Tracing the Origin of Chilades pandava (Lepidoptera, Lycaenidae) Found at Kinmen Island Using Mitochondrial COI and COII Genes

Recent outbreaks of the Cycad Blue, Chilades pandava, have caused severe damage to Cycas plants,affecting their horticultural value. In July of 2007, this butterfly pest was recorded for the first time from Kinmen, offshore of Fujian, where it has caused substantial damage to the ornamental cycad, Cycas revoluta planted on this island. This Cycad Blue colony disappeared by December 2007, but irrupted again in 2008 and 2009. Because neither the Cycad Blue nor native Cycas plants were documented in Kinmen before ornamental cycads were introduced from Taiwan, the origin of the Cycad Blue individuals found on the island was unknown. Two possible scenarios are given herein. Firstly, Cycad Blue may have been introduced via imported Cycas plants from Taiwan. Secondly, Cycad Blue may have invaded from neighboring regions in mainland China, with the planted cycads providing extra resources for colonization. To trace the source of the outbreak in Kinmen, we sequenced 165 specimens covering its neighborhood regions, including Taiwan and mainland China, for the mitochondrial COI and COII genes. Five COI haplotypes and eleven COII haplotypes were found in Kinmen. Most haplotypes were also found in southeastern China, but no haplotype found in Kinmen samples was found in Taiwan. This evidence supports a mainland Chinese origin for Cycad Blue colonies at Kinmen. Our results also show that the turnover colonies of the Cycad Blue had different genetic composition in the three sampled years. In addition, the COI dataset is concordant with the COII dataset, and both of them are considered as good markers for identifying the Cycad Blue populations between mainland China and Taiwan.