WO2010130990A2

WO2010130990A2 - Use of a carboxylic acid or an aldehyde

Info

Publication number: WO2010130990A2
Application number: PCT/GB2010/000941
Authority: WO
Inventors: Mike Birkett; John Pickett; Sarah Dewhirst; Jørgen Brøchner JESPERSEN; Ole Østerlund KILPINEN
Original assignee: Rothamsted Research Limited; Aarhus Universitet
Priority date: 2009-05-11
Filing date: 2010-05-11
Publication date: 2010-11-18
Also published as: GB0908090D0; WO2010130990A3; WO2010130990A8

Abstract

The invention relates to the use of a volatile carboxylic acid or an aldehyde as an attractant for an avian mite and methods and systems thereof.

Description

Use of a carboxylic acid or an aldehyde

One of the most common avian mites is the poultry red mite, Dermanyssus gallinae, which can be a very serious problem.

The poultry red mite is a major arthropod pest of increasing importance to the health and welfare of many types of birds, both domestic and wild birds. In domestic poultry, parasitism by this haemotophagous mite is demonstrated through disturbance of the poultry, irritation, anaemia, transfer of diseases, reduced laying ability, and sometimes even death. Poultry red mite infestations may also lead to downgrading of the eggs due to blood spots on the eggs.

The poultry red mite is an obligatory blood-feeding parasite of birds, which stays on the host only during night. It is during this period that they feed for a short (1 - 2 hours) blood meal. In the day time they are hidden somewhere in the poultry house, such as on cages or in wall cracks, where they digest blood and multiply.

The poultry red mite also generates a serious threat to the health of man and animal by acting as a vector/carrier for important diseases. Avian mite problems have increased considerably in recent years in the developed world due to regional and national policies resulting in a shift from battery systems to more welfare/consumer friendly systems, reduction in number of registered acaricides, and pesticide resistance in mite populations.

Current methods for controlling avian mites are based on heavy use of broad- spectrum persistent synthetic insecticides. Such methods are not desirable, in general, in farming and are completely unacceptable for organic farming practices. Silicium dust is also used in the control of mites but very often such treatments are not sufficiently efficient and it would therefore be preferable if other means of effective control were available.

Poultry red mites represent a special problem because they hide in cracks and crevices making them very difficult to control with conventional pesticides and other alternative control methods.

Thus, there is a requirement for an alternative approach to controlling avian mites that does not have the environmental and health disadvantages that are associated with current methods and a method that will overcome the problem of targeting the mites in their protected hiding places.

The first aspect of the invention provides the use of a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, as an attractant for an avian mite.

The inventors have found that volatile organic compounds with a Cl to Cl 5 alkyl straight chain or branched chain and a carboxylic acid group or an aldehyde group are particularly useful for attracting avian mites.

In one embodiment, the molecule of the invention is a C5 to ClO, including a C6 to C9, alkyl straight chain or branched chain molecule.

In a further embodiment, the Cl to C3 alkyl group is substituted on the first or second carbon atom of the straight chain or branched chain molecule.

In a yet further embodiment, the Cl to C15 alkyl straight chain or branched chain molecule of the invention is pentanoic acid, hexanoic acid, 2-ethyl-hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid and/or octanal. A Cl to Cl 5 alkyl straight chain or branched chain molecule according to the invention can be obtained naturally or a synthetic molecule can be used.

A straight Cl to Cl 5 alkyl straight chain or branched chain molecule, in accordance with the invention, acts as an attractant, i.e. as a lure or a bait, to cause members of an avian mite population to move towards a source of the molecule.

Pentanoic acid (also known as valeric acid) has the general formula CH₃(CH₂)₃COOH.

Hexanoic acid (also known as caproic acid) is the carboxylic acid derived from hexane and has the general formula CH₃(CH₂)₄COOH.

2-Ethyl-hexanoic acid has the formula CH₃(CH₂)₃CH(C₂H₅)COOH.

