Rodent Pest Management the Syngenta Experience

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1 Rodent Pest Management the Syngenta Experience

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3 CONTENTS Rodent Pest Management and Syngenta Brodifacoum Rodents The need for control Biology and behaviour of rodents Rodent Control: An Integrated Approach Talon formulations Rodent pests Commensal species Rodent pests Other common rodent pest species Laboratory evaluations Performance Field studies Resistance to anticoagulants Use patterns Urban environments, farms and animal husbandry Use patterns Audit schemes for food safety Use patterns Field agriculture Product safety Bitrex Talon, biodiversity and conservation Responsible rodenticide use

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5 Rodent Pest Management and Syngenta The problems that rodents cause to human activities are truly immense. Rodents have no equal as global pests of public health, as threats to the welfare of our domesticated animals and as the cause of losses to our food supply, both through direct consumption and spoilage. Rodent pests occur on every continent, even on sub-antarctic islands, and in virtually every country. The three common commensal species Norway rats (Rattus norvegicus), Roof rats (Rattus rattus) and House mice (Mus musculus) are found everywhere and in many countries they are joined as pests by local species that have also adapted to habitats provided by man. As a result of the huge variety of the problems presented by rodents their management is a wide and varied subject. Almost every situation is different and solving rodent pest problems always calls for a flexible and adaptive approach, but one that is based on an understanding of some important general principles. The most important of these principles is that all successful programmes of rodent pest management involve the integration of several different approaches. Killing rodents is often the first approach considered, because in most circumstances the presence of rodents cannot be tolerated even for a moment. But without the adoption of other measures, such as habitat removal and rodent proofing, rodent killing is only a temporary expedient. Another principle is that rodents are highly intelligent and adaptable mammals. Any attempt at their management must involve an understanding of their biology and behaviour and the application of this knowledge in the implementation of the control programme. The anticoagulant rodenticides have been the mainstay of rodent control for more than 50 years and will be for many more years to come. They have an outstanding history of safe and effective use but we must not let familiarity breed contempt. Therefore, another principle is that applications of rodenticides should always be made with appropriate precautions to avoid risks to humans, non-target animals and the wider environment. Finally, the foundation of an effective rodent pest management programme is a proven and reliable rodenticide product. Syngenta, and its legacy companies ICI and Zeneca Public Health, have been marketing TALON for 30 years and during that time have established unparalleled global experience of rodent pests and their control, both in public health and in agriculture. The guidance to be found in the following pages is intended to share some of that experience with you. Syngenta Head Office, Switzerland 1

6 Brodifacoum the World s Most Effective Rodenticide DISCOVERY OF ANTICOAGULANT RODENTICIDES The discovery of the first anticoagulant rodenticide, warfarin, revolutionised the practice of rodent control. Its benefits of efficacy and safety were recognised immediately and, just a few years after its introduction in 1950, almost all rodent pest management programmes world-wide were based on warfarin baiting. The dominance of anticoagulants as the products of choice for rodent control, for both amateur and professional users, has continued without interruption since that time. WARFARIN AND OTHER ANTICOAGULANTS HAVE TWO MAIN ADVANTAGES. The first is that they are extremely effective. Because symptoms of anticoagulant poisoning only occur after several days, rodents are unable to detect their effect and feed readily from anticoagulant baits. This overcomes the problem of bait shyness suffered by the fastacting rodenticides in which rodents sampling small quantities of bait for the first time, experience unpleasant symptoms, survive and refuse to take the bait again. Bait shyness meant that even expert practitioners were unable to achieve complete control of rodent infestations with fast-acting compounds. Anticoagulants made rodent eradication possible for the first time. The mode of action of anticoagulants, in preventing blood clotting, was thoroughly understood when the products were first introduced. This understanding provided the second advantage the antidote, vitamin K 1, which if administered promptly is completely effective at reversing the symptoms of anticoagulation, both in humans and in other animals. Therefore, in the case of anticoagulants, a specific antidote became available for a rodenticide for the first time. Following the success of warfarin, other anticoagulants with similar properties were developed and introduced to the market. These included coumachlor (1951), diphacinone (1952), coumatetralyl (1956) and chlorophacinone (1961), these are now known as first-generation anticoagulants. 2

