Chrysomya megacephala (Fabricius, ) occurs on every continent and is closely associated with carrion and decaying material in human. The Oriental Latrine Fly, Chrysomya megacephala Fabricius, , is notorious in this regard. Adults of the synanthropic form of this species (see below) are. Abstract. Chrysomya megacephala and Chrysomya rufifacies are two predominant necrophagous species in Taiwan. Larvae of the latter can prey on other.

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Chrysomya megacephala and Chrysomya rufifacies are two predominant necrophagous species in Taiwan. Larvae of the latter can prey on other maggots, including that of their chfysomya species as facultative food. This facultative characteristic of C.

In this study, these megacephxla species were colonized in the laboratory, and the main objective was to try to understand the effect of competition on larval development. According to our results, intraspecific competition mostly occurred as competition for food; when the rearing density was increased, larvae pupated earlier, resulting in a lighter adult dry weight.

The tendencies were similar in both species, but C. Our results also showed there were significant interactions between intraspecific competition and the density factor.

However, with interspecific competition, the first-instar larvae of C. The third instars of C. The results indicated that a temporary competitive advantage could only be obtained by C.

In addition, the effects on different larval stages, the responses to different competition intensities, and the temperature-dependent effects on interspecific competition are also discussed. In general, under mixed-species rearing at different temperatures and densities, larval duration, adult dry weight, and survivorship of both species decreased.

However, our results did not completely agree with previous studies, and we suspect that the difference was partially caused by different experimental designs and different biological characters of different blow fly colonies.

Our results also suggest that both the predation ability and defense chrgsomya escape activity should be taken into account when evaluating larval competitive advantages. In conclusion, competition decreased the larval duration of these two species by up to 2 d; this also draws attention to justifying the postmortem interval estimation of using larval developmental data when larval competition exists.

Developmental data of blowflies can be used to estimate the meegacephala postmortem interval PMInormally a few hours to a few days Catts and Goff However, there are many biotic and abiotic factors known to influence insect growth and activity, and determining these factors and their effects has been the most active area of research in forensic entomology Wells and Lamotte Biological factors, especially the behavioral factors of competition megacepuala predation, have nevertheless seldom been thoroughly discussed in previous studies.

Until now, only a few studies related to interactions between different species of blow fly larvae have been published; including interactions between native and introduced blowflies Wells and Greenberg ablarval predation Faria et al. The habitat or “ecological islands” of animal carrion are small and distinct, and communities developing within them have at their disposal a limited amount of energy, which is gradually used up by the activities of the community members Beaver The substrate of carrion is ephemeral, and flies that feed on it rarely complete more than one generation on a single carrion item Beaver ; so the number of eggs or larvae in carrion frequently exceeds its carrying capacity Kneidel So and Dudgeon have also shown that competition is an important factor influencing the structure of necrophagous dipteran communities.

Chrysomya megacephala Fabricius Oriental latrine fly and Chrysomya rufifacies Macquart hairy maggot blow flytwo predominant necrophagous species in Taiwan, are indigenous to the Australasian regions of the Old World tropics. These Old World blowflies of Chrysomya were also introduced to the Americas in the mids and quickly became widespread and abundant in North and South America Baumgartner and Greenberg According to our general survey in the Taipei area Chen et al.


This means that interactions caused by these two megaxephala primary fly species, such as competition and predation, may frequently play important roles in the successional dynamics of this early carrion faunal assemblage. The objectives of this study were to provide more detailed larval developmental and behavior data under intra- and interspecific competition and different temperature effects and to try to determine factors affecting competition when using these developmental data to estimate the PMI.

Laboratory colonies of larvae of C. Maggots were reared on an artificial diet consisting of a mixture of fish meal: Mature third instars were transferred onto sawdust for pupation.

Adult males were randomly sampled and identified 5 d after megacepnala for species megacephalz, and some males and females of the same species were kept in a cm 3 rearing cage for mating. Sugar water and a mixture of milk powder and sugar were provided as food for the adults. Pork liver was used to induce females to lay eggs. For all experimental purposes, larvae were moved out from the stock colony and kept in a ml plastic cup covered with cotton netting and containing 60 g of the artificial diet.

Because postfeeding larvae of C. The cup was inside a container 14 cm in diameter and The treatments were the same for C.

Developmental duration, survivorship, and adult dry weight were recorded for each treatment. Larval developmental duration is the time since egg hatching to pupation pupal stage not includedlarval survivorship is the success rate for pupation, and because the food and sawdust could be easily attached onto the surface of larvae or pupae to further cause measuring errors, adult dry weight was used instead as a parameter in this study.

