In Vitro Acaricidal Activity of Silver Nanoparticles (AgNPs) against the Poultry Red Mite (Dermanyssus gallinae)

Abstract

Dermanyssus gallinae (PRM) is the most common blood-sucking ectoparasite in laying hens and is resistant against numerous acaricides. Silver nanoparticles (AgNPs) represent an innovative solution against PRM. The current study aimed to assess the in vitro acaricidal activity of AgNPs against PRM and describe their potential mechanism of action. Nanoparticles were produced using a wet chemistry approach. Mites were collected using AviVet traps from 18 poultry farms in Greece. Contact toxicity bioassays were carried out for 24 h with negative controls, 20, 40, 60, or 80 ppm AgNPs. Analysis of variance was used to compare the mortality rates of PRM between the control and treatment groups, while LC50, LC90, and LC99 values were estimated using probit regression analysis for the total farms jointly and separately. Nanoparticles displayed strong acaricidal activity, and mortality rates were significantly different between groups and increased by AgNPs concentration. Overall mean LC50, LC90, and LC99 values were 26.5, 58.8, and 112.3 ppm, respectively. Scanning electron microscopy on mites treated with 80 ppm AgNPs revealed cracks in their exoskeleton and limb detachments, presumably resulting from the interaction between AgNPs and the mites’ chitin. Future studies should focus on assessing AgNPs residues in chicken tissues before moving into field trials.

Spatial Distribution of Dermanyssus gallinae Infestations in Greece and Their Association with Ambient Temperature, Humidity, and Altitude

“…Until now, many Greek regions had temperatures ≤5 °C during the winter months, which stopped PRM eggs from hatching [ 1 ], reduced the mites’ activity [ 14 ], and slowed their proliferation [ 67 ]. A slight increase in temperatures above 5 °C during these months could allow the PRM to complete its life cycle throughout the year, posing an even bigger problem for poultry farmers who already have limited choices for treatment [ 18 ]. On the contrary, a slight decrease in RH during winter will not severely affect D. gallinae ’s multiplication since the RH is well above 60% in that season.…”

“…There are limited treatments available for the PRM because the mites have developed resistance against many acaricide classes because of the drug residues in eggs and the removal of acaricides from the market [ 18 ]. In most European markets like Greece, fluralaner is one of the few compounds licensed for treating PRM infestations [ 19 ].…”

Effectiveness of Nanoparticle-Based Treatments in Controlling Oligonychus afrasiaticus (McGregor) (Acari Tetranchidae) Infestation in Date Palm Trees

“…AgNPs have been widely studied for their antimicrobial and insecticidal properties. [21] reported the acaricidal activity of SiNPs against different species of mites. The mode of action involves the release of Ag ions, which exhibit antimicrobial effects on mites, ultimately leading to their mortality.…”