Acaricidal efficacy of orally administered macrocyclic lactones against poultry red mites (Dermanyssus gallinae) on chicks and their impacts on mite reproduction and blood-meal digestion

Abstract

Background The poultry red mite (PRM), Dermanyssus gallinae , is one of the most economically deleterious threats to laying-hen industry worldwide. Macrocyclic lactones (MLs) have been widely used in control of mites in mammals, but the effects of MLs on PRMs are not well studied. The main objective of the present study was to systematically evaluate the effects of three MLs, i.e. eprinomectin (EPR), moxidectin (MOX) or ivermectin (IVM), on PRMs fed on chicks following oral administration. Methods Chicks in treatment groups were orally administrated with EPR, MOX or IVM at a dose of 5.0 mg/kg bodyweight. Chicks in the control group received the carrier solvent without drug. Chicks in each cage were then infested with 200 starved adult D. gallinae . After infestation and feeding for 12 h, engorged mites were collected to evaluate the acaricidal efficacy of the MLs, and its impacts on the reproduction and blood-meal digestion of D. gallinae . Results MOX, IVM and EPR demonstrated higher acaricidal efficacies post-treatment compared with the control, i.e. 45.60% for MOX, 71.32% for IVM and 100% for EPR on Day 10. MLs did not have significant effects on the blood-meal ingestion of PRMs, but significantly slowed down blood digestion ( P < 0.0001). The oviposition rate, egg hatching rate and fecundity of PRMs in treatment groups were remarkably reduced. Among the three MLs, EPR exhibited the highest performance against PRMs, with an oviposition rate of 1.04%, fecundity of 0.33 eggs per mite and a zero egg hatching rate in EPR treated groups. Conclusions EPR, MOX or IVM administrated orally to chicks increased the mortality of D. gallinae , significantly slowed down their blood-meal digestion and significantly reduced their reproductive capability which included the oviposition rate, fecundity and egg hatching rate. The present study highlights the potential of MLs in the control of PRMs.

A blood digestion scoring method for poultry red mites, Dermanyssus gallinae

“…Infestation and recovery of mites were carried out according to the previously described method (Wang et al ., 2018; Xu et al ., 2019). Briefly, when chicks were 6 weeks old, they were challenged with PRMs.…”

“…Dozens of drugs and vaccines have been found to inhibit the blood digestion, interfering in the growth, development and reproduction of haematophagous arthropods. For example, 2 antigens to digestive protease of D. gallinae , Dg-CatD and Dg-CatL could prevent and control D. gallinae by reducing the survival (Bartley et al ., 2012), reproductive capacity (Price et al ., 2019) and blood digestion (Xu et al ., 2019) of mite. Two ferritins are crucial to the survival, reproduction and blood digestion of D. gallinae , showing good potential as an antigen of vaccine against D. gallinae (Xu et al ., 2022).…”

“…Two ferritins are crucial to the survival, reproduction and blood digestion of D. gallinae , showing good potential as an antigen of vaccine against D. gallinae (Xu et al ., 2022). Orally administrated macrocyclic lactones (eprinomectin, ivermectin) to chicks could significantly delay the blood-meal digestion of PRMs, reducing egg production (Xu et al ., 2019). Therefore, developing reliable methods to evaluate the blood digestion of PRMs is a significant step in the development of novel drugs and vaccines.…”

“…Currently, several methods have been used in the assessment of the blood digestion of haematophagous arthropods. The first one is to calculate blood digestion rate based on the change in pest body weight during the digestion (Xu et al ., 2019). Although this method has been widely used, it shows some limitations for small-sized pests (e.g.…”

Two ferritins from Dermanyssus gallinae: characterization and in vivo assessment as protective antigens

“…The remaining mites in each tube were transferred into 96-well plates, after which mortalities and reproductive capacity were observed under a stereomicroscope for 5 days as described previously. 30…”