7 Brodifacoum the World s Most Effective Rodenticide WARFARIN RESISTANCE Unfortunately resistance to warfarin and the other first-generation anticoagulants came along quickly and was first found in Norway rats in Scotland in Resistance was subsequently identified in other species, including the important commensal rodent pests the Roof rat and House mouse, and in many other countries. There was also strong cross-resistance, which meant that not only did warfarin fail to control resistant infestations but the other first-generation compounds were also ineffective. THE DISCOVERY AND DEVELOPMENT OF BRODIFACOUM The conventional strategy in the development of compounds to overcome resistance to one mode of action is to search for new compounds with a different mode of action. However, the advantages of the anticoagulants were so great that this was not done in this case. Instead, second-generation anticoagulants were developed and the most potent of these, brodifacoum, was discovered in 1975 by Sorex Limited in the UK and registered for first sale in Brodifacoum is fully effective against all resistant strains of rats and mice. But it is also more effective than warfarin against susceptible animals. It is so efficient that commercial baits carrying brodifacoum only require 50 parts per million (ppm) of the active ingredient, even against resistant rodents, instead of the 250 or 500 ppm that is normal for the first-generation compounds. Furthermore, whereas firstgeneration compounds need rodents to feed from them over several days for a lethal dose to be accumulated, all species and strains of rodents only require a single day of exposure to brodifacoum baits for complete mortality to be achieved. After discovery, an extensive programme of field trials of brodifacoum was set up across the world, against all important rodent pests of urban and agricultural environments, and this confirmed the outstanding efficacy of brodifacoum. ICI and Zeneca, the legacy companies of Syngenta, then developed a family of bait products based on brodifacoum carrying the name TALON. This extensive testing programme, and the universal effectiveness of brodifacoum against all rodent pests, gave rise to the claim that TALON is: The World s Most Effective Rodenticide References Hadler, M. R. and R. S. Shadbolt (1975). Novel 4-hydroxycoumarin anticoagulants active against resistant rats. Nature 253(5489): Kaukeinen, D. E. and M. Rampaud (1986). A review of brodifacoum efficacy in the U.S. and worldwide. Pp In: Twelfth Vertebrate Pest Conference, (Ed. T. P. Salmon) San Diego, California, University of California, Davis. Buckle, A. P. (1994). Chapter 6. Control Methods: Chemical. Pp In: Rodent Pests and their Control, (Eds. A. P. Buckle and R. H. Smith). Wallingford, Oxon, UK, CAB International: ISBN

8 Rodents the need for control URBAN ENVIRONMENTS Public abhorrence is probably the overriding reason for getting rid of rodents in urban settings. This age-old reaction to the presence of rodents has grown mainly from the knowledge that rodents transmit many diseases; including plague, cholera, Weil s disease (leptospirosis) and food poisoning to name only a few. This is combined with a reaction to the visible filth that rodents leave in places they inhabit, in the form of faeces, urine and hairs. There is also an understandable concern about rat bites, the incidence of which is still high among children in many low-income areas of the world s rapidly expanding cities. Finally, rats inflict physical damage, both to precious personal objects and to structures and installations which cause financial loss and the danger of failure of essential services, such as electricity and water. AGRICULTURE Such problems are of lesser importance in open-field agriculture, where small numbers of rodents are usually tolerated. But, when rodent numbers build up, attacks on field crops can cause devastating losses. This is particularly true in the tropics where agriculture is usually conducted by smallholders growing food staples to satisfy the needs of the family. Agriculture on an industrial scale is also at risk, however, and plantations growing sugarcane, coconuts, cocoa and oil palm routinely implement rodent management to prevent economic losses. But disease transmission is important, even in rural surroundings, because diseases passed from animals to man (i.e. zoonotic diseases) such as leptospirosis and scrub typhus are occupational hazards for those working in rodent infested environments. Families in crowded cities are exposed to rodent-borne diseases Rat damage to growing rice in Indonesia ANIMAL HUSBANDRY Rodents pests are of great importance in all animal husbandry systems as they consume the food put out for stock, transmit devastating diseases, both to workers and livestock, and damage the fabric of buildings. Biosecurity is an increasingly important watchword in animal husbandry because of the emergence of several new global disease threats, including Avian Influenza. Rodents cannot be tolerated wherever animals are reared for meat, milk or eggs, or where they are kept for recreation and companionship. Good rodent control is essential to biosecurity in animal husbandry 4

9 Rodents the need for control QUALITY STANDARDS AND AUDIT SCHEMES Quality standards are becoming more stringent in all aspects of human and animal food preparation, transportation and storage. Consumers, and those that wish to supply them, are increasingly aware of the need for high levels of cleanliness and hygiene at every stage of the food chain. Rodents cannot be allowed to exist, therefore, in any areas where human and animal foods are processed and stored. Therefore, many suppliers are now enrolled in audit schemes which allow them to demonstrate to their customers that their premises comply with the highest standards of rodent pest management. The scheme administered by AIB International is typical of these audit procedures. DISEASES TRANSMITTED BY RODENTS The disease most commonly associated with rodents is leptospirosis and all those who work in infested environments should know the symptoms of this potentially fatal disease, as effective treatment requires early diagnosis. As many as 30% of Norway rats harbour leptospire bacteria and shed them in their urine. However, as more sensitive diagnostic tests are developed an increasing variety of disease-causing organisms has been found in the bodies of rodents. Workers at the University of Oxford captured Norway rats on UK farms and found an astonishing number of disease agents that might affect humans and livestock. These included: Roundworms and Tapeworms (helminths) causing diseases such as capillariasis and toxicariosis and other diaorrheal conditions of humans and animals. Protozoa causing cryptosporidiosis and toxoplasmosis Bacteria causing a wide range of diseases including salmonellosis, leptospirosis, listeriosis, melidiosis and pasteurellosis Rickettsia causes Q fever Viruses causing Hantaan fevers. Often the incidence of the disease, in terms of the percentage of rats that carry it, is high. References World Health Organization (2000). Foodborne disease: a focus for health education. WHO, Geneva. 198 pp. ISBN Webster, J.P. and Macdonald, D.W. (1995). Parasites of wild brown rats (Rattus norvegicus) on UK farms. Parasitology 109: Mills, J. N. (1999). The role of rodents in merging human disease: Examples from the hantaviruses and arenaviruses. Pp In: Ecologically-based rodent management (Eds. Singleton et al.). Australian Centre for International Agriculture Research. Canberra, Australia. ISBN Gratz, N. G. (1994). Chapter 4. Rodents as carriers of disease. Pp In: Rodent Pests and their Control. (Eds. A. P. Buckle and R. H. Smith). Wallingford, Oxon, UK, CAB International. ISBN AIB Consolidated Standards for Food Safety. AIB International, Leatherhead, Surrey, UK. 40 pp. ISBN

