Biology subjects

Beers, E. H.

Publications and source records attributed to Beers, E. H..

3 recordsLinked to original sources

bioRxiv2025

Island invasions by the non-native vinegar fly Drosophila suzukii and its parasitoid wasps

Understanding how island characteristics influence the establishment and impact of invasive species and their natural enemies could inform both island biogeography and biological control theory. We studied the occurrence and relative abundances of the globally invasive fruit fly, Drosophila suzukii, and its recently introduced larval parasitoids, Leptopilina japonica and Ganaspis kimorum, across islands with varying sizes and levels of human-mediated transport in the Gulf and San Juan Islands of British Columbia (Canada) and Washington State (USA). Across two years and 58 sites, we collected D. suzukii and its parasitoids from wild blackberry, Rubus armeniacus, fruit. We predicted that parasitoids were more likely to be present on larger islands with higher levels of human activity and higher D. suzukii densities, and that the less specialized parasitoid species (L. japonica) would be more likely to establish on islands. We detected D. suzukii across all islands, indicating widespread establishment of this invasive pest. In contrast, we observed parasitoids on fewer than half of the islands. Leptopilina japonica was the only parasitoid of D. suzukii detected on islands. Parasitoid presence was marginally positively associated with island area and host density, but not average annual vehicle-ferry traffic (an indicator of human-mediated propagule pressure). Parasitism levels were low throughout the study region and we did not observe lower relative abundances of D. suzukii on islands where parasitoids were present - in fact, the relative abundance of D. suzukii tended to be higher on islands where the parasitoid L. japonica was detected. These findings suggest that island characteristics, host density, and a consumers host specificity may be associated with early establishment of introduced consumers on islands, but that a consumers presence may not inevitably result in host population suppression, at least over the short term.

ecology↗

bioRxiv2021

Population structure of Drosophila suzukii and signals of multiple invasions into the continental United States

Drosophila suzukii, or spotted-wing drosophila, is now an established pest in many parts of the world, causing significant damage to numerous fruit crop industries. Native to East Asia, D. suzukii infestations started in the United States a decade ago, occupying a wide range of climates. To better understand invasion ecology of this pest, knowledge of past migration events, population structure, and genetic diversity is needed. To improve on previous studies examining genetic structure of D. suzukii, we sequenced whole genomes of 237 individual flies collected across the continental U.S., as well as several representative sites in Europe, Brazil, and Asia, to identify hundreds of thousands of genetic markers for analysis. We analyzed these markers to detect population structure, to reconstruct migration events, and to estimate genetic diversity and differentiation within and among the continents. We observed strong population structure between West and East Coast populations in the U.S., but no evidence of any population structure North to South, suggesting there is no broad-scale adaptations occurring in response to the large differences in regional weather conditions. We also find evidence of repeated migration events from Asia into North America have provided increased levels of genetic diversity, which does not appear to be the case for Brazil or Europe. This large genomic dataset will spur future research into genomic adaptations underlying D. suzukii pest activity and development of novel control methods for this agricultural pest.

genomics↗

bioRxiv2020

Large-scale geographic survey provides insights into the colonization history of a major aphid pest on its cultivated apple host in Europe, North America and North Africa

AO_SCPLOWBSTRACTC_SCPLOWWith frequent host shifts involving the colonization of new hosts across large geographical ranges, crop pests are good models for examining the mechanisms of rapid colonization. The microbial partners of pest insects may also be involved in or affected by colonization processes, which has been little studied so far. We investigated the demographic history of the rosy apple aphid, Dysaphis plantaginea, a major pest of the cultivated apple (Malus domestica) in Europe, North Africa and North America, as well as the diversity of its microbiota. We genotyped a comprehensive sample of 714 colonies from Europe, Morocco and the US using mitochondrial (CytB and CO1), bacterial (16s rRNA and TrnpB), and 30 microsatellite markers. We detected five populations spread across the US, Morocco, Western and Eastern Europe and Spain. Populations showed weak genetic differentiation and high genetic diversity, except the ones from Morocco and North America that are likely the result of recent colonization events. Coalescent-based inferences revealed high levels of gene flow among populations during the colonization but did not allow determining the sequence of colonization of Europe, North America and Morroco by D. plantaginea, likely because of the weak genetic differentiation and the occurrence of gene flow among populations. We found that D. plantaginea rarely hosts other endosymbiotic bacteria than its obligate nutritional symbiont Buchnera aphidicola. This suggests that secondary endosymbionts did not play an important role in the rapid spread of the rosy apple aphid. These findings have fundamental importance for understanding pest colonization processes and implications for sustainable pest control programs.

evolutionary biology↗