Occurrence and Seasonal Variation of Heteroligus meles Billb (Coleoptera: Dynastidae) in Upper Niger Delta, Nigeria

Abstract

Studies conducted in 2004/2005 in the rainforest ecological zone of Anwai-Asaba in the Upper Niger Delta, Nigeria, examined the occurrence and seasonal variation in the population of yam tuber beetles (Heteroligus spp). The beetle population started building up in May with the peak occurrence as determined by the light traps occurring in July-August. The population trend is climate dependent and the peak was unimodal. Correlation analysis was negative for temperature (b= -0.662) while it was positively correlated with rainfall (b=0.552) and relative humidity (b=0.543). Based on the coefficient of determination (R 2 ), beetle occurrence can be predicted on weather elements studied to about 52% for rainfall 29% relative humidity and 44% for temperature. The best predictive tools for monitoring the commencement of occurrence of the yam beetle are the three major weather parameters, namely temperature, relative humidity, rainfall but the later was more critical according to this study.