10 Rodents the need for control Diseases carried by Norway rats on UK Farms Parasite Disease of Man Rats %+ve Helminths Capillaria spp Capillariasis 23 Toxocara cati Toxocariasis 15 Hymenolepis nana Rat tapeworm 11 Bacteria Leptospira spp Leptospirosis 14 Listeria spp Listeriosis 11 Yersinia enterocolitica Yersiniosis 11 Pasteurella spp Pasteurellosis 6 Pseudomonas spp Melioidosis 4 Coxiella burnetii (antibodies) Q Fever 34 Salmonella spp Salmonellosis 0 Protozoa Cryptosporidium parvum Cryptosporidiosis 63 Toxoplasma gondii Toxoplasmosis 35 Virus (antibodies) Hantavirus Hantaan-fever 4 Surprisingly, this sample of rodents from the UK did not show any incidence of Salmonella but the World Health Organization considers rodents to be very important in the transmission of many forms of salmonellosis, and also many other forms of gastric infection, to humans and domestic animals. The role of rodents in the transmission of human diseases such as cholera, plague and lassa fever is well established. But rodents are involved in the transmission of many emerging human and animal diseases, such as those caused by hantaviruses and areanviruses. These are the causative organisms of many different haemorrhagic fevers, haemorrhagic fevers with renal syndrome and hantavirus pulmonary syndrome. We also hear increasingly about epidemic diseases of animals, such as Avian Influenza and Foot and Mouth Disease. Those concerned with the control of these globally significant diseases have decided that rodent pest management must be integral to the management of disease outbreaks. 6

11 Rodents the need for control DAMAGE TO GROWING CROPS Across the tropics, all crops grown for human and animal food by smallholders are prone to damage by rodents. These pests threaten the livelihoods and food security of millions of farmers and their families. The crops attacked particularly include cereals such as rice, wheat, barley, millet, maize and sorghum, legumes and root crops such as cassava, taro, yams and potatoes. All vegetable and fruit crops are also taken by rodents. Rice is the dietary staple of hundreds of millions of people across Asia and is especially vulnerable to rodent attack. In Indonesia, the rice-field rat, Rattus argentiventer, was ranked in by crop protection specialists as the most important pest of growing lowland irrigated rice in every growing season from 1983 to Where damage occurs, the average yield loss in Indonesian rice is 18% and this is typical of losses throughout South and South-east Asia. Similar losses occur among all staple cereal crops throughout the developing world. Industrial crops are also prone to attack by rodents. In Malaysian oil palm, populations of Rattus tiomanicus can build up to densities of 500 rats per hectare and inflict losses of up to 10% of crop yield. The production of sugarcane is affected by rodent damage wherever it is undertaken. Loss of cane yield where rodent management is not carried out is normally 10 to 30%. Maize is a staple food of millions and rats attack it from the time of seed sowing until harvesting DAMAGE TO STORED PRODUCE Crops are at their most valuable when in store because of the accrued costs of crop protection and agronomy, harvesting, transport, processing and packing. Rodents damage stored products along the entire post-harvest pipeline, from village stores to vast industrial bulk storage depots. The value of losses is difficult to estimate because few monitoring systems exist. At the level of individual infestations, it was found that a population of 26 rats reduced the value of a tonne of wheat by 18% when they infested it for 12 weeks. On a wider scale, the Food and Agriculture Organization of the United Nations reports losses due to rodents of a wide range of stored crops across the world and estimated that 33 million tonnes of cereals in store were lost each year. FAO also reports losses of rice in store to average 8% from surveys in 14 countries; equivalent values were 16% for maize and 9% for wheat. Importantly, these losses were experienced in countries where food shortages were commonplace. Oil palm is an increasingly important crop and is severely damaged by rodents unless they are properly controlled References Wood, B. J. (1994). Chapter 3. Rodents in Agriculture and Forestry. Pp In: Rodent Pests and their Control. (Eds. A. P. Buckle and R. H. Smith). Wallingford, Oxon, UK, CAB International. ISBN

