Rearing the scuttle fly Megaselia scalaris (Diptera: Phoridae) on industrial compounds: implications on size and lifespan.
ABSTRACT: Megaselia scalaris (Loew, 1866) (Diptera, phoridae) is a cosmopolitan fly species used in forensic science, and has been developed as a laboratory model species. They feed on decaying corpses as well as a wide variety of organic matter, and previous studies have even found them feeding on liquid paint or shoe polish, suggesting the possibility that they could breakdown industrial compounds. To test this possibility, we fed M. scalaris on a variety of industrially obtained materials and found that it was unable to complete its life cycle, dying at the larval stage, with the majority of compounds tested. However, when fed on modeling clay, a substrate that contains starch and inedible compounds, it was able to complete its life cycle. On this diet we observed increased larval development time, decreased pupal development time and a shortened adult life span. Additionally, pupae and adult flies were smaller than control flies. Contrary to previous reports, we find no evidence that M. scalaris is able to survive on modern formulations of liquid paint.
Project description:Termites of the genus Macrotermes (Termitidae: Macrotermitinae) are serious agricultural and structural pests, which also play vital roles in ecosystem functioning, and are crucial for the maintenance of tropical biodiversity. They are widely distributed, mainly in Southeast Asian countries; however, the parasitism of termites has been little researched. This research was conducted to identify and study the ecology of the parasitoids of termites at Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom, Thailand. Macrotermes gilvus (Hagen) soldier termites were collected from 25 mounds. In four of the 25 mounds, scuttle fly larvae were found inside the bodies of the soldier termites, and adult flies were found in all of the mounds. Some of the larvae successfully developed to pupae under laboratory conditions. The percentages of parasitized major soldier termites collected from the four mounds were 43.79%, 47.43%, 0.86%, and 3.49%, respectively, and the percentages of parasitized minor soldier termites were 0.64%, 0.00%, 0.21%, and 0.00%, respectively. Larvae, pupae, and adult flies were identified using both morphological and molecular identifications. Molecular identification used the partial nucleotide sequences of the mitochondrial cytochrome c oxidase I (COI) gene. The results of both identification methods identified the parasitic Diptera as the scuttle fly, Megaselia scalaris (Loew) (Diptera: Phoridae). The phylogenetic analysis of the 23 scuttle fly samples (11 larvae, 7 pupae, and 5 adults) classified them into two clades: (1) Those closely related to a previous report in India; (2) those related to M. scalaris found in Asia and Africa. This is the first discovery of M. scalaris in M. gilvus. Further investgation into termite parasitism by M. scalaris and its possible use in the biological control of termites is needed.
Project description:Drought, rising temperatures, and expanding human populations are increasing water demands. Many countries are extending potable water supplies by irrigating crops with wastewater. Unfortunately, wastewater contains biologically active, long-lived pharmaceuticals, even after treatment. Run-off from farms and wastewater treatment plant overflows contribute high concentrations of pharmaceuticals to the environment. This study assessed the effects of common pharmaceuticals on a cosmopolitan saprophagous insect, Megaselia scalaris (Diptera: Phoridae). Larvae were reared on artificial diets spiked with contaminants of emerging concern (CECs) at environmentally relevant concentrations. Female flies showed no oviposition preference for treated or untreated diets. Larvae exposed to caffeine in diets showed increased mortality, and larvae fed antibiotics and hormones showed signs of slowed development, especially in females. The normal sex ratio observed in M. scalaris from control diets was affected by exposure to caffeine and pharmaceutical mixture treatments. There was an overall effect of treatment on the flies' microbial communities; notably, caffeine fed insects displayed higher microbial variability. Eight bacterial families accounted for approximately 95% of the total microbes in diet and insects. Our results suggest that CECs at environmentally relevant concentrations can affect the biology and microbial communities of an insect of ecological and medical importance.
Project description:Phoridae are a family of necrophagous flies commonly found in indoor death scene. They account for approximately 19.7% of the entomofauna in human cadavers in Korea. Additionally, this taxon is an indicator of indoor hygiene, and these flies appear in environments where access by other necrophagous insects is difficult, such as enclosed rooms. Thus, they are likely to be used as forensic evidence. Despite their importance in forensic investigations and environmental hygiene, detailed studies on the taxonomy and molecular barcoding for this family are scarce, including in Korea. Because accurate taxonomic information regarding necrophagous insects collected from a death-related scene is essential during medicolegal investigations, molecular barcoding data could be useful as well as reliable. In this paper, full-length nucleotide sequences of genes coding for the cytochrome c oxidase subunit I (COI) in 79 Phoridae larvae collected from 20 medicolegal autopsy cases in Korea were phylogenetically analyzed by comparing their sequences to the foreign barcoding data of Phoridae. Six mitochondrial haplogroups were identified, which two of them matched to foreign Phoridae fly species haplotypes, Megaselia scalaris (Loew, 1866) and M. spiracularis Schmitz 1938. Taxonomies of five other haplogroups, with nucleotide distances ranging from 1.68% to 2.26% from the M. scalaris group, could not be confirmed solely based on the molecular barcoding data. Further research should be performed to determine whether these five haplogroups are diverged conspecifics of M. scalaris or a closely related sister cryptic species of M. scalaris.
