Academic literature on the topic 'Brodifacoum'

Context Cereal pellets containing the anti-coagulant poison brodifacoum at 20 ppm are routinely used to rid islands of invasive rodents. The impact, if any, of the poison on invertebrates is not well understood. This is problematic because many of the islands targeted for treatment harbour endemic invertebrate species, including snails where available information about brodifacoum impact is equivocal. Aims Combining field tests and subsequent laboratory analysis, the present study investigated the effect of brodifacoum on the snails of Henderson Island, South Pacific. Methods In the field, we housed snails in plastic boxes for up to 10 days to compare the survival of those kept with and without access to brodifacoum cereal pellets. Subsequently, we analysed brodifacoum levels in those kept with access to poisoned pellets, according to whether they survived or died. Key results There were no detectable differences in the survival between the captive snails kept with and those kept without access to brodifacoum. Among those with access, there were no significant differences in brodifacoum concentrations between the minority that died and the majority that survived. In fact, brodifacoum was detected in only a few samples. Conclusions Brodifacoum appears not to pose a risk to the snails of Henderson Island. Implications Although it would be prudent to test the impact of brodifacoum on the resident snails before proceeding with a rodent eradication on other islands, we suspect the Henderson results can be extended to other sites.

A case of self-ingestion of brodifacoum that resulted in spontaneous intra-abdominal haemorrhage, circulatory shock, rhabdomyolysis and acute renal failure is reported. Current knowledge and management of superwarfarin poisoning are discussed.

The anticoagulant brodifacoum is widely used overseas as a rodenticide and in New Zealand to control rodents and brushtail possums (Trichosurus vulpecula) The efficacy behavioural and pathological changes and times to death were compared between Norway rats (Rattus norvegicus) and brushtail possums poisoned with brodifacoum Caged animals were given brodifacoum in wax or cereal baits observed for signs of toxicosis and changes in behaviour then autopsied after death Brodifacoum caused haemorrhaging and death in both species and although each showed marked changes in behaviour and pathology they differed in character time of onset and duration Results may be explained in part by species differences in behaviour and halflives of blood clotting factors

Abstract Studies were made on the identification, damage and chemical methods of control of rodent pests in irrigated and nonirrigated fields of peanut (Arachis hypogaea L.) at Ludhiana, India. Peanut fields were infested with Bandicota bengalensis, Tatera indica, Rattus meltada and Mus spp., except that B. bengalensis was absent in nonirrigated fields. These rodents reduced peanut yield by an average 3.86%, a loss of 190.18 rupees/ha ($15.12 US). Severe rodent damage was sporadic with a maximum of 18.97% reduction in peanut yield. Rodents inflicted more damage between 80 to 120 days after planting, i. e. during the pod fill stage of crop growth. A single treatment with poison bait at 80 to 90 days after planting with 2.4% zinc phosphide, 0.005% brodifacoum and 0.005% bromadiolone in cereal baits at the rate of 1 kg/ha resulted in 58.07%, 42.26% and 40.88% rodent control, respectively, in nonirrigated fields. In irrigated fields, 58.70% and 67.02% rodent control was achieved with zinc phosphide and brodifacoum baits respectively. Significantly higher rodent control was obtained with 2 treatments of either brodifacoum or bromadiolone than with a single treatment of any rodenticide. Wax blocks containing 0.005% brodifacoum were less effective than cereal baits containing the same rodenticide. Two applications at 10 day interval of either 0.005% brodifacoum or bromadiolone between 80–100 days after planting is suggested for rodent control in peanut fields.

