Spotted-wing drosophila (Drosophila suzukii) host suitability variation between half-high blueberry (Vaccinium corymbosum) cultivars

Spotted-wing drosophila (Drosophila suzukii; SWD) is an invasive pest in the U.S. and responsible for significant economic damage to small fruit world-wide. Females use a serrated ovipositor to deposit eggs inside ripe and ripening fruit. SWD exhibit host use plasticity and utilize a variety of cultivated and wild fruit. Host suitability for SWD depends on physical and chemical characteristics of fruit, with positive correlations reported between SWD oviposition as well as larval development with soluble sugar content, softer fruit and higher pH, and a negative correlation between oviposition and fruit firmness. Cultivar selection is an important tool for integrated pest management, but few studies report host suitability across varieties within a single cultivated crop species for SWD. In this study, we investigated SWD oviposition and larval development in five half-high blueberry (Vaccinium corymbosum) cultivars: ‘Chippewa’, ‘Northblue’, ‘Northland’, ‘Patriot’ and ‘Polaris’ using no-choice and two-choice laboratory bioassays. Using a Host Potential Index, our results showed that ‘Chippewa’ was the most preferred cultivar for oviposition measured in number of eggs laid per fruit and ‘Polaris’ was the least preferred. The inverse was true for larval development, with a higher survival rate and adult emergence in ‘Polaris’ than ‘Chippewa’. There was a negative relationship between fruit firmness and oviposition and a positive correlation between pH and larval development. The results of this study indicate that cultivar selection for half-high blueberries may be a promising integrated pest management tool, however further research under field conditions is needed for validation.