J.H. Guy

Use of Plant-derived Products to Control Arthropods of Veterinary Importance : A Review

The use of synthetic products in veterinary pest management is becoming increasingly problematic. Issues, including pest resistance, product withdrawal, undesirable environmental persistence, and high mammalian toxicity associated with synthetic pesticides, are driving research to identify new pest management approaches. One approach employs the repellent/toxic effects of plant‐derived products (PDPs). Several pesticides based on PDPs are already available in some areas of pest management. This review highlights instances in which such products have been used with success against pests of domestic animals, livestock, apiculture, and poultry.

Red mite (Dermanyssus gallinae) prevalence in laying units in northern England

The poultry red mite Dermanyssus gallinae (De Geer, 1778) is one of the most important ectoparasites affecting egg layers in all production systems across Europe (DEFRA, 2001). It is an obligatory haematophagous ectoparasite (Bruneau et al., 2001), resulting in reduced egg production, increased egg downgrading and occasionally death through anaemia. Infestation rates as high as 67% have been reported in Swedish systems (Hoguland et al., 1995), and although the traditional control strategy is acaricide application, there is a suggestion that in Europe some of these products will be withdrawn (Chauve, 1998). Resistance of red mite to pyrethroid is a risk, so producers are encouraged to use alternative control strategies. The aims of this study were to assess the incidence and severity of red mite infestation in laying farms in Northern England, and producer opinions regarding the effectiveness of current control methods. Egg producers in the region were invited to participate in the study, and sent a questionnaire together with a number of red mite traps made out of either corrugated cardboard or 2 plastic straws mounted on cardboard (10 cm 4 cm). The questionnaire comprised both qualitative and quantitative elements, and asked for a detailed description of their production system (flock size, type and dimensions of buildings, feeding and lighting regimens etc.), and specific questions about red mite infestation and control methods used (if any) (e.g. chemical, rate and frequency of application). Producers were asked to position traps within one or more buildings, as close as possible to, but yet protected from the hens. The traps were removed after a period of about 7 d, placed in a sealable plastic bag and posted to the laboratory where they were processed according to the method described by Arkle et al. (2004). Each trap was counted twice by the same person. Questionnaire data and mite populations were entered onto a database, and analysed by analysis of variance where appropriate. A total of 29 farms participated in the study (response rate1⁄4 60%), primarily of cage and free range systems (Table 1), representing a total of 1.03 million hens. Average flock size was 42,848 hens, producing on average 293 eggs per annum. Red mite was present on 87.5% of farms. The population of nymph and adult mites was significantly higher (P < 0.05) in free range compared with either barn or cage systems. Although differences were not significant, the number of red mite eggs and larvae tended to be lower in cage systems than in the other two systems. However, there was considerable variation in the data, as indicated by the relatively large standard error of the difference (s.e.d.) values. The questionnaire indicated that producer’s primary concern with red mite was its effect on egg production and quality, rather than hen mortality or cost of control. Of the available control methods, some recommended by DEFRA (2001), the most common method used was acaricide application (birds in situ), followed by application with birds removed or blanket application (Table 2). Less common were the strategies of sealing joints where mites may seek refuge, cleaning the outside of buildings or designing new mite-proof housing. Only 8% of farms used no control method at all. Perceived resistance by red mite to acaricide application

The Poultry Red Mite Dermanyssus gallinae as a Potential Carrier of Vector‐borne Diseases

The poultry red mite Dermanyssus gallinae is an obligatory blood‐sucking parasite that is considered to be one of the most important ectoparasites in the poultry industry, mainly because it is responsible for important economic losses, leads to a reduction of welfare of laying hens, and may pose a disease risk to humans. As a result of these problems, much of the current research on this parasite targets new methods of control. Less attention has been paid to the importance of D. gallinae as a carrier of vector‐borne diseases. Some authors have mentioned the possible involvement of D. gallinae in the transmission (both in vitro and directly isolated from the mites) of viral and bacterial agents. Our research group has demonstrated the presence of Mycobacterium spp. within D. gallinae. DNA coding for Mycobacterium spp. was successfully amplified from unfed adult D. gallinae, larvae, and eggs by using reverse transcription‐polymerase chain reaction targeting the 16S rRNA gene. The results have suggested the possible transovarial and transstadial transmission of pathogens by D. gallinae.

