Cochliomyia Research Articles

Adaptation of climex for spatial screwworm fly population dynamics

Adaptation of climex for spatial screwworm fly population dynamics

Cuticular hydrocarbons of the Old World screw-worm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae). Chemical characterization and quantification by age and sex

Abstract 1. 1. The cuticular hydrocarbon compositions of newly emerged male and female C. bezziana are similar and comprise mainly alkanes. 2. 2. As the flies age the relative proportions of hydrocarbons change and sex differences increase. 3. 3. Much of the change has occurred by day 3 and there is little further modification after day 5. 4. 4. The hydrocarbon compositions of immature stages differ markedly from those of the adults. 5. 5. Newly emerged C. bezziana flies represent the most suitable age for studies on genetic variability on hydrocarbon composition.

Responses of female New World screwworm flies, Cochliomyia hominivorax, to swormlure-4 in the laboratory.

The behaviour of 4-day-old virgin female New World screwworm flies Cochliomyia hominivorax Coquerel was investigated in a wind tunnel using video. Addition of the screwworm attractant swormlure-4 to the airstream resulted in an increase in the number of take-offs and in the duration of flight. In the presence of swormlure-4 the flight speed decreased and the rate of turning increased. Take-off was significantly orientated upwind during the period when swormlure-4 was added to the airstream, and significantly orientated downwind in the period after the addition of swormlure-4. The possible means by which this species finds a point source of odour in the field are discussed and compared with the mechanisms used by other flies.

Incidence of Old World screw-worm fly in the United Arab Emirates.

Incidence of Old World screw-worm fly in the United Arab Emirates.

The New World screwworm fly in Libya: a review of its introduction and eradication.

The New World screwworm fly, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), became established in the Old World for the first time during 1988, in the Socialist People's Libyan Arab Jamahiriya. An obligate parasite of mammals in its larval stages, causing wound myiasis, it is one of the most serious insect pests of livestock in the Americas. To avert a major disaster for the livestock industry and wildlife of Africa and southern Europe, the Libyan Government and the Food and Agriculture Organization of the United Nations launched a massive screwworm eradication programme, based on the sterile insect technique, SIT. An initial containment operation involved veterinary teams working in the infested area (25,000 km2 around Tripoli), regularly inspecting livestock and, if necessary, treating them with insecticide. Quarantine stations were also set up, to prevent the movement of infested livestock out of the area. Sterile flies from the Mexican-American Commission for Eradication of Screwworms were first released in December 1990 at the rate of 3.5 million per week. This built up to 40 million per week by May 1991. The release of sterile flies was terminated on 17 October 1991, 6 months after the last detected case of screwworm myiasis in Libya. Intensive surveillance and quarantine activities will, however, continue through 1992. During 1992 the Libyan Government should be able to officially declare the New World screwworm eradicated from Libya, making it one of the most important success stories of pest control.

Genetic variation in the Old World screw-worm fly,Chrysomya bezziana(Diptera: Calliphoridae)

AbstractThe Old World screw-worm fly,Chrysomya bezzianaVilleneuve, occurs in Africa, the Middle East, Malaysia, Indonesia and Papua New Guinea, but it is not found in Australia. Introduction into Australia from any of these source areas would threaten the viability of much of the grazing industry in the northern part of the continent. Proposed control by the sterile insect release method (SIRM) would be compromised by the existence of sibling species withinC. bezziana.This study examines the degree of genetic differentiation throughout the extensive range of the fly to assess if the degree of geographic differentiation indicates the existence of sibling species and, allows identification of the source of any introduced flies. Electrophoretic analysis of 23 loci from samples collected in southern Africa, the Middle East, Malaysia, Indonesia, and Papua New Guinea revealed 11 polymorphic loci. Overall, populations show remarkably little divergence given the geographic distribution of sample sites. None of the populations sampled were fixed for alternative electromorphs. There is no evidence from this study for the presence of sibling species withinC. bezziana.

