Progress 08/01/03 to 07/31/09
Outputs
OUTPUTS: Our data have been presented at international, national and local scientific meetings and have been incorporated into extension presentations given across Kansas and surrounding states. Zurek L. 2003. Insects as vectors of food-borne pathogens. Symposium: Food safety and entomology. The ESA Annual Meeting, Cincinnati, OH, Oct. 2003. Zurek L. 2003. Microbial ecology of house flies. 47th Livestock Insect Workers Conference, June, Atlantic Beach, NC. Alam M.J. and L. Zurek 2004. Prevalence and characterization of E. coli O157:H7 in house flies from a cattle farm, Emerging for Infectious Diseases Conference, Atlanta, GA, Jan. (poster). Romero, A., A. Broce and L. Zurek 2004. Role of bacteria in mediating oviposition responses and larval development of stable flies, Annual meeting of the Entomological Society of America, Salt Lake City, Nov. Talley J., A. Broce, and L. Zurek 2004. Development of stable flies in the winter-feeding sites of hay to cattle. Livestock Insects Worker Conference, Lake Placid, NY, June, 2004. Chakrabarti S., S. Kambhampati, and L. Zurek 2004. Dispersal of house flies from rural to urban environment: Microsatellite study. International Congress of Entomology, Sydney, Australia, July (poster). Talbott, J, L. Macovei, and L. Zurek. Isolation and characterization of enterococci from house flies from fast food restaurants. An. Merck Veterinary Scholars Conference, July 2005, Athens, GA. Zurek, L., L. Macovei, M. Akhtar. Role of house flies in the ecology of antibiotic resistant enterococci. LIWC, June 2005, Bozeman, MT. Akhtar, Helmut Hirt and Ludek Zurek. 2007. Antibiotic Use in Animals: Role of House Flies in Dissemination of Resistant and Virulent Enterococci. May 21-25, 107th General Meeting of American Society of Microbiology, Toronto, Canada. Zurek L., F. Mramba, A. Broce. 2007. Role of bacteria and con-specific eggs in oviposition behavior of stable flies. Livestock Insect Workers Conference, Lexington KY. Zurek, L. Microbial ecology of Muscoid flies. Department of Entomology, University of Nebraska, Lincoln, NE, January 23-24, (invited speaker). Zurek L. 2007. Musoid flies and Food Safety. Annual Multi-State Meeting S-1030, Orlando FL, Jan 11-13. Zurek, L. 2009. Role of house flies in dissemination of E. coli O157. Annual Meeting of the Multi-state project S1030, Baton Rouge, LA, Jan. 9-11. Albuquerque, T., A. Broce, and L. Zurek. 2009. Effect of age and microbial community structure of horse manure on the stable fly, Stomoxys calcitrans (L.), oviposition behavior Annual Meeting of LIWC, French Lick, IN, June 21-24. Zhu, J.J., D.R. Berkebile, and L. Zurek. 2009 Chemical Ecology of Stable Fly and its Future Practical Applications in Control. 26th Meeting of ISCE, University of Neuchatel, Switzerland 23- 27 August 2009. Zurek, L. 2009. Microbial ecology of Muscoid flies. University of Florida, Gainesville, FL Oct. 22 (invited speaker). Doud, C. and Zurek, L. 2009. Role of house flies in dissemination of antibiotic resistant Enterococci from wastewater treatment plants. ESA Annual Meeting, Indianapolis, IN, Dec.13-16. PARTICIPANTS: Alberto Broce, Professor, K-State Entomology (collaborator). Lilia Macovei, Postdoctoral Research Associate, K-State Entomology. Aqeel Ahmad, Postdoctoral Research Associate, K-State Entomology. M. Jahangir Alam, Postdoctoral Research Associate, K-State Entomology. Furaha Mramba, Graduate student (Ph.D.), K-State Entomology. Thais Albuquerque, Graduate student (Ph.D.), K-State Entomology. Seemanti Chakrabarti, Graduate student (Ph.D.), K-State Entomology. Alvaro Romero, Graduate student (MS), K-State Entomology. Mastura Akhtar, Graduate student (Ph.D.), K-State Entomology. Justin Talley, Graduate student (Ph.D.), K-State Entomology. TARGET AUDIENCES: Pest control operators, Kansas farmers and ranchers, restaurant management personnel, sanitarians, hygienists, microbial ecologists, clinicians, general public. