The potential use of allicin as a biopesticide for the control of the house fly,Musca domestica L.

The house fly, Musca domestica L., is a widespread pest of intensively reared livestock, where its presence negatively affects growth and productivity through the irritation their activity causes. Furthermore, adult flies mechanically vector a wide range of animal and human pathogens and, as such, pose a health risk to both livestock and people. The development of resistance in M. domestica populations to most of the insecticides used against them, coupled with diminishing product availability in many regions, means that new fly control methods and materials are constantly required. In the present study, a formulation of allicin, a compound derived from garlic cloves, was evaluated against the eggs, larvae and adults of Musca domestica L.. An in-diet LD₅₀ of 134 ppm against larvae was achieved, whilst marked ovicidal activity was also recorded. Adults were similarly affected when exposed directly and indirectly to surface residues of the compound. The results indicate that allicin exhibits potential to be used against filth flies through incorporation into their developmental substrates and, potentially, for the control of other economically important dipteran pests.     

Interaction between the factor delaying penetration of insecticides and the desethylation mechanism of resistance in organophosphorus-resistant houseflies

The desethylation (gene a) and penetration delaying (pen) factors of resistance to organophosphorus insecticides isolated by genetical methods from the diazinon-selected SKA strain of houseflies (Musca domestica L.) were inbred into a strain whose resistance was compared with that of flies with single factors of resistance and the SKA strain. Pen alone decreases kill marginally, and gene a alone raises LD₅₀ to 1·4–48 times that of susceptible flies, depending on the insecticide. The two factors together increase resistance greatly to many organophosphorus insecticides (up to 5–10 times or more to diazinon, malathion-ethyl and chlorthion-ethyl than of flies with gene a only) indicating that the two factors interact. Interaction is greater against the thionates than the corresponding phosphates, probably because pen delays entry of thionates more than of the corresponding phosphates. The role in resistance of each factor when hetero-and homo-zygous, and the reasons for interaction, are discussed.     

Toxicity of spinosad to susceptible and resistant strains of house flies,Musca domestica

The toxicity of spinosad, a new insecticide derived from the bacterium Saccharopolyspora spinosa, was evaluated against susceptible and resistant strains of house fly (Musca domestica L.). Spinosad was highly toxic to house flies based on 72-h LD₅₀ values and the symptoms of poisoning were consistent with a neurotoxic mechanism of action. Spinosad was relatively slow acting, with the maximum toxicity noted at 72 h. Piperonyl butoxide and S,S,S,-tribu-tylphosphorotrithioate synergized the toxicity of spinosad by 3·0- and 1·8-fold, respectively, while diethyl maleate had no significant effect. These results suggest that there is a small degree of monooxygenase-mediated spinosad detoxification in house flies, while hydrolases may be only minimally important and glutathione transferases may have no role. There were no substantial levels of cross-resistance detected, except in the LPR strain where a low 4·3-fold cross-resistance was observed. The cyclodiene-resistant OCR strain was 2·7-fold more sensitive to spinosad than the susceptible strain (CS). These results suggest that cross-resistance may not be a limiting factor for the use of spinosad against house flies. © 1998 Society of Chemical Industry     

Evaluation of semiochemical toxicity to houseflies and stable flies (Diptera: Muscidae)

