Effects of targets impregnated with the chitin synthesis inhibitor triflumuron on the blowfly Lucilia sericata

The effects of exposure of adults of the blowfly Lucilia sericata (Meigen) for 24 h to cloth targets impregnated with the chitin synthesis inhibitor triflumuron plus sucrose or sucrose only, were considered. When both male and female L. sericata were exposed to targets treated with sucrose only, the percentage egg hatch varied between 60–75%. When both sexes were exposed to targets treated with 10% triflumuron plus sucrose the percentage egg hatch varied between 3–7%. When females alone were exposed to triflumuron, prior to the introduction of unexposed males, egg hatch varied between 4–14%. The exposure of males alone to 10% triflumuron treated targets, prior to the introduction of unexposed virgin females, did not give any consistent significant decrease in the mean percentage egg hatch. However, repetition of this trial with males exposed to targets treated with 15 or 20% triflumuron, resulted in a percentage egg hatch of 3.1% and 10.3%, respectively. These results suggest that at relatively high target concentrations, males can transfer effective doses of triflumuron to unexposed virgin females.The exposure of adults to triflumuron treated targets did not significantly increase the mortality of either male or female L. sericata. Furthermore, bioassays showed that there was no significant decline in the ovicidal effectiveness of targets treated with 10% triflumuron and sucrose solution following exposure to sun and rain for up to 8 weeks in 1995 and 1996.The results suggest that targets treated with triflumuron suspension concentrate and sucrose may form the basis of an effective system for the control of L. sericata in the field. However, the relatively high concentrations of triflumuron required and the low efficiency with which males are able to transfer effective doses to unexposed females may diminish one of the main theoretical advantages of using a chitin synthesis inhibitor, such as triflumuron, over a conventional insecticide.     

Host age and pathogen exposure level as factors in the susceptibility of the house fly,Musca domestica (Diptera: Muscidae) to Beauveria bassiana

Adult house flies, Musca domestica L., of four ages, <1, 3, 7, and 14 day post-eclosion, were exposed to three strains of Beauveria bassiana (P89, L90 and 447). Flies were exposed to moistened filter paper treated with either a low (1.57×10⁴ conidia/cm²) or high (1.57×10⁵ conidia/cm²) concentration of each fungal strain for 6 h. Strain 447 was superior to the two house fly-derived B. bassiana strains in inducing host infection and mortality. Significant spikes in infection and mortality occurred as early as 5 days post-exposure with higher concentration exposures acting more quickly. Few differences were observed in either infection or mortality among the four fly age classes. On Day 10 post-exposure, 77% of the high-concentration, 447-exposed flies were infected, compared with only 24% of the flies from the P89 low-concentration exposure. Potential applications of these results in integrated house fly management programs are discussed.     

Horizontal Transfer of the Tetracycline Resistance Gene <Emphasis Type="Italic">tetM</Emphasis> Mediated by pCF10 Among <Emphasis Type="Italic">Enterococcus faecalis</Emphasis> in the House Fly (<Emphasis Type="Italic">Musca domestica</Emphasis> L.) Alimentary Canal

The house fly (Musca domestica L.) alimentary canal was evaluated for the potential of horizontal transfer of tetM on plasmid pCF10 among Enterococcus faecalis. Two sets of experiments were conducted: (1) house flies without surface sterilization and (2) surface-sterilized flies. Both sets of flies were exposed to E. faecalis OG1RF:pCF10 as donor for 12 h and then E. faecalis OG1SSp as recipient for 1 h. Another group of flies received the recipient first for 12 h followed by exposure to the donor strain for 1 h. House flies were screened daily to determine the donor, recipient, and transconjugant bacterial load for up to 5 days. In addition, the sponge-like mouth parts used for food uptake (labellum) of surface-sterilized house flies were removed and analyzed for donors, recipients, and transconjugants, separately. In both groups of flies (n = 90 flies/group), transfer occurred within 24 h after exposure with a transconjugant/donor rate from 8.6 × 10⁻⁵ to 4.5 × 10¹. Transconjugants were also isolated from the house fly labellum. Our data suggest that the house fly digestive tract provides a suitable environment for horizontal transfer of conjugative plasmids and antibiotic resistance genes among enterococci. Our results emphasize the importance of this insect as a potential vector of antibiotic-resistant bacterial strains.     