12 Rodents the need for control SOILING AND SPOILAGE Rodents produce filth on a truly epic scale. A small infestation of 10 rats will produce 146,000 droppings each year and 54 litres of urine. These are left anywhere the animals are active and, of course, urine is quickly absorbed by dry substrates such as stored cereals. Undoubtedly, the value of losses caused by rodents due to contamination and spoilage by far exceeds the value of stored products actually consumed. Contaminated foodstuffs may be declared unfit for human consumption or may require expensive cleaning. PHYSICAL DAMAGE Rodents have hard teeth and the compulsion to gnaw objects in their surroundings is innate. Domestic infestations of rodents often damage personal objects such as clothes, books, furniture and other valuable possessions. Rodents also damage many structural elements of buildings and installations such as insulation materials, wood and plastic door and window fittings, water conduits, electrical cables, wall partitions and roofing components. Very few estimates of the value of such losses are available because no system of monitoring exists. But one estimate in 1989 put the value of losses due to physical damage by rodents on farms in the UK at GBP 20 million per annum. It was also estimated that 50% of fires on farms are due to damage by rodents to power cables. Although coherent figures are unavailable, the global costs of rodent damage to structures, installations and human possessions are immense. Rodents leave urine and faeces where ever they are found Rat foot prints and tail swipes can be seen on the surface of stored grain Rodents damage to insulating material in a chicken shed 8

13 Biology and Behaviour of Rodents All rodents are intelligent and adaptable animals and an understanding of the important aspects of their biology and behaviour is necessary for their effective control. Of course, behaviour differs among species and there is also much variation between individuals depending on local conditions. But some aspects of biology are common and must be considered when rodent management operations are planned. HOME RANGES Rodents normally range over a familiar area in their day-to-day activities this is the home range. A home range may belong to a single individual or to a group of related individuals. The home range will contain everything rodents require, such as food, water and places for nesting. If all this is found in a small area then home ranges may be very small. For example, House mice living in a granary may have a home range of only a few square meters. Where resources are more dispersed, as is often the case in open field agriculture, home ranges may be many hundreds of square meters. Knowledge of the size of home range of a rodent pest species is obviously necessary when determining the density and positions of bait placements to ensure that baits are placed in the home ranges of all animals in the infestation. Rats are extremely wary of any new objects they find in their surroundings SOCIAL BEHAVIOUR In stable environments rodents will frequently form groups based around a family or extended family, sometimes called a clan. Often a dominant male, and several mature females, will control the range of the clan, keeping strange individuals away from its resources. This is why some rodent control programmes based on baits may take several weeks. Members of a clan will defend food (i.e. bait) in their range until they are killed. This may prevent peripheral and subordinate animals from feeding on the bait for several weeks. Social interactions play an important part in rodent societies DISPERSAL When they become sexually mature rodents, especially males, may be ejected from clans and will be forced to disperse. They may establish a home range on the edge of that held by others in the infestation. These peripheral animals may be tens, or even hundreds, of meters from the main infestation and may be hard to detect. But if they are not detected during an initial site survey, and treated, they are a source of rapid reinvasion of the treated site. Rodents will disperse to infest new territory and water is no barrier 9

14 Biology and Behaviour of Rodents WARINESS OF NEW OBJECTS This is often called new object reaction or neophobia. Most rodents are suspicious of anything new within their home ranges, although mice are certainly less neophobic than rats. In very stable environments this wariness of new objects may be extreme and may last several weeks. But in places where change and human activity is frequent neophobia may be very short-lived. The neophobia response is important in relation to all sorts of objects, including those used in rodent control operations such as baits, bait boxes and traps. The neophobia response of rodents may be particularly strong to complex tamper-resistant bait stations and this may delay uptake of bait from them by several weeks. ALTERNATIVE FOODS All rodent infestations have existing, and frequently abundant, alternative food sources. This is true in both urban environments and open field agriculture. Most rodents will not quickly switch from reliable and trusted food sources to new food, such as rodenticide baits. This is another reason why rodent control treatments may take several weeks. A typical behaviour is that individual rodents will first sample very small quantities of new food and will feed fully on it only after several days of limited sampling. If an adverse reaction to a new food is experienced rodents will not take that food again (this is bait shyness) and may not even return to the place where it was eaten. It is therefore essential that alternative foods are removed as far as possible from sites to be treated with rodenticide baits. In agriculture, it is important to treat rodent infestations early in the crop cycle before yields are produced that are an abundant source of alternative food. TALON baits are particularly valued where alternative food for rodents are abundant because only small quantities of TALON are required to deliver a lethal dose. ACTIVITY RHYTHMS Most rodents are nocturnal. This is because rodents are taken as food by many predatory animals and predation is usually less severe at night. Although, of course, there are some specialised rodent night hunters, such as owls. However, if predation pressure is very low, for example in closed buildings, and there is little other disturbance, rodents may be active during the day as well. Normally, rodent control activities are carried out during the day and treated sites should be left undisturbed at night to allow rodents to behave naturally, particularly to feed on baits. Rodents do not like to be in the open and will carry food back to cover to eat it Roof rats are highly agile climbers References Macdonald, D. W. and M. G. P. Fenn (1994). Chapter 1. The natural history of rodents: preadpatations to pestilence. Rodent Pests and their Control. Pp In: A. P. Buckle and R. H. Smith. Wallingford, Oxon, UK, CAB International: Meehan, A. P. (1984). Rats and mice - their biology and control. Felcourt, East Grinstead, U.K. Rentokil Limited. 383 pages. ISBN Macdonald, D. W., Mathews, F. and Berdoy, M. (1999). The behaviour and ecology of Rattus norvegicus: from opportunism to Kamikaze tendencies. Pp In: Ecologicallybased rodent management (Eds. Singleton et al.). Australian Centre for International Agriculture Research. Canberra, Australia. ISBN

