Studies on Temperature Influence on Oviposition and Development of Immature Stages of the Yam Beetle Dinoderus Porcellus Lesne. Coleoptera: Bostrichidae on Dried Yam Species

Teneral adults of Dinoderus porcellus were raised in the laboratory and exposed to various temperature regimes 10, 15 20, 30, 35 and 40 C respectively. Four dried yam species Dioscorea rotundata, Dioscorea alata, Dioscorea dumetorum and Dioscorea cayenensis were used, to determine the effect of temperature on oviposition and developmental stages of the insect. At 10C, there was no oviposition, at 15 C fewer eggs were laid. Oviposition increases with little variation as temperature increases from 20C 30C. There is reduction in the number of eggs laid at 35C , while zero oviposition was recorded at 40 C. Egg incubation ranges between 6 to 8 days and there were significance difference (P<0.05) in the developmental period of larva and no significance difference (P<0.05) at the pupal stage. However, developmental period was prolonged on Dioscorea cayenensis as temperature increases.