Cochliomyia Hominivorax Research Articles

Flies as Carriers of Gastrointestinal Protozoa of Interest in Public Health in the Northeast of Brazil.

This study aimed to assess the influence of the presence of synanthropic flies in food preparation environments on the transmission of potentially zoonotic gastrointestinal protozoa. Flies were captured using a glass containing water, fruits, and pieces of protein. Approximately 260 flies from four different species were captured: Musca domestica (76.92%; 200/260), Cochliomyia hominivorax (17.31%; 45/260), Lucilia cuprina (3.85%; 10/260), and Hydrotaea aenescens (1.92%; 5/260). Protozoa were identified through microscopic analysis after macerating these arthropods contained in their respective eppendorfs, using two techniques, namely Mini-FLOTAC® and centrifugal sedimentation with Ziehl-Neelsen staining. The analysis revealed a concerning scenario regarding the epidemiological chain of gastrointestinal protozoa in Sergipe, Northeast Brazil. The positivity rate was 26.92% (14/52) of the pools, with 100.00% (5/5) in Aracaju, 30.00% (3/10) in Nossa Senhora do Socorro, 27.27% (3/11) in Nossa Senhora da Glória, 12.50% (2/16) in Carmópolis, and 10.00% (1/10) in Nossa Senhora das Dores. Two species of protozoa were identified, namely Cryptosporidium spp. (23.08%; 12/52) and Entamoeba spp. (9.62%; 5/52). The involvement of two fly species in the maintenance of the life cycle of these protozoa was noticeable, specifically M. domestica (27.50%; 11/40) and C. hominivorax (22.22%; 2/9). Counties analyzed had an human development index (HDI) considered medium; however, they still faced socioeconomic problems such as absence of sanitation systems, waste accumulation in the streets, and illegal waste disposal, which could favor the proliferation of these vectors and the spread of these gastrointestinal protozoa.

Parasitic fauna of wild boars (Sus scrofa) from the northwestern region of São Paulo state, Brazil.

In Brazil, the wild boar (Sus scrofa) is the main invasive exotic species, responsible for causing various economic, environmental, and health damages to biodiversity. In view of the above, we aimed in our study to investigate the occurrence of endo and ectoparasites in free-ranging wild boars in the northwest region of the state of São Paulo, Brazil. In total, 45 animals of different sexes and ages were examined in this research. Fecal and urine samples were processed using coproparasitological techniques. Multiple incisions in muscles, liver, and pancreas were also made to investigate cestodes and trematodes, and the entire epidermal region of the animals was analyzed for ectoparasites search. In our study, we demonstrate an occurrence of 97.77% (44/45) and 43.33% (13/30) of endo and ectoparasites, respectively, in wild boars, with the identification of eggs of Metastrongylus spp., Strongyloides ransomi, Trichuris suis, Stephanurus dentatus, and nematodes of the order Strongylida, as well as oocysts of Eimeriidae protozoa. Ectoparasite infestations were mainly caused by ixodids of the genus Amblyomma spp. and by larvae of Cochliomyia hominivorax.

Forensic and ecological significance of necrophagous insects: Insights from animal carcasses, human cadavers, and myiasis patients

