GLOBAL HABITAT SUITABILITY OF Rhagoletis pomonella (WALSH, 1867) (DIPTERA: TEPHRITIDAE) UNDER CMIP6 CLIMATE CHANGE SCENARIOS PREDICTED BY ENSEMBLE MODEL

Abstract

Climate change significantly impacts species’ distribution globally, which is modifying the geographic ranges and ecological interactions of agricultural pests. This study projected the potential global spread of a significant pest of apples, i.e., Rhagoletis pomonella (Walsh, 1867) (Diptera: Tephritidae) under current and future climatic scenarios (CMIP6) employing ensemble species distribution modeling techniques (combining MaxEnt, GLM, GAM, CTA algorithms). The model was calibrated with 316 occurrence records and 15 environmental and ecological variables (11 environmental and 4 ecological). The results demonstrated excellent prediction performance (ROC >0.90, TSS >0.84). Temperature-related factors, i.e., the mean temperature of the warmest quarter and the annual temperature range, exerted the most significant impact on habitat suitability. Globally, optimum habitats for R. pomonella under present conditions were predominantly located in the temperate zones of North America, Europe, and East Asia. Future climate scenarios (SSP1-2.6 and SSP5-8.5) predict an expansion of suitable habitats northward and to higher elevations, notably affecting areas such northern Europe, southern Canada, northern Japan, and Türkiye. In contrast, severe climate scenarios suggested a possible decline in suitability within historically favorable habitats, including regions of the southern United States and Mediterranean Europe, because of substantial temperature rises. Europe, Turkey and Japan have substantial agricultural economies and vulnerabilities to possible invasions. Turkey exhibited significant growth in suitable habitats, hence elevating threats to apple producing areas. In Japan, especially in the northern islands, suitability is expected to increase markedly, requiring improved monitoring and preventative strategies. This study highlights the crucial need for internationally coordinated biosecurity programs, localized pest control methods, and flexible agricultural policies to alleviate the effects of climate-induced changes in R. pomonella distribution