BACKGROUND: The housefly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.) are cosmopolitan pests of both farm and home environments. Houseflies have been shown to be resistant to a variety of insecticides, and new chemistries are slow to emerge on the market. Toxicities of selected semiochemicals with molecular structures indicative of insecticidal activity were determined against adults from an insecticide‐susceptible laboratory strain of houseflies. The three most active semiochemicals were also evaluated against recently colonized housefly and stable fly strains. RESULTS: Nineteen semiochemicals classified as aliphatic alcohols, terpenoids, ketones and carboxylic esters showed toxicity to houseflies and stable flies. Rosalva (LC₅₀ = 25.98 µg cm^?2) followed by geranyl acetone and citronellol (LC₅₀ = 49.97 and 50.02 µg cm^?2) were identified as the most toxic compounds to houseflies. Permethrin was up to 144‐fold more toxic than rosalva on the susceptible strain. However, it was only 35‐fold more toxic to the insecticide‐tolerant field strain. The compounds generated high toxicity to stable flies, with LC₅₀ values ranging from 16.30 to 40.41 µg cm^?2. CONCLUSION: Quantification of LC₅₀ values of rosalva, citronellol and geranyl acetone against susceptible housefly and field‐collected housefly and stable fly strains showed that semiochemicals could serve as potent insecticides for fly control programs. Copyright © 2010 Society of Chemical Industry     

Insecticidal potency of novel compounds on multiple insect species of medical and veterinary importance

BACKGROUND: Vector‐borne diseases continue to present significant threats to human, animal and plant health. Mosquitoes, houseflies, sand flies and stable flies are well‐known vectors of several human and animal pathogens. The toxicity of selected semiochemicals with molecular structures indicative of insecticidal activity was determined against these insect species with the aim of developing novel insecticides toxic to multiple insect species. RESULTS: Three semiochemicals, namely beta‐damascone, cyclemone A and melafleur, showed remarkable toxicity to three mosquitoes, Aedes aegypti L., Ae. albopictus (Skuse) and Anopheles quadrimaculatus Say, the housefly, Musca domestica L., the stable fly, Stomoxys calcitrans L., and the sand fly, Lutzomyia shannoni (Dyar). The chemicals were equally toxic to several field‐collected permethrin‐tolerant housefly strains. When formulated as 500 mL L^?1 emulsifiable concentrates, the chemicals demonstrated stability and toxicity on filter paper and camouflage military fabrics, with persistence up to 8 days under laboratory conditions. The chemicals were equally effective under field conditions when evaluated on unpainted plywood panels, although a higher dosage was required under field conditions to achieve similar efficacy. CONCLUSION: Laboratory quantification of LC₅₀ values and field efficacy of three semiochemicals as formulated compounds on mosquitoes, houseflies, stable flies and sand flies showed that these semiochemicals could serve as potent insecticides for multiple insect species. Copyright © 2010 Society of Chemical Industry     

Laboratory trials of fatty acids as repellents or antifeedants against houseflies,horn flies and stable flies (Diptera: Muscidae)

BACKGROUND: Straight‐chain, saturated fatty acids (particularly C8, C9 and C10) have some known behavioral effects on insects such as mosquitoes, and were tested in combination for potential repellency/antifeedant activity in bioassays against three significant muscoid flies of medical/veterinary importance: houseflies, horn flies and stable flies. RESULTS: Mixtures of C8, C9 and C10 (1:1:1; 15% total actives in formulation) were highly repellent to houseflies and horn flies at or below 1 mg formulation cm^?2. Repellency time varied from < 1 day for houseflies to usually at least 3 days for horn flies. Individual longer‐chain‐length fatty acids were tested, and C11 repelled houseflies for up to 5–8 days, while C12 lasted 2 days. Minimum statistically significant repellency levels of the C8, C9 and C10 mixture (3 h after application) against horn flies were 0.06–0.12 mg cm^?2. A liquid formulation of the 15% C8, C9 and C10 mixture in a silicone oil carrier (at 2.8 mg AI cm^?2) was highly repellent against hungry stable flies in a blood‐feeding membrane bioassay for at least 8 h. CONCLUSION: The low toxicity and reasonable activity and persistence of these carboxylic acids make them good candidates for development as protective materials against pest flies in livestock settings. Copyright © 2009 Society of Chemical Industry     

An olfactometer for measuring the repellent effect of chemicals on the stable fly Stomoxys calcitrans (L.)

