Cochliomyia Research Articles

Very long-chain methyl-branched alcohols and their acetate esters in pupal internal lipids of developing Coleoptera, Anthonomus grandis and Cylindrocopturus adspersus, and Diptera, Cochliomyia hominivorax and Musca domestica

Mono- and dimethyl-branched primary alcohols from C28 to C56 were identified in the internal lipids of developing mid-stage pupae of two species of Coleoptera; the boll weevil, Anthonomus grandis and the sunflower stem weevil, Cylindrocopturus adspersus, and of two species of Diptera; the screwworm, Cochliomyia hominivorax, and the house fly, Musca domestica. Novel very long-chain dimethyl-branched alcohols (VLMA; C36–C56) were characterized for the first time in these two orders. The major VLMA component was 26,38-dimethylpentacontanol in the boll weevil, 28,38-dimethylpentacontanol in the sunflower stem weevil, and 26,36-dimethyloctatetracontanol in both the screwworm and house fly. These alcohols were six to ten carbons longer than similar alcohols previously reported for Lepidoptera. No terminally-branched or trimethyl-branched alcohols similar to those previously characterized in Lepidoptera were detected.

Random amplified polymorphic DNA of screwworm fly populations (Diptera: Calliphoridae) from Southeastern Brazil and Northern Argentina

Random amplified polymorphic DNA of screwworm fly populations (Diptera: Calliphoridae) from Southeastern Brazil and Northern Argentina

Studies on the Worm Gears, Which Have a Cylindrical Screw.

This paper discusses the contact theories of the worm gears which have a cylindrical screw worm. First, known contact condition similar to that of spur gears is proved easily. Second, the known contact condition and author's contact condition similar to that of spur gears are synthesized and space image of normal is clarified. Third, the solution of the zone of contact and the opposite tooth surface of the worm gears are derived from the contact condition similar to that of spur gears. And solutions of contact condition which is shown by expressions is clarified. Finally, many examples of the zone of contact and the opposite tooth surface of the worm gears are shown and three dimensional expression is tried.

Mating competitiveness of irradiated flies for screwworm fly eradication campaigns

Should the screwworm fly invade Australia, the sterile insect technique (as used successfully overseas) is currently the only feasible method of eradication. Used in conjunction with chemical control methods, it relies on large numbers of factory-reared, sterilized males competing successfully with wild males for the wild females. However, laboratory and field studies have shown that the processes of mass rearing, irradiation and distribution seriously impair the competitiveness of the sterilized flies. This study collates and analyses the relatively sparse information on the relative mating competitiveness of sterilized screwworm flies, from both controlled experiments and large-scale field studies. A population dynamics example then demonstrates that competitiveness will be a key parameter in the effectiveness and economic feasibility of any future eradication campaign.

Identification of the Geographical Source of Adults of the Old World Screw-Worm Fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), by Multivariate Analysis of Cuticular Hydrocarbons

The cuticular hydrocarbon compositions of male and female Chrysomya bezziana from different locations are qualitatively similar but show quantitative differences. The qualitative similarity and lack of marked quantitative differences over its whole range is consistent with C. bezziana being a single species. This accords with the results of studies on hybridization, morphology, allozymes, and chromosomes. Canonical variate analysis of quantitative differences has enabled grouping of locations by geographical regions. Components insensitive to age and sex have been identified that would permit the location by geographical region of a fly of unknown age and sex. However, greater precision is obtained if the sex of the fly be known.

