Attitudes of clients of Dutch pest controllers towards integrated pest management (IPM) and preventive measures in relation to rodent nuisance

BACKGROUND

Rodent management with lethal methods (e.g., rodenticides) comes with downsides for rodent welfare, the environment and non-target species. To reduce chemical use and prevent rodent nuisance, pest controllers in the Netherlands must work according to the principles of integrated pest management (IPM). A condition for the success of IPM is that there is sufficient engagement of all parties involved, including clients of pest controllers. The aim of this study was to gain insight into the attitudes of clients regarding rodent control, IPM and the application of preventive measures. Insight into their attitudes may contribute to a better implementation of IPM and with that to a more sustainable rodent management based on more effective prevention. An online survey among 248 clients of Dutch pest controllers from both the agricultural and other sectors was carried out.

RESULTS

Respondents from the agricultural sector had a relatively negative attitude towards IPM, the new IPM regulations in the Netherlands and had little confidence in prevention. In other sectors, respondents were more positive about IPM and had more confidence in prevention. The respondents from the latter subgroup had a similar attitude compared to Dutch pest controllers who participated in a previous survey.

CONCLUSION

The findings of the study provide information for the further development and practical implementation of IPM and preventive measures and with that a more sustainable and animal friendly rodent management. They can also be helpful for a better communication and cooperation between pest controllers and their clients. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Attitudes of clients of Dutch pest controllers towards animal welfare in the management of liminal rodents

Rodent control tends to involve methods that cause animal suffering, but little attention has been paid to the animal welfare implications of rodent control. The aim of the current study was to gain insight into the opinions and attitudes of clients of Dutch pest controllers, regarding liminal rodents, rodent control, and rodent welfare. A better understanding of their attitudes may contribute to more ethical rodent management programmes. An online survey among 248 clients of Dutch pest controllers was carried out. Respondents, especially those within the agricultural sector, have a relatively negative attitude towards rats and mice. Respondents in the agricultural subgroup do not consider the welfare of liminal rodents important. They also think that the welfare impact of commonly used control methods is limited, and they have low tolerance levels for the presence of rodents. Respondents from other sectors have a far more positive attitude towards rats and mice, consider their welfare to be of greater importance, have a greater estimation of the welfare impact of control methods and show greater tolerance levels towards rodents. The respondents from the latter subgroup have a similar attitude compared to Dutch pest controllers participating in a previous survey. The findings of the current study firstly provide useful information for the further development and practical implementation of preventive control methods. Secondly, they provide input for a more animal-friendly rodent control and for the development of an assessment framework to support ethical decision-making. Finally, they can be helpful for further research and the communication and co-operation between professional pest controllers and their clients.

Large-scale identification of rodenticide resistance in Rattus norvegicus and Mus musculus in the Netherlands based on Vkorc1 codon 139 mutations

BACKGROUND

Resistance to rodenticides has been reported globally and poses a considerable problem for efficacy in pest control. The most-documented resistance to rodenticides in commensal rodents is associated with mutations in the Vkorc1 gene, in particular in codon 139. Resistance to anticoagulant rodenticides has been reported in the Netherlands since 1989. A study from 2013 showed that 25% of 169 Norway rats (Rattus norvegicus) had a mutation at codon 139 of the Vkorc1 gene. To gain insight in the current status of rodenticide resistance amongst R. norvegicus and house mice Mus musculus in the Netherlands, we tested these rodents for mutations in codon 139 of the Vkorc1 gene. In addition, we collected data from pest controllers on their use of rodenticides and experience with rodenticide resistance.

RESULTS

A total of 1801 rodent samples were collected throughout the country consisting of 1404 R. norvegicus and 397 M. musculus. In total, 15% of R. norvegicus [95% confidence interval (CI): 13-17%] and 38% of M. musculus (95% CI: 33-43%) carried a genetic mutation at codon 139 of the Vkorc1 gene.

CONCLUSION

This study demonstrates genetic mutations at codon 139 of the Vkorc1 gene in M. musculus in the Netherlands. Resistance to anticoagulant rodenticides is present in R. norvegicus and M. musculus in multiple regions in the Netherlands. The results of this comprehensive study provide a baseline and facilitate trend analyses of Vkorc1 codon 139 mutations and evaluation of integrated pest management (IPM) strategies as these are enrolled in the Netherlands. © 2022 The Dutch Pest and Wildlife. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Efficacy of Management and Monitoring Methods to Prevent Post-Harvest Losses Caused by Rodents

The presence of pest rodents around food production and storage sites is one of many underlying problems contributing to food contamination and loss, particularly influencing food and nutrition security in low-income countries. By reducing both pre- and post-harvest losses by rodents, millions of food-insecure people would benefit. As there are limited quantitative data on post-harvest rice losses due to rodents, our objectives were to assess stored rice losses in local households from eight rural communities and two rice milling factories in Bangladesh and to monitor the effect of different rodent control strategies to limit potential losses. Four treatments were applied in 2016 and 2017, (i) untreated control, (ii) use of domestic cats, (iii) use of rodenticides, (iv) use of snap-traps. In total, over a two-year period, 210 rodents were captured from inside people's homes, with Rattus rattus trapped most often (n = 91), followed by Mus musculus (n = 75) and Bandicota bengalensis (n = 26). In the milling stations, 68 rodents were trapped, of which 21 were M. musculus, 19 R. rattus, 17 B. bengalensis, 8 Rattus exulans, and 3 Mus terricolor. In 2016, losses from standardised baskets of rice within households were between 13.6% and 16.7%. In 2017, the losses were lower, ranging from 0.6% to 2.2%. Daily rodent removal by trapping proved to be most effective to diminish stored produce loss. The effectiveness of domestic cats was limited.