Necrophagous insects, including flies and beetles, play pivotal roles in decomposition, ecology, and forensics. Their diversity and activities vary across environments, necessitating comprehensive studies for understanding and management. The aim of the study is to investigate insect infestation on animal carcasses, human cadavers, and myiasis patients to enhance ecological, forensic, and medical entomological understanding, aiding in ecosystem management, forensic investigations, and disease control.Various species of flies and beetles were found associated with animal carcasses, human cadavers, and myiasis patients, as indicated by the comprehensive study. On animal carcasses, notable fly species included Chrysomya rufifacies (Macquart, 1842), Chrysomya megacephala (Fabricius, 1794), Lucilia cuprina (Wiedemann, 1830), and Sarcophaga sp., while beetles such as Dermestes maculatus (De Geer, 1774), Necrobia rufipes (Fabricius, 1781), Saprinus quadrigatattus (Fabricius, 1798), Saprinus splendens (Paykull, 1811), Saprinus optabilis (Marseul, 1855), Saprinus chalcites (Iliger, 1807), and Omorgus sp. (Erichson, 1847) were also observed. Similarly, human cadavers exhibited a presence of flies like Chrysomya albiceps (Wiedemann, 1819), Chrysomya rufifacies (Macquart, 1842), Chrysomya megacephala (Fabricius, 1794), and Sarcophaga dux (Thomson, 1869). In cases of myiasis patients, flies including Chrysomya megacephala, Cochliomyia hominivorax (Coquerel, 1858), and Chrysomya bezziana (Villeneuve, 1914) were identified.These findings underscore the diverse range of insect species involved in carcass decomposition, forensic investigations, and medical entomology, illustrating their crucial roles in ecological processes, forensic assessments, and disease management.

Antennal transcriptome analysis reveals sensory receptors potentially associated with host detection in the livestock pest Lucilia cuprina

BackgroundLucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae) is the main causative agent of flystrike of sheep in Australia and New Zealand. Female flies lay eggs in an open wound or natural orifice, and the developing larvae eat the host’s tissues, a condition called myiasis. To improve our understanding of host-seeking behavior, we quantified gene expression in male and female antennae based on their behavior.MethodsA spatial olfactometer was used to evaluate the olfactory response of L. cuprina mated males and gravid females to fresh or rotting beef. Antennal RNA-Seq analysis was used to identify sensory receptors differentially expressed between groups.ResultsLucilia cuprina females were more attracted to rotten compared to fresh beef (> fivefold increase). However, males and some females did not respond to either type of beef. RNA-Seq analysis was performed on antennae dissected from attracted females, non-attracted females and males. Transcripts encoding sensory receptors from 11 gene families were identified above a threshold (≥ 5 transcript per million) including 49 ATP-binding cassette transporters (ABCs), two ammonium transporters (AMTs), 37 odorant receptors (ORs), 16 ionotropic receptors (IRs), 5 gustatory receptors (GRs), 22 odorant-binding proteins (OBPs), 9 CD36-sensory neuron membrane proteins (CD36/SNMPs), 4 chemosensory proteins (CSPs), 4 myeloid lipid-recognition (ML) and Niemann-Pick C2 disease proteins (ML/NPC2), 2 pickpocket receptors (PPKs) and 3 transient receptor potential channels (TRPs). Differential expression analyses identified sex-biased sensory receptors.ConclusionsWe identified sensory receptors that were differentially expressed between the antennae of both sexes and hence may be associated with host detection by female flies. The most promising for future investigations were as follows: an odorant receptor (LcupOR46) which is female-biased in L. cuprina and Cochliomyia hominivorax Coquerel, 1858; an ABC transporter (ABC G23.1) that was the sole sensory receptor upregulated in the antennae of females attracted to rotting beef compared to non-attracted females; a female-biased ammonia transporter (AMT_Rh50), which was previously associated with ammonium detection in Drosophila melanogaster Meigen, 1830. This is the first report suggesting a possible role for ABC transporters in L. cuprina olfaction and potentially in other insects.Graphical

