Showing papers on "Lucilia cuprina published in 1995"

Genotype, environment and the asymmetry phenotype. Dieldrin-resistance in Lucilia cuprina (the Australian sheep blowfly)

Abstract: Dieldrin-resistant (Rdl/Rdl and Rdl/+) and susceptible (+/+) phenotypes of Lucilia cuprina were scored for departures from bilateral symmetry for bristle characters after development at different temperatures, larval densities or concentrations of dieldrin. The asymmetry phenotype of resistant flies was dominant and independent of developmental temperature and larval density. The asymmetry of susceptibles increased for temperatures and larval densities above and below standard rearing conditions. A positive correlation was observed between asymmetry score and dieldrin concentration for all genotypes. The susceptible phenotype did not attain the asymmetry score of resistant in any environment. Resistant phenotypes showed an antisymmetric pattern in each environment; fluctuating asymmetry was observed for susceptibles. The relevance of the results of genetic and general or specific environmental stresses to estimates of developmental perturbation is discussed.

Large-scale trapping of sheep blowflies in the northern North Island of New Zealand using insecticide-free traps

Abstract: Large-scale trapping of sheep blowflies (Diptera: Calliphoridae) was undertaken on a mixed farming property in the north of the North Island of New Zealand over 3 consecutive summers. Traps were placed at a density of 1 trap110 ha and baited with fresh sheep offal every 2 weeks. No insecticide was used in the 150-L traps. The most effective bait trialled was sheep offal <2 weeks old. There was no significant effect of trap colour or trap site on the number of blowflies caught. A 95% decline in the principal flystike blowfly, Lucilia cuprina, was recorded. Flystrike incidence at the site was low during the study so that the effect of trapping on sheep myiasis could not be determined.

Orientation by gravid Australian sheep blowflies, Lucilia cuprina (Diptera: Calliphoridae), to fleece and synthetic chemical attractants in laboratory bioassays

Abstract: Gravid females of Lucilia cuprina (Wiedeman) in a laboratory cage orientated positively to samples of fleece. Newly-wetted fleece was significantly more attractive than dry fleece, an effect resulting from the action of water on the fleece and not just addition of water vapour to the volatile fleece kairomones. Fleece contaminated with serous exudate, resulting from myiasis by L. cuprina, was much more attractive than wet, uncontaminated fleece from the same sheep. Kairomones from wetted fleece consistently augmented the attractive effects of 2-mercaptoethanol and indole in separate experiments, and of hydrogen sulphide (released from saturated aqueous sodium sulphide solution) in one trial out of three, but not overall. It is suggested that volatile fleece kairomones play a part in eliciting orientation to sheep by gravid L. cuprina. Fleece kairomones may augment the efficacy of kairomones released by putrefactive conditions in the fleece, which are known to predispose sheep to fly strike. They may also provide an input which helps to retain L. cuprina populations in the sheep's peridomestic precinct.

The effects on genetic variability following a recent colonization event: the Australian sheep blowfly, Lucilia cuprina arrives in New Zealand

Abstract: The Australian sheep blowfly, Lucilia cuprina, was first identified in New Zealand in 1988 and is now found to have spread throughout many sheep-farming regions. L. cuprina is estimated to have been present in New Zealand 100 years. The aim of this study was to determine the genetic effects of colonization of L. cuprina and to compare populations of L. cuprina from these two countries in terms of genetic variability and differentiation. Allozyme electrophoresis was used which revealed variability at six loci. 1680 blowflies were examined from 56 sites throughout L. cuprina's range in both countries. Genetic variability at each locus in terms of allele composition was found to be high and genetic differentiation varied considerably in New Zealand in comparison to Australia. Temporal sampling in New Zealand suggests seasonal fluctuations of population size in the recently colonized region of the South Island.

Digestion of ovine immunoglobulin G in larvae of the sheep blowfly Lucilia cuprina.