Influence of Attractants on Behavior of Screw worms (Diptera: Calliphoridae) in a Tropical Wet Forest in Costa Rica

In a mark-release-recapture study, sheep wounds and rotted liver were used as attractants to study movements of the screwworm fly, Cochliomyia hominivorax (Coquerel), in a Costa Rican tropical wet forest in the wet season. When sites were monitored for less than 1 h, liver attracted between 3 and 12.2 times more flies of both sexes than did wounds, but proportionately fewer gravid and parous females. Only 24.6% of females marked at liver sites were recaptured; seldom (3.1%) did they visit sheep wounds. Females originally marked at sheep wounds remained at the study site longer, visited both sheep and liver sites, and greater than 50% were recaptured. Some females were observed for 16 d and one laid four clutches of eggs. Only 8% of the marked males were recaptured and none was recaptured less than 2 d later. Only a small proportion of the adult screwworms at a locality visited wounds on sentinel sheep; the majority of the adults were transient.

The efficacy of insecticides against the screw‐worm fly (Chrysomya bezziana)

A number of insecticides used for ectoparasite control in the livestock industry were screened for their efficacy against larvae of the screw-worm fly, Chrysomya bezziana, using in vivo and laboratory tests. Proprietary screw-worm fly treatments (after exposure to outdoor conditions for up to 10 days) were also tested against eggs and adults of C bezziana. Three of these were also evaluated on naturally acquired screw-worm infestations. Residual protection was generally of short duration. Among the organophosphorus compounds, the most effective formulations contained relatively high concentrations (3 to 4% al) of coumaphos, 2.5% fenchlorphos or low concentrations (0.05 to 0.5% al) of diazinon, chlorfenvinphos and fenthion methyl. Two chlorinated hydrocarbon insecticides containing 3% lindane and 5% dieldrin were very effective but are now prohibited for use in Australia. Preparations had serious deficiencies when used under field conditions, especially for treating large, deepseated myiases for which systemic insecticides are recommended. A comparison of methods demonstrated that a laboratory test could supersede live animal experimentation, at least for the initial screening of potential insecticides.

Alternative to Sentinel Animals for Collecting Egg Masses from Wild Females of the Screw worm (Diptera: Calliphoridae)

Egg masses from wild populations of the screwworm, Cochliomyia hominivorax (Coquerel), were obtained by collecting females from rotted liver, holding them for 3 d until egg maturation and then placing them on heated ground beef for oviposition. Nearly 50% of the females oviposited. Fertility of egg masses was 66 and 95% at the two collection sites. Decreased fertility was associated with collections of virgin females. Average weight +/- SD of the egg masses was 13.7 +/- 1.40 mg; the number of eggs per mass averaged 343. This method of obtaining egg masses from wild screwworm females is a cost-effective, sensitive alternative to the use of sentinel animals in the field. The use of rotted liver costs less, takes less time, and takes less equipment than the traditional sentinel animal technique.

Report on a sterile insect release trial for the control of the Old World screw-worm fly Chrysomya bezziana in Papua New Guinea

Australian Veterinary JournalVolume 68, Issue 8 p. 277-279 Report on a sterile insect release trial for the control of the Old World screw-worm fly Chrysomya bezziana in Papua New Guinea GM CLARKE, GM CLARKE DPIE/CSIRO Screw-Worm Fly Unit, PO Box 6712, Boroko, Papua New Guinea *CSIRO Division of Entomology, PO Box 1700, Canberra City, Australian Capital Territory 2601Search for more papers by this author GM CLARKE, GM CLARKE DPIE/CSIRO Screw-Worm Fly Unit, PO Box 6712, Boroko, Papua New Guinea *CSIRO Division of Entomology, PO Box 1700, Canberra City, Australian Capital Territory 2601Search for more papers by this author First published: August 1991 https://doi.org/10.1111/j.1751-0813.1991.tb03243.xCitations: 3 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume68, Issue8August 1991Pages 277-279 RelatedInformation

Field Comparisons of Attractants for the Screw worm Fly (Diptera: Calliphoridae) in a Tropical Dry Forest in Costa Rica

