Title: Clone of Rodent Control on Farms - Part Two

Introduction

Rodent Control on Farms - Part 2

Credits: by Lantra

Lantra, Lantra House, Stoneleigh Park, Coventry, CV8 2LG

02476 696996   www.lantra.co.uk

Click           to expand the viewing screen.

Food chain implications

Credits: by eLaba; source https://cdn.pixabay.com/photo/2016/03/02/21/44/mus-1233165_960_720.jpg

Credits: Cat carrying a house mouse.; by Lxowle; source https://upload.wikimedia.org/wikipedia/commons/thumb/8/82/Cat_and_mouse.jpg/648px-Cat_and_mouse.jpg

Food chain implications

Primary poisoning occurs when an animal directly eats the baits that have been applied

Secondary poisoning occurs when a predator or scavenger eats the animal (dead or alive) that has consumed rodenticides

Non-target species

Characteristics of non-target species

The term 'non-target species' covers animals that are not the target or aim of your work but that may be affected by pest control measures. This covers other pest species for example grey squirrels through to animals that may be heavily protected by law.

Credits: by Peter Trimming from Croydon, England; source https://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Water_Vole_on_Boot_Hill_%285592665124%29.jpg/1200px-Water_Vole_on_Boot_Hill_%285592665124%29.jpg

Water vole - protected species

Characteristics of non target species

Examples of non target species include:

- Water vole.
- Wood mouse.
- Red and grey squirrel.
- Bank and field vole.
- Harvest, long tailed field and yellow necked mice.
- Edible and common dormouse.

Credits: Alexas_Fotos; source https://cdn.pixabay.com/photo/2017/03/27/15/03/wood-mouse-2179259_960_720.jpg

Credits: Field Vole (Microtus Agrestis); by Phil Williams; source https://upload.wikimedia.org/wikipedia/commons/5/57/Field_Vole_%28Microtus_Agrestis%29_-_geograph.org.uk_-_167666.jpg

Wood mouse

Field vole

Credits: source https://upload.wikimedia.org/wikipedia/commons/0/0b/Siebenschlaefer_glis_glis.jpg

Edible dormouse

Predators and scavengers

Credits: Red Kite - Gigrin Farm; by Tim Felce (Airwolfhound); 17 October 2013, 15:05; source https://upload.wikimedia.org/wikipedia/commons/thumb/0/03/Red_Kite_-_Gigrin_Farm_%2810359058775%29.jpg/1200px-Red_Kite_-_Gigrin_Farm_%2810359058775%29.jpg

Predators and scavengers

One really important issue in rodent control is secondary poisoning

As well as following COSHH and environmental assessments and labelling guidelines to determine if baiting is appropriate, there is an industry code under the 'think wildlife' banner which aims to reduce the risks of baiting non-target animals

Predators include birds of prey (red kites, barn owls) as well as foxes and companion animals (e.g domestic pets, horses)

Scavengers include foxes, stoats, weasels, crows, ravens, companion animals

Red kite

Credits: Weasel; source https://upload.wikimedia.org/wikipedia/commons/e/e3/Mustela_nivalis_-British_Wildlife_Centre-4.jpg

Weasel

Small and song birds

These will occasionaly eat bait especially if the bait is unprotected. Slugs and snails could eat rodenticide bait and in turn be eaten by a small bird. Small birds can be at particular risk if using spring traps so it is worth considering covering traps so non-targets can not access.

Pets

Whilst baits usually have a 'taste' to deter humans eating it, it does not always deter pets from eating any bait.

Children

Modern baits contain denatonium benzoate (commonly known as 'Bitex') which has a very bitter taste. This is likely to put humans off consuming bait.  However, if a small child has access to it, the outcome could be very serious. It is also likely that the risk assessment may have been inadequate or the application failed to comply with the label on the bait.

Credits: Yellow Labrador Retriever; by SixtyWeb; source https://commons.wikimedia.org/wiki/File:Yellow_Labrador_Retriever_2.jpg

Credits: by Kucharek; source https://commons.wikimedia.org/wiki/File:Walter_de_Maria_Vertikaler_Erdkilometer.jpg

Campaign for responsible rodenticide use

Campaign for Responsible Rodenticide Use (CRRU)

Research over many years has highlighted two main areas of concern with regard to the use of rodenticides and wildlife.