An olfactometer is described that permits the evaluation of chemicals acting in the vapour phase against the stable fly Stomoxys calcitrans (L.). Hungry flies, held in a metal frame cage covered with soft gauze, are attracted to a target held adjacent to one side of the cage, and emitting an attractive airflow. Flies landing on the target are counted at intervals of 15s. Flies starved for 24h were tested in the olfactometer when 2, 3 and 4 days old. With the exception of the first exposure of the 4-day-old flies, all the flies of the three ages showed greater than 80% attraction to the olfactometer target after exposure for 2 min, for each of four successive exposures at 10-min intervals. For all ages there was a significant increase in attraction at the second exposure but no further increase with subsequent exposures. It is likely that the sensillae, stimulated by the first exposure, subsequently responded faster. Eight chemicals were incorporated into the airflow behind the target to test their effect on flies. Permethrin (a low vapour pressure pyrethroid) and crotoxyphos (a low vapour pressure organophosphate) did not act in the vapour phase. Empenthrin (a high vapour pressure pyrethroid) and dichlorvos (a high vapour pressure organophosphate) both exhibited the toxic effect of knock-down on the flies without repellency. Oil of citronella and citronellol, two known fly repellents, gave a general reduction of attraction that was dose dependent; fewer flies found the target and those that did stayed a shorter length of time. Natural pyrethrum gave a similar effect to these two at lower concentrations, but at higher concentrations, it also showed a repellent effect. N,N-Diethyl-m-toluamide gave a low reduction in attraction. The olfactometer shows potential for use with other flying insects, both to observe the effects of an insecticide and also to study the behavioural responses in the absence of insecticides.     

Knockdown by pyrethroids: Its role in the intoxication process

Using techniques for treating the insects unanaesthetised, knockdown of aduit Musca domestica by pyrethrin I applied topically to or injected into the thorax was assessed by measuring the ED₅₀s on 13 occasions 1 min-48 h after treatment. From 1 min to approximately 1 h after treatment, ED₅₀s for topical application decreased quickly with increasing time. During this “knockdown phase” ED₅₀ values were probably determined mainly by rate of penetration of the insecticide into the insect, but the rate of elimination of the insecticide probably determined the increasing ED₅₀ values during the “recovery phase” which followed. ED₅₀s for injected pyrethrin I were initially much smaller than after topical application but increased continuously until 24 h after treatment. From 100 min onwards ED₅₀s by topical application and injection were similar. These results indicate (1) that the site affected during knockdown is within the insect rather than superficial, and (2) that detoxication and excretion processes determine the ultimate toxicity of the insecticide apparently independently of the method of treatment. Additional tests with a strain of flies having the penetration delaying factor and with the cockroach Periplaneta americana L. supported these conclusions. Speed of knockdown after topical treatment was also affected by the site of application and the solvent in which pyrethrin I was applied. Bioresmethrin was about as effective as pyrethrin I in knocking down flies when applied topically or when injected, but because the ED₅₀ increased very little during the recovery phase it was ultimately much more toxic.     

Insecticidal properties of monoterpenoid derivatives to the house fly (diptera: Muscidae) and red flour beetle (coleoptera: Tenebrionidae)

Monoterpenoid derivatives were synthesized and their insecticidal activities were evaluated against red flour beetles, Tribolium castaneum (Herbst), in fumigant bioassays and against house flies Musca domestica (L.) in topical, fumigant, and ovicidal bioassays. Acetate derivatives and haloacetate derivatives were compared with each other, and with the parent monoterpenoid to determine structure-activity relationships. Acetate derivatives were more active than the propionate derivatives of cyclic monoterpenoids in the topical, fumigant, and ovicidal bioassays. Pivalates were topically more insecticidal than acetates to adult house flies, while the acetates had the greater ovicidal activity. Acetates and pivalates were more effective than haloacetates in the topical, red flour beetle fumigation and ovicidal bioassays. Fluoroacetates of cyclic monoterpenoids were the most effective house fly fumigants, followed by acetates, and trichloroacetates. Several derivatives were produced that displayed enhanced activity relative to the parent alcohols or phenols.     