Blow flies (Diptera: Calliphoridae) of the Baja California Peninsula

The blow fly fauna of the Baja California peninsula, Mexico has been sparsely documented. This study incorporates and lists recent and historical records of blow flies from collecting trips throughout the peninsula, visits to major southern California museums for historical collection records, and a literature search. Seven genera and 16 species are reported from the two peninsular Mexican States, Baja California, and Baja California Sur. Three species are recorded that are not included in the 2020 Catalog of Mexican Calliphoridae by Jaume-Schinkel, & Ibanez-Bernal (2020), they are: Calliphora livida, Calliphora terraenovae, and Calliphora vomitoria. One blow fly species, Cochliomyia hominivorax (the primary Screw-Worm Fly) is not included here but is found in museum collections. Once present in Baja, it is considered eradicated from continental North America as far south as the Panama Canal by the U.S. Department of Agriculture (USDA) however, it is occasionally reintroduced (Skoda et al. 2018) and is still present in some Caribbean islands. It is noteworthy that all calliphorid species from this mountainous desert peninsula are also found in the State of California, USA which supports 11 genera and 47 species in this family (Whitworth 2006) primarily because of its more varied climate and terrain. The Baja peninsula can be considered a southern extension of the State of California, with reduced species representation due to reduced climate and terrain variation, so no separate identification keys are necessary. Forensic entomologists and taxonomists can use the blow fly keys for North America by Whitworth, 2006, and 2017 for this region. The latest key by Jones, Whitworth, and Marshall (2019) is revolutionary and much welcome in taxonomy in that it is an online computer-aided key that has actual macro-photos of species identification characters and is intended to be used with a computer screen next to your microscope for identifications in place of printed material.

Homeopathic Pyrogenium Ointment as Adjuvant in Treatment of Traumatic and Infected Myiasis by Cochliomyia Hominivorax (Diptera: Calliphoridae) in Sheep: A Case Series.

The blowfly Cochliomyia hominivorax (Diptera: Calliphoridae) causes traumatic myiasis in farm animals, with deeply embedded larvae that lead to serious tissue damage and sometimes death. Treating this form of myiasis is difficult, often resulting in poor outcomes. As a homeopathic preparation that can mimic traumatic myiasis symptoms, Pyrogenium could potentially supplement treatment. This study aimed to describe the adjuvant effect that a Pyrogenium ointment might have in the treatment of sheep with traumatic myiasis. The study reports a homeopathic adjuvant treatment with Pyrogenium 12cH ointment in six sheep with traumatic and infected myiasis. Daily clinical examinations were performed to monitor the evolution of the health of animals. Pyrogenium 12cH ointment was applied topically on the wounds, after cleaning and mechanical removal of the larvae from the lesion. Blood samples were collected for blood counts, and wound exudate samples were obtained for bacteriological examination before and after wound treatment. The ointment of Pyrogenium 12cH limited the development of parasitic larvae and was associated with the repair of tissue losses resulting from the myiases and with subsequent wound healing, together with control of fever and local inflammation. Homeopathic Pyrogenium 12cH, formulated as an ointment, may be a useful new and adjuvant therapeutic option for treating traumatic and infected myiasis in animals.

Control of Rhipicephalus microplus on taurine cattle with fluralaner in a subtropical region

BackgroundIn Rio Grande do Sul, Brazil, a region with a subtropical climate, Rhipicephalus microplus is present in taurine cattle raised for beef and milk. In addition, ticks resistant to multiple acaricides are present in this region. Recently, fluralaner (isoxazoline) was launched on the market. Thus, there is a need to evaluate the effects of fluralaner for the control of R. microplus on taurine cattle. In addition, occurrence of myiasis by Cochliomyia hominivorax larvae after tick parasitism and weight gain of cattle during the experimental period were evaluated.MethodsThirty naturally infested cattle were divided into two experimental groups: T01, treated with fluralaner (2.5 mg/kg) pour-on; T02, control. T01 received fluralaner on Days 0 (early summer in January), 42 and 84 (early autumn), whereas T02, a control group, received palliative treatment with a spray formulation when the group mean was ≥ 30 ticks. Counts of R. microplus females and calculation of the efficacy of fluralaner were performed on Days 3, 7, 14, 28, 35, 42, 56, 70, 84, 98, 112 and 126. The occurrence of myiasis was assessed throughout the study period. In addition, the weight, weight gain and daily weight gain of the animals were evaluated.ResultsIn the 12 evaluations performed, the parasitic load of T01 was near zero. Fluralaner showed 99.5% efficacy on the 3rd day after the first treatment and 100% efficacy from Day 7 to Day 126. Cochliomyia hominivorax larvae (n = 6; p = 0.0251) were found only in the control group (T02). At the end of the study, the animals subjected to treatments with fluralaner gained 32.8 kg more than the animals in the control group.ConclusionsApplication of fluralaner in summer and autumn, with 42-day intervals between treatments, was effective to control R. microplus on taurine cattle, which also gained more weight than control cattle. Additionally, no cases of myasis were documented in animals treated with fluralaner.Graphical

