Comparative genomic analysis of necrophagous and parasitic subspecies of Lucilia cuprina (Diptera: Calliphoridae) provides important insights into their divergent biologies

Authors: KAPOOR, SHILPA - University Of Melbourne; Hickner, Paul; DICKEY, ALLISON - North Carolina State University; BAILEY, EZRA - North Carolina State University; BALDASSIO DE PAULA, LETICIA - Universidad De Sao Paulo; BELIKOFF, ESTHER - North Carolina State University; DAVIS, REBECCA - North Carolina State University; TANDONNET, SOPHIE - University Of Barcelona; CANETTIERI, CAROLINA - Universidade De Sao Paulo; BERTONE, MATTHEW - North Carolina State University; ANSTEAD, CLARE - University Of Melbourne; SCOTT, MAXWELL - North Carolina State University

Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2025
Publication Date: 6/18/2025
Citation: Kapoor, S., Hickner, P.V., Dickey, A.N., Bailey, E.M., Baldassio De Paula, L.C., Belikoff, E.J., Davis, R.J., Tandonnet, S., Canettieri, C.K., Bertone, M.A., Anstead, C.A., Scott, M.J. 2025. Comparative genomic analysis of necrophagous and parasitic subspecies of Lucilia cuprina (Diptera: Calliphoridae) provides important insights into their divergent biologies. International Journal for Parasitology. https://doi.org/10.1016/j.ijpara.2025.06.001.
DOI: https://doi.org/10.1016/j.ijpara.2025.06.001

Interpretive Summary: The Australia sheep blow fly can be divided into two subspecies, each with different feeding habits. The parasitic form is an important parasite of sheep in Australia, while the saprophytic form feeds on carrion and garbage. We produced an improved genome assembly for the parasitic form, and a new genome assembly for saprophytic form. We then compared these two assemblies to identify genes associated with a parasitic lifestyle. Though both species had a similar number of genes, we identified several genes specific to only one form. Gene mutations linked to diazinon resistance were exclusively observed in the parasitic form, while malathion resistance was detected in both subspecies. The parasitic form has more genes associated with sensory perception of smell and taste than the carrion feeder. Additionally, we identified genes with accelerated evolutionary rates in each subspecies, which may underlie their distinct feeding behaviors. Phylogenetic analysis confirmed the close relationship between both forms, with the common green bottle fly as their closest relative. This work improves our understanding of the evolutionary adaptations in this important species of blow fly.

Technical Abstract: Lucilia cuprina, a species of blowfly, consists of two recognized subspecies: L. cuprina cuprina and L. cuprina dorsalis. In Australia, L. c. dorsalis is predominantly found in rural areas and is the primary causative agent of sheep myiasis (flystrike), while L. c. cuprina is not a significant pest of livestock in the Americas or elsewhere. Here, we present a chromosome-scale genome assembly for L. c. cuprina and an improved assembly for L. c. dorsalis, enabling comparative genomic analysis between these subspecies. While both genomes share a similar gene content, species-specific genes were identified, which may contribute to their divergent ecological roles. Phylogenetic analyses using anchored hybrid enrichment of genomic DNA and whole genomes reaffirm the close relationship between L. c. cuprina and L. c. dorsalis and position L. sericata as their sister species. Gene mutations linked to diazinon resistance were exclusively observed in L. c. dorsalis, while malathion resistance was detected in both subspecies. Additionally, we identified genes with accelerated evolutionary rates in each subspecies, which may underlie their distinct feeding behaviours—necrophagy in L. c. cuprina and parasitism in L. c. dorsalis. We also conducted a detailed analysis of chemosensory genes, revealing that L. c. dorsalis possesses slightly larger repertoires of all four chemosensory gene families analysed. In comparison to Drosophila melanogaster, both subspecies exhibit an expanded gustatory receptor clade. Our findings provide valuable insights into the genetic factors underpinning parasitism and pesticide resistance and provide a valuable genetic resource for future research endeavours, including the development of engineered strains aimed at genetic biocontrol strategies. This work enhances our understanding of the evolutionary adaptations for this important blowfly species.