Effect of organophosphates in vivo upon acetylcholinesterase isozymes from housefly head and thorax

Four soluble acetylcholinesterase isozymes of head and three from the thorax of housefly (Musca domestica L.) were separated by polyacrylamide gel electrophoresis. Their inhibition in vivo was studied after poisoning with an LD₅₀ of four organophosphates: malaoxon, paraoxon, diazinon and dichlorvos. The isozymes differed greatly in their degree of inhibition. Thoracic isozymes were found to be more sensitive to inhibition than head isozymes. In surviving flies, the recovery rates of head isozymes were much faster than thoracic isozymes. In vitro studies showed that thoracic isozymes differed 4.1- and 2.9-fold in their K_m and V_max.     

Control of Farm Flies in Malta—II. Residual effectiveness of insecticide formulations on various surfaces to Musca domestica and Stomoxys calcitrans

Abstract

Bioassays were carried out under laboratory conditions to determine the residual toxicities to the housefly, Musca domestica L., and the stablefly, Sromoxys calcitrans L., of a range of insecticide formulations sprayed on wood, Maltese limestone, cement-washed and lime-washed stone. Stomoxys were more susceptible to all deposits than were Musca. Wettable powders were more effective than emulsions; some being still highly toxic to flies a year after spraying. Most formulations had a shorter life on stone than on wood but a covering of cement could extend the residual life markedly. With tetrachlorvinphos w.p. on stone, respraying nine weeks after the initial spraying resulted in higher kills and longer residual life following the second spraying than after the first.     

DDT and pyrethroids: Receptor binding in relation to knockdown resistance (kdr) in the house fly

The nature of target site or knockdown resistance (kdr) to DDT and pyrethroids was studied by investigating specific binding of [14_C] DDT and [14_C] cis-permethrin to the previously established membrane receptors from the heads of susceptible (sbo) and resistant (kdr) strains of the house fly, Musca domestica L. In vivo studies showed the heads from sbo flies bound two to three times more DDT than those from kdr flies at all doses tested. Reduced binding was also observed in kdr flies in in vitro [14_C] DDT binding assays. Scatchard analysis indicated that kdr flies have the same affinity but fewer receptors per milligram protein in the CNS than sbo flies. Assays with [14_C] cis-permethrin also showed binding was much reduced in kdr flies in comparison with sbo flies. Based on these results, the nature of the target site insensitivity of kdr flies may relate to their having a reduced number of receptors for the insecticides.     

Multiple Resistance in the Larger House Fly Musca domestica in Germany

Populations of the housefly Musca domestica isolated from farms in different German districts with strong resistance problems were compared to laboratory strains with varying resistance spectra. Resistance against pyrethroids, organophosphates and carbamates was tested using impregnated filter papers, and by topical application using a susceptible housefly strain (origin WHO) for comparison. The multi-resistant fly strains tested had a strong resistance against these insecticide groups, ranging from 37- to >10000-fold for organophosphates and 150- to >6600-fold for pyrethroids. The constituent enantiomer pairs of the α-cyano-pyrethroid cyfluthrin were tested, as was beta-cyfluthrin. With respect to multi-resistant fly strains, the isomers II and IV had the best activity, with LD₅₀ values of 0·012 and 0·014 μg per fly, respectively. In addition, different groups of insect growth regulators (juvenile hormone analogues, chitin synthesis inhibitors and one triazine derivative) were tested in a special larvicidal test. The chitin synthesis inhibitors were quite effective against multi-resistant M. domestica strains except for one strain with strong resistance against chitin synthesis inhibitors, developed after extensive treatments with benzoylphenylureas for several years. The fly strains tested were not resistant against cyromazine. Additionally, the insecticides were combined with the synergists piperonyl butoxide, tributylphosphorotrithioate (DEF) and Cibacron blue and tested against the fly strain with the strongest resistance spectrum (‘Grimm’) in comparison to the susceptible strain (‘WHO-N’). Piperonyl butoxide had the greatest effect on the efficacy of cyfluthrin followed by Cibacron blue and DEF. In a parallel investigation with susceptible and resistant house fly strains, different enzyme activities related with resistance mechanisms were tested, e.g. glutathione S-transferase (3·5-fold) and mixed-function oxidase (2·3-fold). Implications of these results for management of insecticide resistance in M. domestica are discussed.     