Firstly, the remains of individual birds collected are sometimes suspected to have died as a result of the irresponsible or incorrect use of plant protection products and biocides. The scope of this is monitored and reported through a variety of schemes. One is the Wildlife Incident Investigation Scheme (WIIS) run by the Chemicals Regulation Directorate (CRD) and Science and Advice for Scottish Agriculture (SASA) in the UK.

Another concern is that many species of wildlife carry low-level residues of some of the commonly-used rodenticides in their bodies. Research has shown that these residues occur in a high proportion of individuals of some wildlife species, such as barn owls, red kites, buzzards and kestrels. It is not known whether these low-level or sub-lethal residues have any adverse effects, either on the individual animals that carry them or on wildlife populations as a whole. However, those who use rodenticides should do so in ways that seek to reduce to a minimum any exposure to wildlife and other non-target animals.

Campaign for Responsible Rodenticide Use (CRRU)

WIIS investigations normally involve post mortem analysis of carcasses, chemical analysis of tissues for pesticide residues and on-site investigations to determine, if possible, the circumstances of the incident. Mortality is attributed to a pesticide if a residue is found that is above a level considered to represent lethal exposure.

The cause of each incident is attributed as either abuse of a pesticide in the form of deliberate, illegal attempts to poison animals, misuse of a product, careless, accidental or wilful failure to follow correct practice. Approved use of a product, according to the specified conditions of use, unspecified use, where the cause could not be assigned to one of the above categories.

Eradication Campaigns

If target pest rodents have been identified as active during the monitoring process, start an eradication campaign the sooner the better. However it is important to consider the Control Risk Hierarchy (CRH).

For more details visit the CRRU website click here

Non chemical, lethal

Credits: by Jon Worth; source https://c1.staticflickr.com/1/379/31674680301_bab3135ed4_b.jpg

Non Chemical - Lethal

The eradication campaign needs to initially consider if non-chemical lethal options will be effective. Usually the lower the rodent population numbers, the more effective this option alone can be – however it can always form part of the chemical approach as well.

Credits: source https://cdn.pixabay.com/photo/2013/07/18/15/09/mouse-164751_960_720.jpg

Non Chemical - Lethal

Trapping is a widely used control method and although it can be labour intensive, has several advantages over chemical control.  For example, the equipment can be reused multiple times, any pests trapped can easily be removed / disposed from the site and there are no chemical residues.

It may also provide an alternative means of control where the use of rodenticides is unacceptable due to non-target/environmental impact, or where resistance may exist.

Modern snap traps have been designed to reduce the risk of miss-catch and are generally more effective than the traditional break-back traps.  Traps should be placed along rat runs or where moving rats may be intercepted, e.g. along walls or hedgerows, holes in walls, etc.

Credits: Rl; source https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/2005_mousetrap_cage_2.jpg/1200px-2005_mousetrap_cage_2.jpg

Non Chemical - Lethal

Kill traps. It is essential before setting traps, especially those used outdoors for rats, to consider both the target animals and any other animals that may be present and may enter traps accidentally. Best Use;

- Use snap traps or approved spring traps.
- Place many traps along rodent runs, especially with high population.
- Place traps at height to increase success rate. Snap traps are now very easy to set off, of the floor/ ground.
- Secure traps into place, mainly to stop scavenging animals removing ‘post catch’.
- Protect against access by non-target species.
- Check daily to remove carcasses and reset traps.

Credits: by David Shankbone; source https://upload.wikimedia.org/wikipedia/commons/thumb/1/1f/Glue_trap_by_David_Shankbone.jpg/800px-Glue_trap_by_David_Shankbone.jpg

Glueboard

Non Chemical - Lethal

Kill traps

The use of break-back (snap) traps for both rats and mice (as image) is probably the most widespread, cost effective and successful trapping technique. They are not covered within any specific legislation, but their use should be closely monitored to ensure effective operation.

Snap traps are indiscriminate to other small ground mammals that are similar to rats and mice.

Non Chemical - Lethal

Spring traps need to be used in accordance with the Spring Traps Approval Order and any other related animal welfare legislation. They must be checked on a frequent (daily) basis and only used in natural or artificial tunnels / burrows.

