Data from: Attraction, oviposition and larval survival of the fungus gnat, Lycoriella ingenua, on fungal species isolated from adults, larvae, and mushroom compost

We previously showed that the females of the mushroom sciarid, Lycoriella ingenua (Dufour, 1839) (Diptera: Sciaridae), one of the most severe pests of the cultivated white button mushroom, Agaricus bisporus (J.E. Lange) Emil J. Imbach (Agaricales: Agaricaceae), are attracted to the mushroom compost that mushrooms are grown on and not to the mushrooms themselves. We also showed that females are attracted to the parasitic green mold, Trichoderma aggressivum. In an attempt to identify what is in the mushroom compost that attracts female L. ingenua, we isolated several species of fungi from adult males and females, third instar larvae, and mushroom compost itself. We then analyzed the attraction of females to these substrates using a static-flow two choice olfactometer, as well as their oviposition tendencies in another type of assay under choice and no-choice conditions. We also assessed the survival of larvae to adulthood when first instar larvae were placed on each of the isolated fungal species. We found that female flies were attracted most to the mycoparasitic green mold, T. aggressivum, to Penicilium citrinum isolated from adult female bodies, and to Scatylidium thermophilium isolated from the mushroom compost. Gravid female flies laid the most eggs on T. aggressivum, Aspergillus flavus isolated from third instar larval frass, Aspergillus fumigatus isolated from adult male bodies, and on P. citrinum. This egg-laying trend remained consistent under no-choice conditions as females aged. First instar larvae developed to adulthood only on S. thermophilium and Chaetomium sp. isolated from mushroom compost, and on P. citrinum. Our results indicate that the volatiles from a suite of different fungal species act in tandem in the natural setting of mushroom compost, with some first attracting gravid female flies and then others causing them to oviposit. The ecological context of these findings is important for creating an optimal strategy for using possible semiochemicals isolated from these fungal species to better monitor and control this pestiferous mushroom fly species.

我们此前已证实，作为栽培双孢蘑菇（Agaricus bisporus (J.E. Lange) Emil J. Imbach，伞菌目：伞菌科）的主要害虫之一，蘑菇眼蕈蚊（mushroom sciarid，Lycoriella ingenua (Dufour, 1839)，双翅目：眼蕈蚊科（Sciaridae））的雌虫会被栽培蘑菇所用的培养料吸引，而非蘑菇本身。我们同时证实，该雌虫还会被寄生性绿霉菌（Trichoderma aggressivum）吸引。为明确蘑菇培养料中吸引该雌虫的活性组分，我们从成虫（雌雄个体）、三龄幼虫以及蘑菇培养料本身中分离得到了多种真菌。随后，我们采用双选择静态流嗅觉仪（static-flow two choice olfactometer）测定了雌虫对这些真菌底物的趋性，并通过另一套包含选择与无选择两种处理的实验，评估了雌虫的产卵偏好。此外，我们还将初孵幼虫分别接种至各分离真菌菌株上，记录其发育至成虫的存活率。实验结果显示，雌虫对寄生性绿霉菌（Trichoderma aggressivum）、从雌成虫体内分离得到的桔青霉（Penicillium citrinum）以及从蘑菇培养料中分离得到的嗜热帚霉（Scatylidium thermophilium）表现出最强的趋性。怀卵雌虫的最高产卵量则出现在以下基质：致病木霉（Trichoderma aggressivum）、从三龄幼虫粪便中分离得到的黄曲霉（Aspergillus flavus）、从雄成虫体内分离得到的烟曲霉（Aspergillus fumigatus）以及桔青霉（Penicillium citrinum）。随着雌虫日龄增长，该产卵偏好趋势在无选择实验条件下始终保持稳定。仅在接种了嗜热帚霉（Scatylidium thermophilium）、从蘑菇培养料中分离得到的毛壳菌（Chaetomium sp.）以及桔青霉（Penicillium citrinum）的基质上，初孵幼虫才能顺利发育至成虫阶段。本研究结果表明，在蘑菇培养料的自然生态环境中，多种真菌释放的挥发性物质会协同发挥作用：部分真菌的挥发性成分首先吸引怀卵雌虫，另一部分则诱导其产卵。本研究结果的生态学背景，可为利用从上述真菌中分离得到的信息化合物（semiochemicals）构建最优监测与防治策略提供理论依据，以实现对该毁灭性蘑菇害虫的有效防控。