FLY MANAGEMENT IN ANIMAL AGRICULTURE SYSTEMS AND IMPACTS ON ANIMAL HEALTH AND FOOD SAFETY

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: TERMINATED
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1001893
• Project No.: NYC-139819
• Multistate No.: S-1060
• Project Start Date: Oct 31, 2013
• Project End Date: Sep 30, 2018

Project Director
Scott, JE, G.

Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853

Performing Department
Entomology

Non Technical Summary
Federal funding priorities are focused on major issues of national concern, climate change, food safety, food security, biofuels, and obesity. Entomologists play a key and vital role in helping to solve many of these national concerns by researching the potential impact of climate change on insect populations and how these changes can threaten the health and well-being of humans and animals, and compromise the nations safe and secure food supply. Few insects are more influenced by anthropogenic effects than nuisance and pest flies; the house fly, stable fly, horn fly, face fly and blow flies. There is a significant body of literature on the biology and economic impact of these pests but this multidisciplinary project examines closely predictive models influencing pest distribution in light of climate change, the effects of the microbial community of pest populations, and the dispersal of pathogenic microorganisms that compromise a safe and secure food supply. Advances developed in the course of this project will lead to the development of new and innovative pest management technologies to mitigate these threats. Biting and nuisance flies are among the most important pests in livestock and poultry production systems. These flies are responsible for damage and control costs in excess of a billion dollars per year in the United States. In addition to the direct damage these flies inflict upon livestock, their presence as a byproduct of confined livestock and poultry operations has been repeatedly cited as a nuisance, especially when flies enter the vicinity of human habitations and urban environments. Law suits, zoning limitations and animosity between farmers and home owners have resulted. In spite of their ubiquitous presence, importance as pests, and association with diseases of humans and livestock, our knowledge of the biology of these species is seriously wanting and available control technologies remain inadequate. The recent sequencing of the house fly genome (underway), and future sequencing of the stable fly genome (planned) offer great potential for the identification of new opportunities for managing these pests. House flies are considered to be the #1 nuisance pest associated with dairy and other confined animal operations. House flies are capable of carrying more than 65 disease organisms that affect humans and animals, such as the virulent Escherichia coli strain O157:H7. In poultry production, house flies can transmit Salmonella among flocks; and the spotting of eggs with fly specks may reduce the eggs' market value. Stable are among the most serious pests of cattle worldwide. With their painful bites, they can reduce weight gains of cattle on finishing rations up to 20%. The total impact to U.S. cattle industries is estimated to exceed $2 billion dollars annually. Given the economic importance of nuisance and biting flies, control of their populations is critically important. For decades insecticides have provided economical control of these pests. However, the evolution of insecticide resistance compromises the control achieved in many locations around the USA. Stable flies develop as maggots in a wide array of decomposing organic matter, including soiled animal bedding and soiled feed debris that accumulates wherever cattle are confined. Populations build exponentially by continuous reproduction from spring to fall in northern temperate localities. Dairy farm surveys indicate calf hutch bedding is a prominent source of stable flies around dairies, and choice of bedding material can minimize stable fly production. More recently, it has also become apparent that feed debris and manure that accumulate during winter are important sources of stable flies, especially where overwintered debris piles remain intact into the following summer. The face fly is the primary pest of pastured cattle in most state north of the 35th parallel. Adult face flies overwinter in attics and out-buildings and colonize cattle in the spring. The face fly feeds on lachrymal and mucosal secretions of the eyes and nose of cattle. Gravid flies lay eggs exclusively in fresh cattle dung pats, and the life cycle can be completed in as little as 14 days. When face flies are abundant, cattle change grazing habits, which often results in poor utilization of pasture. In addition to the annoyance and irritation associated with its feeding habits, the face fly is the primary means of transmission of Moraxella bovis, the causative agent of infectious bovine keratoconjunctivitis (IBK), also known as pinkeye. Face fly infestations were estimated to cause annual losses of more than $53 million. Action threshold levels of 10-15 flies per face were established to reduce the spread of pinkeye and maximize animal comfort. In the northeast face fly numbers often exceed 100 flies per face. The horn fly is an obligate blood-sucking parasite of cattle and is considered a serious pest of pastured cattle in US. Horn fly feeding annoys cattle, alters their grazing habits, and decreases both milk production and weight gains. Horn fly numbers as high as 10,000 per animal have been reported and they feed 10 to 12 times per day. Horn flies oviposit exclusively in fresh dung, and they do so immediately after it has been deposited. The fly can complete development in 9-12 days, with 50% adult survival at 5 weeks. Horn flies diapause beneath dung pats during the winter months. Horn fly control leads to increased milk production and calf growth. Unlike other kinds of flies that just visit cattle for brief moments, adult horn flies reside on their host animals, which makes then especially vulnerable to control. Organic dairy farmers rely on essential oil repellents to alleviate horn fly problems, but success of these products is limited. Horn flies have been incriminated in the transmission of bovine mastitis, also known as summer mastitis. In NC, 53% of horn flies collected from cattle were positive for S. aureus, and 39% of the cows were positive for the same genotype found in the flies. In 2003, the Northeastern IPM Center Livestock and Field Crop working group created a list of prioritized needs. The group indicated that the "development of new integrated management of key pests of livestock and poultry in confined and pasture settings" was a top priority with specific reference to "stable fly breeding and migration in pasture systems" and "fly control methods for pasture and feedlot situations." Ten of the working group's 17 assessed needs and seven of the top 10 directly referred to muscid flies, including house flies, stable flies, and face flies as top priorities. The objectives of the current proposal address 10 of the 17 needs. Coordinated extension of the research outcomes derived from this proposal to stakeholders will address 2 additional priorities of this working group. Successful completion of this project will provide a better understanding of the interactions between livestock production systems and the life cycles of pestiferous flies. Exploitation of these interactions will provide economically feasible and environmentally friendly technology for reducing the impact of flies on livestock production and human health. The project will provide quantitative data to analyze fly borne spread of pathogens from animal production systems into the urban environment. The project will develop new control technologies for biting and nuisance flies and will assess the fly resistance to insecticides that are currently available or under development. New technological innovations and comprehensive pest management information will be disseminated to producers through a multistate coordinated effort to provide the broadest reach for project outcomes thereby increasing the health and quality of livestock and reducing the economic impact of these pest flies.

