Abstract:

Phenacoccus solenopsis, an exotic invasive species, was firstly reported in 2008 in Guangdong, China. Since it’s discovery, P. solenopsis has been observed in Zhejiang, Guangxi and Yunnan provinces. To discuss whether two cryptic evolutionary lineages or the P. solenopsis complex species existed, we surveyed and sequenced P. solenopsis in Zhejiang Province. During surveys for P. solenopsis in Zhejiang Province, we found P. solenopsis individuals with yellowish color on the body and three pairs of yellow spots on the back. To evaluate potential genetic divergence among these phenotypes, we sequenced mtDNA COI gene sequences (694 bp) of 25 individuals from seven host plants in six locations. We analyzed these sequences and the known sequences of P. solenopsis from GenBank and discovered three haplotypes. Additionally, we calculated intra-species genetic distance of P. solenopsis and inter-species genetic distance of the genus Phenacoccus and constructed phylogenetic trees of P. solenopsis. We found that genetic divergence of P. solenopsis was 0-1.0% compared to samples from Chinese provinces (i.e., Zhejiang, Hainan, Guangdong), the United States (i.e., California), and Pakistan, and varied from 3-3.6% to samples collected from other areas of the United States (i.e., Florida). Further, intra-species genetic distance was obviously smaller than inter-species genetic distance in Phenacoccus(13.0-17.2%). Based on the morphological characters and mt COI gene sequence analysis, these individuals with phenotypic differences are likely true P. solenopsis. However, two distinct evolutionary lineages appear to exist in P. solenopsis, and further evidence is necessary to draw reliable conclusions on the existence of a P. solenopsis complex species.

Key words: Phenacoccus solenopsis, biological invasion, genetic divergence, COI, body-color variation