Survival of diapause larvae of the stem borer, Coniesta ignefusalis (Hampson)(Lepidoptera: Pyralidae), in northern Ghana as affected by the method of storage of millet stalks

English

Studies were conducted in the Sudan savanna zone of Ghana on the effect of method of storage of millet stalks on mortality of diapause Coniesta ignefusalis larvae residing in such stalks. Internal stalk temperatures were generally higher than the corresponding ambient temperatures and peaked between 12.00 and 14.00 h GMT. During these periods of the day, temperature within the stalks stored in the Slll1usually exceeded 40 ·C, the critical threshold for survival of diapausing C. ignefusalis larvae. Larval mortality was positively correlated with internal stalk temperature, and was highest in stalks spread out in the sun. Subjecting stalks to this treatment resulted in 80 per cent larval mortality within 6 weeks compared with 20 per cent mortality in stalks stored in the shade. The results indicate that high temperature resulting in the generation of excessive heat within the millet stalks is a key mortality factor in the population ecology of this insect. The implications of these findings for the integrated management of the insect are discussed

Tanzubil, P. B.; Mensah, G. W. K.; Ansoba, E.; Zakaria, M.; Alem, A.