Mortality effects of Carbon Dioxide atmospheres on ProstephanusTruncatus (Horn) (Coleoptera: Bostrichidae)

The potential of carbon dioxide in the control of P. truncatusinfestations, was investigated by assessing the mortality rate in adult P. truncatus and reduction in emergence of the progeny generation. Different life cycle stages, exhibited variation in their susceptibility to carbon dioxide. The adults, eggs and early larval instars were the most susceptible stages to carbon dioxide. 100% mortality in these stages was achieved after 4 days exposure to 50% C02 (at 55% RH and 27±1oc) or 60% CO2 (at 75% RH and 27±1oC). The late larval instars and pupae, were the most tolerant stages, these were eliminated after 12 days exposure to 80% CO2 at 75% RH and 27±1oC. The toxicity of carbon dioxide against the adult P. truncatus, increased significantly as the relative humidly decreased and visa versa. This effect was not however apparent in the pre-imaginal stages. High levels of carbon dioxide (60-90%) had no adverse effects on the germination of dry seeds (11 to 13% moisture), but caused a significant reduction in the germination of seeds containing 14.8% moisture. The laboratory experiments showed that carbon dioxide has a high potential to control pest damages by P. truncatus infestations in stored maize.