For the mixed-species cultures, an equal ratio of larval numbers of the two species was placed in the same cup, and the experiments were performed at the same density and rearing condition as in the single-species culture. Two-way analysis of variance ANOVA was used to determine the combined effects of competition and larval density. To evaluate the effect of the intensity of interspecific competition, 40 larvae consisting of the two different species were kept in a ml plastic cup with 60 g of artificial diet and different species ratios of Larval developmental time and adult dry weight were recorded for each treatment.

Linear regression was used to determine the effects of different competition intensities on larval development. Temperature is one of the key factors affecting larval development. To understand the role that predation plays in larval competition, a simple experiment was designed to observe the predatory behavior of C.

Following the experimental design of Faria et al. Five larvae of the same instar stage from each species were placed into a ml plastic cup without food. Larval secretions and excretions were left on the food after the larvae had fed, and this may have altered the nearby microenvironment. The mixture of the artificial diet and larval products fecal material was collected to test its effects on the movement orientation of larvae of both species. Fecal material was respectively obtained by collecting the mixture of artificial diet after each instar larvae have fed rearing conditions: The fecal material 1 g from C.

Ten conspecific larvae of same stage 18 [first instar], 36 [second instar[rsqb, and 70 h old [third instar] were washed with distilled water and placed in the middle of the plastic cup.

The “bath” was to try to remove any “odor” of the larvae in advance. Movements of the three instars were recorded every 30 and 60 min. If more than six larvae were found to have aggregated at one end of the mixed diet, the orientation tendency was judged to be sustained and was recorded.


The larval developmental time of C. The maximum reduction was The developmental time of C. The maximum reduction time was Although maximum reductions in the time of larval development under density effects were similar in the two species, C. Effects of different breeding densities on the duration of larval development Aadult dry weight Band larval survivorship C under single-species rearing of C.

The adult dry weights of C. As for larval survivorship, the survivorship of C. The survivorships of C. The survivorship of C.

Similar results were also found for adult dry weight Fig. Effects of different breeding densities on the duration of larval development Aadult dry weight Band larval survivorship C of C. Pure, single-species culture; mixed, mixed-species culture. Competition generally reduced the larval developmental time and adult dry weight of C.

Chrysomya megacephala – Wikipedia

We used the product of the mean adult dry weight and the mean larval survivorship as indicators for the overall fitness of these flies; the results showed that the fitness levels of both species were lower under interspecific competition than under intraspecific competition and gradually decreased as mmegacephala densities increased Fig. The production is the value of the mean adult dry weight multiplied by the mean larval survivorship. Linear regressions of the adult dry weights of C.

As the competition intensity chrysomua, the adult dry weight megacepphala C. However, a linear regression of developmental rate versus competition intensities showed opposite results. Figure 6 shows that the larval developmental duration of C. Linear regression of the adult dry weights of C. Competition intensities are represented by the number of individuals of the different species; 10, 20, and 30 are the respective numbers of individuals of the different species in each treatment of megacephaala larvae total.

Linear regression of the durations of larval development of C. The developmental time was not affected by competition intensities in C. Competition intensities are represented as in Fig. Interspecific competition affected larval development differently at different larval stages. However, interspecific competition strongly changed the developmental duration of both the feeding and postfeeding stages of third instars of C.

In addition, interspecific competition did not chyrsomya the body length of most larval stages of either species Fig. Effects of single- and mixed-species rearing on the developmental times of first- second- and third-instar larvae including the feeding and postfeeding stages of C. Effects of single- or mixed-species rearing on the body lengths of first- second- and third-instar larvae of C.

Compared with the single-species cultures, the larval duration of mixed-species cultures were shortened by 4. Forty larvae per 60 g of medium were reared under five temperature treatments. Larval developmental time megacephaala adult dry weight of C. Results of two-way ANOVA showed the interactions between the two factors of interspecific competition and temperature were statistically significant in both species for C. Figure 10A shows the predation actions of a third-instar larva of C.

Observations also showed that a single C. Chrysomyx, predation of second instars of C. Larval predation of third instars of C.

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A Single third instar of C. B Several larvae usually work together until all of the body fluid of the prey has been sucked out. The experiment on movement orientation showed that blow fly larvae exhibit significant preferences in their movement tendencies toward fecal material. This test was performed for 30 and 60 min for both species; as the time increased to 60 min, C. The results also imply the invasion of maggot masses of C.