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Despite the major advances in Integrated Pest Management, the control of insect pests in many cases relies heavily on the use of broad spectrum insecticides. Food-borne pathogens and antibiotic resistant strains are a serious public health and food industry concern. Some insects, primarily muscoid flies may likely play an important role in the ecology of these microorganisms. Microbially/symbiont-based approaches offer novel venues for management of insect pests and/or vector-borne human and animal pathogens that could alleviate the heavy use of organic insecticides and its associated negative impacts including development and spread of insect resistance, contamination of environment and agricultural products, and killing of non-target species. Unfortunately, the fundamental knowledge of muscoid flies (house flies, stable flies, face flies and horn flies) - microbial associations and their effect on fly biology is lacking. Our results demonstrate stable fly/house fly - bacterial symbiosis; adult flies are capable of selecting an oviposition site based on microbially-derived stimuli that indicate the suitability of the substrate for larval development. The bacterial isolates that stimulate fly oviposition also support the larval development and in contrast, bacteria that do not stimulate or even repel flies from oviposition also do not support or even kill fly larvae. Our study shows a promising starting point for exploiting SF-bacterial associations for development of novel approaches for SF management. Enterobacter sakazakii, Escherichia coli O157:H7 are important food-borne pathogens, enterococci represent an important hub for antibiotic resistance genes that can be transferred to other more virulent bacteria. We have shown that wild stable flies carry E. sakazakii. Moreover, E. sakazakii can survive pupation and colonize the digestive tract of newly emerging adult flies. Enterobacter sakazakii alone provides the nutritional conditions for stable fly larval development. In addition, our data indicate the vertical transfer of bacterial symbionts that play an important role in the oviposition behavior and new habitat selection for stable flies. We have also shown that house flies commonly carry E. coli O157:H7 in the feedlot environment and are capable to transmit this pathogen to naive cattle and other environments. In conclusion: A) We have been able to show that muscoid flies have a close evolutionary relationship with microbes; the immature stages strictly depend on active microbial communities in the developmental habitat and females of these flies are capable of selecting of the new habitat for their offspring based on the cues emitted form the microbes. These studies provide a basis upon which oviposition behavior of muscoid flies and muscoid fly-bacterial association could be developed into novel approaches for integrated pest control. B) Our studies demonstrate that muscoid flies play an important role in the ecology of Escherichia coli O157:H7, Enterobacter sakazakii, and multi-drug resistant enterococci in environment and have to be seriously considered in designing of pre- and post-harvest food safety strategies.
Publications
- Talley J., A. Broce, and L. Zurek (2009). Characterization of the stable fly (Diptera:Muscidae) larval developmental habitat at round hay bale feeding sites. Journal of Medical Entomology 46: 1310-1319.
- Akhtar, M., H. Hirt, and L. Zurek (2009). Horizontal transfer of the tetracycline resistance gene tetM mediated by pCF10 among Enterococcus faecalis in the house fly alimentary canal. Microbial Ecology 59: 509-518.
- Macovei, L., A. Ghosh, V. Thomas, L. Hancock, S. Mahmood, and L. Zurek (2009). Enterococcus faecalis with the gelatinase phenotype regulated by the fsr-operon and with biofilm forming capacity are common in the agricultural environment. Environmental Microbiology. 11:154-1547.
- Ahmad, A. and L. Zurek (2009). Evaluation of metaflumizone granular bait for management of house flies. Medical and Veterinary Entomology 23: 167-169.
