Fungus among us! The potential for biting midge control

Authors: Ewing, Robert; Cohnstaedt, Lee

Submitted to: North American Deer Farmer
Publication Type: Trade Journal
Publication Acceptance Date: 4/2/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary: None needed. Trade Journal

Technical Abstract: As most are aware, biting midges are difficult to manage and may transmit viruses resulting in diseases that can negatively influence profits due to cervid morbidity and mortality. Of major concern are viruses vectored to deer, elk and cattle by Culicoides spp such as bluetongue (BTV) and epizootic hemorrhagic disease (EHDV), which can result in tremendous loss to the farmer/rancher. Management of pest species often involves an integrated approach possibly using chemicals, sanitation or cultural changes such as placing nets around pens or enclosures. As with any IPM program, knowledge of the pest’s life-cycle is key when selecting management tools and methods. As an example, when using pesticides to target newly emerging adults the placement of the chemical requires timing the treatment with adult emergence and knowing the preferred habitat to obtain the highest pest mortality, with the least product and damage to the environment. New techniques and methods are being tested and adapted to not only better understand this pest, but to better target them. The use of novel approaches which may include biocontrol elements may be the path to success. Biocontrol methods are the use of other organisms (agents) that target pest species and attempt to reduce the local pest population. Biocontrol can center on predation - the introduction of spiders in a fly infested barn, herbivory - the use of plants chemical defenses to repel, or parasitism – the use of specific fungi to feed on the species to be controlled. Typically, biocontrol measures involve some form of management from a human perspective. Entomopathogenic fungi (EPF) as the name implies, are fungi which have evolved to utilize insects as a primary source of nutrients and can affect a wide range of insects in varying stages of the insect life cycle. A primary benefit of EPF when compared to other biocontrol agents is that they do not have to be ingested by the insect to cause infection. Some reports of infection through siphon tips, primarily in aquatic larvae, have occurred. However, simple contact with the reproductive spores of the fungi can be enough to generally infect most insects (Rai et al., 2014). Nearly 750 species of fungi can cause infections in insects or mites and while they are able to attack a wide range of insects/mites, individual strains of fungi can be very specific (Abdelghany, 2015). Thus, following label rates/directions and the selection of specific strains for specific pests are key to using EPF’s as a biocontrol measure.