Spring traps are indiscriminate to other, larger non-target animals, such as cats and dogs.

Other types of traps include live traps; electric traps and glue boards. All must be used in accordance with legislation and best practice as applicable.

It is always recommended to complete a trapping course to ensure that users understand all legislation and best practice, effective use and how to reduce the risk to non-target species as accidental by-catch.

Other non-chemical control options are available.

Credits: Victor Rat Trap with rat; by Glogger; source https://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/RatTrapP1050311d.jpg/1200px-RatTrapP1050311d.jpg

The CRRU code - www.thinkwildlife.org/crru-code/

1. Always have a planned approach.
2. Always record the quantity of bait used and where it is placed.
3. Always use enough baiting points.
4. Always collect and dispose of rodent bodies.
5. Never leave bait exposed to non-target animals and birds.
6. Never fail to inspect bait regularly.
7. Never leave bait down at the end of the treatment.

Credits: source http://www.thinkwildlife.org/wp-content/uploads/2013/06/logo-e1373985198164.jpg

Chemical, lethal

Credits: by Ildar Sagdejev (Specious); source https://upload.wikimedia.org/wikipedia/commons/a/a4/2008-09-11_Dead_baby_rat.jpg

Chemical - Lethal

The use of chemical control needs to be considered as a last resort.  Assess each active ingredient and formulation on their merits and efficiency in quickly controlling the rodent activity and to minimize any potential risk to the local environment.

Active ingredients

Anticoagulants

The nature of anticoagulants allows the rodents to keep feeding until a lethal dose has been consumed and death occurs between two to 14 days later. They work by effectively blocking the vitamin K cycle, resulting in an inability to produce essential blood-clotting factors.  Average treatment time may extend over four or five weeks before a whole population has eaten a lethal dose. They were the most common rodenticides until recently. Second Generation Anticoagulants (SGARs) are now in wide use around the UK.

Credits: Structure of Vitamin K1 including stereo; by Tony27587; source https://upload.wikimedia.org/wikipedia/commons/1/1e/Vitamin_K1.png

Active ingredients

First Generation Anticoagulants (FGARs)

First generation anticoagulants e.g. coumatetralyl, are less persistent in animal tissues and may be assumed to present a lower risk of secondary poisoning for non-target animals in most situations.  Therefore, their use is to be preferred over that of the second generation compounds in those areas where there is no resistance to them.

However, they are not free from risk to non-targets as larger quantities of these baits must be applied to ensure that a surplus is always available for rats to feed on. This can have significant primary poisoning issues. There are pocketed issues of resistance to FGARs around the UK, for more information contact the Rodent Resistance Action Group.

Credits: Syringe fitted with needle. Scale in ml.; by Biggishben~commonswiki; source https://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Syringe2.jpg/1200px-Syringe2.jpg

Active ingredients

Second Generation Anticoagulants (SGARs)

SGARs include:

- Brodifacoum.
- Bromadiolone.
- Difethialone.
- Difenacoum.
- Flocoumafen.

Generally these deliver a higher level of toxicity and they are more persistent in body tissues following consumption. As such they present the greatest risk to non-target animals and the local environment.

Active ingredients

Alternative chemical control options (Non-anticoagulants)

Alternative actives are available for the control of rats and mice, which do not affect the blood. However, they often have restrictions in their own conditions of use but do not have issues of resistance. In some situations these may be appropriate, if for example anticoagulant rodenticides cannot be used because of environmental risks identified at the site or if resistance has been confirmed.  There are several products on the market that may fall into the ‘alternatives’ list, however, there is little recognised scientific evidence to support their efficiency.

 The two main active ingredients (outlined on the next 2 slides) have their own conditions of use.

Credits: A dead brow rat with blood oozing out of its mouth; by Muhammad Mahdi Karim; source https://upload.wikimedia.org/wikipedia/commons/thumb/c/c0/Dead_rat_blood.JPG/1200px-Dead_rat_blood.JPG

Active ingredients

Aluminium Phosphide

Aluminium Phosphide may only be used outdoors against rats, (also used for moles and rabbits), and is applied directly into rat burrows, where the tablets absorb moisture and generate a toxic phosphine gas. These tablets are not known to leave long-living toxic residues in the environment or to have any secondary toxic effects.