Immunological effects and productivity variation of red mite (Dermanyssus gallinae) on laying hens - Implications for egg production and quality

Red mite (Dermanyssus gallinae; De Geer, 1778) is currently one of the most detrimental ectoparasites in laying birds across several countries. Symptoms of D. gallinae infestation include reduction in production, poor egg quality, increased mortality and also a compromise to welfare. Feeding on its host for only short periods of time, the red mite spends the vast proportion of its short life-cycle hidden deep within the house substructure. For this reason, it is the preference of red mite to occupy free range or barn systems as opposed to caged, since a greater number of potential hiding places can be sought. A problem which will therefore be amplified within the EU with the impending ban on production in laying cages. This, in conjunction with concern over resistance to acaricides, toxicity risks and acaricide withdrawal, make control particularly problematic and financially draining for producers. Therefore alternative methods must be sought, such as vaccine development. However, in order for this to be achieved, an understanding of mite antigenicity must first be established. Thus, the purpose of this study was to assess immunological response of humeral antibodies to naturally occurring mite antigens, using enzyme-linked immunosorbent assay (ELISA) and SDS-PAGE. Antibodies were derived from egg yolk and blood sera which were collected from commercial laying farms across the UK with varying levels of red mite infestation and using different production systems (caged, barn and free range). In addition, mites were trapped and counted periodically so as to follow population dynamics over a flock lifespan in conjunction with a series of production measures (Laying percentage, eggs per bird per week, mortality and temperature). The results describe the effect of red mite infestation on production parameters, immunological response and the relationship between them.

2004 SPRING MEETING OF THE WPSA UK BRANCH PAPERS

The poultry red mite Dermanyssus gallinae (De Geer, 1778) is one of the most important ectoparasites affecting egg layers in all production systems across Europe (DEFRA, 2001). It is an obligatory haematophagous ectoparasite (Bruneau et al., 2001), resulting in reduced egg production, increased egg downgrading and occasionally death through anaemia. Infestation rates as high as 67% have been reported in Swedish systems (Hoguland et al., 1995), and although the traditional control strategy is acaricide application, there is a suggestion that in Europe some of these products will be withdrawn (Chauve, 1998). Resistance of red mite to pyrethroid is a risk, so producers are encouraged to use alternative control strategies. The aims of this study were to assess the incidence and severity of red mite infestation in laying farms in Northern England, and producer opinions regarding the effectiveness of current control methods. Egg producers in the region were invited to participate in the study, and sent a questionnaire together with a number of red mite traps made out of either corrugated cardboard or 2 plastic straws mounted on cardboard (10 cm 4 cm). The questionnaire comprised both qualitative and quantitative elements, and asked for a detailed description of their production system (flock size, type and dimensions of buildings, feeding and lighting regimens etc.), and specific questions about red mite infestation and control methods used (if any) (e.g. chemical, rate and frequency of application). Producers were asked to position traps within one or more buildings, as close as possible to, but yet protected from the hens. The traps were removed after a period of about 7 d, placed in a sealable plastic bag and posted to the laboratory where they were processed according to the method described by Arkle et al. (2004). Each trap was counted twice by the same person. Questionnaire data and mite populations were entered onto a database, and analysed by analysis of variance where appropriate. A total of 29 farms participated in the study (response rate1⁄4 60%), primarily of cage and free range systems (Table 1), representing a total of 1.03 million hens. Average flock size was 42,848 hens, producing on average 293 eggs per annum. Red mite was present on 87.5% of farms. The population of nymph and adult mites was significantly higher (P < 0.05) in free range compared with either barn or cage systems. Although differences were not significant, the number of red mite eggs and larvae tended to be lower in cage systems than in the other two systems. However, there was considerable variation in the data, as indicated by the relatively large standard error of the difference (s.e.d.) values. The questionnaire indicated that producer’s primary concern with red mite was its effect on egg production and quality, rather than hen mortality or cost of control. Of the available control methods, some recommended by DEFRA (2001), the most common method used was acaricide application (birds in situ), followed by application with birds removed or blanket application (Table 2). Less common were the strategies of sealing joints where mites may seek refuge, cleaning the outside of buildings or designing new mite-proof housing. Only 8% of farms used no control method at all. Perceived resistance by red mite to acaricide application

Variation in the population of Dermanyssus gallinae in a free range laying unit and effectiveness of chemical control.

