Dry season survival, diapause duration and timing of diapause termination in the millet stem borer, Coniesta ignefusalis (Hampson) (Lepidoptera: Pyralidae) in Northern Ghana

Abstract

Studies were conducted between 1996 and 1997 in Northern Ghana on the dry season survival tactics of the millet stem borer Coniesta ignefusalis (Hampson). Results confirmed that the main survival tactic employed by the insect was larval diapause, which lasts from November to May the following year. In both years, diapause termination occurred in the field 4-6 weeks after the resumption of the rains, depending on the year and location. Larval mortality rate was high during diapause with peaks occurring towards the end of the dry season in May. During the 2 years, larval populations declined by at least 50% between the start of diapause and its termination. No parasitoids were encountered during the study period, suggesting that biocontrol agents are probably not very important in the population dynamics of the insect. The implications of these findings for management of the pest are discussed.