Validation of an automated mite counter for Dermanyssus gallinae in experimental laying hen cages

Successful long-term control of poultry red mite (Dermanyssus gallinae) infestations in floor-kept laying hens via integrated pest management-a case report

This case report describes the successful control of poultry red mite [PRM] (Dermanyssus gallinae) infestations in an experimental laying hen house via a combined use of cleaning and disinfection measure, the preventive application of a synthetic silica-based acaricide and frequent mite monitoring. The high number of PRM in the laying hen house was reduced by 99.8% by treatment with fluralaner (Exzolt®, MSD Animal Health Unterschleißheim, Germany; 0.5 mg/kg body weight via drinking water twice, 7 days apart). After the laying hens were removed, the hen house was dry-cleaned, wet-cleaned and disinfected. After drying, synthetic amorphous silica (Fossil Shield® instant white, Bein GmbH, Eiterfeld, Germany) was applied as a preventive measure before the hen house was restocked with pullets for two housing periods of 58 and 52 weeks. Over these periods (i.e. more than 2 years), no PRM was detected during mite monitoring at two-week intervals via tube traps and visual monitoring. This result therefore suggests that the combined use of appropriate chemical and physical prevention measures within an integrated pest management regime can be successfully used for the long-term control of PRM. This could reduce the use of acaricidal drugs, thereby helping maintain their efficacy.

Measuring behaviour in hens using an ethogram to assess analgesia during further refinement of a high welfare, on-hen, poultry red mite feeding device

Background: To refine an on-hen mite feeding device, an ethogram was employed to measure the reactions of hens during a routine experimental procedure (feather plucking) and to assess effects of analgesic cream on those reactions. Methods: Three experimental groups were used; one treated with EMLA 5% before plucking ("EMLA group"); one with aqueous cream ("placebo group") and a "no treatment" group. Behaviours were measured and compared on three days: 'dummy handling day' i.e. no plucking; 'plucking day', plucking the left thigh; and 'treatment day' i.e with right thighs plucked post-treatment. Poultry red mite feeding assays were performed to examine effect of creams on mite feeding rates, mortality and fecundity. All data were analysed using generalised linear (mixed) modelling approaches. Results: Use of the ethogram demonstrated no significant difference in hen behaviours in the EMLA group between dummy handling day and treatment day (p = 0.949) alongside a significant reduction in measured behaviours between plucking day and treatment day in the same group (p = 0.028). There was a statistically significant increase in measured behaviours from the dummy handling day to the plucking day in both placebo (p = 0.011) and no treatment group (p < 0.001). Effect sizes and directions were similar between dummy handling and treatment days in the 'placebo' and 'no treatment' groups, though not statistically significant (placebo, p = 0.064; no treatment p = 0.069). Mite feeding in the EMLA group was significantly lower than in the no treatment group in feeding assay 1 (p = 0.029) only. Mite mortality and fertility were unaffected. Conclusions: The ethogram successfully measured changes in observed behaviours between the dummy handling session and procedures. No adverse effects of EMLA cream on hens were demonstrated at 3mg/kg in hens. Use of analgesia for this routine procedure improves hens' experiences during experimental trials.

Management of the poultry red mite Dermanyssus gallinae with physical control methods by inorganic material and future perspectives

Poultry red mite (PRM), the ectoparasitic mite Dermanyssus gallinae found in laying hen farms, is a significant threat to poultry production and human health worldwide. It is a suspected disease vector and attacks hosts' other than chickens, including humans, and its economic importance has increased greatly. Different strategies to control PRM have been widely tested and investigated. In principle, several synthetic pesticides have been applied to control PRM. However, recent alternative control methods to avoid the side effects of pesticides have been introduced, although many remain in the early stage of commercialization. In particular, advances in material science have made various materials more affordable as alternatives for controlling PRM through physical interactions between PRM. This review provides a summary of PRM infestation, and then includes a discussion and comparison of different conventional approaches: 1) organic substances, 2) biological approaches, and 3) physical inorganic material treatment. The advantages of inorganic materials are discussed in detail, including the classification of materials, as well as the physical mechanism-induced effect on PRM. In this review, we also consider the perspective of using several synthetic inorganic materials to suggest novel strategies for improved monitoring and better information regarding treatment interventions.