Brodifacoum is a highly toxic, second-generation anticoagulant developed for the control of rodent pests. However, information regarding the impacts of brodifacoum on non-target wildlife has been largely collected opportunistically and is generally avian biased. Reviews of non-target impacts of brodifacoum routinely regard reptiles and amphibians as low risk, despite there being no formal evidence supporting this assumption. Recent evidence suggests that some native lizard species will consume cereal baits in addition to toxin-loaded invertebrates. As part of a wider study, we quantified visitation rates to brodifacoum bait stations by Shore Skinks Oligosoma smithi, and recorded the first observation of this species consuming toxic bait. Bait stations (n = 56) recorded up to 81.5% tracking incidence by Shore Skinks across one of two pest-controlled grids. Skinks were occasionally observed inside bait stations feeding on invertebrates. Of the 805 skinks caught in pitfall traps over the 6 month period, none showed clinical or behavioural signs of anticoagulant toxicosis. Further research into the acute toxicity and chronic sub-lethal impacts of pesticides on herpetofauna is required before potential impacts on these fauna can be dismissed.

Brodifacoum is a highly effective anticoagulant rodenticide that presents a secondary hazard to some non-target wildlife. The high acute toxicity of brodifacoum to mammals and birds, and its prolonged persistence in liver predicates secondary risk to predators and scavengers of poisoned rodents. Hence there is a need to improve ability to monitor and predict hazards of brodifacoum to non-targets, and optimise use patterns accordingly. Use of a less persistent anticoagulant rodenticide, diphacinone, is an alternative approach currently under investigation in New Zealand. This thesis describes a series of laboratory and pen studies that address information gaps relevant to the assessment of non-target hazards in continued use of brodifacoum, and of using diphacinone as an alternative. Non-lethal techniques for determining sublethal brodifacoum exposure in birds was investigated in chickens. Elevation of prothrombin time was a less reliable index than residual concentrations in tissues. Samples requiring less invasive procedures, such as dried blood spots or faeces, have potential to detect recent sublethal brodifacoum exposure and refinement of these indices could be useful in proactive monitoring of avian wildlife. Residual brodifacoum in eggs of sublethally-exposed hens raised further questions regarding wider non-target hazard and adverse effects on development of fertile eggs or chicks. A laboratory trial with rats found a positive correlation between residual brodifacoum concentrations in liver and the amount of brodifacoum ingested as bait. An estimated 14-22% of ingested brodifacoum was excreted in rat faeces in the period between ingestion of a lethal dose and death, indicating another potentially significant environmental pathway for brodifacoum transfer. In considering diphacinone as a less persistent alternative rodenticide to brodifacoum, evaluation of residual concentrations and persistence in pig tissues was required to estimate secondary hazard to human consumers and adequate with-holding periods for hunting feral pigs in areas where diphacinone was applied. A pen trial showed that domestic pigs were more susceptible to diphacinone toxicity, and thus primary poisoning risk, than previously estimated. Hepatic half-life of diphacinone in pigs was approximately 14 days, indicating reduced persistence in comparison to brodifacoum and enabling estimates of with-holding periods for hunting feral pigs from areas where diphacinone baits were applied. To investigate potential hazards of diphacinone use to invertebrates a trial using tree weta, a native New Zealand invertebrate, was undertaken. Weta readily ate diphacinone wax block baits with no mortality or weight loss evident, indicating low susceptibility. Residual whole-body diphacinone concentrations did not increase with the amount of diphacinone bait eaten. A simple, deterministic risk assessment suggested that, as a single secondary exposure, the maximum diphacinone concentration measured in weta would present a low risk to non-target birds. Given international recognition of the high secondary hazard and corresponding restrictions on use of brodifacoum, continued availability of brodifacoum to non-licensed users and sustained field applications for possum and rodent control in New Zealand is an exceptional use pattern. New data in this thesis suggest that baiting strategies that minimise the amount of brodifacoum available in the environment are important and regulatory review of some New Zealand brodifacoum applications should address this. In parallel, development of diphacinone as an alternative to brodifacoum should continue, as new data here confirms lower persistence in mammalian liver than brodifacoum, and also indicates low toxicity to invertebrates. However further investigation of multiple-exposure hazard and potential sublethal effects of diphacinone on non-target mammals and birds is warranted before extensive and sustained field applications of diphacinone are undertaken.

