Assessment of potential invasion for six phytophagous quarantine pests in Taiwan

Pest risk assessment is typically performed by expert taxonomists using a pest’s biological data. However, the biological data or expert taxonomists may be difficult to find. Here, we used species distribution modelling to predict potential invasion in which phytophagous quarantine pests survive in Taiwan; the pests (unrecorded yet in Taiwan) included were three notorious quarantine whiteflies (Crenidorsum aroidephagus, Aleurothrixus trachoides, and Paraleyrodes minei) and three aphids (Nasonovia ribisnigri, Macrosiphum euphorbiae, and Viteus vitifoliae). In brief, maximum entropy modelling (MaxEnt) was used to predict the suitability of the pests’ habitats under certain climatic conditions, and then receiver operating characteristic curve analysis was performed (to verify the prediction result). We then analysed environmental variables affecting the habitat suitability and matched them with Taiwan’s crop cultivation areas for the assessment of potential invasion. We observed that the habitat suitability of the cultivation areas of host plants was low for C. aroidephagus, A. trachoides, and N. ribisnigri but was high for the remaining three species. Moreover, precipitation of coldest quarter negatively affected habitat suitability for C. aroidephagus, P. minei, N. ribisnigri, and M. euphorbiae. Seasonal temperature changes also negatively affected the habitat suitability for A. trachoides. This is the first study to demonstrate the use of species distribution modelling as the preliminary step for the pest risk assessment of these emerging pests with limited biological data before their invasion.

Environmental niche modelling as tool for pest risk assessment

The article reviews the concept and technology of pest risk assessment for the spread of quarantine species based on ecological and geographical analysis and ecological niche modeling. Using a quarantine species Ipomoea hederacea (L.) Jacq. as an example, we calculated the ecological requirements of the species. The main ecological factors limiting the spread of I. hederacea were determined and the ecological amplitudes of the species in relation to each factor limiting its distribution were quantitatively estimated. We identified ecologically suitable habitats and compiled a map of the ecological-geographical niche of the species using specially created environmental maps based on the obtained data of the ecological limits of the species. Using the map of the ecological-geographical niche, the I. hederacea distribution risk in the regions of the Russian Federation was estimated. Similar maps can be used for basis of quantitative as well as targeted risk assessment of penetration and establishment of harmful organisms. Obtained information will be useful to compile lists of quarantine species, estimate the potential areas of geographic distribution of pests into Russian Federation, and make decisions for introduction of effective phytosanitary measures to prevent the penetration of these invasive organisms. It can also be used as the basis for organizing and conducting phytosanitary monitoring in the Russian Federation.