Laboratory studies on the biology ofSpalangia nigra [Hym.: Pteromalidae]

At 21 °C,Spalangia nigra Latreille (Hymenoptera: Pteromalidae) averaged 29.3 days between exposure and emergence of 1^st progeny from host house flies,Musca domestica L. (Diptera: Muscidae). At 27 °C, the average developmental time to 1^st emergence was reduced to 26.6 days, and a majority of adult wasps emerged from host house fly puparia between 29 and 40 days postoviposition. The sex ratio of progeny ranged from 1.4 to 1.8 female-to-male, but all progeny of virgin females were male. Male wasps lived from 6.8–15 and females 11–17.8 days at 27 °C; honey as a food source increased longevity. No significant differences in parasitism byS. nigra were associated with host house fly pupal densities ranging from 1 to 200 pupae per female-male pair of wasps, but average percent parasitism decreased at host densities greater than 50. House fly pupae exposed to parasitism at ages ranging from 4 to 96 h did not differ in subsequent production of adult flies.S. nigra did not demonstrate preference for house flies or stable flies,Stomoxys calcitrans (L.) (Diptera: Muscidae) as hosts. The results of these studies indicate thatS. nigra may contribute significantly to previously unexplained mortality of house flies and stable flies.      

Virulence of Different Isolates and Formulations of Beauveria bassiana for House Flies and the Parasitoid Muscidifurax raptor

Adult house flies (Musca domestica) were susceptible (94-100% mortality) to Beauveria bassiana when conidia of the Hf88 isolate were applied to plywood boards at 10⁷ conidia/cm²; a starch dust formulation was more effective than a liquid suspension. Adult flies were also susceptible (90-99% mortality) to this isolate when they were con fined with treated water (10⁸ conidia/ml) or food (10⁸ conidia/100 mg). House fly larvae were not affected by treatments with up to 10⁸ conidia/cm³ of rearing medium. A 2-year survey of house flies cm from New York dairies indicated that most natural infections of house flies occurred in September and October, although prevalence rates never exceeded 1%. Thirteen single-fly isolates obtained during this survey were compared with the Hf88 isolate for virulence against flies; the 2 most virulent isolates were slightly more virulent for flies than for the fly parasitoid Muscidifurax raptor. Incorporation of conidia into a sucrose bait (10⁸ conidia/100 mg) in cages gave high levels of house fly control (78-100% mortality) 5 days after exposure.     

Natural Infections Caused by the Fungus <Emphasis Type="Italic">Beauveria bassiana</Emphasis> as a Pathogen of <Emphasis Type="Italic">Musca domestica</Emphasis>in the Neotropic

A survey for entomopathogenic fungi of Musca domestica adults was conducted in poultry houses in La Plata, Buenos Aires province, Argentina, during the years 2002 and 2003. Adult house flies were found infected with the fungus Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) from field collections, with a natural infected prevalence between 0.4–1.45%. This is the first record of natural infections of house flies caused by B. bassiana for the neotropics. Pathogenicity assays under laboratory conditions showed 94% adult mortality at 14 days post challenge. CIC fellow     

Effects of triflumuron on the two-spotted spider mite,Tetranychus urticae (Acari: Tetranichydae)

The effects of triflumuron on the mortality, fecundity, and fertility of the two-spotted spider mite, Tetranychus urticae, were evaluated in the laboratory. No differences in toxicity for larvae, protonymphs and deutonymphs were observed, but immature stages were 3.8-times more susceptible than adults at the LC₅₀. The compound exhibited a direct contact ovicidal activity influenced by eggs age. 48–72 hold eggs were significantly more sensitive than eggs of the other age classes. No hatch inhibition was observed in eggs laid by treated adult females using a sublethal dose at two physiological times (<12 and 48–72h old). However, fecundity decreased in younger treated females, but it increased in the older-ones. The toxicity for immatures and eggs, and the sublethal effects described suggest that triflumuron could be an interesting incorporation in integrated pest programs of T. urticae. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biological control of <Emphasis Type="Italic">Musca domestica</Emphasis> and <Emphasis Type="Italic">Stomoxys calcitrans</Emphasis> by mass releases of the parasitoid <Emphasis Type="Italic">Spalangia cameroni</Emphasis> on two Norwegian pig farms