- Nagulapally, S.R., A. Ahmad, A. Henry, G.L. Marchin, L. Zurek, and A. Bhandari (2009). Occurrence of ciprofloxacin, trimethoprim-sulfamethoxazole, and vancomycin resistant bacteria in a municipal wastewater treatment plant. Water Environment Research 80: 82-90.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Our data have been presented at international, national and local scientific meetings and have been incorporated into extension presentations given across Kansas and surrounding states. An example for 2007. Ahmad, A. C. Schal and Ludek Zurek. 2007. Role of house flies and German cockroaches in the ecology of antibiotic resistant enterococci in confined swine production environment. Annual Meeting of American Society of Microbiology at Toronto, Canada. Akhtar, Helmut Hirt and Ludek Zurek. 2007. Antibiotic Use in Animals: Role of House Flies in Dissemination of Resistant and Virulent Enterococci. May 21-25, 107th General Meeting of American Society of Microbiology, Toronto, Canada. Macovei, L. and L. Zurek. 2007. Prevalence, antibiotic resistance and virulence determinants of enterococci in ready-to-eat food. 107th General Meeting of American Society for Microbiology, Toronto, Canada, May 21-25. Ahmad, Mastura Akhtar, Helmut Hirt, and Ludek Zurek. Microbial ecology and medical significance of house flies.2007. Annual meeting of National Research Initiative Grants Program, Ventura, CA Ahmad, C. Schal and Ludek Zurek. 2007. Microbial ecology and medical significance of house flies and German cockroach in confined swine environment. Annual Meeting of Entomological Society of America, San Diego, CA. Macovei, L., Zurek L., 2007. Ecology of antibiotic resistance and virulence in environment. AAVMC-sponsored conference "Partnerships for Preparedness: Future directions for Schools of Public Health and Colleges of Veterinary Medicine." May, Atlanta, GE, (poster). Akhtar, H. Hirt and L. Zurek 2007. Role of house fly in ecology of antibiotic resistant and virulent enterococci: Horizontal transfer of antibiotic resistance genes in the house fly digestive tract. December 8-12, Annual Meeting of Entomological Society of America, San Diego, CA. Zurek L., F. Mramba, A. Broce. 2007. Role of bacteria and con-specific eggs in oviposition behavior of stable flies. Livestock Insect Workers Conference, Lexington KY. Lutter D.J., L. Macovei, L. Zurek. 2007. Prevalence and characterization of gelatinase in environmental enterococci. Merk Merial Veterinary Research Scholars Symposium, Washington D.C. , August 25 (poster). Zurek, L. Microbial ecology of Muscoid flies. Department of Entomology, University of Nebraska, Lincoln, NE, January 23-24, (invited speaker) Renter, D. G., R. D. Oberst, M. J. Sanderson, J. Drouillard, D. U. Thomson, L. Zurek, and T. G. Nagaraja. 2007. Ecology of E. coli O157:H7, Non-O157 Shiga-toxigenic E. coli, and Salmonella in Beef Cattle Production Systems. AAVMC-sponsored conference "Partnerships for Preparedness: Future directions for Schools of Public Health and Colleges of Veterinary Medicine." May, Atlanta, GE (poster). Zurek L. 2007. Musoid flies and Food Safety. Annual Multi-State Meeting S-1030, Orlando FL, Jan 11-13. Zurek L. 2007. Antibiotic resistance as a food safety issue. National Agro-Bioterrorism Forum (NABF), K-State, Nov. 30. PARTICIPANTS: Alberto Broce, Professor, K-State Entomology (collaborator) Lilia Macovei, Postdoctoral Research Associate, K-State, Entomology Aqeel Ahmad, Postdoctoral Research Associate, K-State, Entomology M. Jahangir Alam, Postdoctoral Research Associate, K-State, Entomology Furaha Mramba, Graduate student (Ph.D.), K-State, Entomology Thais Albuquerque, Graduate student (Ph.D.), K-State, Entomology Seemanti Chakrabarti, Graduate student (Ph.D.), K-State, Entomology Alavaro Romero, Graduate student (MS), K-State, Entomology Mastura Akhtar, Graduate student (Ph.D.), K-State, Entomology TARGET AUDIENCES: Pest control operators, Kansas farmers and ranchers, restaurant management personnel, sanitarians, hygienists, microbial ecologists, clinicians, general public PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Despite the major advances in Integrated Pest Management, the control of insect pests in many cases relies heavily on the use of broad spectrum insecticides. Food-borne pathogens and antibiotic resistant strains are a serious public health and food industry concern. Some insects, primarily muscoid flies may likely play an important role in the ecology of these microorganisms Microbially/symbiont-based approaches offer novel venues for management of insect pests and/or vector-borne human and animal pathogens that could alleviate the heavy use of organic insecticides and its associated negative impacts including development and spread of insect resistance, contamination of environment and agricultural products, and killing of non-target species. Unfortunately, the fundamental knowledge of muscoid