Phenology and spatial distribution of spotted-wing drosophila (Diptera: Drosophilidae) in lowbush blueberry (Ericaceae) in Saguenay-Lac-Saint-Jean, Quebec, Canada

摘要

Drosophila suzukii(Matsumura) (Diptera: Drosophilidae), the spotted-wing drosophila, is an invasive pest of fruit crops, which appeared in eastern Canada in 2010. It represents a major threat to lowbush blueberry (Vaccinium angustifoliumAiton; Ericaceae) in the Saguenay-Lac-Saint-Jean region, Quebec, Canada, at the northern limits of its distribution. The dynamics, overwintering capacity, population fluctuations, and damage to lowbush blueberry ofD.suzukiiare unknown in Saguenay-Lac-Saint-Jean. We aimed to 1) documentD. suzukiiabundance and phenology in lowbush blueberry in separate localities; 2) evaluate the potential ofD. suzukiito overwinter and examine population dynamics over three seasons; and 3) study the spatial distribution ofD. suzukiiin lowbush blueberry fields with respect to forested borders.Drosophila suzukiiis abundant in lowbush blueberry fields of Saguenay-Lac-Saint-Jean. In spring,D. suzukiiwere absent until late June, when few summer-morph females appeared.Drosophila suzukiidensities started to increase regularly in August, with increasing male proportions, to culminate in fall at high levels with balanced sex ratios. Overwintering remains uncertain,D. suzukiibeing undetectable in spring despite intensive trapping. Appearance of diapausing winter morphs at high densities indicates thatD. suzukiiresponds appropriately to local conditions preceding cold winter. Models of variation ofD. suzukiidensities and lowbush blueberry fruit infestation with distance from borders indicate that forest borders are favoured habitats over lowbush blueberry fields and the source ofD. suzukiimoving to some extent into lowbush blueberry fields.