Intraspecific Competition of Carpophilus hemipterus (Coleoptera: Nitidulidae) on Two Yam Cultivars under Laboratory Conditions in Burkina Faso

Aboulaye Sankara, Jean-Christophe Koussoube, Marcelin Yamkoulga, Koi Kam, Mayouré Ilboudo, Zakaria Ilboudo and Antoine Sanon

Background and Objective: Carpophilus hemipterus is an important storage pest of yam tubers, and its reproductive performance may be influenced by resource quality and intraspecific competition. The present study aimed to investigate the effect of intraspecific competition on the reproductive performance, development, and morphological traits of C. hemipterus when reared on two yam cultivars under laboratory conditions in Burkina Faso. Materials and Methods: In the first experiment, pair of newly emerged adult C. hemipterus were formed and placed in plastic boxes in groups of 1, 2, 3, 4 or 8 pairs, each group was placed in contact with 10 g of chips from each cultivar (x5 replicates). In the second experiment, From the emergence of each density previously tested, five pairs were formed and individually placed in contact with 10 g of chips in plastic boxes. The parameters determined were mean number of eggs laid per female, mean number of emergents produced per female and mean height and weight of emerged individuals. Statistical analyses were performed in R (v4.2.1) using the Shapiro–Wilk test for normality and Student's t-test for normally distributed data (p<0.05). Results: The average water content of Sakampé chips (29.45%) was significantly higher than that of Ponon (22.65%), irrespective of competition effects. Increased intraspecific competition significantly reduced (p<0.05) fertility, as well as the weight and size of the first-generation adults. However, no significant differences (p>0.05) were observed in the weight and size of emerging individuals between the different competition treatments in the presence of the two yam cultivars. Conclusion: Intraspecific competition negatively affects the reproductive performance of C. hemipterus. These findings provide a useful basis for developing effective pest management strategies for yam storage systems.

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