Poultry Mites: Ubiquitous, Spreading, and Still a Growing Threat

Poultry mites continue to be a major threat to poultry meat and egg production all over the world, with some species being blood-feeding arthropods that spend most of their time off-host and others burrowing under the bird's skin. Regardless of feeding strategy, these mites create welfare issues and production losses in poultry production systems in terms of bird growth, egg quality, and egg quantity. Furthermore, some species are able to transmit pathogens, introducing secondary infections that affect the birds' development and survival. Because of national restrictions on acaricide use and the development of mite resistance to available control products, the eradication of poultry mites is far from being achieved. However, new drugs and a better understanding of mite genetic and transcriptomic factors should aid the development of new control and treatment strategies. This review focuses on the main poultry mite species, their significance, and their current and future control.

Population dynamics of a poultry hematophagous mite: characterization of the population growth and identification of factors of its slowdown using closed mesocosms

BACKGROUND

A thorough knowledge of the population dynamics of pests and of the main factors affecting population growth is an important prerequisite for the development of effective control strategies. Failures of various treatments aimed at regulating populations of Dermanyssus gallinae are regularly reported in poultry farms and pullulations occur very quickly after first detection. To finely characterize population dynamics of D. gallinae, and to identify the factors modulating population growth, we conducted two successive multi-generation experiments using closed mesocosms equipped with or without automatic counters and housing a host full- or part-time (three nights per week).

RESULTS

Population growth was very rapid and the adult to juvenile ratio very different from the prediction by a mathematical model. A male-biased sex ratio was observed in some mesocosms from 21 days and in most mesocosms from 35 days of population growth originating from an inoculum of adult females. A dramatic slowdown in growth was measured in mesocosms equipped with trackers, where the mites' path to the host was constrained. The slowdown in population growth induced by the intermittent presence of the host compared to its full-time presence was much less marked.

CONCLUSION

These findings suggest avenues of research for new management methods. They question the relevance of a critical threshold based on traditional trap monitoring to manage D. gallinae. Our results highlight a unique characteristic of D. gallinae that makes it a recalcitrant case to threshold-based practices recommended for integrated pest management (IPM) against other arthropod pests. The dramatic effect of a physical constraint for the mite to access the host (unnatural constrained path) confirms an observation made in 1917 and is a reason to design perches that are less conducive to parasite traffic. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Release of DNA from Dermanyssus gallinae during the Biting Process

Simple Summary

Like many hematophagous parasites, the poultry red mite Dermanyssus gallinae may release some material during the biting process. This investigation evidenced that small amounts of mite DNA may be found in chicken skin after D. gallinae infestation. Since the retrieved DNA is both of nuclear and mitochondrial origin, it is possible to hypothesize that, while biting, the mite releases cellular material.

Abstract

Dermanyssus gallinae is a hematophagous ectoparasitic mite that usually infests poultry, but is also known for occasionally attacking other animals and humans. It represents a major problem for poultry systems all over the world, with detrimental effects for both production and animal welfare. Despite the significance of D. gallinae, very little is known about the biting process to date. Therefore, this study has aimed to verify if mite DNA is injected into the host skin during the blood meal. Mite DNA has been detected by seminested PCR from infested chicken skin and quantified by real-time PCR. Furthermore, its localization within the host tissue has been checked by fluorescent in situ hybridization. Results showed that a very little amount of D. gallinae DNA can be released by mites, suggesting that the latter do not introduce whole or partially destroyed cells into the host, but rather it injects traces of nucleic acids, possibly together with merocrine secretions.

Possibilities for IPM Strategies in European Laying Hen Farms for Improved Control of the Poultry Red Mite (Dermanyssus gallinae): Details and State of Affairs

