Laboratory Rearing of Stable Flies and Other Muscoid Diptera

Stable flies, Stomoxys calcitrans, are serious pests of livestock, humans, companion animals and wildlife worldwide. During the last 20+ years, changes in ...

Ars-Usda

Catnip (Nepeta cataria) is known for its pseudo-narcotic effects on cats. Recently, it has been reported as an effective mosquito repellent against several Aedes and Culex species, both topically and spatially. Our laboratory bioassays showed that catnip essential oil (at a dosage of 20 mg) resulted in average repellency rates of 96% against stable flies, Stomoxys calcitrans (L.) and 79% against houseflies, Musca domestica (L.), respectively. This finding suggested that the application of repellent could be used as part of filth fly management. Further evaluations of catnip oil toxicity were conducted to provide a broad-spectrum safety profile of catnip oil use as a potential biting and nuisance insect repellent in urban settings. Acute oral, dermal, inhalation, primary dermal and eye irritation toxicity tests were performed. The acute oral LD(50) of catnip oil was found to be 3160 mg/kg body weight (BW) and 2710 mg/kg BW in female and male rats, respectively. The acute dermal LD50 was > 5000 mg/kg BW. The acute inhalation LD50 was observed to be > 10,000 mg/m3. Primary skin irritation tested on New Zealand white rabbits showed that catnip oil is a moderate irritant. Catnip oil was classified as practically non-irritating to the eye. In comparison with other U.S. Environmental Protection Agency-approved mosquito repellents (DEET, picaridin and p-menthane-3,8-diol), catnip oil can be considered as a relatively safe repellent, which may cause minor skin irritation.

Efficacy and safety of catnip (Nepeta cataria) as a novel filth fly repellent.

The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), is one of the most serious pests to livestock. It feeds mainly on cattle and causes significant economic losses in the cattle industry. Standard stable fly control involving insecticides and sanitation is usually costly and often has limited effectiveness. As we continue to evaluate and develop safer fly control strategies, the present study reports on the effectiveness of catnip (Nepeta cataria L.) oil and its constituent compounds, nepetalactones, as stable fly repellents. The essential oil of catnip reduced the feeding of stable flies by >96% in an in vitro bioassay system, compared with other sesquiterpene-rich plant oils (e.g. amyris and sandalwood). Catnip oil demonstrated strong repellency against stable flies relative to other chemicals for repelling biting insects, including isolongifolenone, 2-methylpiperidinyl-3-cyclohexen-1-carboxamide and (1S,2'S)-2-methylpiperidinyl-3-cyclohexen-1-carboxamide. The repellency against stable flies of the most commonly used mosquito repellent, DEET, was relatively low. In field trials, two formulations of catnip oil provided >95% protection and were effective for up to 6 h when tested on cattle. Catnip oil also acted as a strong oviposition repellent and reduced gravid stable fly oviposition by 98%.

Nepetalactones from essential oil of Nepeta cataria represent a stable fly feeding and oviposition repellent.

The stable fly, Stomoxys calcitrans (L.), has been considered one of the most serious biting flies of confined and pastured livestock. The economic losses caused by the stable fly to the cattle industry in the United States exceed $2 billion annually. Current practices for managing stable flies using insecticides provide only marginal control. Insecticide resistance has also been recently reported in stable flies. The present study reports the use of plant-based insecticides, for example, essential oils, as alternatives for managing this fly pest. The toxicity of several plant essential oils and selected ingredient compounds was evaluated by contact and fumigant toxicity bioassays. Catnip oil (20 mg dosage) showed the highest toxicity against stable flies, the shortest knock-down time (∼7 min), and the quickest lethal time (∼19 min). Toxicity levels similar to catnip oil were found among three insect repellent compounds (N,N-diethyl-3-methylbenzamide, 2-methylpiperidinyl-3-cyclohexene-1-carboxamide, (1S,2'S)-2-methylpiperidinyl-3-cyclohexene-1-carboxamide). No differences in knock-down and lethal times were found among the catnip oil and its two active ingredient compounds. Similar stable fly mortality was observed using a 20 mg dose of catnip oil in a modified K&D system and a fumigant jar. When catnip oil was topically applied to stable flies, the least lethal dose was 12.5 μg/fly, and a 50 μg/fly dose resulted in 100% mortality. The blood-feeding behavior of stable flies was also negatively affected by the topical application of catnip oil, and the effect was dose-dependent. This study demonstrated that catnip oil has both contact and fumigant toxicity against the stable fly and thus has the potential as an alternative for stable fly control.

Contact and fumigant toxicity of a botanical-based feeding deterrent of the stable fly, Stomoxys calcitrans (Diptera: Muscidae).