Abstract: Larvae of the sheep blowfly Lucilia cupn‘na (Wied.) (Diptera: Calliphoridae) ingest antibodies when feeding on a host sheep or artificial diet containing sheep blood serum (Eisemann et al., 1993). Most proteolysis of ingested immunoglobulin (Ig) apparently occurs in the anterior half of the midgut (Eisemann et al., 1993). The precise location of this proteolysis is relevant to an existing programme of developing a vaccine to protect sheep against blowfly strike using the ‘concealed antigen’ approach (Willadsen et al., 1993). The site and completeness of antibody digestion will determine the extent of exposure of gut structures to ingested functional antibody, and hence the feasibility of vaccination with antigens from these structures. In this paper we report an investigation of the precise location and course of proteolysis of ingested ovine immunoglobulin G (IgG) in third-instar larvae of Lxuprina, and of the resulting distribution of functional intact and fragmented IgG in the midgut. Larvae of L.cuprina were grown to advanced third instar on a diet medium containing 75% (v/v) normal sheep serum (NSS) (Eisemann et al., 1993). They were then transferred to a second medium containing sheep anti-horse myoglobin serum in place of NSS plus 0.5% (w/v) dextran (Mw = 500,000) labelled with fluorescein isothiocyanate (FITC) (Eisemann et al., 1993), and allowed to continue growing for a further 5 h at 34’C. to reach a mean weight of approximately 30mg. Feeding larvae were removed from the medium and immediately dissected in protease inhibitor buffer (Eisemann et al., 1993). The gut was removed and divided by the method described in Eisemann et al. (1993). except that the crop and hindgut were discorded and the midgut divided at the anterior and posterior boundaries of the middle (pale) region (Eisemann et al., 1993), thereby separating it into anterior, middle and posterior regions. These three segments differ in the pH ranges of their contents: 7.4-7.6, 3.3-3.6 and 7.6-8.0 for the anterior, middle and posterior segments, respectively (Waterhouse, 1940). Midgut segments of each kind from thirty larvae were pooled separately in inhibitor buffer and a total of three such pools of each kind were collected. Similar pools were

Elevated In Vitro Monooxygenase Activity Associated with Insecticide Resistances in Field-Strain Larvae of the Australian Sheep Blowfly (Diptera: Calliphoridae)

Abstract: Monooxygenase activity (aldrin epoxidation) was measured in microsomal preparations from 51 samples of the Australian sheep blowfly, Lucilia cuprina (Wiedemann), received by this laboratory over the period of a single blowfly season (August 1992-May 1993). Aldrin epoxidase activity varied over a 74-fold range and was significantly correlated with resistance to diazinon; however, we observed no correlation between enzyme activity and cypermethrin toxicity. Field strains displaying some tolerance of diflubenzuron (currently being developed for blowfly control) showed significantly higher aldrin epoxidase activities. Enzyme activity decreased rapidly in subsequent laboratory-reared generations of 4 strains initially showing enhanced activities. However, high levels of activity were maintained over 11 generations in a strain that initially showed high activity. The correlation between diazinon resistance and aldrin epoxidation suggests that the monooxygenase system may contribute to diazinon resistance in addition to the carboxylesterase-mediated resistance mechanism which is the basis of organophosphorus resistance in this species. The enhanced enzyme system present in some field strains appears to provide larvae with some tolerance of diflubenzuron despite no previous exposure to this insecticide.

Induced Insecticide Tolerance in Larvae of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) Following Dietary Phenobarbital Treatment

Abstract: Insecticide tolerance in the Australian sheep blowfly, Lucilia cuprina, was examined using an enzyme-induction approach. the effects of dietary phenobarbital administration on detoxification-enzyme activities and insecticide tolerances were measured using first and second instars. the LC50 of butacarb to blowfly larvae increased 85-fold following phenobarbital treatment. Tolerance to diazinon and diflubenzuron also increased considerably, with LC50s 12- and 8-fold higher, respectively. Tolerance to deltamethrin only increased slightly (1.4-fold). the degrees of tolerance towards butacarb and diazinon increased with increasing concentrations of phenobarbital in the larval diet. Phenobarbital-treated larvae showed significantly enhanced cytochrome P450 levels relative to controls. Aldrin epoxidase, P450 reductase and glutathione transferase activities were enhanced 168-, 1.7- and 2.2-fold, respectively, in treated larvae. the induced monooxygenase and glutathione transferase systems appear to equip the larvae with the ability to degrade increased amounts of various types of insecticides.

Do Australian Sheep Blowflies, Lucilia Cuprina (Diptera: Calliphoridae), Breed in Either Goat or Sheep Carcasses in a Semi-Arid Environment?