Heptanoic acid (also known as enanthic acid) has the general formula CH₃(CH₂)₅COOH.

Octanoic acid (also known as captylic acid) has the general formula CH₃(CH₂)₆COOH.

Nonanoic acid (also known as pelargonic acid) is composed of a nine-carbon chain terminating in a carboxylic acid with the structural formula CH₃(CH₂)₇COOH.

Decanoic acid (also known as capric acid) has the general formula CH₃(CH₂)₈COOH.

Octanal is an aldehyde with the chemical formula CH₃(CH₂)₆CHO.

A Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention acts as an attractant for an avian mite, which is the same as a pheromone or a semiochemical. A Cl to Cl 5 alkyl straight chain or branched chain molecule according to the invention can be provided in a dose of IOng and 300ng and any amount in between including 20ng, 30ng, 33ng, 40ng, 50ng, 60ng, 70ng, 80ng, 90ng, lOOng, 1 IOng, 120ng, 130ng, 140ng, 150ng, 160ng, 170ng, 180ng, 190ng, 200ng or over and 20ng to 200ng and 50ng to 150ng.

In one embodiment, a Cl to Cl 5 alkyl straight chain or branched chain molecule according to the invention is formulated as a controlled (i.e. slow) release formulation. The controlled or slow release formulation controls release rate per se of a molecule of the invention, the uniformity of release rate and/or period of time over which the molecule will be active. The release rate is adjustable and controllable by the addition of one or more additives to the formulation and can last several weeks or more.

The controlled release formulation can be made from a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention extruded into resin, for example, ethylene vinyl acetate resin. The resin can be over lmm thick, between lmm and 5mm thick, between 2mm and 5mm thick, over 5mm thick or 2mm to 25mm thick. The molecule of the invention can be loaded at a level of less than 5%, 5%-10% or 20%, 10%-20% or over 20% of the controlled release formulation. When the formulation is used in a trap, the size of the formulation can be 10%, 20%, 30% or more of the total trap area.

Other commercially available controlled release formulations can also be used, for example, rubber septa, fibres made of a plastic-like material, such as polyethylene, polypropylene, olefin or similar materials, laminate flakes and microcapsules.

The rubber septa can be impregnated with a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention and the molecule gradually released from the rubber septa over several weeks.

For fibres, these are hollow and sealed at one end and can be filled with a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention. The plastic is impermeable to the molecule of the invention and release occurs by evaporation from the liquid-air interface followed by diffusion through the tube to the open end.

Laminate fibres comprise a central porous layer, which can contain a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention sandwiched between two permeable vinyl layers. The molecule of the invention would be released from the flake following diffusion through the vinyl layers. The release rate can be controlled by varying the thickness of the layers.

Microencapsulation formulations are made up of microcaps that comprise a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention enclosed by a plastic polymeric layer. The release of the molecule can be controlled by altering the chemical composition of the microcap, the microcap thickness and the size of the microcap.

The rate of release from all controlled release formulations will also be influenced by environmental factors such as temperature, humidity, prevailing air currents and other local micro-climate parameters.

As a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention evaporates from solution or is otherwise released, it disperses into the surroundings and is picked up by the mites, who follow the scent to the source of the molecule.

Avian mite, in accordance with the invention, means any mite that feeds on a bird including poultry and wild birds. In one embodiment of the invention, the avian mite is Dermanyssus gallinae. A Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention attracts mites at any stage of the life cycle in which the mite is mobile.

The source of the Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention can be applied or placed on a surface in the vicinity or environment of domestic and/or wild birds that act as a host to the mite. The source of the molecule of the invention can be provided in or on a substrate, for example a lumen or housing. The housing can be any form of container in which the mites can collect. The housing or container can be a trap i.e. the housing or container can include a mechanism such as a glue layer that hinders or prevents the mites leaving the housing or container. The trap could also be a device that serves as a harborage for the mites and which allows easy observation of the level of infestation.

A Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention can be used in combination with another Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention or a different substance to provide a synergistic attractant effect. The molecules and/or substances can be applied simultaneously, separately or sequentially to each other. For example, a combination of any two or more of the following molecules can be used: pentanoic acid, hexanoic acid, 2-ethyl-hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid and/or octanal.

In a further embodiment, the Cl to C15 alkyl straight chain or branched chain molecule of the invention is used in combination with a pesticide, such as silicium dust, and/or a pathogen and/or other control agents. Thus, the attracted mites can be further controlled by exposing the attracted mite population to one or more pesticides and/or pathogens that reduce or eliminate the mite population (so called "lure-and- kill").

The pathogen can be a fungal pathogen including an entomopathogenic fungus such as Beauveria bassiana or species with similar biological traits. The pathogen will infect and kill the attracted mites. In addition, the infected mites can spread the disease to other mites that have not come into direct contact with the pathogen.

The pesticide can be a toxicant, a chemosterilant and/or a growth regulator. For example, the pesticide can be a pyrethroid, a phoxim or silicium dust.

The Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention can be administered simultaneously, separately or sequentially to the pesticide or pathogen that reduces or eliminates the mite population. The pesticide or pathogen can be incorporated into the substrate. For example, if the pathogen is a fungus, fungal spores can be incorporated into the substrate.

A Cl to C15 alkyl straight chain or branched chain molecule of the invention can also be used in accordance with the invention as an attractant to trap mite populations for monitoring purposes. Monitoring mites can be very useful for obtaining information on population trends. In addition, in some circumstances, it is difficult to determine at an early stage if a mite population is increasing. However, if the mites are trapped and monitored, it will be much easier to determine as soon as a mite population starts increasing. This means that control measures can then be implemented before the problem becomes more significant and harder to control.

In addition, attracting mites for monitoring purposes has the benefit of reduced time spent in the field by investigators, thereby reducing costs.

A Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention can be used, in accordance with the invention, to control mites in combination with other known control methods for mites, such as diatomaceous earth, other traps and pesticides.

The use of a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention as an attractant for mites, in accordance with the invention, is helpful in all types of poultry farming but it is particularly so in organic egg production, where the use of pesticides is not possible. A Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention is also useful for acting as an attractant in relation to mites that are feeding on wild birds, as wild birds act as a host for mites that subsequently feed on poultry.

The first aspect of the invention also extends to a method of using a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention as an attractant for an avian mite. This method can also include using an avian mite pathogen and/or pesticide to reduce or eliminate the attracted avian mite population.

The second aspect of the invention provides an avian mite attractant composition comprising a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group.

The third aspect of the invention provides a method of reducing or eliminating an avian mite population comprising the steps of 1) providing a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a C 1 to C3 alkyl group, to attract the mite population and 2) contacting the attracted mite population with an avian mite pesticide and/or pathogen.

When the attracted mite population is contacted with an avian mite pesticide and/or pathogen, the mite population is thereby reduced or eliminated.

A Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention can be provided in the vicinity or environment of domestic and/or wild birds. The birds can have been identified as hosting a mite population. Alternatively, it is possible that the birds have not yet been identified as hosting a mite population.

The fourth aspect of the invention provides a system for attracting an avian mite population comprising a substrate, wherein the substrate comprises a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, and an avian mite pesticide and/or pathogen.

The fifth aspect of the invention provides a composition comprising a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, and an avian mite pesticide.

In one embodiment, a Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention and a pesticide are for simultaneous, separate or sequential administration.

By way of illustration and summary, the following scheme sets out a typical method process by which avian mites may be attracted and reduced or eliminated according to the present invention:

A Cl to C15 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, is extruded into a controlled i.e. slow release formulation, such as a resin. This formulation is then applied to a substrate, such as a trap and the substrate placed or applied in the vicinity or environment of a mite population. The Cl to Cl 5 alkyl straight chain or branched chain molecule of the invention is released at a controlled rate from the formulation and attracts the mites to the substrate. The attracted mite population is then brought into contact with a mite pesticide and/or pathogen and the mite population is reduced or eliminated.

Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art in the field of the present invention.

Throughout the specification, unless the context demands otherwise, the terms "comprise" or "include", variations such as "comprises" or "comprising", "includes" or "including" will be understood to imply the inclusion of stated integer or group of integers, but not the exclusion of any other integer or group of integers. It envisaged that where the term "comprising" is used, it is also possible to use the term "consisting of. Preferred features of the second and subsequent aspects of the invention are as for the first aspect mutatis mutandis.

The present invention is described with reference to the following figures and tables in which:

Figure 1 illustrates coupled GC-MS analysis of solvent wash of mite-infested tubes;

Figure 2 illustrates test arena for behavioural bioassays;

Figure 3 illustrates results of behavioural bioassay on test arena. The average fraction of the mites present in the different areas has been calculated over the entire 15 minutes observation period. The differences between mite activity in the area T including the treated area TC and in the untreated area C is shown for the different compounds tested. Asterisks indicate a significant difference for 0 at a level of 0.01.

For each compound, results are shown for the three test doses: 1 μl of 0.1%, 1% or 10% dilutions in ethanol;

Figure 4 illustrates results of behavioural bioassay on test arena. The average fraction of the mites present in the different areas has been calculated over the entire 15 minutes observation period. The differences between mite activity in the treated area TC and in the untreated area CC is shown for the different compounds tested. Asterisks indicate a significant difference for 0 at a level of 0.01. For each compound, results are shown for the three test doses: 1 μl of 0.1%, 1% or 10% dilutions in ethanol;

Figure 5 illustrates results of behavioural bioassay with hexanoic acid. A plastic lid with a paper surface is mounted with 8 plastic tubes, 2 of which contain known doses of hexanoic acid. 100 fed adult female mites are placed on the paper and left overnight. The following day the number of mites in the tubes and on the paper surface is counted; Figure 6 illustrates the release rate of samples of 5% hexanoic acid formulated in EVA (Elvax) at 28°C;

Figure 7 illustrates the results of a behavioural bioassay with slow release formulation of hexanoic acid on poultry red mites;

Figure 8 illustrates SPME-GC analysis of fed adult D. gallinae (n = 500). Peak numbers correlate to the compounds listed in Example 5;

Figure 9 illustrates a schematic drawing of the experimental set-up for Example 6.

The filter paper disc (12.5 cm diameter) is placed on a larger fly glue trap (not shown) to prevent the mites from escaping. The centre 4 cm (gray area) is treated with the DE. A hiding place (H), consisting of a lcm x lcm paper raised slightly above the surface, is placed on one side of the treated zone together with a drop of attractant (A). The mites are transferred to the untreated release zone (X) and

Figure 10 illustrates the fraction of the mites that did not pass through the treated zone within 24 hr at different levels of DE treatment and attractant dose. Asterisks show significant differences within the three levels of DE dose.

Table 1 lists compounds identified by GC-MS analysis of behaviourally active solvent wash of mite-infested glass vials and

Table 2 contains the results of four-arm olfactometer tests with various extracts. Abs. Values gives the percentage of the 15 minutes test-period spent in either the test-arm or the three control-arms (on average). For each test the four arms are ranked 1-4 according to the time spend in each. Avg. ranking gives the average of these rankings over n tests. The proportion of the tests in which either the arm with the extract or the control arms are ranked as number one is given in the column Ranked #1. The invention will now be further described by way of reference to the following examples, which are provided for the purposes of illustration only and are not to be construed as limiting to the invention.

