viral and bacterial) and parasitism were identified as important mortality factors of the larvae populations but neither prevented the pest population from causing economic damage on the crops. Of the viral diseases, a nuclear polyhedrosis virus (NPV) was the most frequent particularly on larvae collected from Cleome and maize. The abundance and distribution of the mortality factors were found to vary between seasons and host plants and it was therefore concluded that more research is needed before H. armigera natural enemies can be exploited for a biocontrol programme in Western Tanzania.
Notes
Current address: ICIPE, Mbita Paent Field Station, P.O. Box 30, Mbita, Kenya.