Evaluating global Vaccinium germplasm for resistance against invasive Drosophila suzukii (Diptera: Drosophilidae)

Authors: Sampson, Blair; Stringer, Stephen; Hummer, Kim; Babiker, Ebrahiem; Werle, Christopher; Adamczyk, John; Shaw, Donna

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2022
Publication Date: 5/30/2023
Citation: Sampson, B., Stringer, S., Hummer, K., Babiker, E., Werle, C., Adamczyk, J. and Shaw, D., 2023. Evaluating global Vaccinium germplasm for resistance against invasive Drosophila suzukii (Diptera: Drosophilidae). Journal of Economic Entomology, p.toad081. https://doi.org/10.1093/jee/toad081
DOI: https://doi.org/10.1093/jee/toad081

Interpretive Summary: Pest control for the Spotted Wing Drosophila Fly involves insecticides, cultural controls, and some biological control. However, virtually no research has been done to identify host plant resistance among fruit and berry crops attacked by this fly invader. We used a laboratory bioassay or screening method to test 29 species of blueberries and their close relatives. Resistance among of these plants involved reducing the longevity of adult flies and reducing egg and larval loads. Wild blueberries including 3 species within the fly's native range offered the greatest sources of resistance and those genotypes with high numbers of chromosomes were also highly resistant.

Technical Abstract: Integrated Pest Management (IPM) of spotted wing Drosophila (SWD) in fruits and berries emphasizes biological, cultural, and chemical control. Little research has focussed on genetic control via host plant resistance. Identifying resistant germplasm and patterns of host plant resistance are crucial first steps for suppressing invasive insect populations. Therefore, we developed a detached fruit bioassay to screen global Vaccinium germplasm from 8 Sections comprising 29 species and hybrids for resistance (antibiosis) against D. suzukii eggs, larvae, and adults. Ten species showed strong resistance (levels 4.0 – 5.0) based on low levels of oviposition and larval infestation. Three of these more resistant species were diploids originating from within SWD’s native range of East Asia, i.e., V. myrtoides, V. oldhami, and V. bracteatum. Additional resistant species from Central and South American Sections Pyxothamnus and Conchophyllum included V. consanguineum, V. floribundum, and V. meridionale. Large-cluster blueberry, V. amoenum, and three Floridian genotypes of related rabbiteye blueberry, V. virgatum, were the only hexaploids and cultivated species showing strong resistance. Most screened blueberry genotypes from managed lowbush and cultivated highbush types were all susceptible to SWD oviposition and larval infestation (resistance levels from 1.0 – 2.9). Tetraploid blueberries tended to be the most susceptible, whereas diploids and hexaploids harbored 50% – 60% fewer eggs, on average. We hypothesize that smaller, sweeter, and firmer diploid berries are poor oviposition sites for SWD. Females may perceive sweet berries as overripe and unsuitable as a reproductive substrate. More SWD-resistant genotypes of large-fruited tetraploid and hexaploid blueberries (2.0 – 4.0 g) probably possess a thicker or tougher skin e.g. accession MS1167.