EXAMPLES

Semiochemical identification is technically extremely challenging and requires considerable skill in the art. In the case of the poultry red mite, this challenge is compounded by the fact that electrophysiological recordings from mites are technically very difficult to achieve, despite the location of sensory sensilla on poultry red mites. Furthermore, very low levels of biological material are produced by poultry red mites. Significant difficulties were encountered in identifying the molecules of the invention as mite attractants. Thus, alternative, innovative approaches for collecting material and evaluating the effect on the mites were adopted, before the molecules of the invention were eventually isolated and identified as active as attractants.

Example 1

Isolation and identification of semiochemicals that attract poultry red mites Glass vials previously inhabited with fed female D. gallinae for 24 h were extracted with ethanol as solvent. Identification of peaks in the solvent extracts were made by coupled GC-mass spectrometry (GC-MS) (Figure 1 and Table 1). Analysis was carried out on a Thermo-Finnigan MAT95XP instrument fitted with a non-polar HP-I GC column (50m x 0.32 mm i.d.). Ionization was by electron impact (7OeV, 25O⁰C).

Example 2

Mite behavioural bioassay (i)

An initial test for the presence of an aggregation pheromone was carried out in a 4- arm olfactometer. This is a type of olfactometer with 4 inlets through which different volatiles can be introduced. One mite is released in the centre of the olfactometer and the time spent in each of the 4 arms gives an indication of the attractiveness of each volatile. Teflon tubes in which mites had been kept for various periods and allowed to deposit pheromones inside the tubes, where tested directly in the 4-arm olfactometer. This means that the mites were removed from the tube and the tube was attached directly to the olfactometer. This gave a clear behavioural response from the mites ("Teflontube 1 OOF AF 24h directly" in table 2). The next step was to wash off the pheromone deposits inside the tubes to produce an extract that could be tested in the olfactometer. These extracts also gave positive behavioural response, but the procedure of washing was difficult and not suitable for production of a larger amount of extract. The procedure was then changed to keeping the mites in small glass vials which are easier to wash efficiently. The extract from glass vials where 300 fed adult females (FAF) had been kept for 5 days gave a clear behavioural response ("Glass vial 30OF AF 5 days washed with 200μl ether" in table 2).

Mite behavioural bioassay (ii) Activity of individual compounds from the identified extract was tested on an arena bioassay. The arena bioassay consisted of a paper arena (6 cm diameter, see Figure 2) mounted on a fly glue trap to prevent the mites from escaping. 1 μl of a compound (diluted to 10%, 1% or 0.1% in ethanol) was applied in the small circle (Tl) and l μl of ethanol was applied in the other small circle (Cl) for control. Ten fed adult females were transferred to the arena and placed in a temperature and humidity controlled room under a video camera. The behavioural response was recorded over a 15 minute period. For each of three repetitions four arenas, each with 10 mites, were analysed together. The video recordings were analysed by noting the fraction of the mites located in each of the four circles at 30 sec intervals. The difference in the fraction of mites located in circle T and C, as well as in Tl and Cl were tested for significant difference from 0 by means of a t-test (0.01 level of significance). Significant behavioural responses were observed with all straight chain carboxylic acids from pentanoic acid (C5) to decanoic acid (ClO) as well as 2-ethyl-hexanoic acid and the aldehyde octanal (see Figure 3 and 4, asterisks indicate significant differences). For some compounds, mites avoided direct contact with the compounds at the highest doses, shown by the significant negative differences between TC and CC (see Figure 4).

Mite behavioural bioassay (iii)

This behavioural bioassay consists of a circular plastic lid with 8 holes evenly spaced. In these holes plastic test tubes (6 cm long) were fixed so that the mites could walk on the surface of the lid and choose to walk down into the test tubes. The surface of the lid was covered by a piece of paper to provide the mites with a better surface to walk on. Around the edge of the paper a barrier of insect glue prevented the mites from escaping. The overall size of this arena was 14 cm diameter. In each of the eight tubes a small piece of folded filter paper (5x5 cm) provided the mites with narrow hiding places. In the two treatment tubes 1 μl of hexanoic acid in mixtures with ethanol was applied to the paper in the bottom of the tube, resulting in the different quantities as shown in figure 5. In the control tubes 1 μl of ethanol was applied. 100 fed adult female mites were placed on the paper surface and left overnight. The following day the number of mites in each tube and on the paper surface was counted.

