Research Project: Improved Surveillance and Control of Stable Flies, House Flies, and Other Filth Flies

Location: Mosquito and Fly Research

2021 Annual Report

Objectives
1. Develop strategies and technologies for more accurate and efficient surveillance and monitoring of adult stable flies. 1.A. Evaluation of commercially available stable fly traps from outside of the U.S. 1.B. Improved monitoring tools for long-range surveillance of stable flies. 2. Develop strategies and technologies for more accurate and efficient surveillance and monitoring of house flies. 3. Develop novel strategies and new products that lead to improved control and management of adult stable flies. 3.A. Development of trap-based management systems for stable flies. 3.B. Development of attract and kill devices for stable flies. 4. Develop novel strategies and new products that lead to improved control and management of house flies. 4.A. Effect of gut microbiome on fly fitness. 4.B. Beauveria bassiana for adult fly management. 4.C. Development of Tachinaephagus zealandicus as a biological larvicide.

Approach
Objective 1 will evaluate commercially available stable fly traps from outside of the US to determine which ones perform best in the US (Hypothesis 1.A. Commercially available stable fly traps from other countries could be valuable for improving US surveillance and trapping programs). It will also improve monitoring tools used for long-range surveillance of stable fly populations (Hypothesis 1.B. Improved monitoring tools will allow for surveillance of stable fly populations with minimal maintenance and servicing). Objective 2 will develop strategies and technologies needed for more accurate and efficient surveillance and monitoring of house flies (Hypothesis 2. A novel attractant based on constituents of molasses can be developed for house flies with no objectionable odor for indoor use). Objective 3 will develop trap-based management systems for stable flies which are more environmentally friendly than some of the current systems (Hypothesis 3.A. Localized stable fly populations can be maintained at sub-threshold levels by designing management programs based on strategically placed traps). It will also develop labor-saving attract and kill devices for managing stable flies (Hypotheses 3B. Attract and kill devices can be developed which produce substantial fly mortality but require a minimal amount of servicing). Objective 4 will investigate the effect of gut microbiome on fly fitness which could make the flies easier to kill with other management tools (Hypothesis 4.A. Axenic flies have lower fitness than non-sterile flies but can be “rescued” by ingestion of live bacteria). It will also re-visit Beauveria bassiana as a biological method adult fly management (Hypothesis 4.B. Screening wild isolates and subjecting candidate isolates to selection will result in faster-killing B. bassiana that is compatible with natural enemies). And finally, it will develop Tachinaephagus zealandicus, a parasitic wasp that attacks fly larvae, as a biological larvicide (Hypothesis 4.C. Hydrotaea aenescens can be used as production host for the gregarious larval endoparasitoid Tachinaephagus zealandicus).

Progress Report
1. Several suitable locations were found for use for the comparison evaluations between Vavoua traps and Knight Stick traps. These are secure university facilities and are close to CMAVE. Tests in the large cage were postponed because cage was being used for other tests. Cage tests will continue in the fall when the weather is cooler. Aging studies will also continue in the fall using traps from the comparison studies after they have been completed. Additional Vavoua traps are being purchased so some tests can be conducted simultaneously. 2. Knight Stick traps were put out briefly along the outside fences of paddocks to determine if ample numbers of flies were present to collect meaningful data for a test. Fly populations were very low, so it was decided to try again later in the year. Cloth traps can lose their attraction over time in the sun so placement of these traps in the field when no flies are present could adversely affect their use in subsequent studies. 3. Work with the new house fly attractant continued, and encouraging results were obtained by varying the concentration of propionic acid. 4. When the first opportunity came to place traps in the field, stable fly populations were very low, so it was decided to try again later in the year. The study sites have been used in previous studies so determination of best trap placement locations can be made rather quickly later in the year. 5. Results indicated that wire fence cylinders of any diameter reduce the number of flies captured. When wire fence cylinders are covered with an untreated version of the treated fabric, more flies pass over the fabric and become trapped as the diameter of the cylinder is increased. Thus, the cylinder with the smallest diameter is best. 6. House fly eggs that were surface sterilized did not develop in sterile media but did develop in unsterilized media. Eggs that were not surface sterilized developed normally in both sterile and non-sterile media. A method was developed for evaluating house fly larval development under gnotobiotic conditions. 7. Five strains of Beauveria bassiana isolated from house flies were selected for faster kill rates over 10 generations. Two strains began to fail after 8 selections and did not produce any conidia by generation 10. Two of the other three strains appeared to have faster kill rates post-selection, but this will require further testing when the lab is fully reopened. 8. A mass rearing method was developed for Hydrotaea aenescens, and the amount of high-protein ingredients in the larval diet was optimized for economical production. Tachinaephagus zealandicus has now been reared for 22 generations on this host and Sarcophaga bullata, and S. bullata is a superior production host. Releases of T. zealandicus in Alabama poultry houses resulted in significant increases in mortality of house flies.

