Effects of four commercial fungal formulations on mortality and sporulation in house flies (Musca domestica) and stable flies (Stomoxys calcitrans).

The house fly Musca domestica L. (Diptera: Muscidae) and stable fly Stomoxys calcitrans (L.) (Diptera: Muscidae) are major pests of livestock. Biological control is an important tool in an integrated control framework. Increased mortality in filth flies has been documented with entomopathogenic fungi, several strains of which are commercially available. Three strains of Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) and one strain of Metarhizium brunneum (Petch) (Hypocreales: Clavicipitaceae) were tested in commercial formulations for pathogenicity against house flies and stable flies. There was a significant increase in mortality of house flies with three of the formulations, BotaniGard® ES, Mycotrol® O, and Met52® EC, during days 4-9 in comparison with balEnce™ and the control. In stable flies, mortality rates were highest with Met52® EC, followed by Mycotrol® O, BotaniGard® ES and, finally, balEnce™. There was a significant fungal effect on sporulation in both house flies and stable flies. Product formulation, species differences and fungal strains may be responsible for some of the differences observed. Future testing in field situations is necessary. These commercial biopesticides may represent important tools in integrated fly management programmes.

Oviposition Deterrence and Immature Survival of Filth Flies (Diptera: Muscidae) When Exposed to Commercial Fungal Products.

Filth flies are pests of livestock, and can transmit pathogens that cause disease to animals and their caretakers. Studies have shown successful infection of adult filth flies following exposure to different strains and formulations of entomopathogenic fungi. This study aimed to examine the effects of commercial formulations of Beauveria bassiana (Balsamo) (Moniliales: Moniliaceae) (i.e., BotaniGard ES, Mycotrol O, balEnce), and Metarhizium brunneum (Metsch.) (Ascomycota: Hypocreales) (i.e., Met52 EC), on filth fly oviposition and immature fly survival after exposure. House flies, Musca domestica L., laid significantly fewer eggs on Met52 EC-treated surfaces than on surfaces treated with all other products and the control. Similar numbers of eggs were laid on surfaces treated with all B. bassiana products, but egg production was half of the control. Stable flies, Stomoxys calcitrans (L.), laid the fewest eggs on Met52 EC- and Mycotrol O-treated surfaces. This species did not distinguish between the remaining products and the control. In a second experiment, house fly eggs were placed on treated cloths so that hatched larvae contacted the treatment prior to development. Met52 EC had the greatest effect on immature survival with a significant reduction in recovered pupae at the medium and high doses of fungi. Overall, Met52 EC, containing M. brunneum, had the greatest effect on house fly and stable fly oviposition deterrence and immature development of house flies. Management implications are discussed.

Comparison of Host-Seeking Behavior of the Filth Fly Pupal Parasitoids, Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae).

The pupal parasitoids, Spalangia cameroni Perkins and Muscidifurax raptor Girault and Sanders, can be purchased for biological control of house flies Musca domestica L. and stable flies Stomoxys calcitrans (L.) (Diptera: Muscidae). Little is known about the odors involved in host-seeking behavior of these two species, so odors associated with house flies were investigated in the laboratory using a Y-tube olfactometer. Odor stimuli from house fly host puparia, larvae, pine-shavings bedding with horse manure, and developing flies in the pine-shavings-manure substrate were evaluated in bioassays using the two pteromalid species. In choice tests, naïve female S. cameroni were strongly attracted to odor from the substrate containing house fly larvae and secondarily from the uninfested substrate and substrate with puparia versus humidified and purified air. This species also selected the substrate with larvae versus the substrate with the house fly puparia or uninfested substrate. Muscidifurax raptor was attracted to odor from the substrate containing puparia, washed puparia, and substrate with puparia removed. The data suggest that coexistence between the two pteromalid parasitoids, S. cameroni and M. raptor, might be promoted by different host-seeking behavior.