Field trials were conducted to determine the best attractant for adults of the screwworm, Cochliomyia hominivorax (Coquerel), in Costa Rica. The five attractants were wounded sentinel sheep, decayed fruit, rotted beef liver, rotted fish, and medium used to rear larvae of this blow fly. Significantly more adults came to rotted liver than any other attractant. No adults were captured in traps baited with rotted fruit. Significantly more males came to beef liver than were captured at other baits; males were rarely encountered at wounds. Ovarian development of females obtained with different attractants indicated that proportionally more gravid females visited wounded animals than were caught in traps with proteinaceous baits. Most females had mated by egg stage five and mating and and parity in the populations that visited different attractants were similar. Significantly more females (81%) marked initially at wounds returned to wounds than visited traps baited with liver or fish.

Cytological characterisation of heterochromatin in mitotic and meiotic chromosomes of the Old World screwworm fly, Chrysomya bezziana (Diptera: Calliphoridae)

Mitotic and meiotic chromosomes of the Old World screwworm fly, Chrysomya bezziana, were studied using C-banding and quinacrine and counterstain-enhanced fluorescence techniques. The five autosomes in the karyotype are evenly graded in size, with somewhat variable arm ratios. Distinguishing all autosomes on these features alone can be difficult. C-banding produces small centromeric bands in the autosomes, whereas the much longer X and Y chromosomes have extensive dark C-band blocks with intermediate background staining. Most bright fluorescence occurs in the sex chromosomes, particularly the X chromosome, which has remarkable banding detail. Band resolution is greatly increased in mitotic metaphase cells from embryos. Quinacrine staining of mitotic chromosomes produces bright fluorescence at the centromere regions of chromosomes 2, 3, and 4, assisting in their identification. Meiotic chromosomes have distinctly reduced brightness and resolution of fluorescent bands and show marked chromatid asynapsis in the brighter regions of the sex chromosomes. Fluorochromes staining A.T-rich DNA (quinacrine and 4,6-diamidino-2-phenylindole (DAPI) produce bright staining in a large proportion of the sex chromosomes. By contrast chromomycin, which binds preferentially to G.C-rich DNA, stains a much smaller proportion of the sex chromosomes than expected from reciprocal staining. Together with the asynapsis data this indicates that much of the heterochromatin in the sex chromosomes has unusual structural properties.

The new world screwworm fly in North Africa: implications and eradication plans

The New World screwworm fly, Cochliomyia hominivorax Coquerel, arrived in North Africa in 1987, and infests about 25 000 km 2 around Tripoli, Libya. Thousands of livestock animals and over 30 humans have been infected. It is possible that the fly might spread to the rest of Africa, southern Europem and the Middle East unless it is eradicated; consequences to livestock, wildlife, and humans would be devastating. This paper describes implications associated with the presence of screwworms in North Africa, and activities prior to the use of sterile male release technology for eradication.

Ecological consequences of atmospheric and climate change

The ecological outcome of atmospheric and climate change will depend on the rate of such change relative to the rate at which the biota can respond. Change in community structure and composition, and in landscapes and soils, will mostly come about through changes in the frequencies of extreme events. Much of the Southern Hemisphere has incomplete vegetative cover and landscape dynamics (horizontal redistribution of water and nutrients) is a primary ecological determinant which will be significantly altered under a shifting rainfall regime. Predicting vegetation change requires resolving the problems of lag effects, extreme events, the direct effects of increased CO2, secondary effects (e.g. changed fire regimes) and interactive effects of spatial variation. Some Southern Hemisphere examples are presented. Changes in fauna will depend mostly on changes to habitat. In the case of many invertebrate pest species, however, including disease vectors, an increase in minimum temperatures will have significant effects on their distribution and abundance (e.g. locusts, screw-worm fly, the cotton pest Heliothus, tsetse fly, malaria).

