Location: Agroecosystem Management Research
2015 Annual Report
Objectives
Objective 1: Develop sustainable methods for the management of stable flies and other flies impacting livestock production.
Sub-objective 1.1 Identify and test larvicides for stable flies and other flies developing in livestock wastes.
Sub-objective 1.2 Develop attractants for use on traps.
Sub-objective 1.3 Develop adult fly repellents with extended residual activity.
Sub-objective 1.4 Evaluate effects of stable flies on behavior and productivity of cattle.
Sub-objective 1.5 Evaluate the effectiveness of a Push-Pull stable fly management strategy.
Objective 2: Characterize effects of biological, chemical, and physical substrate properties on stable fly larval development.
Sub-objective 2.1 Characterize functional groups of microorganisms in substrates associated with stable fly and house fly larval development.
Sub-objective 2.2 Identify endosymbionts and parasitoids associated with stable flies.
Sub-objective 2.3 Characterize nutritional factors required for stable fly larval development.
Objective 3: Develop a physiologically based demographic model (PBDM) to predict temporal and spatial patterns of stable fly population dynamics under current and potential climatic conditions.
Sub-objective 3.1 Determine physiological responses of stable fly developmental stages to environmental variables.
Sub-objective 3.2 Incorporate parameters from 3.1 into PBDM.
Sub-objective 3.3 Validate PBDM.
Approach
Stable flies are among the most serious arthropod pests of livestock in the United States, costing producers in excess of $2 billion per year in lost production. They exhibit an extraordinary ability to adapt to, and exploit, regional agricultural and animal husbandry practices. Stable fly management has proven to be a daunting task largely due to their adaptability, mobility, and gaps in our knowledge of their behavior and biology. This project will address all of these issues. Primarily, the project will develop new methods for the management of stable flies by exploiting the most vulnerable stages in their life cycles. Secondarily, we will develop a better understanding of stable fly biology and how they interact with their environment and hosts. Finally, new and existing information on stable fly biology will be incorporated into a dynamic, physiologically-based demographic model. This model will permit us to predict the dynamics of stable fly populations under real and potential environmental conditions, as well as provide insight into the validity of our understanding of their interactions with biotic and abiotic factors in the environment for development and reproduction. Successful completion of this project will result in new technologies for the management of stable fly populations, reduced impact of stable flies on livestock production systems, and a greater understanding of their biology for the continued development and evolution of stable fly management technologies.
Progress Report
Larvicides. Studies on Insect Growth Regulators (IGR) for larval control were completed. Two IGRs, cyromazine and novaluron, of different insecticide activity classes provided greater than 90% control of stable fly larvae developing in winter hay feeding sites with a single application. Laboratory toxicity tests of an encapsulated formulation of catnip oil showed over 90% efficacy for stable fly larvae and pupae. Furthermore, we compared the exposure time required to achieve mortality of two commonly used pesticides, Permethrin and Prolate, against adult stable flies relative to catnip oil. Permethrin acted more slowly than the catnip oil and Prolate exhibited lower toxicity (Subobjective 1.1).
Chemical ecology. A new attractant from crushed pineapple stems, m-cresol, was identified. Traps baited with m-cresol collected more stable flies than unbaited traps in studies conducted in Costa Rica and Nebraska. In addition, we observed that the fistulated cattle are highly attractive to stable flies and horn flies in the field and odor collection is being conducted to identify the active compounds. We investigated visual sensitivity of stable flies with a novel electroretinogram (ERG), which showed blue, green orange and red may enhance trap attraction. Field trials are being conducted this summer (Subobjective 1.2).
A new repellent formulation of catnip oil, geraniol and acids (SPLAT, CRADA with ISCA Technologies, Inc.) was evaluated under laboratory conditions and showed >72 hours of activity deterring stable fly blood feeding. A new repellent compound was identified from coconut oil with activity levels similar to catnip oil but with a longer effective period. Studies on the mechanisms of repellency for this compound are underway (Subobjective 1.3).
Cattle behavior. Design of the CattleTracker hardware was completed and preliminary field trials initiated (Subobjective 1.4).
Microbial ecology. Bacterial and fungal isolates from stable fly larvae and pupae were cultured. In collaboration with the Crop Bioprotection Research Unit (Peoria, IL) 25 isolates were selected for identification with matrix assisted laser desorption ionization time-of-flight mass spectrometry. Nearly a third of the isolates were identified as Serratia marcescens, a pathogen of stable fly larvae. Five isolates belonged to the Bacillus genus. Additionally, substrate from a common larval developmental source (a hay, urine, and manure mixture collected from calf bedding) was submitted for 16S and 18S sequencing. Preliminary analysis indicates Flavobacterium is the dominant bacterial genus in substrates supporting larval development. Substrate and larvae have been collected from other sources supporting larval development and are being prepared for DNA extraction and sequencing (Subobjective 2.1).