15 Rodent Control: An Integrated Approach An integrated approach is required to carry out effective management of rodent pests in the long term. The benefits of the removal of a rodent infestation, either by the use of traps or rodenticide bait, will not last long unless other measures are also taken. RODENT CONTROL TREATMENTS Those who undertake rodent pest management usually find themselves in one of two situations. In the first, an existing rodent infestation requires immediate attention and removal. In the second there is a vulnerable site, for example a grain store or a food preparation area but, though no rodents are present, it is necessary to install measures to keep the premises clear of them. These two scenarios are often called clean-up and maintenance treatments respectively. Of course, the successful completion of a cleanup treatment will lead to the need to establish a maintenance regime to prevent recurrence of the infestation. Talon Wax Blocks are used in maintenance treatments AN INTEGRATED APPROACH TO RODENT PEST MANAGEMENT Generally a single measure, such as the use of traps or the application of rodenticide bait, is insufficient to provide a lasting solution to a rodent problem. It is necessary to adopt several measures and to combine their use into an overall management plan this approach to pest problems is called integrated pest management. The different measures available for use in clean-out and maintenance rodent treatments are the same: the deployment of rodenticide bait, the use of traps and sticky boards, the removal of harbourage and alternative foods, the installation of rodent proofing and, the initiation of a continuing programme of cleanliness, observation and record-keeping. But the relative importance of these measures and their order of implementation are different in clean-up and maintenance treatments. 11

16 Rodent Control: An Integrated Approach THE SITE SURVEY A site survey is an essential initial activity in all rodent control operations both clean-out and maintenance treatments. An effective site survey usually requires a map of the site on which can be marked areas of particular importance such as: places where rodent signs are seen (e.g. burrows, droppings, feeding, footprints, runways), areas of harbourage for rodents, such as straw stacks, panelled walls and ceilings, rough and overgrown ground, sources of alternative foods for rodents, sites where bait points may be located, places where rodents are obtaining access to premises, such as ill-fitting doors, holes in masonry and gaps between walls and roof timbers, areas where special care is needed to prevent non-target animals, such as pets and domestic stock, from getting access to bait. It is not only possible to tell if rodents are around by looking at droppings but also to tell which species is present THE CLEAN-UP TREATMENT The first action after the site survey in a clean-up treatment is to start measures aimed at the efficient removal of rodents. Very small infestations, especially of mice, may be eliminated with traps, or sticky boards where these are permitted. These techniques have the advantage that captured animals are available for collection and disposal. However, many infestations will require the use of rodenticide baits. Infested premises are usually left undisturbed before the start of a rodenticide application, except for the removal or covering of alternative rodent food. Baits must be applied according to label recommendations. Usually this involves placing baits in all areas where the site survey has demonstrated the presence and activity of rodents. Baits are placed safely to avoid exposure to non-target animals. Product labels frequently allow some flexibility in the amounts of bait laid, both in terms of the quantity of baits placed at a bait point and in the numbers of bait points used at a site. Heavy infestations require higher rates of bait application and more bait points, smaller infestations require less bait and fewer bait points. Baits are replenished according to a site visit schedule until all signs of feeding stop and there are no other signs of active rodent infestation. Rat runs show where rats are living and feeding and help in the placement of bait points Roof rats have left characteristics smears on wooden beams in a store room where they swing under the floor joists 12

17 Rodent Control: An Integrated Approach AFTER THE CLEAN-UP TREATMENT When the site has been cleared of rodents it is appropriate to consider implementation of measures that will prevent the development of another infestation. This will always involve a thorough clear-up of the site to remove all rubbish and clutter that provide shelter for rodents. Overgrown areas around the site which may hide rat burrows will be cleared. A programme of good house-keeping should also be initiated. All potential sources of food for rodents should be made inaccessible to them. Where produce and materials are stored these should be carefully stacked to allow inspection on all sides of stacks and should be raised above the ground. A programme of regular inspections of the entire site for rodent signs should be initiated. Consideration should then be given to proofing methods that can be installed to prevent rodents from getting into the building. These measures include making sure that doors and windows are tight-fitting, filling in any gaps around utility pipe-work where this enters structures, rat-guards on rain water down-pipes and making sure the general fabric of buildings is in good order. Finally, a maintenance rodenticide treatment may be installed using a system of permanent bait placements installed at strategic locations at the site to be protected. Stacks of stored products should be raised off the ground and away from walls to allow inspection MAINTENANCE TREATMENTS On sites that are clear of rodents, or have just been cleared, it may be prudent, or it may be a requirement of an official audit scheme, to install a system of permanent bait placements. Usually this is done in three rings of bait points: one at the perimeter of the site, on fence lines and against outside walls, one against the exterior wall of all buildings on the site and, finally, with baits placed within the buildings, where this is permitted. The baits stations used in maintenance treatments are usually of a tamper-resistant design. Bait stations are securely fixed to the substrate with specially-designed anchoring rods or wires. Block baits are used in the stations because these remain in good condition between maintenance visits. A programme of regular site visits is initiated and records of visits and rodent activity at the bait stations are kept. Once again, a programme of good-housekeeping is installed and recommendations are made regularly to the site owner about measures that should be implemented to keep the site unattractive to rodents. Measures of rodent-proofing are also implemented where practical. Keep areas outside buildings clean and tidy with no places for rodents to hide Good quality tamper-resistance bait boxes are important in maintenance baiting treatments to reduce risks to non-targets 13

