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Poster: Epidemiology: Pathogen-Vector Interations


Cladosporium interactions with the introduced insect spotted wing drosophila (Drosophila suzukii) may alter raspberry fruit rot epidemiology
C. SWETT (1), C. Carignan (1), K. Hamby (1), E. Koivunen (1) (1) University of Maryland, U.S.A.

In fruit crops, the interaction between frugivorous insects and fungi can alter pest and disease epidemiology, reducing marketable crop yields. In 2015 field surveys of fall red raspberries in Maryland, Cladosporium was recovered from fruit-rot affected berries at three farms, and 30% of Cladosporium-infested berries were co-infested with SWD larvae. Analyses of larval frass microbes recovered Cladosporium from 45% of larvae, with 3.3 colony forming units/ larvae on average. Sequence analysis identified both berry and larval frass isolates as either Cladosporium cladosporioides or C. pseudocladosporioides. All three tested isolates of each species were pathogenic on raspberries in detached berry assays, and one tested isolate could infect both ripe and unripe fruit in attached-berry assays. Disease incidence was significantly enhanced (P < 0.05) both when inoculated detached berries were mechanically wounded and when naturally infested attached berries were exposed to lab-reared SWD adults (ovipositor wounds), compared tounwounded controls. Many endophytic Cladosporium species are entomopathogens, so species causing fruit rot may be deleterious to SWD fitness; alternately, this may represent a commensal or mutually beneficial interaction. Overall, these results are among the first to suggest that SWD may interact with Cladosporium to significantly alter pre- and post-harvest fruit rot epidemiology.