Comparison of the Olfactory Preferences of Four of Filth Fly Pupal Parasitoid Species (Hymenoptera: Pteromalidae) for Hosts in Equine and Bovine Manure.

House flies (Musca domestica L.) and stable flies (Stomoxys calcitrans (L.)) (Diptera: Muscidae) are common pests in equine and cattle facilities. Pupal parasitoids, primarily in the genera Spalangia and Muscidifurax (Hymenoptera: Pteromalidae), can be purchased for biological control of these flies. However, little is known about the host-habitat preferences associated with host-seeking by these parasitoids. The preferences of two Spalangia and two Muscidifurax species to odors associated with house fly hosts in equine and bovine manure were investigated in the laboratory using a Y-tube olfactometer. Odor stimuli from manure without developing flies, third-instar house flies in manure, and fly host puparia in manure were evaluated. In choice tests, S. cameroni and S. endius were strongly attracted to odor associated with equine manure against clean air. Although S. cameroni was attracted to all bovine manure-containing treatments against clean air, S. endius was only attracted to the bovine manure with third-instar flies. There were no significant differences between the Spalangia species in odor responses. Neither Muscidifurax species were attracted to equine manure treatments and were only attracted to the bovine manure with puparia over clean air. In manure comparison studies, bovine treatments with developing flies were more attractive than the equivalent equine treatments to both Muscidifurax species The data suggest that coexistence between the competing pteromalid parasitoids might be promoted by different host-seeking behaviors. Additionally, manure preferences may indicate parasitoid suitability for releases on different livestock and equine facilities.

Enhancement of the Musca domestica hytrosavirus infection with orally delivered reducing agents.

House flies (Musca domestica L.) throughout the world are infected with the salivary gland hypertrophy virus MdSGHV (Hytrosaviridae). Although the primary route of infection is thought to be via ingestion, flies that are old enough to feed normally are resistant to infection per os, suggesting that the peritrophic matrix (PM) is a barrier to virus transmission. Histological examination of the peritrophic matrix of healthy flies revealed a multilaminate structure produced by midgut cells located near the proventriculus. SEM revealed the PM to form a confluent sheet surrounding the food bolus with pores/openings less than 10nm in diameter. TEM revealed the PM to be multilayered, varying in width from 350 to 900 nm, and generally thinner in male than in female flies. When flies were fed on the reducing agents dithiothetriol (DTT) or tris (2-caboxyethyl)phosphine hydrochloride (TCEP) for 48 h before per os exposure to the virus, infection rates increased 10- to 20-fold compared with flies that did not receive the reducing agent treatments. PM's from flies treated with DTT and TCEP displayed varying degrees of disruption, particularly in the outer layer, and lacked the electron-dense inner layer facing the ectoperitrophic space. Both drugs were somewhat toxic to the flies, resulting in>40% mortality at doses greater than 10mM (DTT) or 5 mM (TCEP). DTT increased male fly susceptibility (55.1% infected) more than that of females (7.8%), whereas TCEP increased susceptibility of females (42.9%) more than that of males (26.2%). The cause for the sex differences in response to oral exposure the reducing agents is unclear. Exposing flies to food treated with virus and the reducing agents at the same time, rather than pretreating flies with the drugs, had no effect on susceptibility to the virus. Presumably, the reducing agent disrupted the enveloped virus and acted as a viricidal agent. In summary, it is proposed that the reducing agents influence integrity of the PM barrier and increase the susceptibility of flies to infection by MdSGHV.

Competition between the filth fly parasitoids Muscidifurax raptor and M. raptorellus (Hymenoptera: Pteromalidae).