Dissertação de Mestrado Integrado em Medicina Veterinária
O impacto dos rodenticidas na fauna selvagem, principalmente os anticoagulantes de segunda geração representados pelo Brodifacume e Bromadiolona, foram e são causa de inúmeros envenenamentos primários e secundários, através de ingestão directa ou pela ingestão de animais envenenados. Alguns estudos sugerem que a exposição a doses sub-letais destes xenobióticos podem causar uma morte “indirecta”, devido a uma predisposição a diferentes tipos de trauma ou outras patologias. Neste estudo, é valorada a possível relação entre a presença/ausência destes pesticidas anticoagulantes em animais e outras lesões indirectamente relacionadas com uma intoxicação sub-letal. A população estudada foram todas as aves de rapina que ingressaram num centro de recuperação em Madrid, Espanha, como cadáveres ou que morreram ou foram eutanasiadas durante o seu tratamento, devido à severidade das lesões. Foi utilizado o fígado destas aves para a análise toxicológica mediante a metodologia de Cromatografia de Camada Fina (TLC) com detecção por luz UV. Vinte das cinquenta e três aves analisadas foram positivas a estes compostos e a Bromadiolona foi detectada em 80% dos casos. Foram encontradas relações importantes entre esta positividade e algumas varáveis analisadas como certas lesões visualizadas à necrópsia e baixa condição corporal. Também foi encontrada uma relação positiva entre os animais com resíduos de rodenticida no seu organismo e a causa de ingresso, sendo o trauma contra estrutura a mais significativa.
ABSTRACT - RODENTICIDE INCIDENCE IN BIRDS OF PREY: PREVALENCE STUDY AND POSSIBLE SECONDARY EFFECTS - The impact of rodenticides in the wildlife, mainly the second generation anticoagulant represented by Brodifacoum and Bromadiolone, has caused and still causes innumerous cases of primary and secondary poisoning, by direct ingestion or by ingestion of poisoned animals. Some studies suggest that exposition to sub-lethal doses of theses xenobiotics could cause an “indirect” fatality, due to a bigger predisposition to different kinds of trauma or other pathology. In this study, its assess the possible relation between the presence/absence of anticoagulant pesticides in animals and other injuries not directly related with a sub lethal intoxication present in those animals. The sample population in study was all the birds of prey that had entered in a rehabilitation centre of Madrid, Spain, already dead or that had been dead or sacrificed during the treatment, due to the severity of injuries. A thin layer chromatography (TLC) methodology has been used with UV light detection in the toxicological analysis of the liver of these birds. Twenty of the fifty-three analyzed birds were positive to this compounds and Bromadiolone was found in 80% of the cases. Important relations were found between positive animals and some necropsy findings and poor body condition. It was also found a positive relation between the positive animals and the cause of injury, being the trauma against structure the most significant.