Doxycycline is a viable alternative to tetracycline for use in insect Tet-Off transgenic sexing systems, as assessed in the blowflies Cochliomyia hominivorax and Lucilia cuprina (Diptera: Calliphoridae).

Transgenic insect strains with tetracycline repressible (Tet-Off) female-lethal genes provide significant advantages over traditional sterile insect techniques for insect population control, such as reduced diet and labor costs and more efficient population suppression. Tet-Off systems are suppressed by tetracycline-class antibiotics, most commonly tetracycline (Tc) or doxycycline (Dox), allowing for equal sex ratio colonies of transgenic insects when reared with Tc or Dox and male-only generations in their absence. Dox is a more stable molecule and has increased uptake than Tc, which could be advantageous in some insect mass-rearing systems. Here, we evaluated the suitability of Dox for rearing Tet-Off female-lethal strains of Australian sheep blowfly, Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae), and New World screwworm, Cochliomyia hominivorax (Coquerel, 1858) (Diptera: Calliphoridae), and the effects of dosage on strain performance. For both species, colonies were able to be maintained with mixed-sex ratios at much lower dosages of Dox than Tc. Biological yields of C. hominivorax on either antibiotic were not significantly different. Reduction of Dox dosages in C. hominivorax diet did not affect biological performance, though rearing with 10 or 25 μg/mL was more productive than 50 μg/mL. Additionally, C. hominivorax mating performance and longevity were equal on all Dox dosages. Overall, Dox was a suitable antibiotic for mass-rearing Tet-Off female-lethal L. cuprina and C. hominivorax and was functional at much lower dosages than Tc.

Does tail docking prevent Cochliomyia hominivorax myiasis in sheep? A six-year retrospective cohort study

Abstract Tail docking is a husbandry practice widely incorporated in sheep farms around the world. It is an irreversible mutilation that impairs animal welfare, both immediately and in the longer term. The defence of tail docking as a practice is centred around the perception that doing so contributes to the promotion of local hygiene, allowing the use of the wool, facilitating reproductive management and reducing the chances of myiasis, a disease caused by the invasion of blowfly larvae in the tissues of warm-blooded animals. However, current understanding of farm animal welfare questions the need to maintain practices such as tail docking. Thus, the aim of this study was to evaluate the effect of tail docking on the incidence of Cochliomyia hominivorax myiasis in sheep in an experimental flock in Brazil during a six-year retrospective cohort study. Relative risk, odds ratio and incidence rate ratio were the association measures adopted. A total of 4,318 data-points were collected and supplied the analytical model. Tail docking did not decrease the risk and, on the contrary, was found to increase the chances of sheep being affected by myiasis. The results support the hypothesis that tail docking is not a protective factor against the occurrence of myiasis and further fuel calls for a rethink of tail docking being deployed as a blanket measure in the prevention of myiasis in sheep.