Abstract: Feral goat and sheep carcasses were exposed to insect attack on semi-arid pastoral land each month for one year. The native calliphorids Chrysomya rujifacies and Ch. varipes were by far the most abundant species de.veloping in virtually all carcasses. Sheep blowflies (L. cuprina) were incapable of developing from egg to adult on either feral goat or sheep carcasses during any month. Bush flies (Musca vetustissima) emerged from both feral goat and sheep carcasses from January to May, particularly from the gut contents. Chrysomya species were trapped in all months except June, whereas L. cuprina adults were only trapped from September to December. L. cuprina and Ch. rujifacies adults are very similar in appearance, hence many pastoralists assume that green blowflies on feral goat carcasses are sheep blowflies. However, this study clearly shows that L. cuprina are unable to complete their life cycle on either feral goat or sheep carcasses in the semi-arid environment of Carnarvon, Western Australia.

Influence of Trap Height on Catches of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) in Wind‐Oriented Fly Traps

Abstract: Catches of the Australian sheep blowfly, Lucilia cuprina, were compared in wind oriented traps operated at heights of 0.5, 1.0, 1.5 and 2.0 m above ground. Numbers caught at 0.5 m were significantly lower than the rest. Female catches were significantly higher than male catches, but sex ratios and female age compositions were similar for catches at all heights. Traps that were operated without baits failed to catch any L. cuprina irrespective of whether or not the traps were seeded with adults of both sexes. Total catches of L. cuprina in baited traps were unaffected by seeding the traps with live adults.

Subspecies of the Australian green blowfly (Lucilia cuprina) recorded in New Zealand.

Abstract: Extract The insect fauna of New Zealand comprises both native and exotic species Some of the exotic species are a cause for concern to this country's livestock industryp(l) Over the years, many exotic species of insect, mite or other animals have been intercepted at New Zealand ports, airports and Customs parcel offices and these findings were recorded by the Ministry of Agriculture and Fisheries (MAF)p(2)(3)(4)(5) Since the last publication of these findings in 1984p(5), a fourth species of myiasis-initiating blowfly (Calliphoridae) Lucilia cuprina (the Australian green blowfly) has been identified and has established in both the North and South islandsp(6)(7) A taxonomic review of the New Zealand Calliphoridaep(8) had indicated that L cuprina was not present in New Zealand insect collections and unlikely to establish, but it was recognised as a species that may be encountered by officials at points of entry into the country How L cuprina entered New Zealand is unknownp(1), as is its coun

Do protein‐limited female Lucilia cuprina (Diptera: Calliphoridae) obtain a nutritional benefit from mating?

Abstract: . Cohorts of adult female Lucilia cuprina Wiedemann (Diptera: Calliphoridae) were fed a single 5 μl droplet of liver exudate after which half the females were allowed to mate and the other half left as virgins. Females were housed individually with water and sucrose for between 4 and 7 days after mating. Females were dissected to record the level of ovarian development and the size of their primary oocytes. Mating did not give protein-limited females any significant nutritional benefit in terms of either increased oocyte development, yolk deposition or oocyte size. Hence, it is concluded that male L.cuprina do not provide females at mating with any obvious material benefits beyond their sperm.

Susceptibility to Ivermectin of Pyrethroid-Resistant Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

Abstract: The susceptibility to iverniectin of a highly selected pyrethroid-resistant laboratory strain of the Australian sheep blowfly Lirciliu cuprina was assessed in a paper-serum bioassay and compared with an organophosphate-resistant field strain and a laboratory-susceptible strain. While the pyrethroid-resistant strain has a resistance factor of > 3000-fold to deltamethrin, ivermectin was only 2.5-fold less toxic to this strain than it \%as to the other two strains. These results indicate that pyrethroid resistance is unlikely to affect the larvicidal activity of ivermectin in L. cuprina.

Changes to diazinon resistance frequency in the Australian sheep blowfly, 'Lucilia cuprina' (Wiedemann) following laboratory selection with insecticides

Abstract: Populations of susceptible (+/+) or organophosphate (OP) resistant (2R/+; R/R) 'Lucilia cuprina' were selected each generation by exposure of larvae to diazinon, propetamphos, butacarb or deltamethrin. The groups responded to these treatments by becoming increasingly tolerant of the selecting insecticide. There was a corresponding increase in resistance to diazinon in the propetamphos and butacarb-selected groups, but not in the deltamethrin-selected population. When compared to trends in the untreated control group, there was a significant decline in the frequency of OP-susceptible adult blowflies in the diazinon-, propetamphos-, and butacarb-selected groups, but the susceptible genotype frequency remained unaffected in the deltamethrin-selected population. These results have implications for how insecticide resistance management strategies for sheep ectoparasites should be developed.