Animal Health Component

40%

Research Effort Categories

Basic

70%

Applied

30%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
307	3110	1130	25%
311	3110	1130	25%
315	3110	1130	25%
723	5220	1130	25%

Knowledge Area
311 - Animal Diseases; 723 - Hazards to Human Health and Safety; 307 - Animal Management Systems; 315 - Animal Welfare/Well-Being and Protection;

Subject Of Investigation
3110 - Insects; 5220 - Pesticides;

Field Of Science
1130 - Entomology and acarology;

Keywords

insecticide resistance

pest control

house fly

dairy

poultry

Goals / Objectives
Insecticide resistance detection and management

Project Methods
A nationwide survey for stable fly resistance to permethrin will be conducted. Treated jars will be shipped to collaborating scientists and results will be compiled by the University of Florida. Flies that survive the bioassay will be frozen and archived for evaluation of Vssc mutations using molecular techniques. Although a mutation in the stable fly Vssc has been described, its absence from field collections is probable and would support the presence of other Vssc mutations or other mechanisms of resistance unrelated to the target site. These specimens would enable additional screening. Resistance to benzylphenyl urea and triazine compounds has not been reported for stable fly. Therefore, we will use house fly as a model to evaluate cross-resistance and synergy between these compounds. Cyromazine resistant house fly colonies (3-4) will be established by collecting house flies from poultry operations with a history of using Larvadex (Bloomcamp et al. 1987). Susceptible colonies will be acquired from institutions maintaining susceptible house fly colonies. Bioassays will be conducted to establish LC50 values for cyromazine and novaluron for each colony. If novaluron resistance is observed in cyromazine resistant colonies, they will be crossed with susceptible colonies and progeny independently selected for cyromazine and novaluron resistance. Lines will be evaluated for susceptibility to both insecticides after selection. Synergistic effects of cyromazine, novaluron, and pyriproxyfen on stable fly and house fly will be evaluated as well. Assessment of insecticide resistance in horn flies collected from beef and dairy herds and stable flies from dairy, beef and equine farms will include field surveys using multiple existing registered chemistries. Up to 10 farms will be surveyed and their resistance to insecticides in the pyrethroid (Type I and II) and organophosphate classes will be determined, with other classes added as available. Genetic profiling of for acetylcholinesterase (Ace) and kdr-type mutations (Vssc) as well as other biochemical assays will be carried out on these same fly populations. This study provides an opportunity to identify stable fly populations that may exhibit OP-resistance, facilitating identification of mutations occurring within the stable fly acetylcholinesterase gene (ScAChE) that associate with the OP-resistant phenotype. Sequencing of the house fly and stable fly genomes also offers the potential for rapid identification of the mutations responsible for resistance. Identification of the alleles responsible for resistance allows for detailed studies of the evolution of resistance that are not possible with bioassays. We propose to use high-throughput Illumina sequencing of transcripts between resistant and susceptible house fly strains to rapidly identify the basis of resistance. This would be done for both spinosad and imidacloprid resistant strains. Given the importance of olfaction to stable fly development (host location, oviposition), a more complete understanding of the genes involved in the olfactory pathway provides a means to more rapidly screen attractant/repellent compounds in vitro to evaluate possible use in field settings. Transcriptome data has provided some insight into stable fly olfactory genes (Olafson et al. 2011; Olafson et al., 2013); however, availability of a genome sequence would greatly strengthen this base, especially with respect to identifying the repertoire of ligand-selective odorant receptors that are known to be highly divergent within insects. Once identified, these receptors will be isolated and used in vitro for screening compounds of interest.