The Poultry Red Mite (PRM), Dermanyssus gallinae, is a major threat to the poultry industry worldwide, causing serious problems to animal health and welfare, and huge economic losses. Controlling PRM infestations is very challenging. Conventionally, D. gallinae is treated with synthetic acaricides, but the particular lifestyle of the mite (most of the time spent off the host) makes the efficacy of acaracide sprays often unsatisfactory, as sprays reach only a small part of the population. Moreover, many acaricides have been unlicensed due to human consumer and safety regulations and mites have become resistant to them. A promising course of action is Integrated Pest Management (IPM), which is sustainable for animals, humans and the environment. It combines eight different steps, in which prevention of introduction and monitoring of the pest are key. Further, it focusses on non-chemical treatments, with chemicals only being used as a last resort. Whereas IPM is already widely applied in horticulture, its application is still in its infancy to control D. gallinae in layer houses. This review presents the currently-available possibilities for control of D. gallinae in layer houses for each of the eight IPM steps, including monitoring techniques, established and emerging non-chemical treatments, and the strategic use of chemicals. As such, it provides a needed baseline for future development of specific IPM strategies, which will allow efficient and sustainable control of D. gallinae in poultry farms.

Collecting and Monitoring for Northern Fowl Mite (Acari: Macronyssidae) and Poultry Red Mite (Acari: Dermanyssidae) in Poultry Systems

The two most economically important poultry ectoparasites are the northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), and the poultry red mite, Dermanyssus gallinae (De Geer). Both mites are obligate blood feeders but differ in where they reside. Sampling methods thus focus on-host, especially the vent feathers, for northern fowl mite and off-host, especially cracks and crevices near the nighttime roosting areas, for poultry red mite. Much remains unknown, however, about the basic biology and ecology of both mites. Here we discuss mite detection, quantification, and decision making and provide thoughts on future directions for research.

A sampling and estimation method for monitoring poultry red mite (Dermanyssus gallinae) infestation on caged-layer poultry farms

Background

The poultry red mite, Dermanyssus gallinae, is a serious problem in the laying hen industry worldwide. Currently, the foremost control method for D. gallinae is the implementation of integrated pest management, the effective application of which necessitates a precise monitoring method.

Objectives

The aim of the study was to propose an accurate monitoring method with a reliable protocol for caged-layer poultry farms, and to suggest an objective classification for assessing D. gallinae infestation on caged-layer poultry farms according to the number of mites collected using the developed monitoring method.

Methods

We compared the numbers of mites collected from corrugated cardboard traps, regarding with length of sampling periods, sampling sites on cage, and sampling positions in farm buildings. The study also compared the mean numbers of mites collected by the developed method with the infestation levels using by the conventional monitoring methods in 37 caged-layer farm buildings.

Results

The statistical validation provided the suitable monitoring method that the traps were installed for 2 days on feed boxes at 27 sampling points which included three vertical levels across nine equally divided zones of farms. Using this monitoring method, the D. gallinae infestation level can be assessed objectively on caged-layer poultry farms. Moreover, the method is more sensitive than the conventional method in detecting very small populations of mites.

Conclusions

This method can be used to identify the initial stages of D. gallinae infestation in the caged-layer poultry farms, and therefore, will contribute to establishment of effective control strategies for this mite.

Evaluating the link between predation and pest control services in the mite world

Pest regulation by natural enemies has a strong potential to reduce the use of synthetic pesticides in agroecosystems. However, the effective role of predation as an ecosystem service remains largely speculative, especially with minute organisms such as mites.Predatory mites are natural enemies for ectoparasites in livestock farms. We tested for an ecosystem level control of the poultry pest Dermanyssus gallinae by other mites naturally present in manure in poultry farms and investigated differences among farming practices (conventional, free-range, and organic).We used a multiscale approach involving (a) in vitro behavioral predation experiments, (b) arthropod inventories in henhouses with airborne DNA, and (c) a statistical model of covariations in mite abundances comparing farming practices.Behavioral experiments revealed that three mites are prone to feed on D. gallinae. Accordingly, we observed covariations between the pest and these three taxa only, in airborne DNA at the henhouse level, and in mites sampled from manure. In most situations, covariations in abundances were high in magnitude and their sign was positive.Predation on a pest happens naturally in livestock farms due to predatory mites. However, the complex dynamics of mite trophic network prevents the emergence of a consistent assemblage-level signal of predation. Based on these results, we suggest perspectives for mite-based pest control and warn against any possible disruption of ignored services through the application of veterinary drugs or pesticides.