18 TALON Formulations All TALON formulations contain 50 ppm brodifacoum. Syngenta only obtains brodifacoum from the original manufacturer in the UK in order to ensure the highest quality of this essential ingredient. The use of the 50 ppm strength brodifacoum provides effective rodent control, even in the most difficult circumstances that may be encountered in practice: Against species such as Roof rats and House mice, whose susceptibility to some other anticoagulants is low. For the control of rodents even in the presence of attractive alternative foods, where rodenticide baits may form only a small part of the daily diet of rodents. Against resistant rodents. Although resistance to other anticoagulants is widespread in many countries, no practical resistance to baits containing 50 ppm brodifacoum is known anywhere in the world. Rodents find TALON formulations, such as TALON Pellets, highly palatable. Therefore TALON can be used with confidence in all circumstances and wherever rodent infestations exist. More than 30 years of successful use is evidence of this. As well as the active ingredient brodifacoum, TALON formulations contain only materials of the highest quality. All food materials used in the manufacture of TALON formulations, such as cereals, are of the highest standard available and of human food grade quality. These components are used to produce formulations which are highly palatable to rodents. TALON packs are designed to be robust and to keep baits fresh so that they remain attractive to rodents even after periods of transport and storage. TALON formulations are sold in robust containers to keep them in good condition during transportation and storage. TALON PELLETS TALON Pellets are a cereal-based medium-sized pellet (4.7 mm diameter), intended to be similar in size to cereal grains, the preferred food of many rodent species. Highly attractive to rodents. Provide flexibility in the quantities of bait that can be applied at bait points. Preferred for use in urban environments, where attractive alternative food is frequently available. Have the active ingredient evenly distributed throughout the pellets, unlike grains baits where the rodenticide is applied only to the surface. 14

19 TALON Formulations TALON WAX BLOCKS TALON Wax Blocks are manufactured by the advanced melt and cast process to ensure thorough mixing of ingredients and a highly resistant surface finish. TALON Wax Blocks are manufactured in two sizes 20g and 5g. water- TALON WAX BLOCKS (20G) Intended for use in urban environments. Ideal for use in tamper-resistant bait stations s because they can be anchored inside the boxes though the central hole in each block. Excellent keeping qualities, remaining attractive and in good condition for long periods. Excellent for use in damp environments, such as sewer systems. Less attractive than grain baits to non-target species, particularly to birds which have difficulty feeding on them because of their solid, waxy nature. Unit dose, allowing for accurate bait placements without weighing. TALON WAX BLOCKS (5G) Ideal for use in crop agriculture where small size allows good bait dispersion with many points per hectare of crop. Readily applied to rodent burrows, including those made by mice, because of their small size. Formulated with high melting-point wax for use in tropical conditions. ons. Unit dose, allowing accurate application rates in field crops. Less attractive than grain baits to non-target species, particularly to birds, which are unable to ingest whole 5g blocks. Easy and effective application by airplanes in plantation crops. Talon Wax Blocks are NOT REGISTERED for use in crop in Australia 15

20 Rodent Pests Commensal Species There are about 1,700 different rodent species but only a few dozen of these are important as pests. The three commensal species all have their origins in Asia but have been transported around the globe by human activity and are now found in virtually every country of the world. THE COMMENSAL RODENT SPECIES The three cosmopolitan rodent pests that are associated with human and human activities are: The Norway rat (Rattus norvegicus), also called the Common rat, Sewer rat, Brown rat. The Roof rat (Rattus rattus), also called the Black rat, House rat, Ship rat. The House mouse (Mus musculus). House mouse (Mus musculus) The Norway rat is the largest of the three species and is the most common rat found in towns and cities in the temperate zones. It is frequently associated with water and makes characteristic burrows. In the tropics, Norway rats are often restricted to areas around harbours and docks. The Roof rat is the common rat of human habitations in countries with warm climates. It is more lightly-built than the Norway rat and much more adept at climbing and rarely burrows. Where the two species co-exist, Norway rats will keep to the ground whereas Roof rats will climb into ceilings and lofts to make their nests. The Roof rat occurs in three colour variants (known as morphs) and therefore is not always black. Many sub-species of the Roof rat occur around the world and may be given full species status by some authorities. The House mouse is by far the smallest of the three species. Like the Roof rat it is an excellent climber. It sometimes burrows but in buildings will make nests in any convenient sheltered space, such as in false ceilings and partition walls, in lofts and even in soft furnishings. House mice are thought by some to occur as two sub-species (M. m. musculus and M. m. domesticus), while others consider M. musculus and M. domesticus to be distinct species. The common sub-species of Western Europe is domesticus and it was mainly this sub-species that was carried in ships and spread around the world. Some of the main aspects of the biology and behaviour of these three species and points of recognition are given in the Table. Norway rat (Rattus norvegicus) Roof rat (Rattus rattus) 16