Poison operations are a widely used technique for rodent control in the indigenous forests of New Zealand. This study examined the bait-take and rat monitoring data obtained for continuous poison operations at Boundary Stream Mainland Island (BSMI), Hawke’s Bay, between 1996 and 2007. Since the beginning of the Mainland Island project at BSMI in 1996, 800 ha of indigenous forest have been treated with an ‘Integrated Pest Management’ approach, in which rodents (primarily ship rats) have been targeted by consecutive ground poison operations. The aim of the intensive pest control was to allow the ecosystem to recover and provide a safe environment for threatened native bird species to recover or be re-introduced. Another important aim of this pest control is to provide experience and expert knowledge in management techniques especially applicable to the protection of indigenous habitat on the New Zealand mainland. This research study had two main aims: to identify spatial patterns of the rodent population at BSMI and to determine the efficacy of the different rodenticides applied for their control. The distribution of the rodent population was investigated by spatial analysis of bait-take across the reserve and through time. Visualisation of high and low bait-take areas revealed that there was a noticeable reinvasion from adjacent unmanaged native forests, but not markedly from exotic forest or pasture. Reinvasion from small and isolated adjacent forests ceased to be noticeable consistently after approximately four years of the poison operation, while a large scenic native reserve, as well as a narrow part of the treatment area surrounded by many native bush patches, were continuously affected by reinvasion through the entire project time. Bait-take was visibly higher after the bait had either been removed, or left in the field unserviced, over winter. No consistent areas of no bait-take were identified. Further statistical analysis of bait-take data revealed that bait-take was higher in bait stations within 150 m of the treatment edge than interior bait stations. Bait-take in broadleaf/tawa/podocarp forest was significantly higher than in kamahi/kanuka/rewarewa, beech and cloud-cap forest. The second aim of the study was to determine the efficacy of the various bait types with different active ingredients used during the operation. Rat monitoring data, namely rat tracking indices (RTI) obtained from tracking tunnels, were statistically modelled using Generalised Linear Models. Diphacinone cereal pellets (Pestoff® 50D, 0.05g/kg diphacinone) obtained the lowest RTI, followed by pindone cereal pellets (Pindone Pellets®, 0.5g/kg pindone), brodifacoum cereal pellets (Pestoff® 20p and Talon®, 0.02 g/kg brodifacoum), coumatetralyl paste (Racumin®, 0.375 g/kg) and diphacinone bait blocks (Ditrac®, 0.05 g/kg). Cereal pellet baits worked better than any other bait type used at this location. Season had no statistically significant effect on either RTI or bait-take estimates. The overall goal of the poison operation to decrease rat numbers, and to maintain low levels, has been met. However, the results of this study suggest that baiting needs to be done continuously and over the entire treatment area. Edge bait stations – particularly next to adjacent native forests – should be prioritised to target reinvading rodents. Poisons presented in cereal pellet baits should be preferred to other bait types. Both pindone and brodifacoum showed very good results, as well as diphacinone in cereal pellet baits.

Aerial control using 1080 (sodium monofluoroacetate) baits is widely used in New Zealand for the control of introduced brushtail possums (Trichosurus vulpecula), with the aim of protecting national conservation and agricultural values from these damaging pests. This thesis integrates research, completed over 25 years, that was motivated by growing recognition in the 1970s of the extent of possum impacts and the need to improve the effectiveness and efficiency of the control operation. Field research assessed the palatability of three types of cereal-based pellet baits and carrot baits in different regions, habitat types and seasons. Palatability was assessed by the consumption of the different bait types presented independently of each other on 15-30 plots, with rotation of bait types at plots on successive nights to provide equal exposure to each bait type. There was regional variation in possums' bait preferences, possibly reflecting genotypic differences, whereas seasonal variation was less evident. Carrot bait was preferred or equally preferred to cereal bait in 14 out of 20 field trials. The proportion of possums eating baits was then investigated by, firstly, developing a technique for tracing bait acceptance using rhodamine B, a UV-fluorescent dye. In four field trials, more than 95% of possums accepted three types of dye-marked bait, eliminating bait refusal as a major reason for low kills in winter control operations. In a fifth trial, conducted in summer, only 68% of possums accepted bait suggesting that seasonal availability of favoured foods may influence bait acceptance. Since possums must encounter baits before deciding whether to eat them, field studies were undertaken to assess the coverage achieved in normal aerial baiting operations. Large gaps, up to 400 m in width, were often found between baiting swaths; these could allow some possums to survive. A controlled field experiment, using acceptance of rhodamine-dyed bait as a measure of effectiveness, showed that bait distribution was least accurate where flight paths were not marked. Where gaps of 100 m between flight paths were deliberately created, bait acceptance was slower and less than where coverage was complete. Sowing baits at 3 kg/ha was as effective as at 10 kg/ha, indicating the potential for substantially reducing operational costs by using machinery capable of faultlessly distributing baits at low rates. Navigational guidance systems were evaluated and found to improve the accuracy of bait distribution. During 1993-1997, when a lower sowing rate of 5 kg/ha was adopted operationally by regional managers, control effectiveness was unchanged but annual savings of around $9 million accrued. Because of the lack of suitable sowing machinery, a bucket was developed to permit faultless distribution of baits at lower rates, demonstrating the possibility of yet further cost-savings. The possibility of seasonal food availability affecting bait acceptance was investigated in three different forest habitats. Dyed baits were aerially distributed on 100 ha at each site in each season over two years. In each trial, fat-based condition indices of possums were calculated and the abundance of possum-preferred plant foods described. Bait acceptance was consistently high (85-100%) in the 24 trials, and was not influenced by either condition or availability of preferred foods. It seems likely that seasonal variation in operational effectiveness is caused by either the availability of sharply seasonal, scarce foods that possums may feed on intensively for brief periods, or by warmer temperatures that render 1080 less effective. The influence of 1080 on acceptance of (rhodamine-dyed) baits was investigated in a field trial. Examination of possums for dye-marking showed that 25% of possums refused to eat either a lethal quantity of bait or any bait at all, compared with 98% of possums eating non-toxic bait. This indicated that 1080 is aversive to possums, which is a potential major reason for their surviving control operations. Pen trials were therefore conducted to further examine the problem and to seek solutions. Toxic carrot baits were rejected by 27.5% of possums, equally by smell and taste aversion, whereas toxic cereal pellets were rejected by 34%, mainly by taste aversion. Orange and cinnamon were shown to be among the most preferred of 42 flavours tested and, when applied to toxic baits, 1080 was effectively masked. Bait refusal was reduced to ≤7%, the same as that recorded for possums presented with flavoured non-toxic baits. For long-term control of possum populations, aerial 1080 baiting can be used sequentially with other poisoning methods. However, the compatibility of these methods is dependent on the likelihood of possums developing bait shyness if sublethally dosed. Studies were therefore conducted to characterise and compare the four main toxicants used (1080, cyanide, cholecalciferol and brodifacoum) for induction and mitigation of bait shyness. Shyness was induced in approximately 80% of possums sublethally dosed with cyanide, 60% with 1080, 20% with cholecalciferol, and 0% with brodifacoum. Cyanide and 1080 shyness were found to persist in many possums for at least 12 and 24 months, respectively. Use of alternative bait types, and of baits containing an alternative slow-acting toxin (brodifacoum) were shown to be effective ways of overcoming shyness. This, and other related research, is reviewed to provide operational specifications that maximise the likelihood that all targeted possums will (i) encounter bait, (ii) eat it, and (iii) die. The likely future use of aerial 1080 baiting is described and the technological, economic, environmental and social constraints on its sustainability are discussed. Finally, the uptake of the research by possum managers is considered, and areas identified in the thesis where information is incomplete are summarised as prioritised topics for further research.