Ecología de una taxocenosis de Calliphoridae del área platense (Provincia de Buenos Aires) (Insecta, Diptera)

This paper constitutes the first approach to the knowledge of the ecology of Calliphoridae from Argentina. The selected stüdied area is a rural one located at 34°55’S and 58° W in the suburbs of Villa Elisa, Province of Buenos Aires. Samples were taken hourly from 10.15 am to 4.15 pm, every month from November 1985 to October 1986. Specimens were captured with entomological net while lying on the bait composed by cow meat. The sampling program included shaded and unshaded sites. Air temperature was recorded every hour. Results showed a remarkable heliophily for some of the recorded species. Chrysomya albiceps, Phaenicia sericata, Phaenicia purpurescens and Cochlipmyia macellaria were codominants during spring and summer, while Calliphora vicina and Calliphora nigribasis were so along the winter months. Chrysomya megacephala, Cochliomyia hominivorax,. Compsomyiops fulvierura, Paralucilia fulvinota, Phaenicia eximia, and Sarconesia chlorogaster were poorly represented for most o f the sampling dates. Sex ratio was female biased for the majority of the studied species.

Homeopathic Sulphur Ointment as Adjuvant in the Treatment of Sheep with Myiasis by Cochliomyia hominivorax (Diptera: Calliphoridae): A Case Series.

Myiasis by Cochliomyia hominivorax (Diptera: Calliphoridae) is a serious problem in animal health. Homeopathic Sulphur presents similarity with the clinical presentation verified in these cases and has already shown in vitro efficacy on the blowfly that causes this pathology. This article presents the report of a series of clinical cases of myiasis by C. hominivorax in sheep that underwent adjuvant treatment with homeopathic Sulphur and presents a theoretical-scientific discussion of biological events related to the clinical treatment of the condition. Seven naturally occurring myiases affecting sheep from an experimental farm were treated by an ointment impregnated with the homeopathic medicine Sulph 12cH, used as adjuvant after the manual removal of accessible larvae from the wound during wound cleaning. The animals were treated daily and evaluated clinically until complete healing of the lesions. Clinical information on the evolution of the inflammatory and scarring process was collected. Blood counts and bacteriological examinations were performed before and after topical homeopathic treatment. The homeopathic ointment Sulph 12cH was able to inhibit the development of parasitic C. hominivorax larvae and promote tissue repair and healing in naturally occurring myiasis in the sheep of this study. The homeopathic medicine Sulphur, formulated as an ointment, may be a useful new and adjuvant therapeutic option for treating myiasis in animals.

First report of the efficacy of a fluralaner-based pour-on product (Exzolt® 5%) against ectoparasites infesting cattle in Brazil

BackgroundThis study describes the effectiveness of a novel active pharmaceutical ingredient, fluralaner (isoxazoline class), against important ectoparasites infesting cattle in Brazil.MethodsA total of 13 studies involving a 5% fluralaner-based pour-on formulation (Exzolt 5%; further referred to as Exzolt) were conducted. Specifically, the effectiveness of this formulation was studied against Rhipicephalus microplus (6 studies), Cochliomyia hominivorax larvae (4 studies), Dermatobia hominis larvae (1 study) and Haematobia irritans flies (2 studies).ResultsThe therapeutic efficacy of Exzolt was found to exceed 98% at 4 days post treatment (DPT), while persistent efficacy (> 90% efficacy) against repeated infestations of R. microplus was observed for up to 79 DPT. In field studies, ≥ 98% therapeutic efficacy was demonstrated at all study sites by 7 DPT, and a persistent efficacy (> 90% efficacy) was observed for 42, 49 or 56 DPT. Exzolt prevented C. hominivorax eggs from developing to the larval stage, thus mitigating the development of myiasis in cattle naturally and artificially infested with this screworm. The efficacy of Exzolt against D. hominis larvae was 98% at 3 DPT, while persistent efficacy (> 90% effectiveness) was found to last for up to 70 DPT. Against H. irritans, Exzolt showed therapeutic efficacy (≥ 90%) within the first day of treatment at both study sites, while persistent efficacy (≥ 90%) was observed for 7 DPT at one site and for 21 DPT at the other site.ConclusionsOverall, the results from these studies confirm that Exzolt is therapeutically efficacious against the most important ectoparasites infesting cattle in Brazil. The novel active pharmaceutical ingredient, fluralaner, provides a new treatment option for farmers to control cattle ectoparasites, especially where there is resistance to other chemical classes. In addition, an effective control of ectoparasites will improve overall cattle health and well-being as well as production.Graphical

Identification and functional analysis of Cochliomyia hominivorax U6 gene promoters.

