Showing papers on "Lucilia cuprina published in 1987"

Phenoloxidases from larval cuticle of the sheep blowfly, Lucilia cuprina: Characterization, developmental changes, and inhibition by antiphenoloxidase antibodies

Abstract: A tyrosinase, enzyme A (EC 1.10.3.1, o-diphenol: O2 oxidoreductase), and a laccase, enzyme B (EC 1.10.3.2, p-diphenol: O2 oxidoreductase), have been partially purified and characterized from larval cuticle of the sheep blowfly, Lucilia cuprina. Enzyme A is active toward a range of o-diphenols but not p-diphenols, is strongly inhibited by thiourea and phenylthiourea, has a pH optimum between 6.5 and 7.0, and yields a single, 60,000 molecular weight subunit following SDS gel electrophoresis. Enzyme B is active toward both o-diphenols and p-diphenols, is only slightly inhibited by phenylthiourea, has a pH optimum near 4.5, is highly thermostable, and has an apparent molecular weight of 90,000. Enzyme A appears to be activated from an inactive proenzyme in the cuticle and to be present throughout the wandering phase of the final larval instar, declining at pupariation. Enzyme B is present in active form, increases greatly in the cuticle just at the time of pupariation, and then decreases as sclerotization occurs. Antibodies against enzyme A have been raised in sheep and rabbits, and against enzyme B in rabbits, but diets containing antiphenoloxidase antibodies did not affect development or mortality of fly larvae.

Diazinon resistance in Lucilia cuprina ; mapping of a fitness modifier

Abstract: Modification of the fitness of diazinon resistance genotypes of the Australian sheep blowfly, Lucilia cuprina, in the absence of the insecticide from SS > RS > RR to SS = RS = RR (McKenzie et al., 1982) has been shown previously to be due to the segregation of a gene(s) on chromosome III (McKenzie and Purvis, 1984). In this study the gene (gene complex) is mapped to the w locus region of that chromosome by comparing changes in frequency of SS individuals in population cages initiated with RS genotypes segregating for field derived regions of chromosome III. Comparison of percentage egg hatch, the percentage of first instar larvae reaching adulthood and the time of development from egg to adult for combinations of modifier and resistance genotypes show that the modifier affects only the latter. Developmental time is decreased for RS and RR genotypes. The effect is dominant. The developmental time of SS genotypes is unaffected by modifier genotype.

The origin of sheep blowfly, Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae), attractants in media infested with larvae

Abstract: Laboratory bioassays with gravid females of Lucilia cuprina (Wiedemann) were used to isolate the source(s) of olfactory attractants emanating from larvae-infested media. Adults were not attracted by odours from axenic (micro-organism-free) larvae, but volatiles from xenic larvae were highly attractive. The attractants proved to be kairomones not pheromones, as odours from other species of calliphorids and a sarcophagid species were also attractive. Axenic, proteinaceous media produced a low level of attractive volatiles, which was increased by the activities of axenic larvae growing on the media. A greater degree of attraction occurred to odours from xenic media, and this too was much increased by the actions of growing larvae. The order of attractiveness of such volatiles is therefore: xenic with larvae >> xenic without larvae > axenic with larvae > axenic without larvae. It is concluded that larvae-infested media owe their great attractiveness to the volatiles produced by the action of micro-organisms, not to specific larval volatiles. Larval activity accentuates the output of attractive volatiles from both xenic and axenic proteinaceous media, possibly due to the effects of digestive enzymes, pH changes, mechanical mixing, warming or aeration or a combination of some or all of these factors.

Naturally occurring arrhythmicity in eclosion and activity in Lucilia cuprina: its genetic basis

Abstract: . Colonies of wild-type Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) in our laboratory differed greatly in the degree of rhythmicity of their eclosion when exposed to light/dark cycles, constant darkness or constant light. Among colonies reared in the laboratory for thirty-four to eighty-eight generations and others for more than 360 generations, some were consistently rhythmic, others weakly rhythmic and others arrhythmic. One colony with arrhythmic eclosion was studied further. Arrhythmicity of eclosion in the colony was found to result from homozygosis of a recessive allele (ary) on chromosome 5. Adults from this colony were arrhythmic in spontaneous flight activity under constant darkness though rhythmic under light/dark cycles.

Chromosomal localization of the white gene of Lucilia cuprina (Diptera; Calliphoridae) by in situ hybridization

Abstract: The white gene of Lucilia cuprina was mapped to trichogen polytene chromosomes using in situ hybridization. A tritium-labelled riboprobe made from the first gene cloned from this species was used with techniques modified from standard methods used for Drosophila melanogaster. Cytological data limiting the location of the white gene to a small portion of 3L and complementing the in situ results are also presented. Key words: Lucilia cuprina, white gene, in situ hybridization.

