Diurnal Flight Activity of House Flies (Musca domestica) is Influenced by Sex, Time of Day, and Environmental Conditions

A review of Musca sorbens (Diptera: Muscidae) and Musca domestica behavior and responses to chemical and visual cues

Musca flies (Diptera: Muscidae) have been found culpable in the mechanical transmission of several infectious agents, including viruses, bacteria, protozoans, and helminths, particularly in low-income settings in tropical regions. In large numbers, these flies can negatively impact the health of communities and their livestock through the transmission of pathogens. In some parts of the world, Musca sorbens is of particular importance because it has been linked with the transmission of trachoma, a leading cause of preventable and irreversible blindness or visual impairment caused by Chlamydia trachomatis, but the contribution these flies make to trachoma transmission has not been quantified and even less is known for other pathogens. Current tools for control and monitoring of house flies remain fairly rudimentary and have focused on the use of environmental management, insecticides, traps, and sticky papers. Given that the behaviors of flies are triggered by chemical cues from their environment, monitoring approaches may be improved by focusing on those activities that are associated with nuisance behaviors or with potential pathogen transmission, and there are opportunities to improve fly control by exploiting behaviors toward semiochemicals that act as attractants or repellents. We review current knowledge on the odor and visual cues that affect the behavior of M. sorbens and Musca domestica, with the aim of better understanding how these can be exploited to support disease monitoring and guide the development of more effective control strategies.

House Flies Are Underappreciated Yet Important Reservoirs and Vectors of Microbial Threats to Animal and Human Health

House flies are well recognized as filth-associated organisms and public nuisances. House flies create sanitation issues when they bridge the gap between microbe-rich breeding environments and animal/human habitations. Numerous scientific surveys have demonstrated that house flies harbor bacterial pathogens that pose a threat to humans and animals. More extensive and informative surveys incorporating next-generation sequencing technologies have shown that house fly carriage of pathogens and harmful genetic elements, such as antimicrobial resistance genes, is more widespread and dangerous than previously thought. Further, there is a strong body of research confirming that flies not only harbor but also transmit viable, and presumably infectious, bacterial pathogens. Some pathogens replicate and persist in the fly, permitting prolonged shedding and dissemination. Finally, although the drivers still have yet to be firmly determined, the potential range of dissemination of flies and their associated pathogens can be extensive. Despite this evidence, the house flies’ role as reservoirs, disseminators, and true, yet facultative, vectors for pathogens have been greatly underestimated and underappreciated. In this review, we present key studies that bolster the house fly’s role both an important player in microbial ecology and population biology and as transmitters of microbial threats to animal and human health.

Characterized Gene Repertoires and Functional Gene Reference for Forensic Entomology: Genomic and Developmental Transcriptomic Analysis of Aldrichina grahami (Diptera: Calliphoridae)

Many flies of Diptera are common entomological evidence employed in forensic investigation. Exploring the existence of inter- and intra-species genomic differences of forensically relevant insects is of great importance. Aldrichina grahami is a common blow fly species of forensic importance. The present study characterized the gene repertoires of A. grahami, and provides insights into issues related to forensic entomology, such as necrophagous behavior, gene family features, and developmental patterns. Gene families were clustered and classified according to their function in different aspects of the necrophagous lifestyle, generating several gene repertoires. The genes under positive selection pressure and evolutionary changes were screen and identified. Moreover, genes that exhibited potential prediction value in the post mortem interval (PMI) estimation and development of immature stages were subjected to analysis based on the developmental transcriptome. Related insect species were compared at the genomic level to reveal the genes associated with necrophagous behaviors. The expression of selected genes in separated repositories was verified using qPCR. This work was conducted using a high-quality chromosome-level genome assembly of A. grahami and its developmental transcriptome. The findings will facilitate future research on A. grahami and the other forensically important species.

Landscape distribution and abundance of animal-associated adult filth flies on commercial swine facilities in North Carolina, US

Filth flies associated with animal production transmit pathogens to humans and animals, propagate antimicrobial resistance in microbial communities and provoke nuisance litigation. Although dispersal of flies from facilities is often responsible for these negative effects, filth fly research on swine facilities has been limited to within the barns. Filth fly adaptations in space and time, as well as influences of abiotic and biotic factors impact distribution and abundance of animal-associated filth flies on swine production facilities. In this study, fly surveillance was conducted around four swine facilities in Bladen County, North Carolina, U.S.A. from January 2019 to October 2019. Traps were replaced weekly and animal-associated filth flies were identified. Flies were grouped for comparison based on biology and differences in pest management strategies. There were distinct differences in abundance and spatial distribution of different filth fly groups on the swine facilities, which are likely linked to environmental factors like spatial relation to crop production and species phenology. The impact of the observed temporal and spatial distribution and abundance is discussed in the context of filth fly management.

Review of Methods to Monitor House Fly (Musca domestica) Abundance and Activity

The house fly is a ubiquitous pest commonly associated with animal facilities and urban waste. When present in large numbers, house flies can negatively impact humans and animals through nuisance and the transmission of pathogens. Since the development of fly traps and sticky papers to capture flies in the late 1800s, these and other methods have been used as a means to monitor change in house fly density or fly activity over time. Methods include substrate sampling to record density of immature flies, visual observations of adult fly activity, instantaneous counts of landing or resting flies, accumulation of adult flies on/in traps, or accumulation of fly fecal and regurgitation spots deposited by flies onto white cards. These methods do not estimate true house fly density, but rather provide an index of house fly activity that is related to both fly density and the frequency of individual fly behavior (e.g., frequency of flight, landing events) and which is likely more predictive of negative impacts such as nuisance and pathogen transmission. Routine monitoring of house fly activity is a critical component of a house fly management program. Fly activity should be held to a level below a predetermined activity threshold ('action threshold') above which negative impacts are anticipated to occur. This article is a review of methods utilized for monitoring house fly (Diptera: Muscidae) activity.

Monitoring House Fly (Diptera: Muscidae) Activity on Animal Facilities

Monitoring house fly (Diptera: Muscidae) activity on animal facilities is a necessary component of an integrated pest management (IPM) program to reduce the negative impacts of these flies. This article describes monitoring methods appropriate for use on animal facilities with discussion of monitoring device use and placement. Action thresholds are presented where these have been suggested by researchers. Sampling precision is an important aspect of a monitoring program, and the number of monitoring devices needed to detect a doubling of fly activity is presented for monitoring methods where this information is available. It should be noted that both action thresholds and numbers of monitoring devices will be different for every animal facility. Suggested action thresholds and numbers of monitoring devices are presented only to provide guidance when initiating a fly monitoring program. Facility managers can adjust these values based upon the fly activity data recorded at their facility. Spot cards are generally recommended as an easy-to-use method for monitoring fly activity for most animal facilities. Fly ribbons or similar sticky devices are recommended where several pest fly species may be abundant and identifying the activity of each species is important, but a sampling period of <7 d may be needed in dusty conditions or when fly density is high. Fly ribbons are not recommended for outdoor use. Insecticide-baited traps may be used in outdoor locations where environmental conditions limit the use of spot cards, fly ribbons, and sticky traps.