The development of an “in vivo assay technique” as a tool for measuring protective immune responses of vaccine against myiasis in sheep

An “ in vivo assay technique ” is urgently needed for measuring protective immune effects of a myiasis vaccine in sheep. Such a technique is being developed simultaneously with the development of a vaccine against myiasis caused by the screwworm fly Chrysomya bezziana under a collaborative project undertaken by Balitvet, ITB and CSIRO (Australia) and funded by ACIAR. Experiments were conducted in naive sheep. C. bezziana larvae were allowed to develop on abraded skin in aluminium rings which had been attached to the sheep by means of a glue (Aibon) on the day prior to infection. Rings were arranged on clipped areas close to the mid line of the sheep’s back, two rings on the right side and two rings on the left. Four trials were performed, involving studies on the effects of including wet sponges in the rings to maintain humidity (Trial 1); the effects of sponge and blended meat as counting and transferring media during infection (Trial 2); the effects of the repellants citronella, eucalyptus oil and neem extract in assisting the recovery of larvae (Trial 3); and the effects of the reducing the infective dose from 50 to 25 1st instar larvae/ring and using a fine brush for counting and transferring larvae instead of using a forceps as in the previous groups (Trial 4) on the larval recovery rates (LRR). The results indicated that the inclusion of wet sponges in the rings, the use of sponge and blended meat as counting and transferring media during infection, and the application of repellants all increased the LRR to some extent; however, variations among individual rings remained high. On the other hand, the reduction of infective dose of larvae from 50 to 25 1st instar larvae/ring and using a fine brush for counting and transferring larvae sharply increased the LRR while substantially decreasing the coefficient variations. Key words : Myiasis, Chrysomya bezziana , larval recovery rate

Evaluating the risk of the establishment of screwworm fly in Australia.

To investigate probabilities of establishment of screwworm fly throughout the year, for several locations around Australia's coastline. A simulation model that predicts the spread and economic impact of an established screwworm fly population was modified to include stochastic survival functions, to investigate the risks of the pest actually establishing in this country. The effects of time of year, climate, vegetation and the number of incoming flies or larvae were investigated for four locations around Australia. Analysis of variance identified a dominant three-way interaction between site, time, and the number of introduced flies. These probabilities are graphed. In southern areas, as exemplified by Fremantle, the cold winters limit survival. A high probability of establishment exists year round in tropical regions, except in areas around the Gulf of Carpentaria and in the Northern Territory where dry weather mid-year would limit survival. Despite these comparatively lower risks, there were no areas or times where reductions in quarantine efforts could be justified.

Expression of angiotensin-converting enzyme-related carboxydipeptidases in the larvae of four species of fly

HieACE, a soluble 70 kDa protein related to the angiotensin-converting enzyme (ACE) has recently been identified, characterized and cloned from the adult buffalo fly ( Haematobia irritans exigua). HieACE is enzymatically similar to the mammalian ACEs and its predicted amino acid sequence has 42% identity with the mammalian testicular ACEs. In adult H.i. exigua, HieACE expression is restricted to the compound ganglion and posterior midgut, and the maturing male reproductive system. Western blot analysis was used to investigate the expression of HieACE and its homologues in the larvae of H.i. exigua, Drosophila melanogaster, the sheep blowfly ( Lucilia cuprina), the Old World screwworm fly ( Chrysomya bezziana) and a secondary strike fly, Chrysomya rufifacies. Dipteran ACE homologues of 65–70 kDa were detected in all the larval instars investigated. Most of the immunoreactive proteins were concentrated in the soluble fraction. The first and second larval instars of L. cuprina and C. bezziana appeared to express two ACE homologues. These larvae were also found to secrete (or excrete) the ACE homologue in larval cultures. The presence of ACE-like enzymes in these larvae was confirmed by the measurement of carboxydipeptidase activity that was inhibited by the specific ACE inhibitor, captopril. The tissue distributions of the ACE homologues in the third instar larvae of H.i. exigua and L. cuprina were examined. As in adult H.i. exigua, HieACE was detected in the larval ganglion, but in contrast to the restricted distribution in the adult stage midgut, HieACE was found throughout the digestive system, and in the salivary glands of H.i. exigua larvae. The expression pattern in the gut of L. cuprina larvae was similar despite the differences in diet and habitat. The most striking difference from the adult stage H.i. exigua was the expression of HieACE and its L. cuprina homologues in the hindgut and Malpighian tubules of these larvae. These results suggest that the role(s) played by the dipteran ACE-like enzymes differ between the adult and larval stages.

Did the sterile insect technique or weather eradicate screwworms (Diptera:Calliphoridae) from Libya?