Density independence of survival in myiasis breeding of Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

Abstract: Survival, size and development time were measured for larvae of Lucilia cuprina (Wiedemann) reared in artificially induced strikes on sheep. Between 477 and 18 000 eggs or larvae were implanted in the fleece of 42 sheep. Survival was found not to depend significantly on implant numbers. Size and development time were significantly but only weakly dependent on implant numbers. These results contrast markedly with L. cuprina's performance on carrion.

Genetic architecture and adaptation: quantitative analysis of sheep and refuse tip populations of the Australian sheep blowfly, Lucilia cuprina.

Abstract: Phenotypic differentiation between geographic areas and between sheep and adjacent refuse tip populations was assessed by quantitative analysis of population samples of L. cuprina from New South Wales (Lismore) and Victoria (Mansfield). In addition the genetic structure of populations has been defined and compared by biometrical analysis techniques. For all morphological and fitness characters examined significant phenotypic differentiation was observed both between geographic localities and between sheep and non-sheep populations of each locality. Diallel analysis of the populations revealed architectural differences between sheep and non-sheep populations for both fecundity and egg hatchability. Sheep populations only, regardless of locality, displayed dominant gene effects on these fitness traits. The results suggest that refuse tip populations may be other than transients and that the differentiation may reflect differing patterns of adaptation and history of selection of the populations. The relevance of such differentiation to the successful establishment of a chemical and/or autocidal control zone is considered.

The effects of competition and larval habitats on populations of the Australian sheep blowfly Lucilia cuprina (Wiedemann)

Abstract: The effects of competition on Lucilia cuprina wiih particular reference to the success of this species in carrion breeding in Tasmania was investigated. The spatial and temporal interaction of the necrophagous fly guild was studied in the main sheep raising areas of the state, and laboratory studies were used to examine the effects of larval competition on life history parameters. The field study showed that Chrysomya rufifacies and Chrysomya varipes had a restricted distribution both geographically (occuring in the northern and central areas of the state) and seasonally (first occurrence being usually in mid- to late summer). This was thought to have particular significance to the success of L. cuprina breeding in carrion as the presence of these species tends to supress the number of its larvae emerging from carrion. A series of carrion experiments were designed to assess the success rate of L. cuprina breeding in the presence and absence of Ch. rufifacies. It was found that in the absence of Ch. rufifacies some L. cuprina were seen to emerge from carrion. The temperatures generated within a carcass were monitored and although high temperatures were generated they were within the thermal tolerance of L. cuprina. There was no correlation between the abundance of species emerging and the abundance of species trapped adjacent to the carcasses. The fine scale distribution of L. cuprina was found to be highly correlated with the presence of both live sheep and sheep carcasses. It had a strongly clumped distribution with several strong nodes of abundance within the trapping area (1km\(^2\) of sheep pasture). All of the other species studied showed a high correlation with sheep carcasses but not with live sheep. Laboratory studies were conducted to simulate competition in both carrion and myiasis. These studies showed that L. cuprina had a considerable capacity for compensating preadult mortality by sacrificing adult size. In artificial carrion, adult size and mortality (preadult and adult) were found to be related to the initial larval density. Development rates were generally increased with decreased adult size. Induced myiasis using a range of larval densities showed that adult size and preadult mortality were independent of initial density. Flies emerging from the induced myiasis experiments were in the larger range of adult sizes. Flies emerging, from the artifidal carrion experiments covered the whole range of adult sizes. This observation led to the analysis of the field population for size related effects of competition. It was suggested that the general size distribution of flies was related to the alternative larval habitats. Using this general rule it was concluded that at least 18% of the field population studied originated from conditions of high larval densities and therefore, probably from carrion breeding. This conclusion was supported by the observation that the size distribution of adult L. cuprina emerging from carrion reflected high larval densities. A high proportion of the population was found to be resorbing eggs and this was assumed to indicate a severe shortage of suitable oviposition sites. A major study of the size and age composition of the field populations of L. cuprina was done in the hope that useful data relating to the characterisation of cohorts could be found. This work was largely unsuccessful due mainly to inherrent errors in the aging technique. A simple simulation model was constructed to assess the affects of larval competition on the reproductive fitness of the adult population. This showed that potential reproductive fitness increased with increased competition (and consequently decreased adult size). This result demonstrated that competition occurring in carrion may increase the reproductive potential of the flies emerging, although other factors such as mobility (and thus the probability of a successful oviposition) may be reduced. It was concluded that factors other than adult size (such as number and reproductive potential) should be considered when assessing the contribution of carrion breeding to the persistence of L. cuprina populations.