Predicting the global distribution and invasion scenarios of the Spotted Lanternfly, Lycorma delicatula (White, 1845) (Hemiptera, Fulgoridae)

Lycorma delicatula is a species native to the PR of China that has become invasive in South Korea, Japan, and the United States. It is considered a significant threat to agriculture, particularly the viticulture industry, and its further spread into new areas could exacerbate its economic impact. Species Distribution Models (SDMs) are commonly used to analyze the distribution of invasive species, and while L. delicatula has already been studied using this spatial modeling approach, previous research has mostly focused on the effects of bioclimatic variables, often overlooking the role of habitat characteristics, including the presence of host plants. In our study, to assess the presence of other suitable habitats for the species on a global scale, we developed a two-step SDM calibrated within its native range, within biogeographic barriers. In the first step, we built two separate models: one for habitat suitability (HSM), incorporating land cover, elevation, and host plants, and another for bioclimatic suitability (BSM). The HSM calibration included the allocation of a portion of pseudo-absences (PAs) along background points (BPs) to mitigate the sampling bias of occurrences concentrated in highly urbanized areas (one bias-controlled PA for every four random BPs). In contrast, the BSM calibration was performed using a fully random allocation of BPs. In the second step, the two models were combined to produce an overall suitability map for the native range, which demonstrated excellent validation performance. When projected globally, the model confirmed that the species has already colonized suitable areas. Beyond the currently invaded regions (i.e., North America and East Asia), the model identifies additional colonizable areas exclusively in Europe. To evaluate the invasion dynamics in both currently invaded regions and potential future invasion areas in Europe, we developed a resistance-distance constrained dispersal model based on a) environmental resistance, derived from the overall suitability map produced by the SDM, and b) intrinsic dispersal distance, estimated from the temporal progression of occurrences in the primary invasion area in the eastern United States. The maximum annual dispersal distance was estimated to be approximately 25 kilometers. Given its relatively low annual dispersal capacity, the species appears capable of naturally spreading within areas of medium to high suitability, while its potential for expansion into low-suitability areas remains quite limited. Medium- and high-suitability regions where the species is already present are likely to undergo significant colonization over the next 10 years. In contrast, adventive populations in low-suitability areas seem unable to expand successfully without human-mediated translocations. In the absence of an adaptive capacity to thrive in ecological contexts different from its native range (niche change or niche shift), the species appears to be a relatively modest invader beyond its currently invaded areas or Europe. Successfully managing the invasion of L. delicatula therefore depends on the implementation of early detection and eradication measures, which should be deployed as promptly as possible, especially in highly suitable introduction areas.