Primeros registros de cuatro especies de Calliphoridae (Diptera: Oestroidea) de Yucatán, México

La familia Calliphoridae es un componente integral de la estimación del intervalo post mortem (IPM) debido a su desarrollada capacidad para detectar la descomposición de cadáveres a grandes distancias y la habilidad para colonizarlos a diferentes temperaturas en diversas áreas geográficas. Se reportan cuatro primeros registros de la familia Calliphoridae para la entomofauna de Yucatán, México: Chrysomya putoria Wiedemann, Chrysomya rufifacies Macquart, Lucilia cuprina Wiedemanny y L. sericata Meigen. Se incluye una clave de identificación e ilustraciones para las nueve especies presentes en el estado y comentarios sobre su distribución.

Life Cycle of Chrysomya rufifacies (Diptera: Calliphoridae) Under Semi-Controlled Laboratory Conditions

Adult Calliphoridae flies, as well as their immature stages collected from carcasses, have been used as evidence in forensic investigations to estimate the postmortem interval (PMI), particularly those of the genus Chrysomya as it is one of the first genera to colonize a corpse. Chrysomya rufifacies (Macquart 1842), due to its appearance in cadaveric remains, plays a fundamental role in the study of forensic entomology. For this reason, we determined the biological cycle of C. rufifacies under semicontrolled laboratory conditions: uncontrolled average fluctuating temperature of 29. 76 ± 3. 22°C, uncontrolled average fluctuating humidity of 48. 91 ± 11.13%, and a controlled photoperiod of 12/12 (L/O). We established that the total development time from oviposition to adult emergence of C. rufifacies was 6. 5 d. The eggs took 12 h to hatch after oviposition. The complete larval stage took 60 h (instar 1 = 12 h, instar 2 = 12 h, instar 3 = 24 h, instar 3 post-feeding = 12 h). The pupa had a duration of 84 h. The species needed a total of 4642.8(±4.59) accumulated degree-hours (ADH) to complete its biological cycle.

Sexual Dimorphism in Growth Rate and Gene Expression Throughout Immature Development in Wild Type Chrysomya rufifacies (Diptera: Calliphoridae) Macquart

Reliability of forensic entomology analyses to produce relevant information to a given case requires an understanding of the underlying arthropod population(s) of interest and the factors contributing to variability. Common traits for analyses are affected by a variety of genetic and environmental factors. One trait of interest in forensic investigations has been species-specific temperature-dependent growth rates. Recent work indicates sexual dimorphism may be important in the analysis of such traits and related genetic markers of age. However, studying sexual dimorphic patterns of gene expression throughout immature development in wild-type insects can be difficult due to a lack of genetic tools, and the limits of most sex-determination mechanisms. Chrysomya rufifacies, however, is a particularly tractable system to address these issues as it has a monogenic sex determination system, meaning females have only a single-sex of offspring throughout their life. Using modified breeding procedures (to ensure single-female egg clutches) and transcriptomics, we investigated sexual dimorphism in development rate and gene expression. Females develop slower than males (9 h difference from egg to eclosion respectively) even at 30°C, with an average egg-to-eclosion time of 225 h for males and 234 h for females. Given that many key genes rely on sex-specific splicing for the development and maintenance of sexually dimorphic traits, we used a transcriptomic approach to identify different expression of gene splice variants. We find that 98.4% of assembled nodes exhibited sex-specific, stage-specific, to sex-by-stage specific patterns of expression. However, the greatest signal in the expression data is differentiation by developmental stage, indicating that sexual dimorphism in gene expression during development may not be investigatively important and that markers of age may be relatively independent of sex. Subtle differences in these gene expression patterns can be detected as early as 4 h post-oviposition, and 12 of these nodes demonstrate homology with key Drosophila sex determination genes, providing clues regarding the distinct sex determination mechanism of C. rufifacies. Finally, we validated the transcriptome analyses through qPCR and have identified five genes that are developmentally informative within and between sexes.

Effect of Type of Tissue on the Development of Chrysomya rufifacies (Diptera: Calliphoridae) in Sri Lanka

Chrysomya rufifacies (Macquart), the hairy maggot blow fly, is of great importance for the field of forensic entomology due to its habit as an early colonizer of decomposing vertebrate remains and myiasis producer. Development studies on this species have been conducted in scattered regions of the world, using types of tissue from several species of animals as a rearing medium. Despite the commonality of C. rufifacies in Sri Lanka, developmental studies have never been performed in this region. As well, the effects of diet on development have not been tested. In the current study, C. rufifacies immatures were reared on skeletal muscle, liver, and heart from domestic swine, with flies from colonies maintained at 25 and 28°C. The minimum time needed to complete each stage at 25°C on liver (224.14 h) was fastest followed by skeletal muscle (249.33 h) and heart (251.64 h) respectively, whereas at 28°C, fly development was quickest on heart muscle (178.27 h) followed by liver (178.50 h) and skeletal muscle (186.17 h) respectively. A significant difference in total development time was determined for temperature, while the rearing medium was not significant. Temperature also showed a significant effect on the length and the width of the larvae, while the type of tissue statistically impacted only the width.