Competition bioassays were conducted with the filth fly pupal parasitoids Muscidurax raptor (Girault & Sanders) and M. raptorellus (Kogan & Legner) (Hymenoptera: Pteromalidae) using house fly Musca domestica L. (Diptera: Muscidae) hosts at different host densities. Muscidifurax raptor had a significant impact on M. raptorellus when hosts were limiting in sequential parasitism tests. Fewer than six M. raptorellus adult progeny emerged from groups of 50 fly pupae that were parasitized by M. raptor at the same time or when M. raptor parasitism preceded M. raptorellus by 48 h, respectively, compared with 42-55 M. raptorellus progeny produced when this species was tested alone. Production of M. raptor was significantly lower when parasitism by this species was preceded by M. raptorellus (25) than when M. raptor was tested alone (43). When the two species parasitized hosts at the same time in different proportions at low host:parasitoid densities (5:1), M. raptorellus produced 13 progeny per parent female when it was the sole species present and fewer than two when M. raptor was present. No negative impact of M. raptorellus on M. raptor was observed. Neither species had a substantial effect on the success of the other at higher host:parasitoid densities.

Development and Oviposition Preference of House Flies and Stable Flies (Diptera: Muscidae) in Six Substrates From Florida Equine Facilities.

House flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.), (Diptera: Muscidae), common pests on equine facilities, were studied in the laboratory to determine the success and duration of larval development and oviposition preferences on six substrates commonly found on equine facilities. Substrates tested were hay soiled with urine and manure, fresh horse manure, pine shaving bedding soiled with urine and manure (<12 h old), pine shaving bedding soiled with urine and manure (aged >72 h in a manure pile), builders sand bedding soiled with urine and manure aged 3 d, and soil from an overgrazed pasture mixed with urine and manure of variable age. House fly larvae failed to develop into adults in hay, soil, and sand substrates. Stable flies preferred to oviposit on substrates with plant material and not on fresh manure. However, when eggs were added to the substrates, pupariation was maximal in fresh manure and the fresh pine shaving substrate. Stable flies developed in all six equine substrates, but development was less successful on the substrates with soil. In choice tests, fresh manure and the fresh pine shaving substrates were the most attractive for house fly oviposition. These substrates also yielded the greatest number of house fly puparia from artificially added eggs. An understanding of oviposition preferences and differential larval development of house flies and stable flies on these substrates may help develop options for reducing pest populations by effectively managing equine waste and selecting appropriate bedding materials.

Salivary gland hypertrophy virus of house flies in Denmark: prevalence, host range, and comparison with a Florida isolate.

House flies (Musca domestica) infected with Musca domestica salivary gland hypertrophy virus (MdSGHV) were found in fly populations collected from 12 out of 18 Danish livestock farms that were surveyed in 2007 and 2008. Infection rates ranged from 0.5% to 5% and averaged 1.2%. None of the stable flies (Stomoxys calcitrans), rat-tail maggot flies (Eristalis tenax) or yellow dung flies (Scathophaga stercoraria) collected from MdSGHV-positive farms displayed characteristic salivary gland hypertrophy (SGH). In laboratory transmission tests, SGH symptoms were not observed in stable flies, flesh flies (Sarcophaga bullata), black dump flies (Hydrotaea aenescens), or face flies (Musca autumnalis) that were injected with MdSGHV from Danish house flies. However, in two species (stable fly and black dump fly), virus injection resulted in suppression of ovarian development similar to that observed in infected house flies, and injection of house flies with homogenates prepared from the salivary glands or ovaries of these species resulted in MdSGHV infection of the challenged house flies. Mortality of virus-injected stable flies was the highest among the five species tested. Virulence of Danish and Florida isolates of MdSGHV was similar with three virus delivery protocols, as a liquid food bait (in sucrose, milk, or blood), sprayed onto the flies in a Potter spray tower, or by immersiion in a crude homogenate of infected house flies. The most effective delivery system was immersion in a homogenate of ten infected flies/ml of water, resulting in 56.2% and 49.6% infection of the house flies challenged with the Danish and Florida strains, respectively.

Impact of house fly salivary gland hypertrophy virus (MdSGHV) on a heterologous host, Stomoxys calcitrans.

