Fruit volatiles mediate differential attraction of Drosophila suzukii to wild and cultivated blueberries

Journal of Pest Science - Native to the northeast USA, highbush blueberry is a crop domesticated for close to 100 years and that has been selected mainly for high yields and bigger fruit....     

Spatial and temporal genetic variation of Drosophila suzukii in Germany

Native to Southeast Asia, the spotted wing drosophila (SWD), Drosophila suzukii Matsumura, rapidly invaded America and Europe in the past 20 years. As a crop pest of soft-skinned fruits with a wide range of host plants, it threatens the fruit industry worldwide, causing enormous economic losses. To control this invasive pest species, an understanding of its population dynamics and structure is necessary. Here, we report the population genetics and development of SWD in Germany from 2017–19 using microsatellite markers over 11 different sample sites. It is the first study that examines SWD’s genetic changes over 3 years compared to multiple international SWD laboratory strains. Results show that SWD populations in Germany are highly homogenous without differences between populations or years, which indicates that populations are well adapted, migrate freely, and multiple invasions from outside Germany either did not take place or are negligible. Such high genetic variability and migration between populations could allow for a fast establishment of the pest species. This is especially problematic with regard to the ongoing spread of this invasive species and could bear a potential for developing pesticide resistance, which could increase the impact of the SWD further in the future.

     

Potential host ranges of three Asian larval parasitoids of Drosophila suzukii

Asobara japonica (Hymenoptera: Braconidae), Ganaspis brasiliensis and Leptopilina japonica (Hymenoptera: Figitidae) are Asian larval parasitoids of spotted wing drosophila, Drosophila suzukii (Diptera: Drosophilidae). This study evaluated these parasitoids’ capacity to attack and develop from 24 non-target drosophilid species. Results showed that all three parasitoids were able to parasitize host larvae of multiple non-target species in artificial diet; A. japonica developed from 19 tested host species, regardless of the phylogenetic position of the host species, L. japonica developed from 11 tested species; and G. brasiliensis developed from only four of the exposed species. Success rate of parasitism (i.e., the probability that an adult wasp successfully emerged from a parasitized host) by the two figitid parasitoids was low in hosts other than the three species in the melanogaster group (D. melanogaster, D. simulans, and D. suzukii). The failure of the figitids to develop in most of the tested host species appears to correspond with more frequent encapsulation of the parasitoids by the hosts. The results indicate that G. brasiliensis is the most host specific to D. suzukii, L. japonica attacks mainly species in the melanogaster group and A. japonica is a generalist, at least physiologically. Overall, the developmental time of the parasitoids increased with the host’s developmental time. The body size of female A. japonica (as a model species) was positively related to host size, and mature egg load of female wasps increased with female body size. We discuss the use of these parasitoids for classical biological control of D. suzukii.

     

Plastic mulches reduce adult and larval populations of Drosophila suzukii in fall-bearing raspberry

Journal of Pest Science - The invasive spotted-wing drosophila, Drosophila suzukii, is a major pest of fruit crops worldwide. Management of D. suzukii relies heavily on chemical control in both...     

Tracking the invasion of the alien fruit pest Drosophila suzukii in Europe

Biological invasions are a leading threat to native wildlife, human health and food production worldwide. Understanding the invasion history helps identifying introduction pathways and organizing integrated management strategies especially aimed at avoiding multiple reintroductions. We coupled a recently developed spatial analysis (Geographic profiling) with trade flows quantification to identify the most likely spreading centre of a recent invader of Europe, the spotted wing drosophila, Drosophila suzukii. This polyphagous vinegar fly recently colonized western countries, where it is heavily threatening fruit production causing severe economic losses. Characterized by a rapid spread and a huge impact, the invasion of this pest has a few precedents and it is becoming a model in invasion biology and pest management. Thanks to our spatial approach based on data presence of D. suzukii in European countries in the very first years of it spread, we update the current knowledge of a first spread in Spain and Italy, suggesting on the contrary that the South of France may be the most likely spreading centre of D. suzukii in Europe. Estimates of propagule pressure (fresh host fruits importation) support this finding as imports from contaminated South East Asian countries are higher in France than in Spain or Italy. Our study provides a first step in the comprehension of invasion history of this pest species and emphasizes geographic profiling as an efficient technique to track down invaders colonization patterns.