The New World screwworm, Cochliomyia hominivorax, is an obligate parasite, which is a major pest of livestock. While the sterile insect technique was used very successfully to eradicate C. hominivorax from North and Central America, more cost-effective genetic methods will likely be needed in South America. The recent development of CRISPR/Cas9-based genetic approaches, such as homing gene drive, could provide a very efficient means for the suppression of C. hominivorax populations. One component of a drive system is the guide RNA(s) driven by a U6 gene promoter. Here, we have developed an in vivo assay to evaluate the activity of the promoters from seven C. hominivorax U6 genes. Embryos from the related blowfly Lucilia cuprina were injected with plasmid DNA containing a U6-promoter-guide RNA construct and a source of Cas9, either protein or plasmid DNA. Activity was assessed by the number of site-specific mutations in the targeted gene in hatched larvae. One promoter, Chom U6_b, showed the highest activity. These U6 gene promoters could be used to build CRISPR/Cas9-based genetic systems for the control of C. hominivorax.

Larvicidal activity in vitro of essential oils against Cochliomyia hominivorax

Cochliomyia hominivorax, from the family Calliphoridae, is responsible for causing most myiases in domesticated animals in Brazil. As alternatives to conventional treatments, essential oils (EOs) could possibly be used as natural control of ectoparasites. The aim of this study was to evaluate the in vitro activity of EOs from Salvia sclarea L., Rosmarinus officinalis L., Lavandula hybrida Reverchon, Citrus bergamia Risso, Citrus paradisi L., Juniperus virginiana L., Copaifera reticulata Ducke, Illicium verum Hook f., Pelargonium roseum, Cymbopogon winterianus Jowitt, Cymbopogon flexuosus Steud, Eugenia caryophyllus Spreng, Cinnamomum cassia Presl, Thymus vulgaris L. and Origanum vulgare L. against third-instar larvae of C. hominivorax. To evaluate the mortality rate, filter paper tests were performed at different concentrations and verified after 24 h and 48 h. Essential oils of T. vulgaris, O. vulgare and I. verum induced 100% mortality in the screening test, and their main active components (thymol, carvacrol and anethol, respectively) were also tested alone. In this new test, lethal concentrations (LC50) after 24 h and 48 h, respectively, were 407.1 and 314.2 µg.cm-² for T. vulgaris, 540.9 and 253.8 µg.cm-² for O. vulgare, 314.2 µg.cm-² (after 48 h) for I. verum, 255.6 and 102.3 µg.cm-² for thymol, 970.5 and 931.1 µg.cm−2 for carvacrol and 559.4 µg.cm−2 (after 48 h) for anethol. These results showed the potential of these EOs and their main components for development of ectoparasiticides for veterinary use, especially T. vulgaris EO and thymol.

Synanthropy and ecological aspects of Calliphoridae and Mesembrinellidae (Diptera: Oestroidea) in three ecological areas in Rio de Janeiro State, Brazil.

