Fecundity and survival of Carpophilus hemipterus (Linnaeus, 1758) (Coleoptera: Nitidulidae) on alternative hosts

The tendency of the dried fruit beetle Carpophilus hemipterus (Linnaeus, 1758) (Coleoptera: Nitidulidae) to occur as pests in stores and fields has necessitated investigations on its fecundity and survival on some alternative food hosts such as groundnut, cocoa, cowpea and rice. Two copulating pairs of the adult beetle were introduced on fifty grammes of each food substrate in a no choice test at 28 °C ± 3 °C and relative humidity of 75% ± 5%. The number of eggs laid, emerged larvae, and enclosed adults were recorded. Weight loss of the food substrates was also recorded. Analysis of variance was performed on the data generated. Kaplan Meier analysis was carried out to determine the beetle survival rate on each host. Fewer eggs were deposited on rice compared to the other hosts; however, there was no significant difference (p > 0.05) between the percentage hatchability of the beetle on all the food hosts. As evidenced by the larvae emergence data, cocoa (4.28%) and groundnut (5.42%) suffered significantly higher (p < 0.05) levels of damage. However, based on the Kaplan Meier survival index (Px), it was noted that the adult enclosion and survival of the beetle was lowest on cocoa (0.27) and highest in cowpea (0.64). General Linear Model (GLM) revealed highly significant influence (p < 0.0001) of food substrate (S) on the fecundity of C. hemipterus (F3,320 = 464.099) and its larvae development (F3,199 = 345.042). It also showed the effect of Period (P) on number of eggs (F3,320 = 320.932) and larvae development (F3,199 = 188.167) to be highly significant (p < 0.001). Likewise, there was significant impact (p < 0.0001) of the interaction of food substrate x duration (S x D) on the oviposition of C. hemipterus (F9,199 = 5.167) and larvae development (F9,199 = 13.403). The ability of C. hemipterus to survive on less preferred food hosts is highlighted in this study.