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United States Department of Agriculture

Agricultural Research Service

Research Project: HIGHER DIPTERA PESTS OF LIVESTOCK, POULTRY, AND HUMAN HEALTH: INTEGRATED PEST MANAGEMENT AND ADULT BIOLOGY

Location: Mosquito and Fly Research Unit

Title: Muscavirus (MdHV) disease dynamics in house fly populations – how is this virus transmitted and has it potential as a biological control agent?

Authors
item Lietze, Verena-Ulrike -
item Keesling, James -
item Lee, Jo -
item Vallejo, Cleste -
item GEDEN, CHRISTOPHER
item Boucias, Drion -

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 25, 2012
Publication Date: March 1, 2013
Citation: Lietze, V., Keesling, J.E., Lee, J.A., Vallejo, C.R., Geden, C.J., Boucias, D.G. 2013. Muscavirus (MdHV) disease dynamics in house fly populations – how is this virus transmitted and has it potential as a biological control agent? Journal of Invertebrate Pathology. 112(1):S40-S43.

Interpretive Summary: House flies are important pests associated with animals and humans and transmit a wide array of disease organisms. Efforts to manage flies have traditionally relied on chemical insecticides, but flies have become resistant to most insecticides and there is increasing public demand to reduce pesticide use around animals that are used in the production of meat, milk and eggs. Most biological control research on flies has concentrated on targeting fly pupae with parasitic wasps. In recent years a promising new biological control agent for adult flies has been discovered, salivary gland hypertrophy virus (SGHV). Female flies infected with the virus do not produce any eggs, and infected males do not compete well with healthy males. In this paper, scientists and mathematicians from the University of Florida and USDA/ARS’s Center for Medical Agricultural and Veterinary Entomology examine the known transmission mechanisms for the virus and propose a mathematical model of transmission. The model predicts that male combativeness may result in wounding that makes male flies more susceptible to contact infection with the virus. If this hypothesis is proven to be true it may lead to new virus formulations that incorporate abrasive agents that would wound the fly’s exoskeleton cuticle to enhance infection.

Technical Abstract: The newly classified family Hytrosaviridae comprises several double-stranded DNA viruses that have been isolated from various dipteran species. These viruses cause characteristic salivary gland hypertrophy and suppress gonad development in their hosts. One member, Muscavirus or MdHV, exclusively infects adult house flies (Musca domestica) and, owing to its massive reproduction in and release from the salivary glands, is believed to be transmitted orally among feeding flies. However, results from recent experiments suggest that additional transmission routes likely are involved in the maintenance of MdHV in field populations of its host. Firstly, several hours before newly emerged feral flies begin feeding activities, the fully formed peritrophic matrix (PM) constitutes an effective barrier against oral infection. Secondly, flies are highly susceptible to topical virus treatments and intrahemocoelic injections. Thirdly, disease transmission is higher when flies are maintained in groups with infected conspecifics than when flies have access to virus-contaminated food. We hypothesize that interactions between flies may lead to cuticular damage, thereby opening an avenue to viral particles for direct invasion of the hemocoel. Based on our current knowledge, two options seem plausible for developing Muscavirus as a sterilizing agent to control house fly populations: The virus may either be formulated with PM-disrupting materials to facilitate oral infection from a feeding bait system, or amended with abrasive materials to enhance infection through a damaged cuticle after topical aerosol applications.

Last Modified: 9/10/2014