Project description:Although the mechanisms of apoptotic cell death have been well studied in the fruit fly, Drosophila melanogaster, it is unclear whether such mechanisms are conserved in other distantly related species. Using degenerate primers and PCR, we cloned a proapoptotic gene homologous to Head involution defective (Hid) from the Scuttle fly, Megaselia scalaris (MsHid). MsHid cDNA encodes a 197-amino acid-long polypeptide, which so far is the smallest HID protein. PCR analyses revealed that the MsHid gene consists of four exons and three introns. Ectopic expression of MsHid in various peptidergic neurons and non-neuronal tissues in Drosophila effectively induced apoptosis of these cells. However, deletion of either conserved domain, N-terminal IBM or C-terminal MTS, abolished the apoptogenic activity of MsHID, indicating that these two domains are indispensable. Expression of MsHid was found in all life stages, but more prominently in embryos and pupae. MsHid is actively expressed in the central nervous system (CNS), indicating its important role in CNS development. Together MsHID is likely to be an important cell death inducer during embryonic and post-embryonic development in this species. In addition, we found 2-fold induction of MsHid expression in UV-irradiated embryos, indicating a possible role for MsHid in UV-induced apoptosis.
Project description:The declining cost of DNA sequencing is making genome sequencing a feasible option for more organisms, including many of interest to ecologists and evolutionary biologists. While obtaining high-depth, completely assembled genome sequences for most non-model organisms remains challenging, low-coverage genome survey sequences (GSS) can provide a wealth of biologically useful information at low cost. Here, using a random pyrosequencing approach, we sequence the genome of the scuttle fly Megaselia scalaris and evaluate the utility of our low-coverage GSS approach.Random pyrosequencing of the M. scalaris genome provided a depth of coverage (0.05x0.1x) much lower than typical GSS studies. We demonstrate that, even with extremely low-coverage sequencing, bioinformatics approaches can yield extensive information about functional and repetitive elements. We also use our GSS data to develop genomic resources such as a nearly complete mitochondrial genome sequence and microsatellite markers for M. scalaris.We conclude that low-coverage genome surveys are effective at generating useful information about organisms currently lacking genomic sequence data.
Project description:Background:Phorid flies are amongst the most biologically diverse and species-rich groups of insects. Ways of life range from parasitism, herbivory, fungivory, to scavenging. Although the lifestyles of most species are unknown, many are parasitoids, especially of social insects. Some species of ant-parasitoids are attracted to injured hosts for feeding purposes to develop eggs, as well as for oviposition, requiring each female to find two injured hosts. New information:Females of the phorid fly Megaselia steptoeae Hartop et al. (Diptera: Phoridae) were found to be quickly attracted to crushed glass snails of the species Oxychilus draparnaudi (Beck) (Gastropoda: Oxychilidae). Most females were without mature eggs and apparently were attracted for feeding purposes only; other injured molluscs offered at the same time were not attractive. One female laid eggs in captivity and offspring were reared to the pupal stage. The lifestyle of this species is similar to that of parasitoids of injured ants, which also require separate hosts of the same species for feeding and oviposition. We conclude that injured hosts must be common in the environment to attract these host-specific scavengers.
Project description:The Drosophila gene bicoid functions at the beginning of a gene cascade that specifies anterior structures in the embryo. Its transcripts are localized at the anterior pole of the oocyte, giving rise to a Bicoid protein gradient, which regulates the spatially restricted expression of target genes along the anterior-posterior axis of the embryo in a concentration-dependent manner. The morphogen function of Bicoid requires the coactivity of the zinc finger transcription factor Hunchback, which is expressed in a Bicoid-dependent fashion in the anterior half of the embryo. Whereas hunchback is conserved throughout insects, bicoid homologs are known only from cyclorrhaphan flies. Thus far, identification of hunchback and bicoid homologs rests only on sequence comparison. In this study, we used double-stranded RNA interference (RNAi) to address the function of bicoid and hunchback homologs in embryos of the lower cyclorrhaphan fly Megaselia abdita (Phoridae). Megaselia-hunchback RNAi causes hunchback-like phenotypes as observed in Drosophila, but Megaselia-bicoid RNAi causes phenotypes different from corresponding RNAi experiments in Drosophila and bicoid mutant embryos. Megaselia-bicoid is required not only for the head and thorax but also for the development of four abdominal segments. This difference between Megaselia and Drosophila suggests that the range of functional bicoid activity has been reduced in higher flies.
Project description:The scuttle fly, Megaselia scalaris, is often cited as a model in which to study early sex chromosome evolution because of its homomorphic sex chromosomes, low but measurable molecular differentiation between sex chromosomes, and occasional transposition of the male-determining element to different chromosomes in laboratory cultures. Counterintuitively, natural isolates consistently show sex linkage to the second chromosome. Frequent natural transposition of the male-determining element should lead to the loss of male specificity of any nontransposed material on the previous sex-linked chromosome pair. Using next-generation sequencing data from a newly obtained natural isolate of M. scalaris, we show that even highly conservative estimates for the size of the male-specific genome are likely too large to be contained within a transposable element. This result strongly suggests that transposition of the male-determining region either is extremely rare or has not persisted recently in natural populations, allowing for differentiation of the sex chromosomes of this species.