Assessing the global risk of establishment of Codling moth (Cydia pomonella) using CLIMEX and MaxEnt niche models

Authors: KUMAR, SUNIL - Colorado State University; Neven, Lisa; ZHU, HONGYU - Chinese Academy Of Sciences; ZHANG, RUNZHI - Chinese Academy Of Sciences

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2015
Publication Date: 12/1/2015
Citation: Kumar, S., Neven, L.G., Zhu, H., Zhang, R. 2015. Assessing the global risk of establishment of Codling moth (Cydia pomonella) using CLIMEX and MaxEnt niche models. Journal of Economic Entomology. 108(4):1708-1719.

Interpretive Summary: The codling moth, Cydia pomonella, is a major pest of apples in a majority of temperate zone apple growing regions throughout the world. Concerns over the potential of this pest to establish and spread to additional countries have led to the implementation of strict apple import requirements, which restricts international trade and reduces grower profitability. Scientists at the USDA-ARS Yakima Agricultural Research Laboratory,, Colorado State University Natural Resource Ecology Laboratoty, and the Chinese Academy of Science's Institute of Zoology collaborated to develop ecological niche models using historical and new pest incidence data, including data from the most recent spread, from 2003-2010, of codling moth in Northern China. Two models were developed, one using CLIMEX and another using MAXENT, which are most commonly used mechanistic and correlative modeling software programs. Both models had high accuracy in matching the current known locations of codling moth. Importantly for apple exports, neithre model predicted suitable environments for countries between 20th parallels. These models can be used for developing monitoring programs to detect introductions of codling moth in different countries and may also be used by policy and trade negotiators in making science-based decisions on current and future quarantine procedures.

Technical Abstract: Accurate assessment of insect pest establishment risk is needed by national plant protection organizations to negotiate international trade of horticultural commodities that can potentially carry the pests and result in inadvertent introductions in the importing countries. We used mechanistic and correlative niche models to quantify and map the global patterns of the potential for establishment of codling moth (Cydia pomonella L.), a major pest of apples, peaches, pears and other pome and stone fruits, and a quarantine pest in countries where it currently does not occur (e.g. Colombia, Japan and South Korea). The mechanistic model CLIMEX was calibrated using species-specific physiological tolerance thresholds whereas the correlative model MaxEnt used species occurrences and climatic spatial data. Projected potential distribution from both models conformed well to the current known distribution of C. pomonella. None of the models predicted suitable environmental conditions in countries located between 20°N and 20°S (e.g., Colombia, Peru, and Venezuela) potentially because of shorter photoperiod, and lack of chilling requirement (<60 days at or below 10°C) in these areas for C. pomonella to break diapause. Models predicted suitable conditions in South Korea and Japan where C. pomonella currently does not occur but where its preferred host species (i.e. apple) is present. Average annual temperature and latitude (representing the length of day light hours) were the top environmental variables associated with C. pomonella distribution at global level. The predictive models and maps developed in this study present the global risk of establishment of C. pomonella, and can be used for monitoring potential introductions (via trade) of C. pomonella in different countries and by policy makers and trade negotiators in making science-based decisions.