Geographical variations of elytral color polymorphism inCheilomenes sexmaculata(Fabricius) (Coleoptera:Coccinellidae)

Abstract

AbstractThe geographical variation in elytral color polymorphism inCheilomenes sexmaculata(Fabricius) was analyzed based on data from specimen surveys. In all, 1549 individuals collected from different latitudes throughoutIndonesia toJapan were categorized into 20 morph types of elytra. Results show that the morph types have a geographical cline: dark types increased with latitude, although the light types showed higher relative frequency in lower latitudes, which suggests that the geographic variation in elytral color polymorphism inC. sexmaculatais a product of selection by climate. The darker morph types might be advantageously able to make fuller use of insolation at higher latitudes, whereas the lighter morph types were likely to reduce heat stress at lower latitudes. In most areas acrossSoutheast andSouthAsia, all specimens were of the lightest type, which may imply either: (i) the saturation of genes expressing light morph types, which have less solar absorption, due to tropical climate; or (ii) an enhanced warning function of bright red against predators. OnMiyakoIsland ofJapan, a unique frequency of morph types was found compared to the adjacent areas.