The American screwworm, Cochliomyia hominivorax Coquerel, was detected in northwestern Libya in 1988. By August 1990, a screwworm epizootic extended over 26,000 km2 but collapsed in December and disappeared in April 1991. The relative contributions of winter weather and sterile insect releases on screwworm eradication in Libya were assessed by using temperature data and population demography. A screwworm overwintering threshold mean temperature of approximately 9.7 degrees C for 3 mo is supported strongly by published experimental and epizootiological data. In Libya, temperatures were above this overwintering threshold at Zawia, Sorman, and Tripoli weather stations. At Gharyan, in the interior highlands, mean winter temperatures from 1 December 1990 to 28 February 1991 were less than the putative overwintering threshold. No kill of screwworm pupae or adults was likely as a result of low temperatures near any weather station in the winter of 1990-1991. Evidence of screwworm overwintering in 1990-1991 was provided by the detection of a natural infestation in April and trap captures of numerous wild adult females in February, March, and April. Successful screwworm overwintering was highly probable in the coastal plain of Libya but unlikely in much of the interior highlands. The high rate of animal inspections by eradication personnel achieved as much as a 30% chance of detecting a screwworm case in domestic animals. Generation times and expectation of life among feral adult flies were estimated. Case reports for January to June 1991 were consistently less than estimates based on historical experience in Libya 1989-1990 and in Texas 1962-1983. Phenological simulations of sterile mating rates in feral screwworm flies supports the contention that sterile fly releases led to a greatly reduced case incidence from January to the time that eradication was declared in October 1991.

Effects of temperature on Cochliomyia macellaria (Diptera:Calliphoridae) development.

Growth curves were studied for the egg, larva, and pupa of the secondary screwworm, Cochliomyia macellaria (F), under mean cyclic temperatures of 15.6, 21.1, 26.7, 32.2, and a constant 25.0 degrees C. Development from egg to adult under all regimes ranged from 170 to 588 h. A constant temperature regime of 25 degrees C produced a range of pupation times from 92 to 142 h, with adult emergence ranging from 196 to 261 h. The maximal preferential temperature of 39 degrees C was determined for maggots by using a gradient system. The minimal variation in the range of larval lengths and development time makes this species suitable for establishing relatively narrow confidence intervals when constructing a postmortem interval estimate for use in legal investigations.

Mitochondrial DNA restriction site map of Cochliomyia macellaria (Diptera:Calliphoridae).

The mitochondrial DNA of the secondary screwworm, Cochliomyia macellaria (F.), was cleaved with 15 restriction endonucleases to produce 54 restriction fragments. Forty-three restriction sites recognized by 12 enzymes were assigned positions on a restriction site map. Both the restriction fragments and the restriction site map were compared with published data from the screwworm, Cochliomyia hominivorax (Coquerel). The restriction site maps were aligned using a combination of highly conserved restriction sites. Estimated nucleotide divergence between the 2 species based on the fragments was 0.052. The divergence based on the restriction site map was 0.093. The data provide a baseline for future population or phylogenetic investigations.

Myiasis in Humans: An Overview and a Report of Two Cases in the Republic of Panama

This paper on myiasis provides varied references from documented sources as an overall review. A review of two case studies, a primary screwworm (cochliomyia hominivorax) infestation and a human botfly (Dermatobia hominis) infestation, as well as information on approaches to positive intervention and remediation are presented. Human myiasis found in the subtropical and tropical regions of the world is a health threat. As a result of the military's expanding role in medical support to various regions where myiasis is endemic, this paper serves to familiarize health care providers with this condition and to provide guidance when dealing with patients affected by myiasis.

Isolation and identification of bacteria associated with the screwworm fly Cochliomyia hominivorax, coquerel and its myiasis.