Dermanyssus gallinae (De Geer, 1778) is currently the most economically deleterious ectoparasite of layer hens in several countries (Chauve, 1998). Also termed the chicken mite or poultry red mite (Nordenfors et al., 1999), D. gallinae is an obligatory haematophagous ectoparasite of both domestic and wild birds (Bruneau et al., 2001), with infestation resulting in irritation, restlessness, anaemia, reduced egg production and occasionally death. The red mite is a temporary parasite, as it is only found on the host during darkness when obtaining a blood meal. The remaining part of its lifecycle is spent concealed in cracks and crevices within the house, therefore any method of control must penetrate deep into the house substructure, via means such as chemical spraying. The primary objectives of this study were to investigate the variation in population of red mites within different locations of a commercial laying system, and the effectiveness of spraying a chemical acaricide. This study was carried out on a free-range unit of 4000 laying hens (at 51 weeks of age) of a commercial genotype over a 13 week period. The house was sprayed with an approved acaricide (containing 80% bendiocarb, diluted at a rate of 3 g/l of water) in weeks 4 and 10 (Figure). At weekly intervals, 20 mite traps were secured to the underside of perches at regular distances along the length and on both sides of the house. Hens could access pasture from only one side of the building. The traps consisted of two drinking straws attached to a 100 mm 40 mm piece of cardboard and were replaced weekly (before any spraying took place). Contaminated traps were placed in sealed polythene bags along with 25 ml of 70% ethanol, in order to both kill and preserve the mite. Traps were filtered using a water-driven vacuum pump, and then washed with ethanol into a plastic bottle, topped up to a volume of 25 ml. A known volume of this solution was taken and mites were counted under a light microscope by two different observers. Three different mite stages were identified, and the mean count number of eggs, larvae and adults and nymphs (fed and unfed) recorded. Mite numbers were multiplied up to estimate the total numbers in a 25 ml sample. Results were analysed by analysis of variance (ANOVA) in Minitab (v 13), plotted in Excel and fitted with logarithmic trendlines. The results reveal a wide variation between different weeks (Figure). Significant differences (P < 0.001) in mean adult and nymph numbers were seen between week 1 and week 4 and 10, and in egg numbers between weeks 1 and 10.

Immunological control of the poultry red mite

In the current study whole poultry red mite antigens were extracted and birds were immunized subcutaneously with either antigen in adjuvant (antigen group) or PBS in adjuvant (control group). Immune responses of birds following immunization were investigated by ELISA and Western blotting, while vaccine efficacy was assessed by feeding of red mites on birds. Immunized birds showed a significant (P < 0.05) increase in IgY titers after immunization compared to controls, while immunoglobulin A (IgA) and IgM did not change significantly. However, the antigen group had a generally higher increase in all immunoglobulin titers compared to the controls. Western blotting identified a number of protein bands at different molecular weights, although these were not different between treatments. PCR analysis of whole mite protein identified bacterial DNA that might have confounded immunological data. In addition, there was a trend toward reduced survival rate of red mites feeding on antigen‐immunized birds, but the difference was not statistically significant compared to controls. This study demonstrates the potential for somatic red mite antigens to stimulate an antibody‐mediated immune response, although this response did not confer protection to birds.

Effect of enrichment with Pecka-Blocks™ on the behaviour and feather condition of commercially-reared broilers

even in the first half of the experiment. Food conversion efficiency (FCE, weight gain/food intake) was similar in all diets. Breast muscle weight, in both absolute and relative terms, was highest on the ideal protein diets but this effect did not attain statistical significance. Fat pad weight did not differ significantly between diets but tended to be lowest on the ‘‘high protein’’ diet. In general terms, the results of this experiment confirmed those of Kim and MacLeod (2001), in that reducing total crude protein content while maintaining the intake of essential amino acids reduced nitrogen losses without showing any significant detrimental effects on growth rate, body composition or breast meat yield. This work was supported by DEFRA.