House flies (Musca domestica L.) and stable flies (Stomoxys calcitrans (L.)) (Diptera: Muscidae) are nuisance pests on livestock farms. In the present study we tested the effect of biweekly mass release of Spalangia cameroni Perkins (Hymenoptera: Pteromalidae), the most common parasitoid of house flies and stable flies in southern Norway, on pig premises with scattered fly breeding sites. The study spanned two successive summer periods, with two control and two release units each year. Spalangia cameroni suppressed both house flies and stable flies in one release unit during the first year, and stable flies in one release unit the second year. The apparent lack of success in fly control in the other release units was likely due to immigration of flies in two of the trials and high temperatures in one trial. Recommendations concerning release of S. cameroni in similar pig production premises are given. Handling editor: Torsten Meiners.     

Laboratory evaluation of Lactobacillus johnsonii CRL1647 metabolites for biological control of Musca domestica

The house fly, Musca domestica L. (Diptera: Muscidae), is a key problem in animal producing and rearing areas. Currently, the use and abuse of chemical pest‐control compounds has generated resistance in M. domestica and, hence, new approaches are required. In this work, the potential entomopathogenic activity of Lactobacillus johnsonii Fujisawa et al. CRL1647 was evaluated against M. domestica, under laboratory conditions. Bioassays were done for three consecutive years using bacterial cell suspensions (CS) and cell‐free supernatants (CFS) under controlled conditions (27 ± 1 °C, 57 ± 2% r.h., and L12:D12 photoperiod). Both the CS and CFS displayed high levels of larvicidal (96%) and pupicidal (97%) activities. Chemical characterization of the CFS revealed that the bioactive metabolites are acidic compounds, not affected by thermal treatment or by trypsin. Organic acids were identified and quantified by high‐performance liquid chromatography (HPLC); only lactic acid (129.7 ± 1.0 mM), acetic acid (37.3 ± 0.8 mM), and phenyllactic acid (0.3 ± 0.1 mM) were detected. A significant decrease in fecundity of the house flies was observed in females from larvae fed on CFS; male fertility was not affected. Interestingly, only the mixture of organic acids exerted the biological effects. These results suggest that the metabolites synthesized by L. johnsonii CRL1647 can be used in a novel biocontrol strategy against house flies.     

Circadian locomotor activity of Musca flies: Recording method and effects of 10 Hz square-wave electric fields

Musca domestica flies that were exposed to a uniform vertical 10 Hz electric square-wave field of 1 kVm⁻¹ changed the period length of their circadian locomotor activity rhythm. Under constant conditions, the clock of short-period flies was slowed down by the field, whereas the clock of long-period flies either was affected only scarcely (experiments at about 19°C) or ran faster (experiments at 25°C). If the field was applied for only 12 h daily, then 30–40% of the flies were synchronized. Thus, the field could function as a weak “Zeitgeber” (synchronizer). If the field was increased to 10 kVm⁻¹, then 50–70% of the flies were synchronized. Flies avoided becoming active around the onset of the 12 h period of exposure to a 10 Hz field. The results of these experiments are discussed with respect to similar experiments by Wever on the effects of exposure to a 10 Hz field on the circadian system of man. © 1996 Wiley-Liss, Inc.     

Overwintering biology ofMyiopharus aberrans andMyiopharus doryphorae (Dipt.: Tachinidae) larval parasitoids of the colorado potato beetle (Col.: Chrysomelidae)

The overwintering biology ofMyiopharus aberrans (Townsend) andMyiopharus doryphorae (Riley), tachinid parasitoids of the Colorado potato beetle, was investigated. Sixty seven overwintered Colorado potato beetle adults were dug from the soil before beetle emergence in the spring of 1990 from a field that had been planted to potatoes the previous year. Five adultM. aberrans and two adultM. doryphorae flies were reared from seven beetles. This is the first record of howM. aberrans andM. doryphorae flies overwinter.      

