Mapping the disjunct distribution of introduced codling mothCydia pomonellain China

Eastern China was once listed as an area infested with the invasive codling moth Cydia pomonella L. (Lepidoptera: Tortricide). Intensive efforts later revealed the absence of such infestation. Currently, the majority of the population is distributed in western China. A disjunct population is also observed in the north east. In present study, the disjunct distribution was interpreted by mapping the climate dimension and potential distribution using an ecological niche modelling approach. The preferred niche models were utilized to identify the relative roles of climate, human influence and vegetation with respect to the present distribution and also to extrapolate the climate dimensions suitable for the codling moth in China. The results of the present study suggest that a combination of climate suitability and human influence explain the range expansion. Undistributed areas in eastern China were found to have low to medium climate suitability. Nonetheless, these areas belong to apple-growing regions that have high propagule pressure; thus, eventual establishment appears to be possible because of host plant availability, human activity and the wide ecological flexibility of the moth. Highly suitable habitats were found to be strongly related to high temperature and low precipitation throughout the year, whereas areas with low temperature and plenty of rainfall are unfavourable.