Progress 10/31/13 to 09/30/18

Outputs
Target Audience:Entomologists and other professionals involved in house fly research/control at animal production facilities. Indirect contact with diary, beef and poultry producers via studies done for collaborators across the United States. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training opportunities were provided for five undergraduate students, one graduate student, one visiting student and the PI. Undergraduates were employed as lab assistants and obtained experience working in a lab and participating in research. Two undergraduates conducted honors thesis research related to this project and graduated with research honors. The graduate studentis learning how to conduct independent research and she attended the annual multistate annual meeting where she presented her results. The PI attended the National Entomological Society of America meetings where he presented research results, networked with colleagues and learned new approaches that could be employed for future studies. How have the results been disseminated to communities of interest?Three papers were published in high quality peer-reviewed journals and two talks were given at scientific meetings (annual Entomological Society of America meetings and annual American Chemical Society national meetings). In addition, the results of our testing of house fly populations in the US were immediately relayed to our collaborators that had made the collections, along with suggestions about what the facility could do, and should not do, in terms of insecticides for house fly control. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? House flies (Musca domestica) are major pests at animal production facilities. Insecticides, particularly pyrethroids, have been used for control of house fly populations for more than 30 years, but the evolution of resistance will likely jeopardize fly control efforts. A major mechanism of pyrethroid resistance in the house fly is target site insensitivity (due to mutations in the Voltage sensitive sodium channel, Vssc). Based on a survey of house fly populations in 2007 and 2008, the most common resistance allele at 2/3 of the states in the USA is kdr-his. This was unexpected given the relatively lower level of resistance this allele confers, and led to speculation that the kdr-his allele may have a minimal fitness cost in the absence of insecticide. The goal of this study was to evaluate the fitness cost of kdr-his by monitoring the changes in allele frequency over 15 generations in the absence of insecticide. In crosses with two different insecticide susceptible strains, we found that kdr-his had a significant fitness cost. Future studies are needed to compare the relative fitness cost of the kdr-his allele with other resistance alleles, in order to understand the evolution of pyrethroid insecticide resistance more fully. Neonicotinoids are the largest class of insecticides and are used (primarily as baits) for control of house fly populations at animal production facilities throughout the world. There have been several reports of neonicotinoid resistance in house fly populations, but identification of the factors involved in resistance has proven challenging. The KS8S3 population of house flies is highly resistant to the neonicotinoid insecticide imidacloprid due to two factors: one on chromosome 3 and one on chromosome 4. A comparative transcriptomic approach was used, followed by validation using transgenic Drosophila melanogaster to investigate the genes responsible for resistance in the KS8S3 strain. Overexpression of a microsomal glutathione S-transferase (Mdgst) was identified as the factor likely responsible for resistance on chromosome 3. Resistance on chromosome 4 appears to be due to an unidentified trans-regulatory gene which causes overexpression of a galactosyltransferase-like gene (Mdgt1). No single nucleotide polymorphisms were found that could be associated with imidacloprid resistance. Identification of the underlying processes that cause imidacloprid resistance is an important first step towards the development of novel and sensitive resistance monitoring techniques. It will be valuable to investigate if overexpression of Mdgst and Mdgt1 are found in other imidacloprid resistant populations. In collaboration with colleagues, we tested house flies from across the USA to determine the levels of resistance and frequencies of resistance alleles. These results were reported back to the collaborators who were working directly with animal production facility staff to identify the most effective means of controlling their house fly populations.