Brodifacoum is a potent second-generation anti-coagulant toxin routinely used to control problem populations of introduced mammalian pests (such as possums (Trichosurus vulpecula), rats (Rattus rattus) and mice (Mus musculus) in New Zealand forests. The toxin is packaged in the form of cereal bait pellets, which are distributed into managed forest locations in bait stations or by aerial drops. The toxin is persistent in vertebrate tissues, and there has been increasing concern recently about the potential for secondary poisoning of threatened insectivorous bird species via invertebrates that have fed on bait containing brodifacoum. This thesis studied relevant aspects of the ecology of forest invertebrates and the use of brodifacoum bait at Trounson Kauri Park, Katui Scenic Reserve and Wenderholm Regional Park, North Island, New Zealand. Video recording equipment was used to monitor invertebrate activity at bait stations, revealing that weta (Orthoptera) and cockroaches (Blattodea) were significant users of bait stations loaded with brodifacoum bait. These animals were attracted to full bait stations, and could spend considerable time in contact with toxic bait. Weta were even observed grazing poison baits. Pitfall traps, ‘weta boxes’ and rodent tracking tunnels were used to sample the invertebrate populations in the three study areas. Wetas and beetles were present in significantly greater numbers at Trounson and Wenderholm compared to Katui. It was concluded that this difference was due to the reduction in pest mammal populations, resulting from the intensive pest control at the two former sites. Invertebrates captured in pitfall traps were sent for brodifacoum residue analysis to determine if brodifacoum was present in their tissues. Weta, cockroaches, beetles and other miscellaneous invertebrate species recorded significant residues of brodifacoum (up to 7.47 µg/g). Residues were found to be dependent on the loading of toxic bait into stations. Levels recorded after bait was loaded were significantly higher than levels recorded before bait was loaded in bait stations. Invertebrates carrying brodifacoum were found to disperse up to 10 metres from the source of the toxin (loaded bait stations). Residue levels recorded decreased significantly the further away from the full bait stations that samples were taken. After toxic bait had been removed from bait stations, residue levels in invertebrates took in excess of 4 weeks to return to background levels. Trace levels of brodifacoum were still detectable up to 10 weeks after bait had been removed. Physiological experiments on the effect of brodifacoum consumption on captive locusts found no evident harmful effects. Locusts fed readily on toxic bait with no significant increase in mortality. They excreted brodifacoum rapidly, and there was no evidence of long-term bio-accumulation of the toxin. A risk assessment was made exploring the potential for invertebrates to secondarily poison insectivorous bird species. This found that bird species that consume substantial numbers of weta, cockroaches and beetles (eg. kiwi (Apteryx spp), ruru (Ninox novaeseelandiae) and robin (Petroica australis)) are at risk of secondary poisoning from their food supply during pest control operations using brodifacoum. The risk is higher during and immediately after bait containing brodifacoum is loaded in bait stations. Risks decreases progressively after bait is removed, as invertebrates excrete any brodifacoum residues present in their tissues. The risk of secondary poisoning is likely to be greater during warmer months, due to increased invertebrate activity (and residues in invertebrates) during this time. The frequency of consumption of contaminated invertebrates by birds was also determined to affect risk of secondary poisoning. A series of management recommendations are made to reduce risks of secondary poisoning when using brodifacoum for pest control in New Zealand.