flies (house flies, stable flies, face flies and horn flies) - microbial associations and their effect on fly biology is lacking. Our results demonstrate stable fly/house fly - bacterial symbiosis; adult flies are capable of selecting an oviposition site based on microbially-derived stimuli that indicate the suitability of the substrate for larval development. The bacterial isolates that stimulate fly oviposition also support the larval development and in contrast, bacteria that do not stimulate or even repel flies from oviposition also do not support or even kill fly larvae. Our study shows a promising starting point for exploiting SF-bacterial associations for development of novel approaches for SF management. Enterobacter sakazakii, Escherichia coli O157:H7 are important food-borne pathogens, enterococci represent an important hub for antibiotic resistance genes that can be transferred to other more virulent bacteria. We have shown that wild stable flies carry E. sakazakii. Moreover, E. sakazakii can survive pupation and colonize the digestive tract of newly emerging adult flies. Enterobacter sakazakii alone provides the nutritional conditions for stable fly larval development. In addition, our data indicate the vertical transfer of bacterial symbionts that play an important role in the oviposition behavior and new habitat selection for stable flies. We have also shown that house flies commonly carry E. coli O157:H7 in the feedlot environment and are capable to transmit this pathogen to naive cattle and other environments. In conclusion: A) We have been able to show that muscoid flies have a close evolutionary relationship with microbes; the immature stages strictly depend on active microbial communities in the developmental habitat and females of these flies are capable of selecting of the new habitat for their offspring based on the cues emitted form the microbes. These studies provide a basis upon which oviposition behavior of muscoid flies and muscoid fly-bacterial association could be developed into novel approaches for integrated pest control. B) Our studies demonstrate that muscoid flies play an important role in the ecology of Escherichia coli O157:H7, Enterobacter sakazakii, and multi-drug resistant enterococci in environment and have to be seriously considered in designing of pre- and post-harvest food safety strategies.
Publications
- Macovei L., B. Miles and L. Zurek (2008). The potential of house flies to contaminate ready-to-eat food by antibiotic resistant enterococci. Journal of Food Protection 71:432-439.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Enterobacter sakazakii in the gut of stable flies can survive pupation and colonize the digestive tract of newly emerging adult flies. In addition the E. sakazakii alone provides the nutritional conditions for stable fly larval development. In addition, our data indicate the vertical transfer of bacterial symbionts that play an important role in the oviposition behavior and new habitat selection for stable flies. These data have been published in the peer-review journal and have been incorporated into extension presentations given across Kansas and surrounding states.
PARTICIPANTS: Alberto Broce, Professor, K-State Entomology (collaborator) Furaha Mramba, Graduate student (Ph.D.), K-State Entomology Thais Albuquerque, Graduate student (Ph.D.), K-State Entomology
TARGET AUDIENCES: Pest control operators, Kansas farmers and ranchers, restaurant management personnel, microbial ecologists, clinicians, general public
Impacts
Enterobacter sakazakii is an opportunistic food-borne pathogen causing meningitis, enterocolitis, and sepsis, primarily in immunocompromised infants. It has been suggested that stable flies, Stomoxys calcitrans L., are a vector/reservoir of this pathogen. In this study, we assessed a) vector competence of adult stable flies (SF) for E. sakazakii, b) effect of E. sakazakii on SF development, and c) survival of E. sakazakii during SF development and colonization of the digestive tract of newly emerged flies. Our data show that in the colony, adult SF can maintain E. sakazakii for at least 20 days regardless of the food source (blood or sugar) and contaminate the food source. The concentration of the pathogen per individual SF ranged from 1.8 x 105 to 6.4 x 106 CFU. E. sakazakii supported development of immature SF in sterilized cattle manure and sterilized artificial medium (78.3 and 76.7% SF survival to adult stage, respectively). In addition, E. sakazakii survived