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Reid, W. R., Sun, H., Becnel, J. J., Clark, A. G. and Scott, J. G. 2018. Overexpression of a glutathione S-transferase (Mdgst) and a galactosyltransferase-like gene (Mdgt1) is responsible for imidacloprid resistance in house flies. Pest Manag. Sci. DOI 10.1002/ps.5125.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Hanai, D., Yoshimizu, M. H. and Scott, J. G. 2018. The insecticide resistance allele kdr-his has a fitness cost in the absence of insecticide use. J. Econ. Entomol. 111: 2992-5 DOI: 10.1093/jee/toy300.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Meisel, R. P. and Scott, J. G. 2018. Using genomic data to study insecticide resistance in the house fly, Musca domestica. Pestic. Biochem. Physiol. 151: 76-81. doi:10.1016/j.pestbp.2018.01.001.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Entomologists and other professionals involved in house fly research/control. Indirect contact with diary, beef and poultry producers. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training was provided for three undergraduate students, one graduate student and one visiting scientist. This was professionally important for all of those involved; in particular it contributed to their abilities to complete a research honors thesis and a PhD degree. How have the results been disseminated to communities of interest?Three papers were published in peer review journals, two talks were given at scientific meetings and results were presented at the annual meeting of the Multistate project. Specific collaborations took place with two colleagues who identified animal production facilities having house fly control problems. We were able to confirm the resistance and report on cross-resistance patterns so that alternative insecticides could be selected. What do you plan to do during the next reporting period to accomplish the goals?Determine the frequency of the novel mutations Vssc in populations of house flies from different states.

Impacts
What was accomplished under these goals? The house fly, Musca domestica, is a serious pest because it transmits a large diversity of human and veterinary diseases. Insecticides, particularly pyrethroids, are commonly used to control house flies. However, the evolution of pyrethroid resistance has reduced the effectiveness of these insecticides. A major mechanism of resistance to pyrethroids is target site insensitivity caused by the mutations in the voltage-sensitive sodium channel (Vssc) gene (e.g. kdr [L1014F] and super-kdr [M918T + L1014F]). Recently, two novel Vssc alleles, super-kdr + D600N and kdr + T929I were detected in a field collected resistant house fly population in Kansas, USA in 2013. To determine the levels of resistance that these new alleles confer to pyrethroids, we isolated strains having the unique Vssc alleles, but being otherwise congenic to the susceptible strain, aabys. We compared levels of resistance conferred to 14 pyrethroids and determined the inheritance of resistance to 8 pyrethroids. Our results revealed that super-kdr + D600N conferred higher levels of resistance to seven pyrethroids relative to super-kdr, and kdr + T929I showed super-kdr-like levels of resistance in house flies. Our results are compared with previous studies and reveal that addition of T929I to the kdr mutation (L1014F) increased resistance to all pyrethroids (except etofenprox), and enhanced resistance by ~1000-fold to acrinathrin and flumethrin.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: . Diversity of knockdown resistance alleles in a single house fly population facilitates adaptation to pyrethroid insecticides. Insect Molec. Biol. 26: 13-24.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Scott, J. G. 2017. Evolution of pyrethroid resistance in Musca domestica. Pest Manag. Sci. 73: 716-22.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Sun, H., Kasai, S. and Scott, J. G. 2017. Two novel house fly Vssc mutations, D600N and T929I, give rise to new insecticide resistance alleles. Pestic. Biochem. Physiol. 143:116-121.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Entomologist and other professionals involved in house fly research/control. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training was provided for three undergraduate students, one graduate student and one visiting scientist. This was professionally important for all of those involved; in particular it contributed to their abilities to complete a research honors thesis and a PhD degree. How have the results been disseminated to communities of interest?Two papers were published in peer review journals, three talks were given at scientific meetings and results were presented at the annual meeting of the Multistate project. What do you plan to do during the next reporting period to accomplish the goals?Search for novel mutations in Vssc in populations of house flies and evaluate their role in resistance.