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.     

Embryonic Development in House Fly Eggs Fertilized with Genetically Deficient Sperm

In house flies, Musca domestica L., eggs fertilized with sperm that have chromosome deficiencies and duplications do not hatch, but develop to a stage where a fully differentiated, prehatch larva is formed. Fifteen different chromosome translocations involving most of the 10 arms of the 5 autosomes were studied by crossing male translocation heterozygotes to normal females. Egg hatch was reduced to 36–66% depending on the translocation used. Eggs that did not hatch after 24 hours were fixed, stained, and examined for stage of development. Several translocations involving the right arm of chromosome 4 indicate that the region closest to the centromere contains genes that affect the process of syngamy or early cleavage divisions, but do not reduce the ability of the sperm to compete for egg fertilization. Approximately 70% of the autosomal genes can be absent from sperm (not simultaneously but in different crosses) without inhibiting embryonic development.     

The culture ofEntomophthora muscae (C) Fres. in carrot flies (Psila rosae F.) and the effect of temperature on the pathology of the fungus

A method for maintaining anin vivo culture ofEntomophthora muscae (C) Fres. on its original host, adult carrot flies (Psila rosae F.), is described. The lethal time for adult carrot flies was greatly influenced by temperature, both for infected and for uninfected flies. In the range 8.2°C–20.2°C the LT₅₀ for infected flies was about 5.4 times shorter than the estimated average life-span for uninfected flies. The discharge of primary spores was also strongly dependent on temperature. The total number of primary spores discharged per fly at 100% RH and in darkness ranged between 1.2×10⁴ and 9.6×10⁴ with a mean of 5.1×10⁴.      

Parasitism of the house fly parasitoid <Emphasis Type="Italic">Spalangia cameroni</Emphasis> on Norwegian pig farms: local effect of release method

Mass release of parasitoids (Hymentoptera: Pteromalidae) is one possible control method of house flies (Musca domestica L.) on livestock farms. To improve the success of this method, however, there is a need for more detailed recommendations. In the present study, parasitism was evaluated in and around pens following release of the parasitoid Spalangia cameroni Perkins by hand and from containers. The study was conducted at conventional Norwegian pig farms with scattered breeding grounds for house flies. The experiment was carried out twice, with a total of seven trials of each release method followed by four weeks of monitoring parasitism by house fly sentinel pupae. No significant difference was found between the two release methods. Parasitism decreased with temperature (range 18–23°C) and was low on farms with few sites for the parasitoids to hide.     

Search duration ofDrosophila melanogaster on Homogeneous sucrose patches: Relative effects of starvation period,sucrose concentration and patch size

Search duration of adultDrosophila melanogaster on homogeneous sucrose patches increased with the period that flies were starved, the concentration of sucrose which they ingested, and the size of a patch onto which they were released. Since in all conditions the sucrose concentration tested in patch experiments was above the taste threshold, the results indicate that a fly has a set of rules for specifying search duration that integrates external information (resource quality and size) and internal information (period of starvation).     

Survey of insect growth regulator (IGR) resistance in house flies (Musca domestica L.) from southwestern Turkey

Insect growth regulators (IGRs) are currently the fastest‐growing class of insecticides, and in Turkey these products represent a new approach to pest control. In recent years, several IGRs were also registered for the control of the house fly, Musca domestica L. (Diptera: Muscidae), in Turkey. A field survey was conducted in the summers of 2006 and 2007 to evaluate resistance to some agriculturally and medically used IGRs on house flies from livestock farms and garbage dumps in the greenhouse production areas (Merkez, Kumluca, Manavgat, and Serik) of Antalya province (Southwestern Turkey). The results of larval feeding assay with technical diflubenzuron, methoprene, novaluron, pyripoxyfen, and triflumuron indicate that low levels (RF<10‐fold) of resistance to the IGRs exist in the house fly populations from Antalya province. Exceptions, however, were two populations, Guzoren and Toptas, from the Kumluca area which showed moderate resistance to diflubenzuron with 11.8‐fold in 2006 and 13.2‐fold in 2007, respectively. We found substantial variation in susceptibility of field‐collected house fly populations from year to year and from product to product. We generally observed an increase in resistance at many localities sampled from 2006 to 2007. The implications of these results to the future use of IGRs for house fly control are discussed. It will be critically important to continue monitoring efforts so that appropriate steps can be taken if resistance levels start to increase.     