during SF development and colonized the gut of emerging adult SF. This study shows that SF adults have a potential to carry E. sakazakii for an extended period of time. E. sakazakii supports SF development, and can survive during SF pupation and then colonize the gut of newly emerged flies. In another study, the aggregated oviposition in SF was investigated under laboratory conditions. SF were allowed to lay eggs prior to the experiments and used in bioassays to measure different parameters of oviposition. A series of two-, three-, and five - choice tests demonstrated that gravid stable flies preferred to oviposit in the vicinity of conspecific freshly laid eggs (2 h old) than on substrates with old eggs (24 h old). In contrast, the 24 h old eggs did not enhance oviposition at all. The concentration of bacteria isolated from the surface of old eggs was 10 fold (106 CFU / egg) higher than that obtained from the surface of freshly oviposited eggs (105 CFU / egg). The increase of
bacteria in old eggs most likely mediates inhibition of further oviposition. This is also supported by the results of assays using different concentrations of bacteria on the surface of sterilized eggs that demonstrated that low (≤105 CFU /egg) and high concentrations (109 ≥ CFU / egg) of bacteria did not stimulate oviposition. This study provides a basis upon which oviposition behavior of stable flies and stable fly-bacterial association could be developed into integrated pest control. Food-borne pathogens are a serious public health and food industry concern. We have been able to show that insects, primarily muscoid flies, play an important role in the ecology of these pathogens in environment and have to be seriously considered in designing of pre- and post-harvest food safety strategies. In addition, muscoid flies have a close evolutionary relationship with microbes; the immature stages strictly depend on active microbial communities in the developmental habitat and
females of these flies are capable of selecting of the new habitat for their offspring based on the cues emitted form the microbes.
Publications
- Mramba F., A. Broce, and L. Zurek* (2007). Vector competence of stable flies (Stomoxys calcitrans L.) for Enterobacter sakazakii. Journal of Vector Ecology 69: 671-673.
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Progress 01/01/06 to 12/31/06
Outputs
Microbially/symbiont-based approaches offer novel venues for management of insect pests and/or vector-borne human and animal pathogens. Unfortunately, the fundamental knowledge of the stable fly, Stomoxys calcitrans (SF)-microbial associations and their effect on SF biology is lacking. The occurrence of aggregated oviposition in stable flies (Diptera:Muscidae) was investigated under laboratory conditions. Stable flies were allowed to lay fresh eggs prior to the experiments and used in bioassays to measure different parameters of oviposition. The series of two, three, and five choice tests demonstrated that gravid stable flies preferred to oviposit in the vicinity of conspecific freshly laid eggs (2 hrs old) than substrates with old eggs (24h old). The stimulant(s) originating from the eggs can be removed by hexane, surface sterilization with ethanol and sodium hypochlorite, or by water alone. In contrast, the 24h old eggs did not enhance oviposition at all. The
concentration of bacteria isolated from the surface of old eggs was 10 fold (106 CFU per egg) higher than that obtained from the surface of fresh eggs (105 CFU per egg). The increase of bacteria in old eggs likely mediates inhibition of oviposition to prevent further oviposition so that stable flies offspring are not subjected to competition. This is also supported by results of bioassays using different concentrations of bacteria on the surface of sterilized eggs showing that low (≤105 CFU per egg) and high concentrations (109 ≥ CFU per egg) of bacteria do not stimulate oviposition. Enterobacter sakazakii is an opportunistic food-borne pathogen causing meningitis, enterocolitis, and sepsis, primarily in immunocompromised infants. Previously, it was suggested that stable flies are a vector/reservoir of this pathogen. In this study, we assessed a) vector competence of adult stable flies (SF) for E. sakazakii, b) effect of E. sakazakii on SF development and c) survival of E.
sakazakii during SF development and colonization of the digestive tract of newly emerged flies. Our data show that the colony of adult SF can maintain E. sakazakii for at least 20 days regardless of the food source (blood or sugar) and contaminates the food source. The concentration of the pathogen per individual SF ranged from 1.8 x 105 to 6.4 x 106 CFU. E. sakazakii supported SF development in sterilized cattle manure and sterilized artificial medium with 78.0% and 77.5% SF survival to adult stage, respectively. E. sakazakii also survived SF development and colonized the gut of adult SF, however, only when SF larvae were maintained on sterilized cattle manure inoculated with E. sakazakii (12% prevalence in adult SF) and on the sterile artificial medium with E. sakazakii (21% prevalence in adult SF). E. sakazakii was not recovered (from flies or the substrate) when larvae were reared on cattle manure with complex microbial community (non-sterilized) with the E. sakazakii inoculum.
