Sexual size differences and colour polymorphism of Rhynchophorus phoenicis in the Southwest region of Cameroon

A total of 174 specimens of the African palm weevil Rhynchophorus phoenicis (F.) were sampled during 2010, in eight different localities of the Southwest region of Cameroon. Male and female weevils were measured (body length, abdomen length, abdomen width, pronotum length, pronotum width, head size, and length from tip of rostrum to antennal insertion), and the different pronotum patterns are described. Statistical analysis shows that all morphometric parameters correlate with body length in both males and females, and seven pronotum pattern types are identified, three of which are new. African palm weevil adults show sexual dimorphism: abdomen and head size are significantly greater in females, while pronotum length is significantly greater in males. No statistical differences in the frequencies of pronotum pattern types were seen between males and females, or among localities. A significant difference was seen for the abdomen width between two localities.