Figure 5 shows the results for the different amounts of hexanoic acid one day after application. The lowest amount of hexanoic that could attract mites was 10 nl and the optimal amount in this test was 100 nl. With 1000 nl of hexanoic acid the mites would not enter the treated tubes, but they were often found on the lid surface around the entrance holes to the treated tubes.

Example 3 Development of a slow/controlled release formulation

Hexanoic acid was extruded into an ethylene vinyl acetate resin (Elvax® from DuPont) at a 10% loading level. A number of types of Elvax® were tested initially to see which absorbed the hexanoic acid more optimally. Absorption into the Elvax® was slow but did not appear to differ significantly between types.

Several different thicknesses of extrusion were produced and tested to determine which had the best release rates, lmm thick extrusions with a 10% loading released the hexanoic acid too rapidly, so it was decided that a thicker (2.5 mm or 5mm) extrusion was the best approach to controlling release. A lower loading of hexanoic acid (5%) was also used. Extrusions were made up by AgriSense and sent to DPIL for testing in the summer 2006. Small pieces of the lures (5-40 mg) were placed into tubes with poultry red mites and all showed evidence of attraction.

Extrusions of the 5% hexanoic acid (25mm thick) were set up in the "hot room" at AgriSense (approximately 28°C) to give an accelerated release rate. Release rates were monitored over three months. 50% loss of hexanoic acid occurred in approximately 15 days at this temperature (see Figure 6), although release would be considerably slower at the lower temperatures encountered in poultry houses.

Example 4 Use of controlled-release formulation of hexanoic acid to attract mites

The slow-release 5% hexanoic acid formulation was tested in the same type of bioassay as with the pure hexanoic acid. Small pieces of slow-release formulation were placed in two tubes on each platform. 100 fed adult female mites were placed on the platform and left overnight. The following day the number of mites in the tubes on the paper was counted. All doses resulted in attraction of mites but the most effective was 80 mg (Figure 7).

Example 5

Quantification of compounds in glass vial washing The peak areas of identified compounds in the behaviourally glass vial washing (Figure 1, Table 1) were determined, and compounds were shown to exist in the following ratios: Compound Ratio

Dodecanoic acid 14.55

Decanoic acid 9.1 1

Nonanoic acid 8.55

Octanoic acid 6.19 Heptanoic acid 4.97

Hexanoic acid 55.28

Ethyl hexanoic acid 5.27

Pentanoic acid 4.06 Butyric acid 1

Octanal 152.95

SPME headspace analysis of fed adult D. gallinae

Fed adult D. gallinae (n = 500) were subjected to solid-phase microextraction (SPME) for 20 hours at ambient temperature. The mites were kept in a tightly capped microvial, into which a preconditioned PDMS fibre was inserted via a PTFE septum. The exposed fibre was left in the vial for 20 hours to collect emitted mite volatiles in the headspace. The fibre was withdrawn and then analysed immediately by GC-FID, using an Agilent 6980 GC equipped with a DB-I column (50 m x 0.32 mm i.d. x 0.32 μm film thickness) and a flame ionization detector (FID). The carrier gas was hydrogen. Volatiles were desorped from the SPME fibre by insertion of the fibre into a heated PTV injector unit (25O⁰C). The oven temperature was programmed to start at 40°C for 1 min, then rise to 15O⁰C at a rate of 5°/min, hold for 0.1 min, then rise to 230°C at a rate at 10°/min, and a final hold for 35 min. Compounds were identified by comparison of retention indices with those of authentic samples, calculated using a

C₇-C₂₂ alkane series.

