Diapause termination in the millet stem borer, Coniesta ignefusalis (Lepidoptera : Pyralidae) in Ghana as affected by photoperiod and moisture

Studies were conducted in northern Ghana in 1997 and 1998 on the effects of contact moisture and photoperiod on the termination of larval diapause in the stem borer, Coniesta ignefusalis (Hampson). Results obtained over the t wo years consistently showed that on its own, photoperiod had no significan t effect on diapause termination. In combination with contact moisture, how ever, a long day photoperiod of 13L:11D accelerated diapause termination an d increased the cumulative percentage pupation. Contact with moisture was c rucial for diapause termination but its influence was more pronounced in la rvae collected from the field after March. Generally, access to moisture ea rlier than April resulted in very high larval mortality. These observations , together with the fact that some of the larvae (12%) denied access to wat er throughout the experimental period subsequently pupated, suggest that mo isture may not be the sole factor triggering diapause termination in C. ign efusalis. The implications of these findings are discussed.