Attraction of female sciarid flies (Lycoriella ingenua, Dufour) to Trichoderma aggressivum infested substrate and the capacity to vector the fungal spores in commercial Agaricus bisporus mushroom production

The sciarid fly Lycoriella ingenua is a major pest of commercial mushroom production.  Larvae graze on mushroom mycelia reducing overall yields, and adults are suspected vectors of the most serious fungal disease of Agaricus, Trichoderma aggresivum, the incidence of which is commonly associated with fly populations inside mushroom houses. The capacity of L. ingenua to physically vector T. aggressivum spores was evaluated by placing adult females on agar plates containing colonies of T. agressivum. Spores were washed from a subsample of flies into suspensions for spore counts. Remaining flies were plated onto fresh agar for fungal colony formation evaluation. Additionally, female attractiveness to T. aggressivum was evaluated through preference assays between fungal infested substrats and non -infested substrates. Results showed that flies can potentially carry enough viable spores for new fungal colonies to form. Females also displayed a tendency to prefer T. aggressivum infested substrates for oviposition. This is the first report of the capacity of Lycoriella ingenua to effectively vector Trichoderma aggresivum and is the first step in confirming previous anecdotal observations. With this evidence of the vector potential pest status of L. ingenua significantly increased.