Location: Mosquito and Fly Research
2017 Annual Report
Objectives
1. Evaluate the effects of climate change on filth fly populations and their
natural enemies.
1A. House fly management under high temperature conditions.
1B. Verify seasonality, resource preference and range of Stomoxys niger in East Africa.
2. Increase the efficiency of integrated pest management programs by the
development and improvement of traps and behavior-altering surfaces and chemicals.
2A. Identify and develop stable fly optical or chemical attractants which will improve trap efficacy.
2B. Conceive of or develop applications for behavior-altering devices, surfaces and chemicals (e.g., attractants, repellents, and pesticides) for practical use on and around livestock and poultry.
3. Develop management techniques for fly larvae.
3A. Development of more effective larval detection and control techniques for filth flies.
3B. Autodissemination of Insect Growth Regulators (IGR’s) by house flies.
4. Improve biological control techniques for filth flies.
4A. Improved efficacy of Beauveria bassiana by formulating combination products with other agents.
4B. Location of host pupae by filth fly parasitoids.
4C. Improve the quality of commercially available fly parasitoids.
Approach
Objective 1 will investigate and identify methods for management of house flies
under the higher temperatures expected to occur with global warming. It will also
use trapping data to determine risk of introduction of exotic Stomoxys spp. in the U.S.
Objective 2 will develop chemical or optical attractants that will enable traps for stable flies to become more efficient and capture greater numbers of flies. It will also adapt behavior-altering devices, such as pesticide-impregnated fabrics, for different uses, such as attract and kill devices.
Objective 3 will evaluate new methods for determining the presence of sub-surface
immature fly populations in field habitats. It will also further develop methods to allow house flies to spread selected IGRs throughout their habitats.
Ojective 4 will improve the efficacy of a biological control agent by formulating
it with other selected lethal agents. It will also investigate the methods (e.g.,
chemical cues) used by parasitic wasps to locate fly pupae in field habitats.
Finally, we will gain new knowledge on the effects of long-term colonization on the performance of parasitic wasps being released into the field.
Progress Report
After 20 generations of selection for heat tolerance in wild house flies, selected flies had significantly higher tolerance for high temperatures than unselected flies. Initial results on selection with the parasitoids Muscidifurax raptor and Spalangia (S.) cameroni indicate that the parasitoids are much less adaptable to changing temperature conditions than the flies. Reciprocal crosses were made of 4 geographic strains of S. cameroni to produce a super-heterotic strain that is being tested for efficacy and heat tolerance. Contact has been maintained with the cooperator for the stable fly project in Kenya. State Department travel restrictions to Kenya were lifted in January, 2017, but after 36 months into the project it was decided that increased efforts in other project subobjectives might produce more tangible results, based on the intermittent unrest in Kenya. Optically attractive materials lab and field tested against stable flies and traps are being evaluated for optimum placement to allow significantly more flies to be captured. Behavior-altering chemicals for application to fly resting sites are being evaluated for their repellent or attractive qualities. Devices to physically capture flies without adhesives flies are in the primary stages of evaluation. Capture of headspace volatiles produced by fly larvae developing in selected laboratory media or substrates is underway after the evaluation of selected capture methods. The final method will allow for the capture of chemicals without changing the behavior or activity of the larvae within the substrate. Field and large outdoor cage studies with an improved pyriproxyfen (PPF) autodissemination device for house flies resulted in significant but small degrees of fly control in the vicinity of the devices. Flies are reluctant to alight or walk on PPF-treated surfaces. A comparison of PPF performance in different fly breeding substrates also revealed that PPF was 60X less effective in dairy manure than in the wheat bran diet used in lab assays. Experiments demonstrated that only 25% of the flies in an area need to be treated with PPF to achieve >85% control. Screening of potential carriers for Beauveria (B.) bassiana and 3 bacterial pathogens (Serratia marscens, Pseudomomans protegens and Photorhabdus temperate) revealed that the spreader-sticker CapSil was most effective for pathogen survival and spreadablity on the fly cuticle. B. bassiana was largely compatible with the bacterial pathogens, and exotoxins produced by P. protegens were surprisingly toxic to flies. New bait formulations were evaluated for B. bassiana, and combinations of fungal spores with the sugar alcohols xylitol and erythritol provided superior fly mortality without providing with flies with any nutrition during visits to the baits.
Accomplishments
1. The Knight Stick sticky fly trap catches more stable flies when placed close to host animals. The Knight Stick (KS) sticky fly trap has been shown to be highly effective for attracting and catching stable flies. However placement of traps where they will produce the best results can be difficult. At the Smithsonian’s National Zoo (SNZ) approval was given to place KS traps inside selected animal exhibits and protect them with electric fence. For comparison, equal numbers of KS traps were placed around exhibit perimeters. During a 21-wk study, ARS scientists in Gainesville, Florida, and SNZ researchers found that traps inside exhibits captured 6-9 times more stable flies than traps placed along exhibit perimeters. The increased numbers of flies captured should provide relief and greatly improve animal health and welfare. We believe this is the first study where traps were used to capture stable flies in zoological exhibit yards. A publication has been submitted.