This study shows that SF adults have a potential to carry E. sakazakii for an extended period of time, E. sakazakii supports SF development and can survive during SF development and colonize the gut of newly emerged flies.
Impacts
Our studies demonstrate: a) SF females are capable of selecting an oviposition site based on the microbially-derived stimuli originating from the surface of con-specific young eggs that indicate the suitability of the substrate for larval development. Our study shows a promising starting point for exploiting SF-bacterial associations for development of novel approaches for SF management; b) SF have a good potential as a mechanical vector of E. sakazakii.
Publications
- Mramba F., A. Broce, and L. Zurek. (2006). Isolation of Enterobacter sakazakii from stable flies (Stomoxys calcitrans L.). Journal of Food Protection 69: 671-673.
- Romero A., A. Broce and L. Zurek. (2006). Role of bacteria in oviposition behavior and larval development of stable flies (Diptera: Muscidae). Medical and Veterinary Entomology 20: 115-122.
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Progress 01/01/05 to 12/31/05
Outputs
Microbially/symbiont-based approaches offer novel venues for management of insect pests and/or vector-borne human and animal pathogens. Unfortunately, the fundamental knowledge of the stable fly, Stomoxys calcitrans (SF)-microbial associations and their effect on SF biology is lacking. In our study, SF clearly preferred to lay eggs into a substrate with an active microbial community (>95% of total eggs oviposited) than into the sterilized substrate. In addition, SF larvae could not develop in a sterilized natural or artificial substrate/medium. Bacteria were isolated and identified from a natural SF oviposition/developmental habitat and their individual effect on SF oviposition response and larval development was evaluated in laboratory bioassays. Of nine bacterial strains evaluated in the oviposition bioassays, Citrobacter freundii stimulated oviposition to the greatest extent. C. freundii also sustained SF development, but to a lesser degree than Serratia fanticola.
Serratia marcescens and Aeromonas spp. neither stimulated oviposition nor supported SF development. Prevalence of Enterobacter sakazakii in SF was investigated. E. sakazakii is an opportunistic food-borne pathogen causing meningitis, enterocolitis, and sepsis, primarily in immunocompromised infants. The reservoirs and vectors of this pathogen are not known. Previously, it was suggested that SF were a vector/reservoir of this pathogen. In our study, using a culturing approach combined with 16S rDNA PCR - RFLP genotyping and sequencing, we screened 928 individual SF collected in Kansas and Florida. Two SF (0.2%) were found positive for E. sakazakii. In addition, 411 (44%) SF carried bacteria forming red colonies (presumably enterics) on a violet red bile glucose agar (VRBGA) (mean count: 6.4 x 104 CFU per fly); and 120 (13%) stable flies carried fecal coliforms (mean count: 8.7 x 103 CFU per fly). Sequencing of 16S rDNA revealed that enterics from VRGBA were represented by several
genera, including Escherichia, Shigella, Providencia, Enterobacter, Pantoea, Proteus, Serratia, and Morganella.
Impacts
Our studies demonstrate: a) SF larval development depends on a live microbial community in the natural habitat, and SF females are capable of selecting an oviposition site based on the microbially-derived stimuli that indicate the suitability of the substrate for larval development. Our study shows a promising starting point for exploiting SF-bacterial associations for development of novel approaches for SF management; b) SF carry bacteria typically present in animal manure (a developmental site of SF larvae) that indicates that the natural reservoir of E. sakazakii is the digestive tract and/or manure of domestic animals.
Publications
- Romero A., A. Broce, and L. Zurek. 2005. Role of bacteria in oviposition behavior and larval development of stable flies. Medical and Veterinary Entomology (in press).
- Mramba F., A. Broce, and L. Zurek. 2005. Isolation of Enterobacter sakazakii from stable flies (Stomoxys calcitrans L.). Journal of Food Protection (in press).
