Location of olfactory organs and architecture of gustatory organs in the poultry red mite, Dermanyssus gallinae (Acari: Dermanyssidae)

Dermanyssus gallinae is a hematophagous ectoparasitic mite in the poultry industry worldwide. Its current control mainly relies on spraying acaricides with many deficiencies. It's urgently needed to develop novel control approaches, such as pheromones. The pheromones are detected by chemoreceptors , which are not well investigated in D. gallinae . In the current study, Y-tube olfactometer bioassays revealed that extracts of feces of mites could attract D. gallinae , indicating aggregation pheromones existed in feces. After varnishing the tips of the foreleg tarsi, the female mites' response to feces extracts disappeared in Y-tube olfactometer bioassays. Still, their response to guanine (a non-volatile compound acting as a potential arrestment pheromone) remained in filter paper contact bioassays. These results suggested that the sensilla at tips of the foreleg tarsi had olfactory function, and the sensilla at the tips of the pedipalpal tarsi could have gustatory function and the gustatory organs were located in other body parts of female mites. Through scanning electron microscopy (SEM), it was found that adults and nymphs possess a cluster of 8 peg-like sensilla as well as 2 blunt, peg-like sensilla at the tip of each pedipalpal tarsus. Nevertheless, the larvae had only a cluster of 5 blunt peg-type sensilla. Each sensillum has a terminal pore or depression, suggesting it functions as gustatory organ. The present study confirmed the location and explored the architecture of gustatory organs of D. gallinae , which would facilitate the development of novel control method based on pheromones .