The effect of Musca domestica salivary gland hypertrophy virus (MdSGHV) on selected fitness parameters of stable flies, Stomoxys calcitrans (L.), was examined in the laboratory. Virus-injected stable flies of both genders suffered substantially higher mortality than control flies. By day 9, female mortality was 59.3 +/- 10.1% in the virus group compared with 23.7 +/- 3.7% in the controls; mortality in virus-injected males was 78.1 +/- 3.1% compared with 33.3 +/- 9.3% for controls. Fecundity of control flies on days 6-9 was 49-54 eggs deposited per live female per day (total, 8,996 eggs deposited), whereas virus-injected flies produced four to five eggs per female on days 6-7 and less then one egg per female per day thereafter (total, 251 eggs). Fecal spot deposition by virus-injected flies was comparable to controls initially but decreased to approximately 50% of control levels by day 4 after injection; infected flies produced only 26% as many fecal spots as healthy flies on days 6 and 7. None of the virus-injected stable flies developed symptoms of salivary gland hypertrophy. Quantitative real-time polymerase chain reaction demonstrated virus replication in injected stable flies, with increasing titers of virus genome copies from one to four days after injection. MdSGHV in stable flies displayed tissue tropism similar to that observed in house fly hosts, with higher viral copy numbers in fat body and salivary glands compared with ovaries. Virus titers were approximately 2 orders of magnitude higher in house fly than in stable fly hosts, and this difference was probably due to the absence of salivary gland hypertrophy in the latter species.

Development of Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae) on live house fly (Diptera: Muscidae) pupae and pupae killed by heat shock, irradiation, and cold.

The objective of this study was to evaluate the suitability of killed house fly (Musca domestica L) pupae for production of two economically important pupal parasitoids. Two-day-old fly pupae were subjected to heat shock treatments of varying temperatures and durations in an oven at >or=70% RH; exposure to temperatures of 55 degrees C or higher for 15 min or longer resulted in 100% mortality. Exposure to 50 degrees C resulted in 40 and 91% mortality at 15 and 60 min, respectively. All (100%) pupae placed in a -80 degrees C freezer were killed after 10-min exposure; exposure times of <5 min resulted in <21% mortality. Progeny production of Spalangia cameroni Perkins and Muscidifurax raptor Girault and Sanders (Hymeoptera: Pteromalidae) from pupae killed by heat shock or 50 kR of gamma radiation was not significantly different from production on live hosts on the day when pupae were killed. Freeze-killed pupae produced 16% fewer S. cameroni than live pupae and an equivalent amount of M. raptor progeny on the day when pupae were killed. When killed pupae were stored in freezer bags at 4 degrees C for 4 mo, heat-killed, irradiated, and freeze-killed pupae remained as effective for production of M. raptor as live pupae. Production of S. cameroni on heat-killed and irradiated pupae was equal to parasitoid production on live pupae for up to 2 mo of storage, after which production on killed pupae declined to 63% of that observed with live pupae. Production of S. cameroni on freeze-killed pupae was 73-78% of production using live pupae during weeks 2-8 of storage and declined to 41 and 28% after 3 and 4 mo, respectively. Killing pupae by heat shock provides a simple and low-cost method for stockpiling high-quality hosts for mass-rearing both of these filth fly biological control agents.

Sex pheromone of the tsetse species, Glossina austeni: isolation and identification of natural hydrocarbons, and bioassay of synthesized compounds.