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Progress 01/01/04 to 12/31/04
Outputs
House fly (HF) larvae were grown on the artificial medium (trypticase soy egg yolk agar) individually inoculated with eight different Enterococcus species. Enterococcus hirae, E. avium, and E. durans supported the development of HF larvae to a great extent (76, 64, 64 % survival, respectively), while two important nosocomial human pathogens, E. faecalis and E. faecium did not (24 and 36% survival). However, puparia and newly emerged adult flies were commonly heavily contaminated by all Enterococcus species tested. This indicates that can enterococci survive the pupation process and colonize the gut of newly emerged adult flies making them competent vectors for enterococci and associated antibiotic resistance genes. Enterococci isolated from the field collected adult flies from four different sites (swine, horse, chicken, beef cattle facilities) were tested for resistance/susceptibility to seven antibiotics of clinical and veterinary importance. High resistance of
enterococci from all facilities was detected neomycin (84%), erythromycin (90%), and tetracycline (98%). Diversity of genes coding for ribosomal protection proteins of tetracycline resistant isolates was assessed by polymerase chin reaction (PCR). TetM was dominant determinant among isolates from flies form all the facilities (92-100% prevalence), tetS and tetO were also detected. Enterococcus identification to the species level and genotyping using PFGE is currently in progress. After very promising bioassays testing efficacy of boric acid against stable fly (SF) larvae in the natural medium under laboratory conditions, in the spring 04 we conducted the first field trial. Boric acid was applied in the liquid form on residues of the hay winter feeding sites for pastured cattle. However, the adult SF emergence from the treated sites was high and comparable to that of the control sites (treatment with water only). We believe that this was caused by the fact that boric acid in liquid
form was absorbed by the dry layer of hay on the surface of these sites and did not penetrate to the depth where the SF developed. The field trial will be repeated in the spring 2005, however, the top layer of dry hay will be removed before the treatment. In addition, efficacy of other insecticides, including methoprene, tetrachlorvinphos, and spinosid will be tested under the laboratory conditions. Furthermore, biological (microbial) and physical (pH, temperature, moisture) will be monitored throughout the SF season to better characterize the environmental conditions required for the SF development.
Impacts
The microbial ecology studies of these flies may lead to the development of novel control strategies for these insect pests. Analysis of antibiotic resistance of enterococci will offer new insights into the role of insects in the ecology of antibiotic resistance genes. Stable flies are the most important pests of pastured cattle in the United States. Currently, there are no effective methods for management of stable flies in this environment.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Cell mass of Escherichia coli DH5a as a sole source of nutrients supported the development of house flies from the neonate larvae to the pupal stage. Pupae failed to eclose, however, that's most likely because of the high moisture in the test tubes and not nutritional deficiency. These data indicate that bacterial cell mass can serve as the sole source of nutrients for larval development and house fly larvae developing in animal manure are feeding on microbes. More bacterial isolates, including Flavobacteria spp. will be tested and the physical conditions will be adjusted to accommodate the pupal eclosion process. House fly adults were collected from different animal operations, including swine, poultry, dairy, beef, horses and urban environment (apartment complex in Manhattan). Fifty flies from each environment were randomly selected, surface sterilized, and processed for the isolation of enterococci. Enterococci were isolated from the majority of samples and the
population size ranged from 50 to 6x105 CFU per fly. Preliminary screening of selected isolates indicates a high resistance to tetracycline, erythromycin, and neomycin. Future analysis will focus on the diversity of tetracycline ribosomal protection proteins by PCR. Laboratory assessment of efficacy of boric acid and sodium bisulfate was conducted using artificial and natural rearing media for stable flies. While sodium bisulfate did not show any effect on the survival of stable fly larvae, boric acid was very effective. Mortality of stable fly larvae was 97.7% and 100% on artificial and natural (mixture of hay and cattle manure) media, respectively. Different concentrations of boric acid will be tested on natural media to determine LD50 and LD90.
Impacts
House flies and stable flies are insects of great medical and veterinary importance. Studies on the microbial ecology of house flies may lead to the development of novel control strategies for these insect pests. Analysis of antibiotic resistance of enterococci will offer new insights into the role of house flies in the ecology of antibiotic resistance genes. Stable flies are the most important insect pests of cattle on pastures in the United States. Currently, there are no effective methods for management of stable flies in this environment. Boric acid appears to be a very effective management tool for stable fly larvae developing on pastures.
Publications
- No publications reported this period
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