[[alternative]]Analysis of Eurema hecabe host-plant adaptation

Abstract

[[abstract]]Larval host-plants of Eurema hecabe Linnaeus in Taiwan include three families, twenty species according to literature. Only certain members of each family are utilized by the larva, which often does not accept alternative potential hosts. In Japan, Eurema hecabe Linnaeus consists of two distinctive morphs. They differ in the fringe color of wings（brown or yellow）and other phenotypes. It has recently been found that sexual isolation exists in these two types. Both types（brown or yellow）of Eurema hecabe are also present in Taiwan. Whether there are isolation mechanisms occurred between them still remains to be confirmed. The present study used Rhamnus formosana, Breynia officinalis, Cassia surattensis and Sesbania cannabiana as larval host-plants. According to larval hosts, four types of Eurema hecabe were recognized, namely, S. cannabiana type, C. surattensis type, B. officinalis type and R. formosana type, respectively. Some experiments were performed to test their morphological difference, larval performance and oviposition preference to infer whether isolation presents among these types. Seperated by morph, growth rate and principal-components analysis（PCA）,C. surattensis type and S. cannabiana type are the same group. R. formosana type and B. officinalis type are the other group. Seperated by wing color pattern, C. surattensis type and S. cannabiana type are the same group,whereas R. formosana type and B. officinalis type represent different kinds of groups. Seperated by host-plant adaptation and oviposition preference, C. surattensis type and S. cannabiana type maybe the same group. R. formosana type and B. officinalis type represents different kinds of groups. Besides, R. formosana type and B. officinalis type may have evolved from Fabaceae associated ancestors. In conclusion, Eurema hecabe in Taiwan are divided into three distinctive groups, ie, C. surattensis type and S. cannabiana type as the same group, whereas R. formosana type and B. officinalis type each represents a distinctive group. R. formosana type and B. officinalis type may have evolved from the Fabaceae-feeding ancestors. Finally, C. surattensis type and S. cannabiana type probably represent the brown type, whereas R. formosana type the yellow type, and B. officinalis type a previously unrecognized group. There are many host-plants of Eurema hecabe remained untested. Whether there is present any new host types needs further research. This study provides the first report to the analysis of relationship among host types of Eurema hecabe in Taiwan.