The blowfly, Aldrichina grahami (Diptera: Calliphoridae), is a well-known forensically important insect. Basic data related to A. grahami have been well documented; but despite the pivotal role of gut microbes in various facets of insect biology, little is known about its gut microbiome. To investigate the gut bacterial community of A. grahami and explore its stability, diet and developmental stage were selected as the two variables. Larvae were reared on bovine liver, swine manure, and chicken manure, and high-throughput sequencing of the 1st, 2nd, and 3rd instar larvae and the newly emerged adults was performed. According to our results, the alpha diversity of the gut bacterial community did not significantly vary among different diets and developmental stages. Principal coordinate analysis revealed that the gut microbiome of A. grahami clustered together among different diets and developmental stages. The main phyla in the gut microbial community of A. grahami were Firmicutes and Proteobacteria, and the dominant genera were Vagococcus, Providencia, Lactobacillus, and Morganella. These findings characterized the gut microbiome of A. grahami and demonstrated that the gut bacterial community is fairly stable. The dominant genera Vagococcus, Providencia, Lactobacillus, and Morganella have the potential to serve as core microbiomes within the gut microbial community of A. grahami.

In warmer environments, most ectotherms exhibit a plastic reduction in body size (the temperature–size rule, TSR). However, in such environments, growth is usually accelerated and would be expected to result in maturation at a larger body size, leading to increases in fecundity, survival, and mating success, compared to maturation at a smaller size (the ‘life-history puzzle’). To explore these mechanisms, we reared Aldrichina grahami at 20 °C, 25 °C, and 30 °C, and added a nutritional challenge by using dilutions of pork liver paste to provide diets that ranged in quality from high (undiluted) to moderate (1/8), low (1/16), and poor (1/24). Larvae were randomly sampled for weighing from hatching. Growth curves were fitted to the relationships between growth rate and weight for the third instar larvae. Our results showed that body size was affected by an interaction between temperature and diet, and that following or not following the TSR can vary depending on underfeeding. Moreover, when the TSR was followed as temperature increased, there was a cross-over point that divided the two growth curves into early and later stages, which could be used to help understand the life-history puzzle in warmer temperatures, with the instantaneous growth rate being faster in the early stages of development and then slower in later stages. This study reminds us that animals have evolved to cope with multiple simultaneous environmental changes, and it has thus offered a better understanding of life-history puzzles.

To advance sustainable swine manure management through insect-mediated bioconversion, this study implemented a comparative evaluation of the flesh fly Boettcherisca peregrina (Robineau–Desvoidy) (Diptera: Sarcophagidae) and the blow fly Aldrichina grahami (Aldrich) (Diptera: Calliphoridae). We quantified: (i) larval viability and bioconversion efficiency under manure-fed conditions, (ii) nutritional profiles and heavy metal accumulation in larval biomass, and (iii) agronomic value and residual heavy metal speciation of processed residues. B. peregrina exhibited higher adaptability, achieving a 95% survival rate and maximum biomass within 72 h, achieving a 35.6% swine manure mass reduction, slightly outperforming A. grahami (34.3% over 84 h). Both species produced nutrient-dense larvae (56.2% to 56.4% crude protein, 24.5% to 25.2% lipid) and pupae (61.3% to 63.8% protein, 18.4% to 19.1% lipid), with balanced essential amino acid profiles suitable for animal feed. However, arsenic accumulation in larvae approached EU feed safety limits, highlighting the need for substrate optimization. Processed residues showed enhanced agronomic value, with available phosphorus increasing by 24% to 29%, while most heavy metals remained below phytotoxic thresholds; however, chromium approximately doubled after bioconversion. From an application perspective, the short development time (3 to 5 d) and relatively high conversion efficiency of both species suggest economic advantages over longer-cycle insects such as black soldier fly, although successful scale-up will require careful management of substrate variability, biosecurity, and trace-metal risks. Overall, these findings identify B. peregrina and A. grahami as promising candidates for circular agriculture systems.

Breech flystrike is a painful, debilitating and potentially lethal disease caused by the larvae of the blowfly, Lucilia cuprina, and, despite many years of research, it remains a serious financial and animal-welfare issue for the Merino sheep industry in Australia. The common methods of prevention, namely insecticides, crutching and ‘mulesing’, are problematical, so alternative approaches are needed. Breeding for resistance to breech strike is a fundamentally attractive proposition, but the trait itself is difficult and expensive to quantify in large numbers of sheep in extensive production systems. Several indirect traits are correlated with susceptibility to flystrike, but a large proportion of the variation in susceptibility remains unexplained. The common thread through those indirect traits is odour, so we turned to the biology of insect olfaction and its role in fly–sheep interactions. L. cuprina uses odours to detect and locate potential hosts over long distances, to guide orientation and landing behaviour, and to select egg-laying sites. Preliminary studies demonstrated the importance of confining our work to gravid female L. cuprina, and also validated the use of flies reared in the laboratory for experimentation. Using laboratory-reared flies and a combination of gas chromatography–mass spectrometry with electroantennographic detection, we identified odouriferous compounds from sheep that the antenna of L. cuprina can detect. To determine whether the identified compounds were attractive or repulsive, we needed to use a behaviour test. In preliminary studies, we compared four behaviour bioassays (Y-tube, landing time, visiting frequency, and trap) and found the trap to be the most effective. We observed that L. cuprina was attracted by several compounds in Merino wool, including octanal, nonanal and dimethyl trisulfide. We also found that the wool levels of octanal and nonanal are heritable in Merino sheep, suggesting that these compounds might be useful as traits in selection for flystrike resistance. Another possibility is that these olfactory-active compounds might guide efforts to modify the genome of sheep, or perhaps even L. cuprina. Success in these endeavours could save as much as A$200 m per year for the Australian Merino-based industries, while also improving the image of wool in world markets.

In warmer environments, most ectotherms reach maturity at a smaller body size (the temperature-size rule, TSR). However, in such environments, growth is usually accelerated and would be expected to result in maturation at a larger body size, leading to increases in fecundity, survival, and mating success, compared to maturation at a smaller size (the ‘life-history puzzle’). To explore mechanisms, we reared Aldrichina grahami at 20 ℃, 25 ℃ and 30 ℃, and added a nutritional challenge by using dilutions of pork liver paste to provide diets that ranged in quality from high (undiluted, control) to moderate (1/8), low (1/16) and poor (1/24). Larvae were randomly sampled for weighing from hatching. Growth curves were fitted to the relationships between growth rate and weight for the third instar larvae. Our results showed that body size was affected by an interaction between temperature and diet, and that TSR and TSR exceptions (E-TSR) could be interconverted by underfeeding. Moreover, when the TSR was followed as temperature increased, there was a cross-over point divided the two growth curves into early and later stages, which could be used to help understand the life-history puzzle in warmer temperatures, with the instantaneous growth rate being higher in the early stages of development and then lower in later stages. This study reminds us that animals evolved to cope with multiple simultaneous environmental changes, and offered a better understanding for life-history puzzles.