Effect of gender on water, feed intake and dry matter consistency of broilers

reduction in the microbial population in the gut. Similarly the inclusion of garlic powder, (1.0 g) would decrease the GE by about 6%. Thus the lack of improvement in ME seen with garlic powder may be due to the reduction in energy from the garlic powder. In our previous in-vitro study on microbial fermentation with chicken gut contents, thyme oil suppressed, while garlic powder promoted, microbial fermentation. The lack of improvements in the metabolisable energy from soybean meal (when the energy from the supplements are accounted for) with either thyme oil or garlic powder included up to 2.0% demonstrates an inconsistency between the effects of phytochemicals in broiler diets. Cross et al. (2003) did not observed improvements with inclusion of thyme oil up to 5% in broiler diets and in fact noted a reduction in intake at the highest inclusion rate. However, the strong antibacterial properties of thyme oil protected the birds from colisepticaemia. Lee et al. (2003) observed a 7% improvement in feed conversion with an inclusion of 16.5 g/kg garlic in male broilers only between 17–27 d and not 7–17 days. In contrast, Demir et al. (2003) observed improvements in body weights of female broilers given garlic and thyme powder at 1 g/kg between 0–14 d and not 0–42 d. This improvement was attributed to the significant reduction in the depth of the crypts if the ileum with the inclusion of thyme and garlic which point to the antimicrobial properties of thyme and garlic. The results of this study indicate that thyme oil and garlic do not improve the nutritional value of soybean meal and the improvements observed in some of the studies could have been due to their antimicrobial effects. It was noted that thyme oil tended to improve the utilisation of N from the SBM and the effects on amino acid utilisation will be investigated. SAC is supported by SEERAD. S. Shanmugavelu is grateful to the Malaysian Agricultural Research and Development Institute for financial assistance in the support of his studies.

2004 SPRING MEETING OF THE WPSA UK BRANCH PAPERS: Red mite ( Dermanyssus gallinae ) prevalence in laying units in Northern England

The poultry red mite Dermanyssus gallinae (De Geer, 1778) is one of the most important ectoparasites affecting egg layers in all production systems across Europe (DEFRA, 2001). It is an obligatory haematophagous ectoparasite (Bruneau et al., 2001), resulting in reduced egg production, increased egg downgrading and occasionally death through anaemia. Infestation rates as high as 67% have been reported in Swedish systems (Hoguland et al., 1995), and although the traditional control strategy is acaricide application, there is a suggestion that in Europe some of these products will be withdrawn (Chauve, 1998). Resistance of red mite to pyrethroid is a risk, so producers are encouraged to use alternative control strategies. The aims of this study were to assess the incidence and severity of red mite infestation in laying farms in Northern England, and producer opinions regarding the effectiveness of current control methods. Egg producers in the region were invited to participate in the study, and sent a questionnaire together with a number of red mite traps made out of either corrugated cardboard or 2 plastic straws mounted on cardboard (10 cm 4 cm). The questionnaire comprised both qualitative and quantitative elements, and asked for a detailed description of their production system (flock size, type and dimensions of buildings, feeding and lighting regimens etc.), and specific questions about red mite infestation and control methods used (if any) (e.g. chemical, rate and frequency of application). Producers were asked to position traps within one or more buildings, as close as possible to, but yet protected from the hens. The traps were removed after a period of about 7 d, placed in a sealable plastic bag and posted to the laboratory where they were processed according to the method described by Arkle et al. (2004). Each trap was counted twice by the same person. Questionnaire data and mite populations were entered onto a database, and analysed by analysis of variance where appropriate. A total of 29 farms participated in the study (response rate1⁄4 60%), primarily of cage and free range systems (Table 1), representing a total of 1.03 million hens. Average flock size was 42,848 hens, producing on average 293 eggs per annum. Red mite was present on 87.5% of farms. The population of nymph and adult mites was significantly higher (P < 0.05) in free range compared with either barn or cage systems. Although differences were not significant, the number of red mite eggs and larvae tended to be lower in cage systems than in the other two systems. However, there was considerable variation in the data, as indicated by the relatively large standard error of the difference (s.e.d.) values. The questionnaire indicated that producer’s primary concern with red mite was its effect on egg production and quality, rather than hen mortality or cost of control. Of the available control methods, some recommended by DEFRA (2001), the most common method used was acaricide application (birds in situ), followed by application with birds removed or blanket application (Table 2). Less common were the strategies of sealing joints where mites may seek refuge, cleaning the outside of buildings or designing new mite-proof housing. Only 8% of farms used no control method at all. Perceived resistance by red mite to acaricide application