Invasive facilitates infestation and sour rot outbreaks in the vineyards.

How do invasive pests affect interactions between members of pre-existing agrosystems? The invasive pest is suspected to be involved in the aetiology of sour rot, a grapevine disease that otherwise develops following infestation of wounded berries. We combined field observations with laboratory assays to disentangle the relative roles of both in disease development. We observed the emergence of numerous , but no flies, from bunches that started showing mild sour rot symptoms days after field collection. However, bunches that already showed severe rot symptoms in the field mostly contained . In the laboratory, oviposition by triggered sour rot development. An independent assay showed the disease increased grape attractiveness to ovipositing females. Our results suggest that in invaded vineyards, facilitates infestation and, consequently, favours sour rot outbreaks. Rather than competing with close species, the invader subsequently permits their reproduction in otherwise non-accessible resources and may cause more frequent, or more extensive, disease outbreaks.