Impacts
What was accomplished under these goals? Target site insensitivity because of mutations in the voltage-sensitive sodium channel gene (Vssc) is a major mechanism of resistance to pyrethroid insecticides in the house fly, Musca domestica. There are three known Vssc alleles that confer resistance to pyrethroids in the house fly: knock down resistance (kdr; L1014F), super-kdr (M918T1L1014F) and kdr-his (L1014H), but there has been no side-by-side comparison of the resistance levels that they confer. We compared the levels of resistance conferred by the three Vssc alleles in congenic strains to 19 structurally diverse pyrethroids, and compared the full-length Vssc cDNA sequences from each strain. Generally, the levels of resistance conferred were kdr-his<kdr<super-kdr. However, there was significant variation in this pattern, especially for super-kdr, for which both high and low resistance ratios were observed for several pyrethroids. We also examined the levels of resistance in heterozygotes. Resistance in each of the hybrids was generally inherited as an incompletely recessive trait, except for the kdr-his/kdr hybrids, which showed incompletely to completely dominant resistance (i.e., had resistance levels comparable to kdr homozygotes).

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Meisel, R. P., Davey, T., Son, J. H., Gerry, A. C., Shono T. and Scott, J. G. 2016. Is multifactorial sex determination in the house fly, Musca domestica (L.), stable over time? J. Heredity 107: 615-625
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Sun, H., Tong, K.P., Kasai, S. and Scott, J. G. 2016. Overcoming super-kdr mediated resistance: Multi-halogenated benzyl pyrethroids are more toxic to super-kdr than kdr house flies. Insect Molec. Biol. 25: 126-137.

Progress 10/01/14 to 09/30/15

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Undergraduates were trained in various aspects of insecticide toxicology, genetics and genomics. How have the results been disseminated to communities of interest?Three papers were published in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals?Evaluate strains with different Vssc mutations to understand what pyrethroids they are resistant to.

Impacts
What was accomplished under these goals? Adult house flies, Musca domestica L., are mechanical vectors of more than 100 devastating diseases that have severe consequences for human and animal health. House fly larvae play a vital role as decomposers of animal wastes, and thus live in intimate association with many animal pathogens. Insecticides are the primary means for control of house fly populations, but house flies have shown a remarkable ability to rapidly evolve resistance to insecticides. Detection of the mutation(s) responsible for resistance are critically important to understand and manage insecticide resistance. However, such studies often take years to accomplish. Knowing the genome of the house fly will accelerate our ability to identify resistance mutations. We have sequenced and analyzed the genome of the house fly using DNA from female flies. The sequenced genome is 691 Mb. Compared with Drosophila melanogaster, the genome contains a rich resource of shared and novel protein coding genes, a significantly higher amount of repetitive elements, and substantial increases in copy number and diversity of both the recognition and effector components of the immune system, consistent with life in a pathogen-rich environment. There are 146 P450 genes, plus 11 pseudogenes, in M. domestica, representing a significant increase relative to D. melanogaster and suggesting the presence of enhanced detoxification in house flies. Relative to D. melanogaster, M. domestica has also evolved an expanded repertoire of chemoreceptors and odorant binding proteins, many associated with gustation.This represents the first genome sequence of an insect that lives in intimate association with abundant animal pathogens. The house fly genome provides a rich resource for enabling work on innovative methods of insect control, for understanding the mechanisms of insecticide resistance, genetic adaptation to high pathogen loads, and for exploring the basic biology of this important pest. The genome of this species will also serve as a close out-group to Drosophila in comparative genomic studies.