Copulatory responses of male Glossina austeni (Newstead) (Diptera: Glossinidae), that were elicited after contact with frozen female tsetse, were not observed after solvent washing of cuticular lipids. Chromatographic analysis of extracts from laboratory-reared and field-collected G. austeni females yielded natural hydrocarbons that were highly stimulatory to males. Most of this activity was produced by compounds in the alkene fraction. Gas chromatograms (GC) contained five natural alkenes; these were separated by preparative GC for bioassays conducted in Tanzania. The two major alkenes were identified using gas chromatography-mass spectrometry (GC-MS) to be 13,17-dimethyltritriacont-1-ene and 13,17-dimethylpentatriacont-1-ene, after the samples had undergone derivatization using dimethyl disulphide and saturation with deuterium. These alkenes and natural alkanes were quantified from G. austeni of both sexes from laboratory and field samples to confirm that their presence was consistent in this species. Trials of synthetic samples resulted in the order of biological activity for the stereoisomers of 13,17-dimethyltritriacont-1-ene as follows: S,R-33:1 > R,S- 33:1 > S,S-33:1 > R,R-33:1. Dose-response data showed an ED(50) at 5 microg per treated, solvent-washed male decoy. Of the four stereoisomers of 13,17-dimethylpentatriacont-1-ene, R,R-35:1 showed the most activity. This is the first report of alkene-induced sexual activity in males of the genus Glossina.

Mechanical barrier for preventing climbing by lesser mealworm (Coleoptera: Tenebrionidae) and hide beetle (Coleoptera: Dermestidae) larvae in poultry houses.

Mechanical barriers consisting of bands of polyethylene terepthalate resin attached to wooden posts by latex caulk adhesive and staples were 100% effective in preventing passage of dispersing lesser mealworm, Alphitobius diaperinus (Panzer), larvae in the laboratory. Barriers continued to be 100% effective after beinig held in a caged layer poultry house for 3 mo. Polyethylene terepthalate barriers installed on support posts in a pullet house in Brooker, FL, were >92% effective against natural populations of lesser mealworm larvae 6 mo after installation. The barriers also were >94% effective against natural populations of larvae of the hide beetle, Dermestes maculatus DeGeer, when fly populations were low. Fecal spot depositions by house flies in excess of 31 cumulative fly spots per square centimeter on spot cards reduced the effectiveness of the barriers to 79-90%, and barrier efficacy was reduced to 40-56% when fly spots covered >80% of the surface of the plastic. Washing the barriers with water to remove fly spots restored their effectiveness against hide beetle larvae to >99%.

Effect of airflow on house fly (Diptera: Muscidae) distribution in poultry houses.

Numbers of fecal and vomit spots deposited by house flies, Musca domestica L., on spot cards were about twice as high on cards placed on the downwind sides as on the upwind sides of building support posts in caged-layer poultry houses with tunnel ventilation in Brooksville, FL. This trend was stronger at the ends of the houses where airflow is faster than in the relatively still-air center of the houses. A similar evaluation conducted in a pullet house (Zephyrhills, FL) with an evaporative cooling ventilation system revealed significantly higher fly counts on spot cards and sticky cards in downwind compared with upwind orientations. Flies in the pullet house were concentrated in both ends of the house and in the center, with comparatively fewer flies in the intermediate regions. There was a high degree of correlation between spot card and sticky card counts in the pullet house.

Gas chromatography/mass spectrometry analysis of the cuticular hydrocarbons from parasitic wasps of the genus Muscidifurax.

Parasitic Hymenoptera can be difficult to identify by conventional taxonomic techniques. Examination of the cuticular hydrocarbons (CHCs) provides a basis for chemotaxonomic differentiation, which may lead to the discovery of pheromones, and can be a means of examining colonies for species cross-contamination. The parasitic wasps examined were Muscidifurax raptor, M. zaraptor, M. uniraptor, and the gregarious form of M. raptorellus. Species within the genus Muscidifurax, as well as the sex, can clearly be differentiated by examining the gas chromatograms of the CHCs. Identification of the alkanes by mass spectrometry shows uncommon dimethylalkanes and trimethylalkanes for members of the genus. The methyl branched cuticular hydrocarbons of these insects are rare compared to those found on insects reported in the literature, but are present in significant amounts on these insects. Additionally, sexual dimorphism is observed in long chain alkanes (C21-C39) present on male and female cuticular surfaces for these species. Females tend to have cuticular hydrocarbons with methyl branches located externally on the carbon backbone chain for dimethyl-, trimethyl-, and tetramethylalkanes, whereas males tend to have dimethyl- and trimethylalkanes located internally on the hydrocarbon backbone chains. Mass spectra of novel and rare methyl branched compounds identified on these parasitoids are presented.