The peak areas for the annotated peaks in Figure 8 are as follows (see figure for GC trace) :-

Peak No Compound Peak Area (pA)

1 Butyric acid 17.63

2 Pentanoic acid 11.69 3 Hexanoic acid 11.52

4 Heptanoic acid 2.47

5 Octanoic acid 2.49

6 Nonanoic acid 1.01

7 Decanoic acid 79.65 8 Dodecanoic acid 74.44 Example 6

Diatomaceous earth (DE) is widely used in poultry houses as one of the few remaining control methods against poultry red mites. However, the efficacy of such applications is not always high enough. One problem could be that these products can have a repellent activity which might reduce the exposure of the mites to the control agent.

The purpose of this test was to investigate whether it is possible to overcome the repellency of a DE treatment by means of one of the attractants identified here. The test was carried out with two doses of the DE, Diamol, and two doses of the mite attractant, hexanoic acid. The attractant was diluted in ethanol and placed as a 1 μl drop at location "A" (Figure 9). Ethanol alone was used as control.

A 4 cm zone on a 12.5 cm filter paper was treated with the DE at doses of 0.34 g/m and 0.85 g/m². After placing 25 mites on one side of the barrier the mites had to pass through the treated zone to reach a hiding place and the location of the attractant (Figure 9).

After 24 hours at 25°C and 55% RH the number of mites that had passed through the treated zone was observed. For each dose of DE and attractant, three replicates each with 25 mites were included, and the test was conducted three times.

The lowest DE dose was not repellent (Figure 10). The high dose of DE resulted in an average repellency over 60% without the attractant. Adding the low and high dose of attractant reduced the fraction of repelled mites to 34% and 27%, respectively.

These changes were significantly different from the result without the attractant, indicating that the attractant can overcome the repellency of the DE treatment to some extent. Table 1.

Table 2

Claims

1. Use of a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a C 1 to C3 alkyl group, as an attractant for an avian mite.

2. The use of claim 1, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is formulated as a controlled release formulation.

3. The use of claim 1 or claim 2, wherein the mite is Dermanyssus gallinae.

4. The use of any one of claims 1 to 3, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is used in combination with a pesticide and/or a pathogen.

5. The use of any one of claims 1 to 4, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is pentanoic acid, hexanoic acid, 2-ethyl-hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid and/or octanal.

6. An avian mite attractant composition comprising a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group.

7. The composition of claim 6, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is formulated as a controlled release formulation.

8. The composition of claim 6 or claim 7, wherein the mite is Dermanyssus gallinae.

9. The composition of any one of claims 6 to 8, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is pentanoic acid, hexanoic acid, 2- ethyl-hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid and/or octanal.

10. A method of reducing or eliminating an avian mite population comprising the steps of 1) providing a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, to attract the mite population and 2) contacting the attracted mite population with an avian mite pesticide and/or pathogen.

11. The method of claim 10, wherein Cl to Cl 5 alkyl straight chain or branched chain molecule is formulated as a controlled release formulation.

12. The method of claim 10 or claim 11 , wherein the mite is Dermanyssus gallinae.

13. The method of any one of claims 10 to 12, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is pentanoic acid, hexanoic acid, 2- ethyl-hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid and/or octanal.

14. A system for attracting an avian mite population comprising a substrate, wherein the substrate comprises a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, and an avian mite pesticide and/or a pathogen.

15. The system of claim 14, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is formulated as a controlled release formulation.

16. The system of claim 14 or claim 15, wherein the mite is Dermanyssus gallinae.

17. The system of any one of claims 14 to 16, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule is pentanoic acid, hexanoic acid, 2-ethyl- hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid and/or octanal.

18. A composition comprising a Cl to Cl 5 alkyl straight chain or branched chain molecule comprising a -COOH or a -CHO group, optionally substituted on any carbon atom in the chain by a Cl to C3 alkyl group, and an avian mite pesticide.

19. The composition of claim 18, wherein the Cl to Cl 5 alkyl straight chain or branched chain molecule and the pesticide are for simultaneous, separate or sequential administration.