Association between the poultry red mite Dermanyssus gallinae and potential avian pathogenic Escherichia coli (APEC)

Avian pathogenic Escherichia coli (APEC) is a group of strains responsible for avian colibacillosis, an impactful disease for poultry farming. The spread of APEC is mainly horizontal, and insects may play a role in their dissemination. However, no data are available about the interaction of APEC with Dermanyssus gallinae, a major arthropodal parasite of poultry. Escherichia coli was detected in the microbiome of the mite, but no specific data have been published till now. Therefore, the presence of the most diffused APEC-associated serogroups has been assessed by PCR in mites collected from 30 flocks of 21 Italian commercial laying hens farms. Escherichia coli was found in 53.3% of the tested groups, corresponding to 66.7% of farms. The most frequent serogroup was O2, but O8, O78, and O109 were also detected. More detailed investigations were carried out in a laying hen farm that was experiencing colibacillosis by APEC O2. The same serogroup was found in both hens and mites, and the maximum likelihood estimation (MLE) of the infection rate (IR) resulted in 24.39 infected mites per thousand, with a pathogen load of 171.47 E. coli O2 cells per mite. The results strongly support the hypothesis of an association between PRM and APEC, confirmed by the contemporary circulation of the same serogroup in both hens and mites, suggesting the potential of D. gallinae as a reservoir or APEC.

Survey on the prevalence of Dermanyssus gallinae in commercial laying farms in Portugal

Dermanyssus gallinae, also known as the poultry red mite (PRM), is a blood-feeding ectoparasite of poultry and sylvatic birds. This mite is endemic in many parts of the globe and poses a threat to the egg industry, while compromising the health and welfare of hens, both directly and as a vector of diseases. In addition, people attacked by D. gallinae may develop gamasoidosis. Despite the high prevalence in several European countries, epidemiological information on D. gallinae in Portugal is scarce. This study aimed to assess the prevalence and infestation levels in laying farms in Portugal and evaluate the perception and attitudes of producers regarding D. gallinae. A survey was performed between August 2016 - November 2017, which included 24 farms in the NUTS2 regions Centro and Norte. Mites were sampled with corrugated cardboard traps and the perception and attitudes of farmers regarding the PRM were evaluated with the European COREMI questionnaire prepared by WG 1 of the COST action FA1404. D. gallinae was detected in 95.8% of farms (95% CI: 79.8-99.3%). The average number of trapped mites among farms was 5200 ± 16,522, with a median of 359 mites (interquartile range = 46-3135). Results from the questionnaire show that insufficient monitoring, under-detection and late and suboptimal treatment may contribute to the maintenance of significant infestation levels. The present data highlight the need for adequate monitoring of D. gallinae, timely action and effective treatment in order to improve poultry productivity and ensure human and animal health and welfare. RESEARCH HIGHLIGHTS A survey on the prevalence of D. gallinae in Portuguese layer farms is presented The perceived importance of D. gallinae was assessed with a questionnaire D. gallinae was detected in 95.8% of farms The results emphasize the need for adequate monitoring and treatment optimization.

The efficiency of a new automated mosquito larval counter and its impact on larval survival

To achieve consistent and standardized rearing for mosquito immature stages, it is crucial to control the initial number of larvae present in each larval tray. In addition, maintaining an optimal and synchronized development rate of larvae is essential to maximize the pupal production and optimize male sorting in a mass-rearing setting. Manual counting is labor intensive, time consuming and error prone. Therefore, this study aimed to investigate the use of a customized automated counter for the quantification of mosquito larvae. The present prototype of the mosquito larval counter uses a single counting channel consisting of three parts: a larvae dispenser, an electronic counting unit and computer control software. After the separation of the larvae from eggs and debris, batches of different numbers of Aedes aegypti first instar larvae were manually counted and introduced into the counter through the upper loading funnel and channeled out from the bottom of the counter by gravitational flow. The accuracy and repeatability of the mosquito larval counter were determined in relation to larval density and water quality. We also investigated its impact on larval survival. Results showed an impact of larval density and water quality on the accuracy of the device. A −6% error and a repeatability of +/− 2.56% average value were achieved with larval densities up to 10 larvae/mL of clean water. Moreover, the use of the mosquito larval counter did not have any effect on larval survival or development. Under recommended conditions, the mosquito larval counter can be used to enumerate the number of mosquito larvae at a given density. However, future developments involving the use of multiple channels or larger input larvae container would help to expand its use in large-scale facilities.