21 Rodent Pests Commensal Species NORWAY RAT Also called Brown, Common and Sewer Rat (Rattus norvegicus) ROOF RAT Also called Ship, House or Black Rat (Rattus rattus) HOUSE MOUSE (Mus musculus) BODY Large, robust Sleek, graceful smaller than Norway Small, slender ADULT SIZE Average weight 300 gm 200 gm 15 gm Length (Head and Body) cm cm 6-9 cm Tail cm cm 7 1 / 2-10 cm SNOUT Blunt Pointed Pointed EARS Small, covered with short hairs Large, nearly naked Large EYES Small Large, prominent Small TAIL Dark above, pale beneath Uniformly dark Small, uniformly dark FUR Harsh, shaggy. Top brown with some scattered black. Underneath gray to yellow/white Gray to black, smoother, softer Light brown - light gray DROPPINGS Capsule-shaped, approximately 20 mm Spindle-shaped, up to 12 mm Rod-shaped, 3-6 mm SENSES Sight Poor, colour blind Poor, colour blind Poor, colour blind Smell, taste, hearing, touch Excellent Excellent Excellent FOOD Omnivorous, eats more meats than Roof Rat 28 gm/day Omnivorous, mainly fruits, nuts, grains vegetables, 28 gm/day Prefers cereal grains, 3 gm/day WATER Free water or food with high water content Same as Norway Usually from food FEEDING HABITS Shy, nervous of new objects Shy, nervous of new objects Nibblers, less nervous of new objects CLIMBING Can climb, not very agile Agile, active climber Good climber NESTS Mainly burrows Mainly walls, attics, vines, trees Loners, generally within stored materials but will burrow SWIMMING Excellent swimmer Can swim, not fond of water Can swim HOME RANGE Large, m Same as Norway Small, 3-6 m, very territorial LIFE SPAN 9-12 months 9-12 months 9-12 months MATURITY 2-3 months 2-3 months 1 1 / 2 months YOUNG/LITTER LITTER/YEAR Maximum

22 Rodent Pests OTHER COMMON RODENT PEST SPECIES HISPID COTTON RAT Sigmodon hispidus The Cotton rat is found in the southern states of the USA and throughout Central America. In South America it is replaced by several very closely related species. The Cotton rat is a medium-sized animal, adults weigh g, and has rough fur with a grizzled appearance given by a mix of black, yellow and brown hairs. The Cotton rat is a pest of all cultivated crops but is particularly important, as the name suggests, in cotton fields. It is also a major pest of sugarcane, rice and sorghum. Cotton rats are fast-breeders and females may have as many as nine litters a year. Hispid Cotton rat (Sigmodon hispidus) NILE RAT Arvicanthis niloticus A common rodent pest of sub-saharan Africa, Arvicanthis niloticus is also called the African Grass rat. It lives naturally in open grasslands, where it builds large communal burrows. Well-used runways radiate from the burrow system to feeding areas. The Nile rat is an important pest of cultivation and attacks all smallholder crops grown for food and fodder. It is also implicated in the transmission of a number of tropical diseases, including plague and shistosomiasis. It is a medium-sized species, adults weigh on average 120g, and is grey-brown above and light grey below. Lesser Bandicoot rat (Bandicota bengalensis) MULTIMAMMATE RAT Mastomys (=Praomys) natalensis The Multimammate rat is the most important rodent pest of southern Africa. It is a small species, adults weigh up to about 100g. It occurs in bushy areas but also inhabits villages, often nesting in roof thatch. As its name suggests, females have many nipples (up to 24) and can produce very large litters. This prodigious breeding capacity may lead to population explosions after rains and when food is abundant. It is a pest of all cultivated crops but is also implicated in disease transmission, including the dreaded Lassa Fever. A closely related species, M.coucha is found in South Africa. Nile rat (Arvicanthis niloticus) LESSER BANDICOOT RAT Bandicota bengalensis Unlike many other rodent pests, the lesser bandicoot is equally at home in urban environments and in agriculture. It occurs across South Asia and down into Southeast Asia. It is a large species, adults weigh up to 400g, and is know for its aggressive behaviour. Its coat is generally dark grey-brown, with long guard hairs giving it a spiky appearance. Both the Cotton rat and the Lesser Bandicoot are common pests of sugarcane plantations 18