In 1995, the Canadian Wildlife Service attempted to eradicate introduced Norway rats (Rattus norvegicus) from Langara Island and adjacent Cox and Lucy Islands with the application of the second generation anticoagulant rodenticide brodifacoum. However, anticoagulant rodenticides are non-species specific pesticides and pose a poisoning risk to non-target species. This thesis addresses the short term poisoning impacts to non-target species from brodifacoum used to eradicate the rats from Langara and Lucy Island. In 1994, during testing of the baiting protocol on Lucy Island, the native dusky shrew (Sorex monticolus elassodon) population size fell from an estimated 25 unique shrews/ha before the baiting to four unique shrews/ha after the baiting. This prompted a monitoring program in three regions on Langara Island in 1995. While shrews were attracted to bait in stations, the decline in their population was non-significant. Shrews in breeding condition were at greater risk of poisoning likely due to their ability to range widely. Shrews entered and chewed on bait blocks in up to 80% of bait stations. The risk of secondary poisoning to avian scavengers from poisoned toxic rat carcasses was investigated. In 1994, common ravens (Corvus corax) were identified as the most significant scavenger of rat carcasses. In 1995, two of 15 radio-collared Norway rats poisoned with brodifacoum died above ground and one was scavenged. Whole body brodifacoum residues from other rats found dead above ground ranged from 2.40-16.51 mg/kg. Between 1995 and 1996, 20 raven remains were found or reported. In 1995, 13 raven livers tested positive for brodifacoum. Ravens were secondarily poisoned from scavenging rat carcasses and primarily from raiding bait stations. Brodifacoum was detected in Northwestern crows (Corvus caurinus) 9 months after the cessation of baiting on Lucy Island in 1994, but before the baiting on Langara Island. Brodifacoum residues were detected in the plasma of 15% of bald eagles (Haliaeetus leucocephalus) sampled (0.037-1.74 ppm). The invertebrates as a source of brodifacoum to non-target species was investigated. Snails (Vespericola sp. and Haplotrema sp.) and banana slugs (Ariolimax sp.) were common and abundant invertebrates found feeding on bait in stations. The blue coloured bait could be seen through the translucent bodies and the molluscs tested positive for brodifacoum. Carrion insects readily consumed rat carcasses containing brodifacoum. Blowfly larva (Calliphora sp.) tested positive for brodifacoum residues. The invertebrates found feeding on the bait and carrion insects were a secondary and tertiary poisoning risk to non-target species such as the song sparrow (Melospiza melodia).