2. Toxic cloth target attract-and-kill device eliminate more stable flies than expected. Flat 1-m2 cloth targets can be effective for stable fly management, but numbers of flies killed are difficult to determine in the field because dead flies flutter to the ground and are lost. For research purposes, targets paired with sticky traps cause traps to catch more flies than they would catch by themselves. This indicates target efficacy but not fly numbers killed. By putting targets between 2 electric grids, ARS researchers in Gainesville, Florida, and their cooperators at Louisiana State University found that flies attracted by targets and killed by the grids could be counted. When targets in grids were paired with traps, traps attracted only 28% of the flies. A publication is in preparation.
3. Commercial microbial control products vary widely in effectiveness against flies. Naturally occurring fungi, primarily Beauveria (B.) bassiana and Metarhizium (M.) anisopliae, can be effective for management of house flies and stable flies. However little is known about how efficacy may be altered by commercial formulation. ARS researchers in Gainesville, Florida, and North Carolina State University colleagues evaluated four commercially available B. bassiana or M. anisopliae products for their ability to kill flies and produce spores that could infect other flies. Three products, BotaniGard® ES, Mycotrol® O, and Met52®, caused high fly mortality and produced a second generation of spores from the cadavers of infected flies. A fourth product, balEnce®, produced low mortality and spore formation. Results confirm that commercial formulation can have a substantial effect on the efficacy of microbial biocontrol agents.
4. Spalangia cameroni for fly control on horse farms. Previous research has shown that some parasitic wasps (parasitoids) are able to learn from their environment after emergence as adults. However, it was unknown whether the two common pupal parasitoids, Spalangia (S.) cameroni and Muscidifurax (M.) raptor, could change habitat preferences for searching for pupae to parasitize based on their postemergence experience. In this study, ARS researchers in Gainesville, Florida, and University of Florida colleagues exposed emerging S. cameroni and M. raptor adults to host fly pupae in horse and cattle manures and to fly pupae not associated with manure. They were then tested for manure preferences. The results showed that horse manure is highly attractive to S. cameroni but repellent to M. raptor. We recommend that only S. cameroni or species mixtures with a high proportion of this species be used for fly control on horse farms.
5. A better way to release parasitoids for fly control. Parasitic wasps that kill flies in the pupal stage can be an effective alternative for fly management. Wasps still inside fly pupae are shipped by commercial insectaries. These parasitized pupae can be scattered over fly breeding areas or placed in sheltered release stations. A concern about the scatter method is that the emerged wasps might waste too much time examining and rejecting the empty pupal cases from which they emerged rather than finding and killing live fly pupae. In this study, ARS researchers in Gainesville, Florida, tested two wasp species, Muscidifurax raptor and Spalangia cameroni, to determine how easily they found live fly pupae mixed among empty pupal cases from which wasps had already emerged (“duds”). One species was unaffected by the presence of duds and the other was only slightly affected when duds made up 90% of the population. Results support the recommendation to use the scatter method when releasing the wasps for fly control.
Review Publications
Machtinger, E.T., Weeks, E.N., Geden, C.J. 2016. Oviposition deterrence and immature survival if filth flies (Diptera: Muscidae) when exposed to commercial fungal products. Journal of Insect Science. doi:10.1093/jisesa/iew032.
Weeks, E.N., Machtinger, E.T., Gezan, S.A., Kaufman, P.E., Geden, C.J. 2016. Effect of four commercial fungal formulations on mortality and sporulation of house flies (Musca domestica) and stable flies (Stomoxys calcitrans). Medical and Veterinary Entomology. 31:15–22.
Taylor, C.E., Machtinger, E.T., Geden, C.J. 2016. Manure preferences and postemergence learning of two filth fly parasitoids, Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae). PLoS One. 11(12):e0167893.
Machtinger, E.T., Weeks, E.N., Geden, C.J., Kaufman, P.E. 2016. House fly (Musca domestica) (Diptera: Muscidae) mortality after exposure to commercial fungal formulations in a sugar bait. Biocontrol Science and Technology. 31:15–22.
Hogsette, Jr, J.A., Kline, D.L. 2017. The knight stick trap and knight stick sticky wraps: new tools for stable fly (Diptera: Muscidae) management. Journal of Economic Entomology. doi:10.1093/jee/tox042.
Holderman, C.J., Wood, L.A., Geden, C.J., Kaufman, P.A. 2017. Discovery, development, and evaluation of a horn fly-isolated (Diptera: Muscidae) Beauveria bassiana (Hypocreales: Cordyciptaceae) strain from Florida, U.S.A. Journal of Insect Science. 17(2):51:1-6.