The determination of the synanthropic index is essential to evaluate the degree of association between species, such as diptera and man, based solely on their degree of preference for urban areas. This research aimed to study the synanthropic behavior of Calliphoridae and Mesembrinellidae flies in Rio de Janeiro, Brazil. The experiment was conducted between 2021 and 2022 in three areas, where four traps containing 300 g of fresh liver or with 48 h of putrefaction were installed, remaining exposed for 48 h; after collection the dipterans were sacrificed and taxonomically identified. A total of 2,826 dipterans were collected, represented by nine species of Calliphoridae (89.24%) and ten of Mesembrinellidae (10.76%), with the first record of Mesembrinella currani in this biome. The Kruskal-Wallis test showed that the abundance of individuals did not differ among the three analyzed environments. The Mesembrinellidae family was exclusively asynanthrope, along with two species of Calliphoridae: Hemilucilia benoisti (Séguy 1925) and Paralucilia nigrofacialis (Mello 1969) which were exclusive of the forest area, while Calliphoridae had varied synanthropy. Lucilia eximia (Wiedemann 1819) alone represented 57.18% of the total sampled, being the most abundant in all environments except the urban area where Hemilucilia segmentaria (Fabricius 1805) totaled 55.73%. No species were exclusive to the urban area, however Cochliomyia hominivorax (Coquerel 1858) and Lucilia cuprina (Wiedemann 1830) were exclusive to the rural area. The most synanthropic species were Chrysomya megacephala (Fabricius 1794) and Chrysomya albiceps (Wiedemann 1819).

Cuterebra baeri Infecting Grey-Legged Night Monkeys (Aotus griseimembra) and Red Howler Monkeys (Alouatta seniculus) in Colombia.

Myiases are parasitic infections caused by the larval stages of some fly species. In American nonhuman primates (NHP), three bot fly species causing cutaneous myiasis have been reported: Cuterebra baeri, Cochliomyia hominivorax, and Dermatobia hominis. Studies on myiasis in NHP are scarce and mainly based on morphologic identification of larvae, while molecular approaches have been barely used. This study aimed to molecularly identify bot flies parasitizing two NHP species living sympatrically in central Colombia. Bot fly larvae were collected from two grey-legged night monkeys (Aotus griseimembra) and from a howler monkey (Alouatta seniculus). Larvae were measured and photographed for morphologic evaluation; subsequent molecular characterizations of a partial region of the cytochrome c oxidase subunit 1 mitochondrial gene were performed. Sequence analysis allowed the identification of all specimens as Cuterebra baeri, enabling confirmation of this species parasitizing Alouatta seniculus and Aotus griseimembra in Colombia.

A new formulation of screwworm fly attractant with reduced hazardous chemicals and transport restrictions.

New World screwworm flies, Cochliomyia hominivorax (Coquerel), are obligate parasites of warm-blooded animals. They were eradicated from North and Central America during the mid-20th to early-21st centuries using the sterile insect technique (SIT), a method presently employed to maintain a permanent barrier between Central and South America. Lures are an important component of the screwworm eradication program, where they are used for surveillance, sample collection, and strain evaluation in the field. The first chemical lure, later named swormlure, was developed based on the attractiveness of C. hominivorax to volatile organic compounds (VOCs) produced from decomposing animal tissues. The formulation has changed little over the years and presently contains 10 chemicals, one of which is dimethyl disulfide (DMDS). Restrictions on the transport of DMDS have recently impeded its use in swormlure-4 (SL-4). However, dimethyl trisulfide (DMTS) is not as highly restricted and can be shipped via air transportation. Both chemicals are produced by microbial decomposition of animal tissues. Here, we conducted field trials using three releases of sterile C. hominivorax, each comprising approximately 93,000 flies, to test the efficacy of SL-4, containing DMDS, to swormlure-5 (SL-5) containing DMTS. Traps baited with SL-4 and SL-5 captured 575 (mean = 191.7, SD 17.9) and 665 (mean = 221.7, SD 33.2) C. hominivorax, respectively (df = 19, F = 1.294, P = 0.269). However, traps baited with SL-5 captured considerably more Cochliomyia macellaria (Fabricius), a closely related but nontarget fly.

Effect of diazinon (organophosphate) on the composition and succession of Calliphoridae assemblages in rabbit carcasses in the Eastern Amazon.

