Field assessment of brix and firmness affecting <i>Drosophila suzukii</i> (Diptera: Drosophilidae) infestation in California sweet cherry cultivars

Spotted-wing Drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), is a damaging insect pest of sweet cherry fruit worldwide including in the central valley of California where it was first reported as an economic pest in spring 2009. The aim of this field-based study was to assess the relationship of Brix level and skin firmness on D. suzukii oviposition and infestation in 4 commercially important sweet cherry cultivars: Bing, Black Tartarian, Brooks, and Rainier. Results of this field study found that both higher Brix values and lower skin firmness resulted in increased fruit infestation in all varieties, highlighting the importance of these factors in host susceptibility. Other potential factors are also discussed as they relate to D. suzukii fruit infestation. Implications of these findings are discussed as well as how they might be used in future D. suzukii management in sweet cherries.