We studied eight different myiasis of sheep caused by screwworm flies under laboratory conditions. Swabs were taken from the wound, before, during, and after the myiasis. Seven hundred and thirty-one samples were streaked on different bacteriological media. All samples were identified by Api System (bioMerieuex). We found thirty-eight different bacterial species in the exudates from the myiasis (before, during, and after the parasitic cycle). The analysis of bacterial flora of the screwworm showed, on larvae stage 1, 10 different bacterial species, on larvae 2, 12 bacterial species; larvae 3, 15 bacterial species; crawl off, 15 bacteria species, pupa, 9 bacterial species; and adults, 2 bacterial species and on the pioneer fly, 14 different bacterial species were isolated and identified.

Dispersal and Distribution of Calliphoridae (Diptera) Immatures from Animal Carcasses in Southern Louisiana

Spatial distributions of calliphorid pupae (based on adult emergence) from swine carcasses located in woods and pasture were determined during 4 seasons in southern Louisiana. Adult emergence was substantially greater in pastures than woods for all seasons except winter. Secondary screwworm, Cochliomyia macellaria (F.), was the predominant calliphorid species collected ( > 95%) during summer and fall; whereas, black blow fly, Phormia regina (Meigen), was the primary species (86%) during spring. The highest densities of calliphorid pupae per square meter were located within 0.9 m of the animal carcasses in the woods and the pasture (summer); however, the number of calliphorid pupae per square meter during the summer was substantially greater in the pastures than in the woods (2,370/m2 compared with 77/m2). Postfeeding calliphorid larvae preferred to disperse toward the southeastern quadrant during summer and spring and toward the southeastern to southwestern quadrants in fall. The winter evaluation period was the most prolonged (85 d), had the least number of emergent adults (only 6-11% of the populations that emerged in the other seasons), and consisted of predominantly, Phaenicia sericata (Meigen).

Mitochondrial DNA variation in screwworm.

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was used to characterize mitochondrial DNA (mtDNA) variation in screwworms, Cochliomyia hominivorax, and secondary screwworm, C.macellaria, from the Caribbean, North America and South America. Four amplicons, totaling 7.1 kb, were analysed with sixteen restriction enzymes. A total of 133 restriction sites was observed in the two species, 104 in C.hominivorax, of which nineteen were variable, and ninety-five in C.macellaria, none of which was variable. Fourteen mtDNA haplotypes were observed among eighteen C.hominivorax examined. Mean divergence between C.hominivorax haplotypes (d) was 0.0064 substitutions per base-pair and genotypic diversity (G) was 0.97. Mean divergence between C.hominivorax and C.macellaria was 0.0824. Cochliomyia hominivorax haplotypes could be divided into three assemblages representing North America, South America and Jamaica, based on UPGMA clustering with d values. The assemblages did not exhibit complete geographic fidelity. These data were discordant with previously published allozyme data indicating little differentiation between screwworm populations. A scenario invoking historically isolated populations coming into contact with the introduction and movement of European livestock is proposed to explain the observed population structure of screwworm.

Identification of screwworm species by polymerase chain reaction-restriction fragment length polymorphism.

Restriction fragment length polymorphisms in polymerase chain reaction amplified fragments (PCR-RFLP) of mitochondrial DNA were used to differentiate species of New World screwworms (Diptera: Calliphoridae). Twenty-seven restriction enzymes were screened on five regions of mtDNA. Eleven restriction fragment length patterns differentiated New World screwworm, Cochliomyia hominivorax (Coquerel), from secondary screwworm, Cochliomyia macellaria (F.). Five restriction fragment length patterns were polymorphic in C.hominivorax while all fragment patterns were fixed in C.macellaria. Diagnostic restriction fragment length patterns were used for species diagnosis, whereas intraspecific variable patterns were used to characterize field samples and laboratory strains. The PCR-RFLP technique is flexible with regard to developmental stage of the sample and method of preservation. We were able to characterize specimens of all life stages from egg to adult including larvae preserved in alcohol and pinned adults. PCR-RFLP is rapid and inexpensive, enabling specimens to be characterized within 24 h for less than $2.50.

Oestrus Ovis Infection in Cyprus.

