While biological distributions are not static and change/evolve through space and time, nonstationarity of climatic and land‐use conditions is frequently neglected in species distribution models. Even recent techniques accounting for spatiotemporal variation of species occurrence basically consider the environmental predictors as static; specifically, in most studies using species distribution models, predictor values are averaged over a 50‐ or 30‐year time period. This could lead to a strong bias due to monthly/annual variation between the climatic conditions in which species' locations were recorded and those used to develop species distribution models or even a complete mismatch if locations have been recorded more recently. Moreover, the impact of land‐use change has only recently begun to be fully explored in species distribution models, but again without considering year‐specific values. Excluding dynamic climate and land‐use predictors could provide misleading estimation of species distribution. In recent years, however, open‐access spatially explicit databases that provide high‐resolution monthly and annual variation in climate (for the period 1901–2016) and land‐use (for the period 1992–2015) conditions at a global scale have become available. Combining species locations collected in a given month of a given year with the relative climatic and land‐use predictors derived from these datasets would thus lead to the development of true dynamic species distribution models (D‐SDMs), improving predictive accuracy and avoiding mismatch between species locations and predictor variables. Thus, we strongly encourage modelers to develop D‐SDMs using month‐ and year‐specific climatic data as well as year‐specific land‐use data that match the period in which species data were collected.

The spread of invasive species is a threat to global biodiversity. The Japanese beetle is native to Japan, but alien populations of this insect occur in North America, and recently, also in southern Europe. This beetle was recently included on the list of priority species of European concern, as it is a highly invasive agricultural pest. Thus, in this study, we aimed at (i) assessing its current distribution range, and identifying areas of potential invasion, and (ii) predicting its distribution using future climatic and land-use change scenarios for 2050. We collected species occurrences available on the citizen science platform iNaturalist, and we combined species data with climatic and land-use predictors using a Bayesian framework, specifically the integrated nested Laplace approximation, with a stochastic partial differential equation. We found that the current distribution of the Japanese beetle was mainly, and positively, driven by the percentage of croplands, the annual range of temperature, habitat diversity, percentage of human settlements, and human population density; it was negatively related to the distance to airports, elevation, mean temperature diurnal range, wetlands, and waters. As a result, based on current conditions, the Japanese beetle is likely to occur in 47,970,200 km², while its distribution will range from between 53,418,200 and 59,126,825 km², according to the 2050 climatic and land-use change scenarios. We concluded that the Japanese beetle is a high-risk invasive species, able to find suitable conditions for its colonization in several regions around the globe, especially in light of ongoing climatic change. Thus, we strongly recommend strict biosecurity checks and quarantines, as well as regular pest management surveys, in order to reduce its spread.

The impact of invasive species is not limited to the loss of biodiversity; it also represents significant threats to agriculture on a global scale. The Japanese beetle Popillia japonica (native to Japan but an invasive agricultural pest in North America) recently occurred in the Po plain (Italy), one of the most cultivated areas in southern Europe. Thus, our aims were to identify (i) the main landscape predictors related to the occurrence of the Japanese beetle and (ii) the areas of potential invasion of the Japanese beetle in the two Northern Italian regions in which this invasive species currently occurs, Piedmont and Lombardy. Specifically, we combined Japanese beetle occurrences available in the citizen science online platform iNaturalist with high-resolution landscape predictors in an ensemble approach and averaged the results of Bayesian generalized linear and additive models developed with the integrated nested Laplace approximation (with stochastic partial differential equation). We found that the occurrence of the Japanese beetle was negatively related to the percentage of broadleaf forests and pastures, while it was positively related to sparse and dense human settlements as well as intensive crops. Moreover, the occurrence of the Japanese beetle increased in relation to the percentage of rice fields until a peak at around 50%. The Japanese beetle was likely to occur in 32.49% of our study area, corresponding to 16,000.02 km², mainly located in the Po plain, low hills, and mountain valleys. We stress that the Japanese beetle is a high-risk invasive species in human-dominated landscapes. Thus, we strongly recommend that local administrations quickly enact pest management in order to reduce further spread.