Competition Among Three Forensically Important Blow Fly Species (Diptera: Calliphoridae): Phormia regina, Lucilia sericata, and Chrysomya rufifacies

Avoiding competition is thought to explain insect successional patterns on carrion, but few studies have looked at competition directly. We use replacement series experiments with three species of blow flies: Phormia regina (Meigen) (Diptera: Calliphoridae), Lucilia sericata (Meigen) (Diptera:Calliphoridae), and Chrysomya rufifacies (Macquart) (Diptera:Calliphoridae) to characterize competitive relationships. From experimental results, P. regina showed a significant competitive advantage over L. sericata. Infestation of carrion differs between L. sericata and P. regina; specifically, L. sericata oviposits on carrion without any delay, while P. regina typically delays oviposition. Our findings are consistent with the notion that differences in oviposition times represent a mechanism for L. sericata to avoid potential competition. Competition by C. rufifacies differs since C. rufifacies, in the event of a limited food supply, will prey on other maggot species. In replacement series experiments, C. rufifacies killed all P. regina in mixed treatments, representing an ultimate competitive advantage. In the United States, these two species do not often overlap because of differences in seasonal distribution. However, with climate change, phenological separation may grow less distinct. Surprisingly, in replacement series experiments with C. rufifacies and L. sericata, no competitive interactions were observed. In other studies, L. sericata has been shown to form clusters away from predaceous maggots, allowing improved survival, which may account for the absence of predation by C. rufifacies. Finally, this study shows that replacement series models are useful in measuring competition, supporting the notion that interspecific competition between necrophagous insect species may have driven life history traits of those species.

The genomes of a monogenic fly: views of primitive sex chromosomes

The production of male and female offspring is often determined by the presence of specific sex chromosomes which control sex-specific expression, and sex chromosomes evolve through reduced recombination and specialized gene content. Here we present the genomes of Chrysomya rufifacies, a monogenic blow fly (females produce female or male offspring, exclusively) by separately sequencing and assembling each type of female and the male. The genomes (> 25X coverage) do not appear to have any sex-linked Muller F elements (typical for many Diptera) and exhibit little differentiation between groups supporting the morphological assessments of C. rufifacies homomorphic chromosomes. Males in this species are associated with a unimodal coverage distribution while females exhibit bimodal coverage distributions, suggesting a potential difference in genomic architecture. The presence of the individual-sex draft genomes herein provides new clues regarding the origination and evolution of the diverse sex-determining mechanisms observed within Diptera. Additional genomic analysis of sex chromosomes and sex-determining genes of other blow flies will allow a refined evolutionary understanding of how flies with a typical X/Y heterogametic amphogeny (male and female offspring in similar ratios) sex determination systems evolved into one with a dominant factor that results in single sex progeny in a chromosomally monomorphic system.

Dietary Effects on the Development of Calliphora dubia and Chrysomya rufifacies (Diptera: Calliphoridae): Implications for Postmortem Interval

Forensic entomology relies on insect development data generated within a laboratory setting in the estimation of minimum postmortem interval (mPMI). The methodologies used to produce these data vary considerably within the field and there is no accepted standard approach to laboratory rearing of forensically relevant species. A wide range of rearing media are used across published studies, including different species of animal and types of tissue (e.g., muscle and liver). Differing methodologies, particularly rearing diet, can introduce considerable variation into the baseline data upon which forensic estimates of the mPMI are calculated. Consequently, research establishing a widely available, standard and/or optimal, rearing medium for blow fly development for forensic application is desirable. This study examined dietary effects on the development of two forensically relevant blow fly species: Calliphora dubia Macquart, 1855, and Chrysomya rufifacies Macquart 1842 (Diptera: Calliphoridae). Larvae of both species were reared on pork liver, pork mince, pork loin, beef liver, beef mince, and guinea pig carcass under two constant temperature regimes (24 ± 1°C and 30 ± 1°C; 70 ± 10% humidity; 12-h/12-h photoperiod) to assess the influence of temperature on developmental response to diet. Fundamental developmental data pertaining to both species are reported. Developmental response to diet was species-specific and influenced by temperature with indication that the optimal temperature for C. dubia development is below 30°C. Pork mince was the most appropriate dietary standard of the rearing media investigated for the formulation of forensic development data for both species investigated.