Sexual difference of morphological characters of scales on metasternum of West Indian sweet potato weevil, Euscepes postfasciatus fairmaire

Abstract

The density, arrangement and length of scales on the metasternum of Euscepes postfasciatus adults were measured to develop a convenient method for identifying adult sexes. The central part of the metasternum of males was more densely clothed with scales than that of females. The mean densities of scales on the central part (125 × 200 μm) in males and females were 13.7 and 9.5, respectively. In males, the scales on the central part were sub-recumbent to the post-central part of the metasternum and length was more uniform. However, the scales of females were more erect and length varied considerably. We could easily and exactly recognize the adult sexes by observing these characteristics of the scales on the central part of the metasternum under a binocular microscope.