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Abstract BackgroundThe blowflyLucilia cuprinais a destructive parasite of sheep that causes flystrike or myiasis. Larvae consume the animal’s living flesh, producing large wounds that can lead to death. The main aim of this study was to identify genes that may play important roles in the behavior and physiology ofL. cuprinalarvae. MethodsAn RNA-Seq analysis of RNA from whole larvae at different developmental stages and third-instar head and gut tissues was used to identify sensory receptors and other genes relevant to the physiology ofL. cuprinalarvae. In addition, CRISPR/Cas9 gene editing was used to obtain a loss-of-function mutation for theL. cuprinaodorant coreceptor gene (LcupOrco). The response of mutant larvae and adult females to fresh and rotten meat at different temperatures was evaluated. ResultsThe RNA-Seq analysis suggested that odorant (OR), gustatory, ionotropic, andPickpocketreceptors may not play a central role in theL. cuprinalarval sensory signaling and digestive systems. Rather, ATP-binding cassettes (ABCs) were highly enriched in head and gut RNA, and odorant-binding proteins (OBPs) only in the head. To confirm that ORs are not essential for larval detection of rotten beef, diet-choice assays were performed including larvae and adults homozygous for a null mutation inLcupOrco. While the attraction of adult females to rotten beef was disrupted,LcupOrcomutant larvae showed no change in diet preference. ConclusionsThe expression pattern of the ABC and OBP gene families suggests a central role in the sensory system of theL. cuprinalarva for these receptors. Behavioral assays showed that ORs are essential for the adult female response to rotten beef, but not for larval behavior. These findings are consistent with high levels of expression ofLcupOrcoin the adult female antenna but very low expression in larvae. Graphical abstract
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Antennal transcriptome analysis reveals sensory receptors potentially associated with host detection in the livestock pest Lucilia cuprina
Abstract BackgroundLucilia cuprina(Wiedemann, 1830) (Diptera: Calliphoridae) is the main causative agent of flystrike of sheep in Australia and New Zealand. Female flies lay eggs in an open wound or natural orifice, and the developing larvae eat the host’s tissues, a condition called myiasis. To improve our understanding of host-seeking behavior, we quantified gene expression in male and female antennae based on their behavior. MethodsA spatial olfactometer was used to evaluate the olfactory response ofL. cuprinamated males and gravid females to fresh or rotting beef. Antennal RNA-Seq analysis was used to identify sensory receptors differentially expressed between groups. ResultsLucilia cuprinafemales were more attracted to rotten compared to fresh beef (> fivefold increase). However, males and some females did not respond to either type of beef. RNA-Seq analysis was performed on antennae dissected from attracted females, non-attracted females and males. Transcripts encoding sensory receptors from 11 gene families were identified above a threshold (≥ 5 transcript per million) including 49 ATP-binding cassette transporters (ABCs), two ammonium transporters (AMTs), 37 odorant receptors (ORs), 16 ionotropic receptors (IRs), 5 gustatory receptors (GRs), 22 odorant-binding proteins (OBPs), 9 CD36-sensory neuron membrane proteins (CD36/SNMPs), 4 chemosensory proteins (CSPs), 4 myeloid lipid-recognition (ML) and Niemann-Pick C2 disease proteins (ML/NPC2), 2pickpocketreceptors (PPKs) and 3 transient receptor potential channels (TRPs). Differential expression analyses identified sex-biased sensory receptors. ConclusionsWe identified sensory receptors that were differentially expressed between the antennae of both sexes and hence may be associated with host detection by female flies. The most promising for future investigations were as follows: an odorant receptor (LcupOR46) which is female-biased inL. cuprinaandCochliomyia hominivoraxCoquerel, 1858; an ABC transporter (ABC G23.1) that was the sole sensory receptor upregulated in the antennae of females attracted to rotting beef compared to non-attracted females; a female-biased ammonia transporter (AMT_Rh50), which was previously associated with ammonium detection inDrosophila melanogasterMeigen, 1830. This is the first report suggesting a possible role for ABC transporters inL. cuprinaolfaction and potentially in other insects. Graphical Abstract
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- Award ID(s):
- 2030345
- PAR ID:
- 10524647
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Parasites & Vectors
- Volume:
- 17
- Issue:
- 1
- ISSN:
- 1756-3305
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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