The secondary screwworm, Cochliomyia macellaria (F.), is an important blowfly species affecting both livestock and humans. It can transmit pathogenic disease agents mechanically and is an agent of facultative myiasis, which leads to economic losses. The adult flies are attracted to decomposing carcasses, carrion, or rotten meat in order to deposit their eggs, and the hatched larvae develop on these decaying organic materials. This research was aimed to identify volatiles emitted from rotten chicken livers that were reported previously to attract gravid females. In laboratory oviposition assays, gravid females laid significantly more eggs on rotten livers than on fresh livers, and rotten chicken liver was more attractive than rotten beef liver. Volatiles from the two livers were collected using solid phase microextraction. Significantly different volatile profiles were detected from the rotten livers of beef and chicken. Electroantennography (EAG) was performed to determine antennal responses to chemicals released from the most attractive chicken liver that are candidate oviposition attractants. Seven compounds from rotten chicken liver elicited significant EAG responses from antennae of gravid females. Oviposition assays showed that the 7-component blend stimulated gravid females to lay significantly more eggs than the other combinations tested. This 7-component blend may have potential for use in monitoring and sampling populations of secondary screwworm and their associated disease epidemiology. 

Identification of oviposition attractants of the secondary screwworm, Cochliomyia macellaria (F.) released from rotten chicken liver.

Substrates composed of hay residues, dung, and urine accumulate around winter hay feeding sites in cattle pastures, providing developmental habitats for stable flies. The objective of this study was to relate physiochemical and microbial properties of these substrates to the presence or absence of stable fly larvae. Properties included pH, temperature, moisture, ammonium concentration, electrical conductivity, and numbers of coliform, fecal coliform,Escherichia coli, andEnterococcusbacteria. Each physiochemical sample was classified as a function of belonging to one of the three 2-m concentric zones radiating from the feeder as well as presence or absence of larvae. In total, 538 samples were collected from 13 sites during 2005-2011. Stable fly larvae were most likely to be found in moist, slightly alkaline substrates with high levels of ammonium and low temperature. The probability of larvae being present in a sample was the highest when the moisture content was 347% relative to dry weight and the average pH was 8.4. Larvae were recovered within all zones, with a nonsignificant, but slightly higher, percentage of samples containing larvae taken 2-4 m from the center. All methods used to enumerate bacteria, except total coliform, indicated decreasing concentrations in hay bale residue throughout the summer. In addition to the environmental parameters, cumulative degree day 10°C had a significant effect on the probability of observing stable fly larvae in a sample, indicating that unidentified seasonal effects also influenced immature stable fly populations.

Environmental Parameters Associated With Stable Fly (Diptera: Muscidae) Development at Hay Feeding Sites.

Semiochemical-based pest management technology has been widely used to monitor and control insect pests in agricultural, forestry, and public health sectors in the western world. It became a popular tool in the early 1970s with tremendous efforts in developing environment-friendly control technologies for the integrated pest management. However, in China, similar research lagged 15 to 20 years and was not initiated until the late 1980s. In this review, we present the early history of pheromone research that has led to the current practical applications in China, particularly in the development of pheromone-based pest management products. We also provide information regarding the current status of pheromone-based product manufacturing, marketing, and regulatory issues related to local semiochemical industries, which may be useful to other international companies interested in pursuing business in China. In addition, we share some research topics that represent new directions of the present pheromone research to explore novel tools for advancing semiochemical-based pest management in China. 

Pheromone-Based Pest Management in China: Past, Present, and Future Prospects.

Stable flies are blood feeding parasites and serious pests of livestock. The immature stages develop in decaying materials which frequently have high ammonium content. We added various ammonium salts to our laboratory stable fly rearing medium and measured their effect on size and survival as well as the physical properties of the used media. The addition of ammonium hydroxide, ammonium phosphate and ammonium sulfate reduced larval survival. These compounds decreased pH and increased ammonium content of the used media. Ammonium bicarbonate had no effect on pH and marginally increased ammonium while increasing survival twofold. The optimal level of ammonium bicarbonate was 50 g (0.63 mol) per pan. Larval survival decreased when pH was outside the range of 8.5 to 9.0.

Augmenting Laboratory Rearing of Stable Fly (Diptera: Muscidae) Larvae With Ammoniacal Salts.

The dynamics of stable fly, Stomoxys calcitrans (L.), populations relative to temperature and precipitation were evaluated in a 13-yr study in eastern Nebraska. During the course of the study, >1.7 million stable flies were collected on an array of 25 sticky traps. A log-normal model using degree-days with a 15 °C threshold and weekly lags 0-4 for temperature and 2-7 for precipitation provided the best fit with the observed data. The relationships of temperature and precipitation to stable fly trap catches were both curvilinear, with maxima at 6.6 degree-day-15 (≈22 °C) and 7.4 mm precipitation per day, respectively. The temperature and precipitation model accounted for 72% of the variance in seasonal trap catches.

Jerry J. Zhu

Agroecosystems Management Research Unit

Ars-Usda

Laboratory Rearing of Stable Flies and Other Muscoid Diptera

Jerry J. Zhu

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Ars-Usda

Laboratory Rearing of Stable Flies and Other Muscoid Diptera

Agroecosystems Management Research Unit