Spotted wing drosophila
Identifying strawberries and raspberries with resistance to SWD
NIAB’s Michelle Fountain, Adam Whitehouse and Feli Fernandez outline some promising results emerging from a Growing Kent & Medway funded research project. Since the arrival of spotted wing drosophila (SWD) in the UK in 2012, NIAB’s entomologists at East Malling have led a host of industry research projects to learn more about its biology and behaviour in UK conditions and how best to manage and control it. Most recently exciting progress has been made through the use of precision monitoring in the winter months, use of bait sprays, and the development of Sterile Insect Technique (SIT) in collaboration with commercial company BigSis. However, one approach to control that hasn’t been fully explored is variety resistance to the pest. Ripening soft and stone fruits are highly attractive to adult SWD, with the female making an incision in the skin of the fruit and laying eggs under the surface. The resulting larvae feed on the flesh of the fruit, leading to fruit collapse and an unmarketable product. If any accessions (varieties, selections, or species) of soft fruits are found to have berries that
are less attractive to SWD or that inhibit egg laying or larval emergence, we could then investigate the fruit traits that are associated with this and utilise such traits in the NIAB breeding programmes. In this Growing Kent & Medway funded project, NIAB scientists are collaborating with Asplins PO and WB Chambers to screen many accessions (varieties, selections, or species) of strawberry and raspberry, initially to identify if any show resistance to SWD and then find out what such resistance might be caused by. In 2022, the focus was on strawberry and a wide range of strawberry genotypes were chosen based on their origin and pedigree. The material tested was diverse, ranging from old English bred June-bearer variety ‘Cambridge Favourite’, to the large, firm Californian variety day-neutral type ‘Diamante’. The range included differing traits like skin colour, skin firmness, flesh firmness, size, and sugar levels (Brix). SWD Adult on raspberry ©Washington State University
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