23 Rodent Pests It inhabits complex burrow systems, which have numerous chambers and escape holes. It occurs in fields, gardens and orchards, as well as in villages, towns and cities. It is an important pest of growing rice, sugarcane, wheat, barley and legumes, is common also in crop stores, and is known for its role in the transmission of several important tropical diseases, including plague and leptospirosis. RICE-FIELD RAT Rattus argentiventer The Rice-field rat is found throughout Southeast Asia, from the north of Vietnam, down the peninsula of Thailand and Malaysia onto the islands of Indonesia and the Philippines. It is principally a pest of rice but is also found in plantations of oil palm and sugarcane. The Rice-field rat is a medium-sized species, with adults usually in the range 100 to 250g. Its coat is a grizzled mixture of grey, orange and black hairs. It lives in burrows made in uncultivated land and in the rice-field bunds. In rice, its breeding is co-ordinated with the flowering of the crop, which results in large populations, and huge crop losses, at harvest time. A high percentage of Rice-field rats carry leptospire bacteria and shed them with their urine into the paddy water. WOOD RAT Rattus tiomanicus The Wood rat is a highly arboreal pest of plantation crops in southern Thailand, Malaysia and Indonesia. It occurs in plantations of cocoa and coconuts, but is mainly known for the damage it does in oil palm plantations, where population densities can exceed 500 rats per hectare. It is a small species, adults rarely exceed 100g. Its coat is reddish brown on the back and creamy white underneath, with a clear line demarcating the two colours. Thanks to research conducted in Malaysia we know more about the biology of this species than almost any other rodent crop pests. Rice-field rat (Rattus argentiventer) Polynesian rat (Rattus exulans) Polynesian rats are common pests of coconut plantations POLYNESIAN RAT Rattus exulans The original home of R. exulans was probably the mainland of Southeast Asia but it spread across the islands of the Pacific, as far as Hawaii, with the expansion of the Polynesian peoples. It is an excellent climber and mainly a pest of houses and gardens, but may cause severe damage in agriculture, especially in coconut plantations and, occasionally, rice fields. It is a small species, adults rarely exceed 50g, and is reddishbrown to grey on the back and light grey beneath. References Wood, B. J. (1994). Chapter 3. Rodents in Agriculture and Forestry. Pp In: Rodent Pests and their Control. (Eds. A. P. Buckle and R. H. Smith). Wallingford, Oxon, UK, CAB International. ISBN

24 Performance Laboratory Evaluations During the years after its invention brodifacoum was tested more extensively in the laboratory than any other rodenticide by researchers all over the world. The results showed that brodifacoum was exceptionally potent against all important pest rodents. Standardised methods for the laboratory testing of anticoagulant rodenticides are published by the European and Mediterranean Plant Protection Organisation and were generally used in obtaining the data provided here. ACUTE TOXICITY OF BRODIFACOUM The most common way of measuring potency of rodenticides is the acute oral LD 50. This is the dose that will kill 50% of individuals in a population. Brodifacoum LD 50 values are given below for the three cosmopolitan commensal species and for a range of species that are of regional importance. Most rodents die 4 to 6 days after their first exposure to brodifacoum baits. The delay between ingestion and death ensures that animals are unable to associate intake of the bait and the symptoms they subsequently experience, and so poison shyness never occurs. Species Source/ Strain LD 50 (mg/kg) Days to death (range) Commensal rodents Mus musculus LAC Grey Rattus norvegicus Wild 0.22 (male) 3-9 Wistar 0.26 (female) 3-10 Rattus rattus USA Field rodents Bandicota bengalensis Bangladesh Cricetus cricetus Hungary Holochilus venezuelae Venezuela Meriones hurrianae India Mesocricetus auratus USA Microtus arvalis Hungary Microtus pinetorum USA Rattus argentiventer Malaysia Rattus tanezumi Philippines Rattus tiomanicus Malaysia Sigmodon alstoni Venzuela Tatera indica India References Redfern, R., Gill, J. E. And Hadler, M. R. (1976). Laboratory evaluations of WBA 8119 (brodifacoum) as a rodenticide for use against warfarin-resistant and non-resistant rats and mice. Journal of Hygiene, Cambridge 77: Kaukeinen, D. E. and Rampaud, M. (1986). A review of brodifacoum efficacy in the U.S. and world-wide. Pp In: Twelfth Vertebrate Pest Conference. (Ed. T. P. Salmon.) San Diego, California, USA, University of California, Davis, USA. 20

25 Performance Laboratory Evaluations Brodifacoum is widely acknowledged to be the most effective toxicant against the broad range of pest rodents which currently occur around the world. It is generally more potent than any other anticoagulant rodenticide, including the more recent compounds flocoumafen and difethialone. This is illustrated for commensal rodents in the following tables. The LD 50 data are given both in terms of the active ingredient and of bait at the concentrations most commonly used. Note in particular that, while some anticoagulants are almost as potent as brodifacoum against some species, brodifacoum is highly effective against all species and strains tested. Acute oral LD 50 of several anticoagulants to Rattus norvegicus (in most cases albino laboratory strains were used) Anticoagulant LD 50 (mg/kg)* Normal concentration in bait (% a.i.) LD 50 (g of bait for a 250g rat) Second-generation anticoagulants brodifacoum bromadiolone difenacoum difethialone flocoumafen First-generation anticoagulants coumatetralyl warfarin * where two values are given these are for male and female rats respectively Acute oral LD 50 of several anticoagulants to Mus musculus (in most cases albino laboratory strains were used) Anticoagulant LD 50 (mg/kg)* Normal concentration in bait (% a.i.) LD 50 (g of bait for a 25g mouse) Second-generation anticoagulants brodifacoum bromadiolone difenacoum difethialone flocoumafen First-generation anticoagulants coumatetralyl warfarin * where two values are given these are for male and female mice respectively 21