Accomplishments
1. Flies vomit to death after eating artificial sweeteners. House fly control is a global problem because of high levels of insecticide resistance. Recent research has demonstrated that flies are killed when they feed on the artificial sweeteners erythritol and xylitol, which are safe for humans and the environment. The reason for their toxicity to insects has not been determined. In this study, scientists at Northern Illinois University and USDA-ARS in Gainesville, Florida, and Manhattan, Kansas, evaluated several mechanisms designed to clarify the way that mortality is induced in house flies by these sweeteners. The possible mechanisms included: 1) dehydration from excessive regurgitation; 2) arrestment of physiological processes due to abnormally high hemolymph osmolality or osmotic diarrhea; and, 3) reduction of the gut microbiome. Results showed that flies consuming the sweeteners die from complications caused by excessive vomiting. This work supports the continued evaluation safe materials as tools for house fly control where insecticides are no longer effective or for use in organic production systems.

2. Searching for fast-killing fungal biocontrol agents. House flies are worldwide pests of humans and animal agriculture. Although the flies can transmit pathogens of humans and animals, flies are also affected by their own pathogens, some of which can be used to control them. Diseases include fatal infections from the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae. Although flies can be infected by making pathogen releases, their practical use in pest management is limited by the time they require to produce mortality. The rate of kill can be increased by evaluating and then selecting pathogen strains with shorter kill times than currently used strains. In this study USDA, ARS, Gainesville, Florida, and Texas A & M University scientists compared 5 fungal strains in the laboratory. Three strains of B. bassiana, including a strain isolated from house flies by an ARS scientist in Florida (NFH10), had particularly high fly virulence. Ten generations of selection for faster kill times with NFH10 did not result in a faster-killing sub-strain. An already available commercial strain not yet registered for house fly control was one of the superior strains. Results could be used to support label expansion for products already registered with EPA for other pests.

Review Publications
Geden, C.J., Johnson, D.M., Taylor, D.B. 2020. Improved sentinel method for surveillance and collection of filth fly parasitoids. Journal of Insect Science. 20(6):1–7. https://doi.org/10.1093/jisesa/ieaa026.
Johnson, D.M., White, R.L., Pereira, R.M., Geden, C.J. 2020. Beauveria bassiana culturing and harvesting for bioassays with house flies. Journal of Insect Science. 20(6):1–7. https://doi.org/10.1093/jisesa/ieaa072.
Burgess, E.R., King, B.H., Geden, C.J. 2020. Oral and topical insecticide response bioassays and associated statistical analyses used commonly in veterinary and medical entomology. Journal of Insect Science. 20(6):1–9. https://doi.org/10.1093/jisesa/ieaa041.
Rachimi, S., Burand, J.P., Geden, C.J., Stoffolano, J.G. 2021. The effect of the Musca domestica Salivary Gland Hypertrophy Virus (MdSGHV) on food consumption in its adult host, the common house fly (Diptera: Muscidae). Journal of Medical Entomology. https://doi.org/10.1093/jme/tjaa281.
Hogsette, Jr, J.A. 2021. Factors affecting numbers of house flies (Diptera: Muscidae) captured by ultraviolet light traps in a large retail supermarket. Journal of Economic Entomology. 114(2):988-992. https://doi.org/10.1093/jee/toaa319.
Hogsette, Jr, J.A. 2021. Evaluation of cluster buster fly traps in a large commercial establishment. Journal of Agricultural and Urban Entomology. 37(1):6-9. https://doi.org/10.3954/1523-5475-37.1.6.
White, R.L., Geden, C.J., Kaufman, P.E., Johnson, D.M. 2021. Comparative virulence of Metarhizium anisopliae and four strains of Beauveria bassiana against house fly (Diptera: Muscidae) adults with attempted selection for faster mortality. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjab027.
White, R.L., Geden, C.J., Kaufman, P.E. 2020. Exposure timing and method affect Beauveria bassiana (Hypocreales: Cordycipitaceae) efficacy against house fly (Diptera: Muscidae) larvae. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjaa156.
Junnila, A., Traore, M.M., Mckenzie, K., Hogsette, Jr, J.A., Kline, D.L., Kone, A.S., Diarra, R.A., Petranyi, G., Troare, I., Sangare, P., Diakite, A., Traore, S.F., Kravchenko, V., Xue, R., Revay, E.E., Müller, G.C. 2021. Performance of the Atrakta™ Mosquito Lure in combination with Dynatrap® (Models DT160 and DT700) and a CDC Trap (Model 512). Journal of the Florida Mosquito Control Association. 86(1):48-55. https://doi.org/10.32473/jfmca.v68i1.129099.
Traore, M.M., Junnila, A., Hogsette, Jr, J.A., Kline, D.L., Mckenzie, K., Kravchenko, V., Kone, A.S., Diarra, R.A., Traore, S.F., Petranyi, G., Sangare, P., Diakite, A., Troare, I., Beier, J.C., Revay, E.E., Xue, R., Müller, G.C. 2021. Evaluation of Dynatraps® DT160 as an inexpensive alternative to CDC traps for adult mosquito monitoring in Mali, West Africa. Journal of the Florida Mosquito Control Association. 68(1):38-47. https://doi.org/10.32473/jfmca.v68i1.129098.
Maiquez, V.F., Pitzer, J.B., Geden, C.J. 2020. Insecticide resistance development in the filth fly pupal parasitoid, Spalangia cameroni (Hymenoptera: Pteromalidae), using laboratory selections. Journal of Economic Entomology. 114(1):326-331. https://doi.org/10.1093/jee/toaa286.