New findings of pest sciarid species (Diptera, Sciaridae) in Ukraine, with the first record of Bradysia difformis

Abstract

Sciarids (Diptera, Sciaridae) or black fungus gnats are small, mainly dark coloured insects whose larvae usually develop in rotting plant remains permeated by fungal hyphae. Typical habitats for sciarids are shaded forests and wet meadows, but some species can migrate from natural biotopes to anthropogenic ecosystems and live as synanthropes. Synanthropic sciarid species in the case of their larvae mass development, may cause significant damage to agricultural plants and mushrooms and are considered as pests. The information on pest activities of sciarids in the literature is provided for 34 species, but only 7 species can be considered as dangerous pests. In the framework of taxonomic and ecological research on Sciaridae in Ukraine, some chorological and faunistic peculiarities of pest sciarids have been studied. We collected material during the expeditions and excursions in different biotopes of Ukraine from 2012 to 2018 using the Malaise trap, by the method of non-count sweeping with entomological net and with exhauster directly from substrate. The collected imagoes were placed into 5 mL vials with 70% ethanol. In the lab, the fixed material was dehydrated in absolute ethanol and mounted on slides in Euparal. All of the studied material is kept in Andriy Babytskiy’s Private Collection, Kyiv (PABK) and mostly availible to the public on the UkrBIN. In Ukraine 4 species of harmful sciarid pests from 3 genera are recorded, namely Bradysia brunnipes (in Crimea), B. difformis (in Kyiv and Volyn Regions), Lycoriella ingenua (in Kyiv and Volyn Regions) and Pnyxia scabiei (Western regions excluding the Carpathians). B. brunnipes, also known as “cucumber gnat”, is one of the widespread cucumber pests in greenhouses, damaging roots and above-ground shoots of cucumbers. In Ukraine, mass development of this species and significant loses of the harvest caused by it have not been reported. B. difformis is a widespread pest sciarid, but in Ukraine it has been recorded for the first time. The mass development of this species was recorded in hothouses with cacti and other succulent plants at the O. V. Fomin Botanical Garden, where the larvae of B. difformis cause significant damage to these plants, especially to their sprouts. L. ingenua is the most common sciarid pest which damages mushrooms in hothouses. In Ukraine it was massively recorded  in cellars and on vegetables in storages. P. scabiei was recorded in Western Ukraine, except the Carpathians, as a potato pest species that damages sprouts in the fields and tubers in storages. Considering the absence of records of P. scabiei in natural biotopes of Ukraine, it is likely that this species was introduced to our country from America together with potatoes and should be recognized as an alien species to the natural entomofauna of Ukraine.