Assays characterizing larval olfaction were optimized and initiated. Behavioral responses of third-instar larvae to chemicals from 9 classes were observed. Larvae are highly attracted to ammonium and esters. A protocol for doing electroantennograms on stable fly larvae was developed. They showed a strong response to ammonia (Subobjective 2.3).
Repellent candidates, such as catnip oil and its active components (ZE-nepetalactone and EZ-nepetalactone) were observed to have strong antibacterial activity in stable fly developmental substrates (Subobjective 2.1).
Symbionts. A novel species of Herpetomonas was isolated from stable flies and is being maintained in culture. The 18S rRNA gene was partially sequenced and found to be most similar to Herpetomonas ztiiplika, a trypanosomatid isolated from an adult biting midge. Infection with the herpetomonad is ubiquitous; stable flies are infected across all life stages collected at all field sites. Three isolates have been prepared for scanning and transmission electron microscopy studies (Subobjective 2.2).
Stable fly pupae were collected from field sites and processed for subsequent isolation and identification of pteromalid parasitoids (Subobjective 2.2).
Life history. A collaborative investigation of stable fly phenology involving 13 collaborators in the United States and Canada was initiated. Collaborators will collect adult stable flies for eight weeks beginning with the first appearance of adults in their area. The objective of the study is to evaluate the mechanisms used by stable flies to colonize environments in the spring in diverse geographical regions (Subobjective 3.1).
The effects of heat stress on stable fly development are being examined with transcriptomics. Research personnel have been trained in bioinformatics procedures and laboratory procedures have been optimized (Subobjective 3.1).
A preliminary study of stable fly development relative to temperature and diet quality was completed. Stable flies were reared on four diets with nutrient content varying from full to one-eighth that of the standard laboratory diet. Three temperatures, 15, 25 and 35 were included in the study. Nutrient level, temperature and their interaction all had significant effects upon size and developmental rate of stable flies. Egg to larva developmental time was 20% longer with the lowest nutrient diet compared with the other diets and it took larvae three times longer to pupate when reared at 15° relative to those reared at 25°C. Wings of flies reared on the standard diet were 20% longer than those of flies reared on the poorest diet Subobjective 3.1).
Control. Field trials of Push-Pull strategy showed that stable flies are effectively driven away from repellent treated cattle while pesticide-treated cattle, not treated with repellent, in the herd act as trapping devices (lure-kill) (Subobjective 1.5).
Accomplishments
1. Electroantennograms of stable fly larvae. Mechanisms of olfactory orientation of stable fly adults are well understood. However, how stable fly larvae orient within their environment is unclear. Stable fly larvae are dependent upon microbial metabolic byproducts for nutrition. Laboratory bioassays have demonstrated that stable fly larvae use olfactory cues to direct movement through their habitat. ARS researchers at Lincoln, Nebraska developed a method and performed the first electroantennogram (EAG) recordings from the dorsal organ of stable fly larvae. Positive EAG responses were obtained with compounds associated with larval substrates, including ammonia. This represents the first demonstration of EAG with an immature muscoid fly. The methodology greatly advances our ability to understand how mucoid fly larvae interact and orient within their larval developmental substrates.
Review Publications
Tangtrakulwanich, K., Albuquerque, T.A., Brewer, G.J., Baxendale, F.P., Zurek, L., Miller, D.N., Taylor, D.B., Friesen, K.M., Zhu, J.J. 2015. Behavioural responses of stable flies to cattle manure slurry associated odourants. Medical and Veterinary Entomology. 2015:1-6. DOI: 10.1111/MVE.12103.
Zhu, J.J., Brewer, G.J., Boxler, D.J., Friesen, K.M., Taylor, D.B. 2015. Comparisons of antifeedancy and spatial repellency of three natural product repellents against horn flies, Haematobia irritans (Diptera: Muscidae). Pest Management Science. DOI: 10.1002/PS.3960.
Chaudhury, M.F., Zhu, J.J., Skoda, S.R. 2015. Response of Lucilia sericata (Diptera: Calliphoridae) to Screwworm Oviposition Attractant. Journal of Medical Entomology. 52(4):527-31.
Zhou, X., Quian, K., Tong, Y., Zhu, J.J., Qiu, X., Zengt, X. 2014. De novo transcriptome of the hemimetabolous German cockroach (Blattella germanica). PLoS One. 9(9):e106932 Page 1-11. DOI: 10.1371/journal.pone.0106932.
Taylor, D.B., Friesen, K.M., Zhu, J.J. 2015. Stable fly control in cattle winter feeding sites with Novaluron. Arthropod Management Tests. 39(1):K1. DOI: 10.4182/AMT.2014.K1.
Friesen, K.M., Chen, H., Zhu, J.J., Taylor, D.B. 2015. External morphology of stable fly (Diptera: Muscidae) larvae. Journal of Medical Entomology. 52(4):626-637. DOI: 10.1093/JME/TJV052.