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.

Comparative toxicity of seven insecticides to immature stages of Musca domestica (Diptera: Muscidae) and two of its important biological control agents, Muscidifurax raptor and Spalangia cameroni (Hymenoptera: Pteromalidae).

The toxicity of seven insecticides was evaluated against unparasitized Musca domestica L. pupae and pupae parasitized by Muscidifurax raptor Girault & Sanders or Spalangia cameroni Perkins, two important biological control agents. Only pyrethrins + piperonyl butoxide (Pyrenone) was less toxic to M. raptor compared with house flies. Conversely, all of the insecticides except crotoxyphos were less toxic to S. cameroni compared with house flies. A plateau in the tetrachlorvinphos bioassay line for S. cameroni suggested that this colony had approximately 45% resistant individuals. The selectivity observed between immature stages of house flies and M. raptor or S. cameroni is different from that reported against adult stages of these same species, suggesting that selectivity of an insecticide varies considerably between different life stages.

Susceptibility of insecticide-susceptible and wild house flies (Diptera: Muscidae) to abamectin on whitewashed and unpainted wood.

Unpainted plywood panels treated with 0.1% abamectin (avermectin B1) provided greater than 90% control of house flies, Musca domestica L., susceptible to insecticides for 4 wk and greater than 70% control for 7 wk compared with 46-92% control observed with permethrin at the same time and rate of application. Efficacy of abamectin on whitewashed panels was similar to that observed on unpainted panels, whereas permethrin was ineffective on whitewashed panels at all rates tested (range, 0.001-0.1%) at all intervals after treatment. Bioassays of newly colonized house flies resistant to permethrin indicated that wild populations may be cross-resistant to abamectin.

Cattle lice (Anoplura, Mallophaga) in New York: seasonal population changes, effects of housing type on infestations of calves, and sampling efficiency.

A year-long survey was made of commercial dairy herds in New York for cattle lice (Anoplura and Mallophaga). All herds were infested with lice. The cattle bitting louse, Bovicola bovis (L.), accounted for about 90% of the observed infestations; infestations of mature animals were most common during the winter months, especially March (26% infested); and infestation rates of calves were high (30-45%) from January through June. Cows that were housed in stanchion barns were about twice as likely to be infested (24.7%) as were those in free stalls (11.1%). Calves housed in individual outdoor hutches had substantially lower infestation rates (4.5%) than calves maintained inside barns in collective stalls and pens (46.0%).

Efficacies of mixtures of disinfectants and insecticides.

Efficacies of mixtures of diluted commercial formulations of selected insecticides and disinfectants were evaluated. Insecticides tested included representative pyrethroids (fenvalerate [Ectrin WDL and WD] and permethrin [Ectiban EC]), organophosphates (dichlorvos [Vapona EC], tetrachlorvinphos [Rabon WP] and dichlorvos/tetrachlorvinphos [RaVap EC], and a carbamate (carbaryl [Sevin S]). Disinfectants tested included representatives of cresylic acid (Biolene), cresylic acid/phenol (BioGuard X-185), phenol (1-Stroke Environ), quaternary ammonium (BioGuard S-3 and PFP-4), quaternary ammonium/formalin (DC & R), and formalin classes of disinfectants. Mixtures were tested for toxicity to two target insects (Musca domestica on plywood, Alphitobius diaperinus in litter) and two bacteria (Pseudomonas aeruginosa and Staphylococcus aureus). Of 56 mixtures evaluated, 24 showed reduced insecticidal toxicity and 35 showed reduced bactericidal activity compared with insecticides or disinfectants alone.