Distinguishing between carbamate and organophosphate insecticide poisoning in house flies by symptomology

Three criteria, latency to convulsions, still period, and recovery are used to distinguish between carbamate and phosphate insecticide poisoning in house flies, Musca domestica. Because of shorter latencies with carbamate-treated flies, the central nervous system was considered more sensitive to the presence of carbamates than phosphates. Recovery from carbamate-induced tetany was considered correlated with reactivation of carbamylated cholinesterase. There appeared to be a fundamental difference between the insecticidal actions of carbamates and phosphates not wholly explainable by cholinesterase inhibition. Tethered or held house flies were less susceptible to poisoning than unrestrained flies.     

An electrophysiological investigation of the susceptible (cooper) and resistant (kdr; super-kdr) strains of the adult housefly,Musca domestica L

The electrical activity of abdominal nerves of the housefly, Musca domestica L., was used as a bioassay to study nerve sensitivity to DDT and deltamethrin in susceptible (Cooper) and resistant (kdr, super-kdr) strains. By this technique the resistant strains were less sensitive (approximately 10 000-fold) than Cooper, but the bioassay could not distinguish between super-kdr and kdr in their responses to either compound and so could not account for the greater resistance shown by flies with super-kdr above kdr flies when these insecticides are applied topically. Although factors other than nerve insensitivity may be involved, the compounds were applied to the preparation in aqueous saline solutions at, or close to, their solubility limits and this could have masked differences in responses of nerves from the resistant strains.     

Quantitative structure-activity study of insecticidal 2-methoxy-5-(substituted-phenyl)-1, 3, 2-oxazaphospholidine 2-sulfides against Musca domestica L. by topical application

The quantitative relationship between the structure of 2-methoxy-5-(substituted-phenyl)-1, 3, 2-oxazaphospholidine 2-sulfides (5-PMOS) and their insecticidal activity against the house fly. Musca domestica L., was analyzed using reported physicochemical parameters and regression analysis. The electronic nature of the substituent on the phenyl group of 5-PMOS has the most significant effect on the activity, followed by hydrophobic and steric effects; the optimum value of Σρ is zero and the more hydrophobic the substituents on the phenyl group, the higher the insecticidal activity. The plots of observed pLD₅₀, values against calculated pLD₅₀ values for compounds having substituents in the ortho-position deviated downwards from those of compounds having substituents at the meta and/or para positions. This ortho-effect, which reduces the insecticidal activity of compounds having substituents at the ortho-position, was expressed by a dummy parameter D, which has the value 2 for di-ortho-substituted derivatives, 1 for mono-ortho-substituted derivatives and zero for others. Thus, the highest activity was obtained for 2-methoxy-5-phenyl-1, 3, 2-oxazaphospholidine 2-sulfide, and the activity was decreased by the introduction of any substituents on the phenyl group.     

