A Review of the Scientific Literature on Fungus Gnats (Diptera: Sciaridae) in the Genus Bradysia2

Abstract

The majority of the literature concerning fungus gnats in the genus Bradysia (Family Sciaridae) can be divided into two groups, addressing their cytogenetics or their role as economically important pests. Cytological anomalies in sciarids are recognized in (1) chromosome complement, (2) differential chromosome contributions of the sperm and egg, (3) alteration of chromosome complement during embryogenesis, (4) and alteration during gametogenesis. The literature concerning these cytological events is reviewed within the context of the development of the science of cytogenetics and as they relate to the taxonomy and systematics of this group. Although species of Bradysia were recognized as pests of various seedling plants over a century ago, their economic importance in plant and mushroom production was largely overlooked until recently. A review of the scientific literature on the biology and management of the sciarids indicates that members of the genus Bradysia may be especially pestiferous in greenhouse plant production. Although, a fungal food source appears to be critical to successful development and reproduction of fungus gnats, larvae also will feed on healthy plant tissue. Feeding activities of larvae directly damage seedlings, whereas both larvae and adults indirectly contribute to plant damage through the spread of fungal phytopathogens. The relatively recent confirmation of fungus gnats as potential disseminators of plant pathogens has placed these insects in the category of a more serious pest. As expected with any recently recognized pest, critical information regarding monitoring and economic thresholds is lacking. However, because these flies have been considered a nuisance, chemical control methods are available, as are alternatives which have been integrated most successfully into management programs in European glasshouses.