Halyomorpha halys in Mediterranean areas: local and landscape predictors, genetic diversity, and potential biological control

The brown marmorated stink bug Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive species currently established in several non-native regions, where it causes severe economic losses for growers. The factors driving H. halys spread are, however, poorly understood. Here, we studied H. halys populations in Apulia region (southern Italy), where the pest is present but not established. We monitored pest occurrence in different habitats selected along a gradient of urban cover in the landscape, and measured the potential biological control by natural enemies. Finally, to identify the potential pathways of entry in the region, we carried out a preliminary genetic characterization of Apulian populations. We found that high proportions of urban habitats in the landscape generally supported a higher occurrence and abundance of H. halys in crop fields, whereas high cover of semi-natural habitats increased parasitism rate. A higher predation rate was observed in crop fields compared to urban areas. The parasitoids Anastatus bifasciatus and Ooencyrtus sp., important control agents in areas where the pest is already established, were the most common species observed. Our findings suggest that the agricultural matrix affects the occurrence and the biological control of H. halys in newly invaded areas, potentially influencing its establishment probability. Finally, the high gentic similarity with the northern Italian populations suggested continuous introduction events, probably from the northern part of the country. Future monitoring programs focused on urban and cultivated areas will be fundamental to track the spread of the pest.