Gassing is variable in its efficacy and unlikely to provide the complete solution to any rat infestation.  However, it can be a valuable method of reducing the size of a rat population quickly, especially in ‘Open Areas’ locations such as hedgerows or soil heaps.

Because of the significant risk of such products to human health for those transporting and applying them, this product is strictly regulated as to where it can be applied; who can use them and how they should be applied; for example no closer than 10 meters to a building.  From November 2015, all users need to demonstrate professional competence for their use with a Lantra Awards Level 2 Qualification allowing them to purchase and use these formulations.

Active ingredients

Alphachloralose

The acute rodenticide alphachloralose is a narcotic, approved for use only against house mouse and only indoors.

Alphachloralose works through reducing the metabolic rate with subsequent death through hypothermia. As such it is more effective in colder environments ideally below 14-15˚C. Once a lethal dose has been consumed by the mouse, death occurs relatively quickly.

Unless a lethal dose is consumed at the first feed, the mouse will recover and may shy away from further feeds. It is recommended that you do not apply the bait for more than 24 hours in one campaign, then remove from the treatment location and reassess any potential remaining activity.  If required, redeploy four or five days later.

Use the product in the same way as other edible baits i.e. place in secure locations, prevent non-target access, remove alternative foods and place bait points at high density throughout the area of activity. Due to the mode of action, it's generally not considered to have secondary toxic effects in low quantities.

Multi vs single feed

Multi-feed vs Single-feed

Rodenticides are classified as acute (fast acting) and chronic (slow acting).

When considering which rodenticide to apply, review and consider the Control Risk Hierarchy (CRH) and select the product and active ingredient that will be effective to control activity effeciently and safely.

The toxicity can be gauged from the LD50 which can be found on the Material Safety Data Sheet (MSDS). The LD50 is a laboratory term meaning 'lethal dose' required to kill 50% of a test population (usually rats). It is normally expressed in terms of Mg/Kg i.e. milligrams of product required to kill based on a kilogram to target body weight.

Simply - the lower the LD50 number, the higher the toxicity.

Multi-feed vs Single-feed

Multi-feed rodenticides, bromadiolone, coumatetralyl or difenacoum require rodents to repeatedly feed on the baits until they have consumed a quantity that is sufficient to start the process of killing the rodents, also known as the Lethal Dose.

These actives will need to be constantly available to the rodents during the eradication campaign i.e. make sure the bait does not run out and make sure it is available throughout the location where the rodents are active.

Multi-feed vs Single-feed

Environmental Impact. The use of multi-feeds baits, where they are constantly available can have a significant impact on small mammal non-target species through primary poisoning, especially the SGARs as they are more persistent in body tissue.  However the use of these lower toxicity rodenticides can have a lower accidental (primary) poisoning on larger non-target mammals as the animal will potentially have to consume larger quantities in order to achieve the lethal dose. This is not always the case and it is vitally important that non-target species do not have access to any baits.

Multi-feed baits work and are effective in controlling rodents however, they need to eat it first! The need to reduce access / eliminate alternative foods is very important.  In accordance with manufacturers recommendations use multi-feed baits as part of the routine control of rodents, do not be tempted to switch to automatically using single feed baits.

Multi-feed vs Single-feed

Single feed rodenticides, brodifacoum, difethialone and flocoumafen, are higher in toxicity, being they have a lower LD50 number than bromadiolone or difenacoum and as such rodents need to consume less rodenticide in order to reach a lethal dose. This can often be achieved in a ‘single-feed’ often as little as 2g for rats.

Due to this higher toxicity, it is important not to use single feed with the same approach as multi-feeds.  There is no need for it to be consistently available during the eradication campaign and increasingly it is being seen as good practice to let the baiting stations run empty following the first application and to only replace consumed baits on a 10 – 14 day cycle.

Credits: structure of difethialone, a rodenticide; by Klever; source https://upload.wikimedia.org/wikipedia/commons/thumb/1/12/Difethialone.png/932px-Difethialone.png

Structure of difethialone

Multi-feed vs Single-feed

Environmental Impact. If the quantity required to be consumed is less for rodents, this can equally apply to any other mammal that may consume the baits.