Acetylcholinesterase inhibition by nootkatone and carvacrol in arthropods

The essential oils from many botanicals have been screened for insecticidal activity. Two constituents of the Alaskan yellow cedar tree, the monoterpenoid carvacrol and the sesquiterpenoid nootkatone, both are toxic against several arthropods. The mode of action through which nootkatone and carvacrol exert their insecticidal activity remains uncertain. It has been hypothesized that they may inhibit acetylcholinesterase enzyme activity. The degree of acetylcholinesterase inhibition of carvacrol and nootkatone was compared to that of carbaryl, a known acetylcholinesterase inhibitor, in the house fly (Musca domestica), yellow fever mosquito (Aedes aegypti), American dog tick (Dermacentor variabilis) and American cockroach (Periplaneta americana). The concentration of carbaryl, at which 50% of the acetylcholinesterase activity was inhibited (IC₅₀), was less than 2 μM in all four arthropod models. Carvacrol was observed to cause slight inhibition of the acetylcholinesterase enzyme in house flies, ticks and cockroaches, but it did not inhibit the mosquito acetylcholinesterase enzyme. Nootkatone did not inhibit the acetylcholinesterase enzyme in any of the four arthropod models tested. From this study, we conclude that the acetylcholinesterase inhibition is not likely the primary mode of action for insecticidal activity by nootkatone or carvacrol.     

Quantitative structure-activity relationships of pyrethroid insecticides

The structure-activity relationships of two congeneric series of pyrethroid insecticides, the methylbenzyl (1RS)-cis,trans-chrysanthemates tested against Musca domestica (houseflies) and Phaedon cochleariae (mustard beetles), and the (E)-4-aryl-3-chlorobut-2-enyl chrysanthemates and their corresponding 2,2,3,3-tetramethylcyclo-propanecarboxylates tested against M. domestica only, have been examined using multiple regression analyses and substituent constants. With M. domestica, different optimum partition values (π) were indicated for knockdown and toxicity; with P. cochleariae, an optimum π value for toxicity, similar to that for M. domestica, was obtained 24 h after application, but at later times the more lipophilic compounds were more effective. For the methylbenzyl chrysanthemates, a steric constraint associated with 3,5-dimethyl substitution reduced toxicity approximately five-fold. The influence on toxicity of geometrical isomerism and electronic effects are briefly discussed. Differences between the required polarities for knockdown and toxicity are attributed to variations in the binding affinities of pyrethroid molecules at the sites of action.     

Genetic and biochemical mechanisms limiting fipronil toxicity in the LPR strain of house fly,Musca domestica

Fipronil is a new insecticide which exerts its toxic action by interacting with the insect GABA-gated chloride channel. Previous studies have shown that cyclodiene-resistant insects have low to moderate levels of cross-resistance to fipronil, while other resistant strains are usually susceptible. In contrast, we recently found a strain (LPR) of house fly (Musca domestica L) with 15-fold cross-resistance to fipronil that was not associated with cyclodiene resistance. Fipronil cross-resistance in LPR was inherited as an intermediately dominant, autosomal, multigenic trait. [¹⁴C]Fipronil was observed to penetrate into LPR flies more slowly than into susceptible flies. S,S,S-tributylphosphorotrithioate and diethyl maleate pretreatment did not reduce the level of fipronil cross-resistance, while piperonyl butoxide resulted in a slight decrease. These results indicate that decreased penetration and monooxygenase-mediated detoxification may be mechanisms contributing to fipronil cross-resistance in the LPR strain. © 1999 Society of Chemical Industry     

Insecticidal and repellent properties of nine volatile constituents of essential oils against the American cockroach,Periplaneta americana (L.)

The toxic and repellent properties of nine major constituents of essential oils, comprising benzene derivatives and terpenes, were evaluated against Periplaneta americana (L.). Contact and fumigant toxicities to adult females and repellency to nymphs were determined. The decreasing order of knockdown activity via contact was methyl-eugenol>isosafrole=eugenol>safrole. The killing effect via contact was in the order eugenol=methyl-eugenol=isosafrole>safrole. Fumigant toxicity was only observed for safrole and isosafrole, with safrole being the more potent. Isoeugenol and the tested terpenes had neither contact nor fumigant toxic effect. The decreasing order of repellency to nymphs was safrole>isosafrole>methyl-eugenol=α-pinene> eugenol>isoeugenol. The benzene derivatives were generally more toxic and repellent to P. americana than the terpenes. The distance of the side chain double bond from the aromatic ring and the substitution of a methoxy group to these compounds appeared to be important determinants of their toxicity and repellency. © 1998 Society of Chemical Industry