Landscape, Drosophila suzukii and host plants: a three-factor evaluation of Leptopilina japonica establishment

Abstract: Leptopilina japonica, an Asian parasitoid of the invasive Drosophila suzukii, was
monitored over two years in Lombardy (Northern Italy) to assess its presence, distribution, and ecological relationships with the surrounding landscape. From June to September, ripe fruits were collected at six sites along an altitudinal gradient and incubated to document parasitoid emergence and its interactions with D. suzukii, other drosophilids, and host plants. L. japonica was consistently detected throughout the two years, with most emergences recorded from Rubus spp. Ongoing analyses combine host–plant data with environmental and landscape variables to identify factors influencing the establishment and distribution of the species. Overall, this monitoring effort provides an updated picture of L. japonica in Lombardy and helps clarify how host availability and landscape complexity may shape its ecological dynamics and potential role in the natural control of D. suzukii.