Fatal poisonings with diazinon may occur both accidentally or intentionally in suicide cases. Forensic entomotoxicology can aid in understanding these deaths by detecting and analyzing the interference of toxic substances in the biology of necrophagous insects. Hence, this study sought to evaluate diazinon's effect on the composition and succession of calliphorid species in the tropical savannas of the Amazon. Nine rabbit carcasses were divided into three groups: one control and two diazinon treatments (100mg/kg and 300mg/kg); each group had three replicates. Three fragments of the Amazon tropical savanna were selected for the experiments. Daily collections of adult and immature calliphorids were performed. Five decomposition stages were observed: fresh, bloated, active decay co-occurring, advanced decay, and dry. Eight species of Calliphoridae were identified among the collected adults: Chloroprocta idioidea (0.1%), Chrysomya albiceps (58.3%), Chrysomya megacephala (14.2%), Chrysomya putoria (2.6%), Cochliomyia hominivorax (1.3%), Cochliomyia macellaria (0.5%), Lucilia eximia (19.8%), and Paralucilia paraensis (3.3%). The adult specimens in the control group with the highest abundance were observed only from the advanced decay stage onward. In the dry stage, abundance was higher in control than in treated carcasses. From the sampled 941 Calliphorid immatures, three species were identified: C. albiceps (76,3%), C. putoria (1%), and L. eximia (22,7). The number of immatures was higher in control than in treated carcasses. Therefore, diazinon interferes with the putrefaction timeframe in carcasses, slowing the decomposition stages and affecting their colonization by immature forms of Calliphoridae.

Efficacy of lotilaner against myiasis caused by Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs

BackgroundThe New World screwworm fly, Cochliomyia hominivorax, is widely distributed across South America. This parasitic insect is a significant cause of primary myiasis in animals, including dogs. There is an urgent need for a rapid and efficient treatment to improve the recovery of affected animals. In the present study we evaluated the potential of lotilaner for the treatment of myiasis caused by C. hominivorax larvae in naturally infested dogs. Lotilaner belongs to the isoxazoline class of chemical compounds and is marketed as Credelio™ for use against ticks and fleas in dogs and cats.MethodsEleven dogs with naturally acquired myiasis were enrolled in this study based on the severity of lesions and the number of identified larvae. All animals received a single oral administration of lotilaner at a minimum dose of 20.5 mg/kg body weight. After treatment, the number of expelled larvae, live or dead, was determined at 2, 6 and 24 h, and the larval expulsion rate, larvicidal effect and overall efficacy were calculated. After 24 h, the remaining larvae were removed, counted and identified. The lesions were cleaned, and palliative treatment was administered when necessary, according to the animal's health status.ResultsAll larvae were identified as C. hominivorax. The larval expulsion rate was 80.5% and 93.0% at 2 and 6 h post-treatment, respectively. Lotilaner showed an overall efficacy of 100% at 24 h post-treatment.ConclusionsLotilaner demonstrated a rapid onset of action and a high efficacy against C. hominivorax. We therefore recommend lotilaner for the effective treatment of myiasis in dogs.Graphical

Development of a diagnostic single nucleotide polymorphism (SNP) panel for identifying geographic origins of Cochliomyia hominivorax, the New World screwworm

The New World screwworm, Cochliomyia hominivorax, causes myiasis in livestock, humans, and other warm-blooded animals in much of South America and the Caribbean. It has been eradicated from North and Central America using the sterile insect technique and a biological barrier is currently maintained at the Panama - Colombian border. However, C. hominivorax is still a threat to eradicated areas as outbreaks can and do occur. In order to identify the origin of a fly involved in an outbreak scenario, diagnostic tools would be beneficial. Recently, the geographic population structure of this species was identified using single nucleotide polymorphisms (SNPs). Here we characterize the three major regional clusters: South America, the Inner Caribbean, and the Outer Caribbean. The objective of this study was to develop a SNP (single nucleotide polymorphism) panel to distinguish between these three clusters. A panel was developed using two unique SNPs per region for a total of six SNPs. This diagnostic SNP assay will allow for rapid source determination of flies from future incursions in order to intercept introductory pathways and aid in the control of New World screwworm.