Fungal communities differ between fruit-types and across ripening, and Saccharomycetales yeasts abundances positively correlate with fruit Drosophila suzukii susceptibility

Fungal volatiles attract the Drosophila suzukii insect pest which oviposits in unripe fruits, but there are few data describing the fungal microbiomes of D. suzukii susceptible commercial fruits. We tested the hypothesis that both fruit type and ripening stage have a significant effect on fruit surface fungal communities using DNA metabarcoding approaches and found strong support for differences in all three fungal community biodiversity metrics analysed (numbers, types, and abundances of taxa). There was an average 5-fold greater difference in fungal communities between fruit types (strawberry, cherry, raspberry, and blueberry) than across maturation (four stages, from green to ripe fruit) showing fruit type is the greater factor defining fungal community assemblage. Metabarcoding analysis is generally not quantitative, but the addition of a fungal benchmark showed cherry had relatively static fungal populations across ripening. Raspberry had a greater prevalence of Saccharomycetales yeasts, including Hanseniaspora uvarum, attractive to D. suzukii. This is an intriguing observation as raspberry are among the fruits with the greatest susceptibility to D. suzukii. Greater knowledge of how yeast communities change during fruit maturation and between species may be valuable in finding additional attractive yeasts which can be exploited in integrated pest management strategies to control D. suzukii.