The use of visual information by house flies,Musca domestica (Diptera: Muscidae), foraging in resource patches

Summary House flies, Musca domestica, respond to visual contrasts on the substrate if a resource is associated with the contrasting patterns. Visible resource patch boundaries serve as a signal to flies that they are about to leave a rewarding patch. Searching flies respond to such visual information by walking along the resource patch boundary and turning back into the patch at its edge. This edge detection and response serve as a mechanism for flies with visual cues to stay in a rewarding patch and locate more resources within it. The intensity of their response correlates with the quality of the resource. In the absence of visual cues, patch shape affects foraging success; flies find more resources in circular than in linear resource distributions. The effects of visual cues, however, render patch shape unimportant. Various substrate contrasts are effective as resource information for flies: dark (e.g., green) figures on bright (e.g., white) backgrounds or bright figures on dark backgrounds. Responses to substrate contrasts measured in this study indicate that, over the short term, house flies can learn a visual cue associated with a food source.     

Campylobacter jejuni in Musca domestica: An examination of survival and transmission potential in light of the innate immune responses of the house flies

The house fly, Musca domestica, has been implicated as a vector of Campylobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors for Campylobacter jejuni. We investigated the period after C. jejuni had been ingested by house flies in which viable C. jejuni colonies could be isolated from whole bodies, the vomitus and the excreta of adult M. domestica and evaluated the activation of innate immune responses of house flies to ingested C. jejuni over time. C. jejuni could be cultured from infected houseflies soon after ingestion but no countable C. jejuni colonies were observed > 24 h postingestion. We detected viable C. jejuni in house fly vomitus and excreta up to 4 h after ingestion, but no viable bacteria were detected ≥ 8 h. Suppression subtractive hybridization identified pathogen‐induced gene expression in the intestinal tracts of adult house flies 4–24 h after ingesting C. jejuni. We measured the expression of immune regulatory (thor, JNK, and spheroide) and effector (cecropin, diptericin, attacin, defensing, and lysozyme) genes in C. jejuni‐infected and ‐uninfected house flies using quantitative real time PCR. Some house fly factor, or combination of factors, eliminates C. jejuni within 24 h postingestion. Because C. jejuni is not amplified within the body of the housefly, this insect likely serves as a mechanical vector rather than as a true biological, amplifying vector for C. jejuni, and adds to our understanding of insect–pathogen interactions.     

Does behaviour play a role in house fly resistance to imidacloprid‐containing baits?

The objective of this research was to examine the role and type of behavioural mechanisms that function in house fly, Musca domestica L. (Diptera: Muscidae), resistance to an imidacloprid‐containing commercial fly bait, QuickBayt^®, using an insecticide‐susceptible and an imidacloprid‐resistant strain. Mortality and feeding behaviour were observed through choice bioassays of three post‐imidacloprid selected house fly generations to determine whether flies would consume the bait in the presence of an alternative food source. Mortality rates in choice containers progressively decreased in post‐selection flies as QuickBayt^® no‐choice selections proceeded. There were no differences between the proportions of flies observed contacting QuickBayt^® and sugar, respectively, a finding that eliminates repellency as a mechanism of stimulus‐dependent behavioural resistance. However, differences in QuickBayt^® consumption and subsequent mortality between choice and no‐choice containers provided strong support for the evolution of consumption irritancy‐ or taste aversion‐related behavioural resistance. The results of this study support the responsible rotation of insecticide bait formulations for house fly control.