Ensure that non-target species do not have any access to these single-feed baits.  In addition, if the target species, mainly rats, are allowed to consume these higher toxicity baits for a longer period they may have a greater secondary poisoning impact.

Rodenticide formulations

The formulation is the physical make-up and composition of the rodenticide, i.e. what it looks like and what base mixture or substance is used.

Each substance will have an attractant towards rats and mice often referred to as palatability. All rodenticides are now supplied ready-to-use and must be used (without any added attractants) as they appear.

During a CoSHH and environmental assessment, consideration should be given to the formulation of bait type used and whether it could compromise security by being removed, hoarded or spilled during baiting operations. Check the authorisation conditions granted for each product intended for use on either the product label or the MSDS.

When selecting the most appropriate formula, consider the game ‘rock, paper, scissors’. Each formulation will have advantages and disadvantages over other types. It is important to understand these variable elements and use them to select the most effective formulation.

Example formulations

Description | Advantages | Disadvantage
Loose grain- The most common formulation consisting of whole grain. | These tend to be preferred foods for most rural rodents. Difficult for rodents to hoard or relocate into open locations. | Easy to spill. Birds and other non-target at risk as these are difficult to secure in place.

Whole wheat

Description | Advantages | Disadvantage
A variety of cereals in one formulation. Some mixed with feeding enhancers others using cut wheat or pellets. | Added food attractant within baits to make it more attractive for rodents to eat and ideally consumed in one sitting. | Easy to spill. Birds and other non-targets at risk as these are difficult to secure in place.

Mixed cereals

Example formulations

Place packs

Description | Advantages | Disadvantage
Loose grain in a bag which rodents will chew through to gain access to baits. | Reduce the operator exposure through contamination. Premeasured and capable of lasting longer externally. | Larger quantitites of portable rodenticides are within one pack and may be dragged by rats into exposed areas.

Credits: Rat poison; by Iwan Gabovitch; source https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwi6v_WVgYvTAhXICBoKHWo7D40QjRwIBw&url=https%3A%2F%2Fwww.flickr.com%2Fphotos%2Fqubodup%2F29898228042&bvm=bv.151426398,d.ZGg&psig=AFQjCNH030mwdvuNys8IVN5ybknNvyZILA

Canary seed bait

Description | Advantages | Disadvantage
Canary seed base with rodenticide to control mice. | Activity based feeding allowing mice to pick up bait. Clear evidence left behind once mice have stripped outer shell. | Easy to spill. Birds and other non-targets at risk as these are difficult to secure in place.

Example formulations

Description | Advantages | Disadvantages
Rodenticide formulated into a wax or hard food based block. | Often easier to secure in place and prevent movement. Can be more tolerant to damp conditions so lasts longer. | Larger quantity of rodenticide in one package.

Wax and extruded blocks

Description | Advantages | Disadvantages
Often high calorie soft formulations applied in 'ready to use' sachets. | Fixed quantity of rodenticide that can be used in most locations. Higher lard / oil based formulation useful in drier environments. | Additives make these smell appealing. This can also work on larger non-target species. The sachet formulation may be 'hoarded' by rats.

Pasta or gel sachets

Example formulations

Caulking gel

Description | Advantages | Disadvantages
Similar to the soft blocks but applied with a caulking tube. | Variable quantity can be applied as supplied in 300ml tubes. | In consistantly warm weather the product has been known to leak the oil. However, this is being improved.

Contact products (generally indoor use)

Description | Advantages | Disadvantage
Non-edible gels and foam applied to pich points where rodents are active. | Ingested as part of natural grooming so no requirement for rodents to ingest the baits. | Will dry up in warm buildings. Cannot be used within 2 metres of a food surface.

Credits: by Dan Brady; source https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Indian_pigments.jpg/1200px-Indian_pigments.jpg

Rodenticide Formulations

During the eradication campaign continually reassess progress and ensure that all actions and activities are positively contributing to reducing and eliminating the rodent infestation.  Use all products and control options in accordance with product labels, any legislative requirements and best practice.

Thankyou for completing part 2.

Click back to 'Rodent Control on Farms - Part 2' on the left hand navigation pane.

Select 'Assessment Questions for Part 2'

Remember, the pass mark is 70% and you have up to 3 attempts to complete sucesssfully.

Click            to reduce to viewing screen.