Effects of intra- and inter-specific competition on fitness of sweetpotato weevil and West Indian sweetpotato weevil

The sweetpotato weevil Cylas formicarius (Fabricius) (Coleoptera: Brentidae) and West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) are major pests of sweet potato Ipomoea batatas (L.) Lam., in tropical and subtropical regions. Effects of intra- and inter-specific competition on the number of progeny (fecundity), body weight and developmental time of C.formicarius and E.postfasciatus were examined in single- and mixed-species treatments under laboratory conditions. Cylas formicarius tended to outcompete E.postfasciatus, whereas E.postfasciatus rather than C.formicarius tolerated higher conspecific densities. We discuss the implications of the results for pest management and resource partitioning of pestiferous weevils.