The term ‘screw worm’ is used to describe certain types of cutaneous myiasis that predominantly affect animals. They are conventionally divided into “new world” screw worms which are found from the Southern U.S. down to Argentina, including Cochliornyia horninivorax, and “old world” screw worms that are found in Africa, Asia, and Oceania, including various Chrysornyu species. Their importance is largely veterinary, cattle, horses, goats, and sheep being mostly afTected.The organisms are obligatory parasites of living animal tissues and attack primarily the nasal and pharyngeal areas, although they may infest minor breaches in the skin.’ Morbidity and mortality may be significant; prior to 1958, it was estimated that the American livestock industry lost 120 million dollars annually as a direct result of C. horninivorux infection.’ Man is uncommonly affected by both new and old world forms, but severe damage may occur to soft tissues if the condition is untreated. Oestrus ovis is known as the sheep screw worm or sheep nasal botfly. It is found in the “old world,” mainly in the Middle East and Central Asia, although it is now reported wherever sheep are raised commercially. The usual hosts are sheep and goats, but occasionally man can be affected. A 29-year-old man was resident in the Republic of Cyprus as a member of the British Forces. One afternoon he drove to a local beach where he spent several hours sunbathing and swimming prior to returning to his base.That evening he reported to his local Medical Center with an irritation of his right eye. O n examination, he was found to have a severe conjunctivitis with marked associated 1acrimation.A small white foreign body was noted to be embedded in the cornea. It resisted attempts to wash it out. Finally the cornea was anesthetized, and the foreign body extracted.The patient’s

Population Genetics and Gene Variation in Secondary Screwworm (Diptera: Calliphoridae)

Allozyme variation in 4 populations of secondary screwworm, Cochliomyia macellaria (F.), representing North, Central, and South America was examined. Variability was observed in 12 of 13 enzyme loci, and the frequency of the most common allele was <0.95 for 6 loci. Observed and expected heterozygosities were 0.149 and 0.154, respectively. Nei's genetic distances were ≤0.001. Goodness-of-fit statistics for Hardy Weinberg equilibrium and Wright's F IS statistics indicated random mating within populations. Wright's F ST statistics and chi-square contingency analyses indicated homogeneous gene frequencies among the populations. These data suggest that C. macellaria is a panmictic species with high levels of gene flow between populations.

Genetic variability in mitochondrial DNA of the screwworm,Cochliomyia hominivorax (Diptera: Calliphoridae), from Brazil

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) was used to examine genetic variation and population structure of screwworm flies in four populations from São Paulo State, Brazil. The total DNA of 405 individuals was digested with 15 restriction endonucleases and probed with five cloned HindIII fragments representing the entire mitochondrial genome of Cochliomyia hominivorax. The survey revealed that four enzymes (HaeIII, HindIII, MspI, and PvuII) were suitable to detect mtDNA variation among all populations. Based on the fragment patterns obtained for these four enzymes, a total of 15 haplotypes in combination was detected. Heteroplasmic individuals for the PvuII pattern were obtained in one of the populations. The estimated average for nucleotide sequence divergence (delta) was 0.92%. The cladogram of the geographical distribution among the observed haplotypes suggests that the sampled screwworms probably belong to a single evolutionary lineage with populations interconnected by reduced gene flow.

Dispersal of the Old World screw‐worm fly Chrysomya bezziana

Dispersal of the Old World screw-worm fly, Chrysomya bezziana Villeneuve, was studied in Papua New Guinea by releasing radio-isotope labelled, laboratory-reared flies and collecting their labelled egg masses from sentinel cattle. A log-linear model was developed to describe recapture rate. Distance was found to dominate the model and was represented by a bilinear ('broken-stick') term as log-distance. Further terms in the model such as attractiveness of the site (estimated from the number of non-labelled egg masses), the season of the year and a time trend were statistically significant but of minor importance. From the model, the median distance females dispersed before depositing an egg mass was 10.8 km. The maximum distance from the release site that egg masses were recovered was 100 km. The dispersal ability of C. bezziana is discussed in terms of its impact on the prospects of eradicating this species using SIRM if an outbreak occurred in Australia.