Publications

• Type: Journal Articles Status: Published Year Published: 2015 Citation: Scott, J. G., Warren, W. C., Beukeboom, L. W., Bopp, D., Clark, A. G., Giers, S. D., Hediger, M., Jones, A. K., Kasai, S., Leichter, C. A., Li, M., Meisel, R. P., Minx, P., Murphy, T. D., Nelson, D. R., Reid, W. R., Rinkevich, F. D., Robertson, H. M., Sackton, T. B., Sattelle, D. B., Thibaud-Nissen, F., Tomlinson, C., van de Zande, L., Walden, K. K. O., Wilson, R. K. and Liu, N. 2014. Genome of the house fly (Musca domestica L), a global vector of diseases with adaptations to a septic environment. Genome Biol. 15: 466.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Hamm, R. L., Meisel, R. P. and Scott, J. G. 2015. The evolving puzzle of autosomal versus Y-linked male determination in Musca domestica. G3 5: 371-384.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Meisel, R. M., Scott, J. G. and Clark, A. G. 2015. Transcriptome differences between alternative sex determining genotypes in the house fly, Musca domestica. Genome Biol. Evol. 7: 2051-2061.

Progress 10/31/13 to 09/30/14

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Undergraduates were trained in various aspects of insecticide toxicology. How have the results been disseminated to communities of interest? Two papers were published in peer-reviewed journals. What do you plan to do during the next reporting period to accomplish the goals? Evaluation of the mechanisms of resistance to spinosad and imidacloprid.

Impacts
What was accomplished under these goals? The housefly, Musca domestica L., is a global pest and has developed resistance to most insecticides applied for its control. The insecticide spinosad plays an important role in housefly control. Females of the Danish housefly strain 791spin are threefold more resistant to spinosad than males in this strain. The factor responsible for spinosad resistance in the strain is unknown, but previous studies suggest a role of cytochrome P450s for detoxification of spinosad. Sex determination in the housefly is controlled by amale-determining factor (M), either located on the Y chromosome or on one of the five autosomes (I to V). Theauthors performed a series of crosses andbackcrosses, starting with crossof 791spin andthe susceptible reference strain aabys (bearing morphological mutations on each autosome). These flies were evaluated for gender and bioassayed to determine levels of resistance to spinosad. Sex determination in 791spin is due to amale factor on autosome 3. The most likely explanation for the differentiation of spinosad resistance between males and females is a recessive spinosad resistance factor on autosome III. Imidacloprid is the most widely used neonicotinoid insecticide against house flies, which are major pests at animal production facilities worldwide. However, cases of both physiological and behavior resistance have been reported. Recently, physiological resistance to imidacloprid was found in the United States (California and Florida). However, no studies have been undertaken to characterize this resistance in house flies from the United States. Three imidacloprid selections of a strain originally collected from Florida increased the level of resistance, ultimately resulting in a strain that had 2,300-fold resistance in females and 130-fold in males. Resistance levels were higher in females than males. Imidacloprid resistance was not overcome with piperonyl butoxide (PBO) suggesting that resistance is not due to detoxification by cytochrome P450s. Resistance was mapped to autosomes 3 and 4. There was ≥100-fold cross-resistance to acetamiprid and dinotefuran, but no cross-resistance to spinosad. The resistance in this imidacloprid selected population was unstable and declined over a period of several months.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Kavi, L.A.K., P.E. Kaufman, and J.G. Scott, 2014 Genetics and mechanisms of imidacloprid resistance in house flies. Pestic. Biochem Physiol. 109: 64-69.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: H�jland, D.H., J.G. Scott, K.-M.V. Jensen, and M. Kristensen, 2014 Autosomal male determination in a spinosad resistant house fly strain from Denmark. Pest Man. Sci. 70: 1114-1117.