Oviposition by Screwworm Flies (Diptera: Calliphoridae) on Contact with Host Fluids

Factor affecting oviposition by screwworm flies, Cochliomyia hominivorax (Coquerel), contacting different host fluids were examined in a laboratory bioassay. Fresh bovine blood, which does not release the attractive odors involved in host finding, nevertheless stimulated as many or more females to oviposit than did the other fluids tested. These other fluids included attractive fluid from screwworm-infected wounds (a favored oviposition site in nature) and cultures of Providencia rettgeri (a bacterium implicated in attractant production). Oviposition did not vary with batch of fresh blood or frozen storage, making blood a useful standard for comparing oviposition rates among studies. Oviposition did vary with the substrate to which the blood was applied, suggesting that an interaction between tactile and chemical stimuli is important for host recognition. Both insemination and darkness during bioassay increased oviposition rates, but the magnitude of these effects was small compared with that due to substrate. Age had no effect for at least 1 wk after females became gravid.

Studies on the screwworm flyCochliomyia hominivorax in Libya: Effect of temperature on pupation and eclosion

The American screwworm fly Cochliomyia hominivorax has recently been reported in Libya (El-Azazy 1989). Fly larvae were cultured on blood agar at different temperatures (-5 degrees, 5 degrees, 18 degrees, 20 degrees, 30 degrees, 37 degrees, or 40 degrees C). Larvae pupated at 18 degrees, 20 degrees, 30 degrees, or 37 degrees C, and the highest pupation (100%) occurred at 20 degrees C. Adult flies emerged from pupae that were maintained at 18 degrees, 20 degrees, 30 degrees, or 37 degrees C; the maximal eclosion (94%) occurred at 20 degrees C. Correlation of these findings with meteorological temperature data from local areas in which C. hominivorax myiasis occurs suggests a crucial role for temperature in the determination of the effective environment for this fly species.

The New World screw-worm fly in North Africa

The course of the North African outbreak of New World screw-worm myiasis (Cochliomyia hominivorax) since its discovery in 1988 is described. Chemical and biological control measures are reviewed, including the current progress of the 'sterile male' (SIT) eradication programme.

The use of irradiated embryos of Chrysomya bezziana for the detection of the Old World screw‐worm fly

Irradiation of Chrysomya bezziana embryos 1 h before hatching with doses less than or equal to 7 kilorad (kr) had a significant effect on percentage egg hatch, weights and survival of larvae. Doses greater than or equal to 1 kr allowed larval development to the end of the 3rd instar stage in vitro, but prevented normal pupal development. Cattle with wounds infested with 1st instar larvae derived from irradiated embryos had 3rd instar larvae present after 3 d but these failed to pupate. Thus it would be feasible to use such larvae for wound infestation for the enhanced detection of screw-worm fly in areas where the release of fertile flies is undesirable.

Age-determination in the old-world screw-worm fly Chrysomya bezziana by pteridine fluorescence

Highly significant positive relationships were observed between pteridine fluorescence in the head and chronological age for both sexes of the old-world screw-worm fly Chrysomya bezziana Villeneuve in the laboratory and in field mark-release-recapture trials in Papua New Guinea. The relationships were multiplicative in form and, in most cases, age accounted for in excess of 80–90% of the variance in fluorescence. The rate of accumulation of pteridines with age was greater for males than females, was not affected by the absence or presence of protein in the diet, but was highly dependent on temperature. Pteridine levels appear to be a good indicator of age in this species and will enable the chronological age of wild flies to be determined with a relatively high degree of accuracy.

Observations on Dispersal of Sterile Screwworms (Diptera: Calliphoridae) in Relation to a Clear-Cut Utility Right of Way in Southern Mexico

Dispersal of ground-released sterile screwworm flies, Cochliomyia hominivorax (Coquerel), in relation to a clear-cut utility right of way was studied near Tuxtla Gutierrez, Chiapas, Mexico, during October and November 1984. Collection data from wind-oriented traps suspended below trees along the edge and along transects 150 m into the woods along both sides of the right of way indicated male and female flies exhibited the same dispersal patterns. Chi-square analysis of these data indicated that the right of way was not important as a flight corridor for screwworm flies. All traps caught flies, indicating dispersal in all directions from the release site. Man-made topographic features such as utility right of ways probably do not affect adult screwworm dispersal through wooded areas. Wind appeared to be a factor in dispersal patterns in that traps downwind collected significantly more flies than traps upwind