Circulation dynamics of Salmonella enterica subsp. enterica ser. Gallinarum biovar Gallinarum in a poultry farm infested by Dermanyssus gallinae

Dermanyssus gallinae (Mesostigmata: Dermanyssidae, De Geer, 1778) is an ectoparasite of poultry, suspected to play a role as a vector of Salmonella enterica subsp. enterica ser. Gallinarum. Despite an association between them being reported, the actual dynamics in field remain unclear. Therefore, the present study aimed to confirm the interactions among mites, pathogen and chickens. The study was carried out in an industrial poultry farm infested by D. gallinae, during an outbreak of fowl typhoid. The presence of S. Gallinarum in mites was assessed and quantified by a semi-nested polymerase chain reaction (PCR) and real-time PCR, respectively, in mites collected during two subsequent productive cycles and the sanitary break. The anti-group D Salmonella antibodies were quantified by an enzyme-linked immunosorbent assay. During the outbreak and the sanitary break, S. Gallinarum was constantly present in mites. In the second cycle, scattered positivity was observed, although hens did not exhibit signs of fowl typhoid, as a result of the vaccination with BIO-VAC SGP695 (Fatro, Ozzano Emilia Bo, Italy). The data strongly suggest that D. gallinae acts as reservoir of S. Gallinarum, thus allowing the pathogen to persist in farms. Furthermore, the present study has highlighted the interactions among D. gallinae, S. Gallinarum and hens with respect to enhancing the mite-mediated circulation of S. Gallinarum in an infested poultry farm.

Experimental validation of the AVIVET trap, a tool to quantitatively monitor the dynamics of Dermanyssus gallinae populations in laying hens

Dermanyssus gallinae (D.gallinae) infestation causes economic losses due to impaired health and production of hens and costs of parasite control across the world. Moreover, infestations are associated with reduced welfare of hens and may cause itching in humans. To effectively implement control methods it is crucially important to have high quality information about the D.gallinae populations in poultry houses in space and time. At present no validated tool is available to quantitatively monitor the dynamics of all four stages of D.gallinae (i.e., eggs, larvae, nymphs, and adults) in poultry houses.This article describes the experimental validation of the AVIVET trap, a device to quantitatively monitor dynamics of D.gallinae infestations. We used the device to study D.gallinae in fully equipped cages with two white specific pathogen free Leghorn laying hens experimentally exposed to three different infestation levels of D.gallinae (low to high).The AVIVET trap was successfully able to detect D.gallinae at high (5,000 D.gallinae), medium (2,500 D.gallinae), and low (50 D.gallinae) level of D.gallinae infestation. The linear equation Y = 10∧10∧(0.47 + 1.21X) with Y = log10 (Total number of D.gallinae nymphs and adults) in the cage and X = log10 (Total number of D.gallinae nymphs and adults) in the AVIVET trap explained 93.8% of the variation.The weight of D.gallinae in the AVIVET trap also appears to be a reliable parameter for quantifying D.gallinae infestation in a poultry house. The weight of D.gallinae in the AVIVET trap correlates 99.6% (P < 0.000) to the counted number of all stages of D.gallinae in the trap (i.e., eggs, larvae, nymphs, and adults) indicating that the trap is highly specific.From this experiment it can be concluded that the AVIVET trap is promising as quantitative tool for monitoring D.gallinae dynamics in a poultry house.

Poultry red mite (Dermanyssus gallinae) infestation: a broad impact parasitological disease that still remains a significant challenge for the egg-laying industry in Europe

The poultry red mite, Dermanyssus gallinae, has been described for decades as a threat to the egg production industry, posing serious animal health and welfare concerns, adversely affecting productivity, and impacting public health. Research activities dedicated to controlling this parasite have increased significantly. Their veterinary and human medical impact, more particularly their role as a disease vector, is better understood. Nevertheless, red mite infestation remains a serious concern, particularly in Europe, where the prevalence of red mites is expected to increase, as a result of recent hen husbandry legislation changes, increased acaricide resistance, climate warming, and the lack of a sustainable approach to control infestations. The main objective of the current work was to review the factors contributing to this growing threat and to discuss their recent development in Europe. We conclude that effective and sustainable treatment approach to control poultry red mite infestation is urgently required, included integrated pest management.