Location: Mosquito and Fly Research Unit
Title: Status of biopesticides for control of house flies Author
Submitted to: Journal of Biopesticides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 7, 2012
Publication Date: May 15, 2012
Citation: Geden, C.J. 2012. Status of Biopesticides for Control of House Flies. Journal of Biopesticides. 5(supplementary):1-11. Interpretive Summary: House flies continue to be major pests of livestock, poultry and humans throughout the world. Fly control is a difficult matter, in part, because of the rapidity with which house flies have developed resistance to insecticides that are used to control them. This article by a research scientist at USDA’s Center for Medical, Agricultural and Veterinary Entomology summarizes the status of biopesticides for fly control and discusses some new approaches being explored at that location. “Biopesticides” refers to microbial and botanical control tools that can be used as an alternative to the chemical insecticides that are the mainstay of insect management. Entomopathogenic nematodes kill fly larvae readily in the laboratory and in certain kinds of field situations, but most animal manures are too harsh for the nematodes. There are several fungal pathogens that can be used for fly control, and one of them (Beauvereia bassiana) has been developed into a commercial product. Field testing with this agent has given very promising results. Bacteria (Bacillus thuringensis) have been developed into commercial products, and further exploration may reveal new strains with superior activity against flies. Salivary gland hypertrophy virus (SGHV) has the virtue of sterilizing adult female flies, but there are still technical problems to be overcome before it can be used as a practical biopesticide. Finally, there is a vast array of potential products from plant sources. Essential oils of many plants are toxic to flies and have potential for field use. A new product that contains a mixture of essential oils from rosemary and peppermint is effective against adult flies and may have activity against eggs as well.
Technical Abstract: House flies (Musca domestica L.) have resisted human attempts to control them since antiquity, and the global problem of fly resistance to conventional insecticides has resulted in renewed interest in biopesticides as alternative management tools. Entomopathogenic nematodes such as Steinernema and Heterorhabditis spp. and their associated symbionts are virulent for fly larvae in certain substrates (e.g., cow manure mixed with soil), but the harsh environments presented by poultry and swine manure are inimical to their survival. Entomophthora muscae is an important natural regulator of fly populations, but constraints imposed by production, storage stability, and slow kill rate have limited its use as an operational control agent. Beauveria bassiana has many advantages and has been developed into commercial fly control products. B. bassiana is compatible with other biological agents and strains with superior kill rates have been identified. Field tests of this pathogen in poultry houses and calf hutches have been largely positive. New developments in genetic modification of B. bassiana could lead to new faster-acting biopesticide products that are competitive with conventional insecticides. Early research with exotoxin-producing strains of Bacillus thuringiensis was promising, but the shift in emphasis to endotoxin-only strains with high activity against Lepidoptera limited discovery of fly-active strains. Surveys have suggested that strains with high levels of the Cry1B endotoxin are more virulent than other strains for muscoid flies. Recent successes with B. thuringiensis var. israelensis on poultry farms suggest that Bti warrants further study. House fly salivary gland hypertrophy virus (MdSGHV) has the appealing property of shutting down reproductive development in adult flies but attempts to develop infective baits have been hampered by the refractoriness of older flies to oral infection. Space sprays to treat flies directly may have more potential for delivering MdSGHV into fly populations. Essential oils with substantial amounts of 1,8-cineole, pulegone, limonene, and menthol have high toxicity against fly adults. Combinations of house fly-active oils (e.g., rosemary, peppermint, pennyroyal mint, blue gum, bay laurel) could be more effective than products that focus on single active constituents. New formulations and possible use of synergists could increase the efficacy of botanicals for fly control.