Comparative morphological and transcriptomic analyses reveal chemosensory genes in the poultry red mite, Dermanyssus gallinae

Abstract

Detection of chemical cues via chemosensory receptor proteins are essential for most animals, and underlies critical behaviors, including location and discrimination of food resources, identification of sexual partners and avoidance of predators. The current knowledge of how chemical cues are detected is based primarily on data acquired from studies on insects, while our understanding of the molecular basis for chemoreception in acari, mites in particular, remains limited. The poultry red mite (PRM), Dermanyssus gallinae, is one of the most important blood-feeding ectoparasites of poultry. PRM are active at night which suck the birds' blood during periods of darkness and hide themselves in all kinds of gaps and cracks during the daytime. The diversity in habitat usage, as well as the demonstrated host finding and avoidance behaviors suggest that PRM relies on their sense of smell to orchestrate complex behavioral decisions. Comparative transcriptome analyses revealed the presence of candidate variant ionotropic receptors, odorant binding proteins, niemann-pick proteins type C2 and sensory neuron membrane proteins. Some of these proteins were highly and differentially expressed in the forelegs of PRM. Rhodopsin-like G protein-coupled receptors were also identified, while insect-specific odorant receptors and odorant co-receptors were not detected. Furthermore, using scanning electron microscopy, the tarsomeres of all leg pairs were shown to be equipped with sensilla chaetica with or without tip pores, while wall-pored olfactory sensilla chaetica were restricted to the distal-most tarsomeres of the forelegs. This study is the first to describe the presence of chemosensory genes in any Dermanyssidae family. Our findings make a significant step forward in understanding the chemosensory abilities of D. gallinae.

De novotranscriptome sequencing of the northern fowl mite,Ornithonyssus sylviarum, shed light into parasitiform poultry mites evolution and its chemoreceptor repertoires

“…The major limitation of the study is that, the transcriptome data of NFM is generated from a pooled sample comprising all life-stages and sexes, and thus their transcripts are likely to be highly diluted in the pooled sample. It is also important to note that the number of candidate chemosensory receptors identified in NFM is similar to that found in a recent transcriptome analysis of chemosensory gene expression in different organs in PRM (Bhowmick et al, 2020), but considerably smaller than that described in other free-living mite and tick species, as well as in insects (Figure 3). Relying on only transcriptomic data, however, may not be suitable to assess the presence or absence of IRs and GRs.…”

“…Some of these receptors including GPCRs (G-protein coupled receptor) are difficult to identify in the transcriptome assembly because they are present in specialized sensory tissues (e.g. Haller’s organ in ticks and foretarsal sensory organ in mites) and lower level of gene expression profiles (Bhowmick et al, 2020; Pietrantonio et al, 2018; Vizueta et al, 2020b).…”