Wild rodents and insectivores as carriers of pathogenic Leptospira and Toxoplasma gondii in The Netherlands

Small mammals such as rodents can to carry zoonotic pathogens. Currently, there is impaired knowledge on zoonotic pathogens in rodents and insectivores in the Netherlands. This limits opportunities for preventive measures and complicates risk-assessments for zoonotic transmission to humans. Leptospira spp. and Toxoplasma gondii are present on a list of prioritized emerging pathogens in the Netherlands and were therefore the focus of this study. Both pathogens have the ability to survive under moist environmental conditions. In total, a group of 379 small mammals (rodents & insectivores) were tested on pathogenic Leptospira spp., and 312 on T. gondii. Rodents and insectivores were trapped at various sites, but mostly on pig and dairy farms throughout the country. Over five percent of the animals (5.3%, n = 379) tested positive for Leptospira DNA, and five of the animals (1.6%, n = 312) tested were positive for T. gondii DNA. The animals positive for T.gondii were all brown rats and the ones for Leptospira spp. were various species. Our results show that insectivores and rodents might be used as an indicator for the environmental contamination and/or the contamination in wildlife for Leptospira spp.

Clostridium difficile in wild rodents and insectivores in the Netherlands

With wild rodents and insectivores being present around humans and their living, working and food production environments, it is important to gain knowledge of the zoonotic pathogens present in these animals. The enteropathogen Clostridium difficile, an opportunistic anaerobic bacteria, can be carried by both animals and humans, and is distributed globally. It is known that there is genetic overlap between human and animal sources of C. difficile. In this study, the aim was to assess the presence of C. difficile in rodents and insectivores trapped on and around pig and cattle farms in the Netherlands. In total 347 rodents and insectivores (10 different species) were trapped and 39·2% tested positive for presence of C. difficile. For all positive samples the ribotype (RT) was determined, and in total there were 13 different RTs found (in descending order of frequency: 057, 010, 029, 005, 073, 078, 015, 035, 454, 014, 058, 062, 087). Six of the RTs isolated from rodents and insectivores are known to be associated with human C. difficile infection; RT005, RT010, RT014, RT015, RT078 and RT087. The presence of rodents and insectivores in and around food production buildings (e.g. farms) could contribute to the spread of C. difficile in the human environment. In order to enable on-farm management for pathogen control, it is essential to comprehend the role of wild rodents and insectivores that could potentially affect the ecology of disease agents on farms. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that rodents and insectivores in and around food production buildings (e.g. farms) can carry Clostridium difficile ribotypes associated with human C. difficile infection (CDI). C. difficile spores in rodent and insectivore droppings are able to survive in the environment for prolonged periods, leading to host-to-host exposure and transmission. Therefore we can state that rodent and insectivore presence on farms is a risk for zoonotic pathogen transmission of C. difficile.

The need to implement the landscape of fear within rodent pest management strategies

Current reactive pest management methods have serious drawbacks such as the heavy reliance on chemicals, emerging genetic rodenticide resistance and high secondary exposure risks. Rodent control needs to be based on pest species ecology and ethology to facilitate the development of ecologically based rodent management (EBRM). An important aspect of EBRM is a strong understanding of rodent pest species ecology, behaviour and spatiotemporal factors. Gaining insight into the behaviour of pest species is a key aspect of EBRM. The landscape of fear (LOF) is a mapping of the spatial variation in the foraging cost arising from the risk of predation, and reflects the levels of fear a prey species perceives at different locations within its home range. In practice, the LOF maps habitat use as a result of perceived fear, which shows where bait or traps are most likely to be encountered and used by rodents. Several studies have linked perceived predation risk of foraging animals with quitting-harvest rates or giving-up densities (GUDs). GUDs have been used to reflect foraging behaviour strategies of predator avoidance, but to our knowledge very few papers have directly used GUDs in relation to pest management strategies. An opportunity for rodent control strategies lies in the integration of the LOF of rodents in EBRM methodologies. Rodent management could be more efficient and effective by concentrating on those areas where rodents perceive the least levels of predation risk. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Environmental impact of replacing soybean meal with rapeseed meal in diets of finishing pigs

The major impact of the livestock sector on the environment may be reduced by feeding agricultural co-products to animals. Since the last decade, co-products from biodiesel production, such as rapeseed meal (RSM), became increasingly available in Europe. Consequently, an increase in RSM content in livestock diets was observed at the expense of soybean meal (SBM) content. Cultivation of SBM is associated with high environmental impacts, especially when emissions related to land use change (LUC) are included. This study aims to assess the environmental impact of replacing SBM with RSM in finishing pig diets. As RSM has a lower nutritional value, we assessed the environmental impact of replacing SBM with RSM using scenarios that differed in handling changes in nutritional level. Scenario 1 (S1) was the basic scenario containing SBM. In scenario 2 (S2), RSM replaced SBM based on CP content, resulting in reduced energy and amino acid content, and hence an increased feed intake to realize the same growth rate. The diet of scenario 3 (S3) was identical to S2; however, we assumed that pigs were not able to increase their feed intake, leading to reduced growth performance. In scenario 4 (S4), the energy and amino acid content were increased to the same level of S1. Pig performances were simulated using a growth model. We analyzed the environmental impact of each scenario using life-cycle assessment, including processes of feed production, manure management, piglet production, enteric fermentation and housing. Results show that, expressed as per kg of BW, replacing SBM with RSM in finishing pig diets marginally decreased global warming potential (GWP) and energy use (EU) but decreased land use (LU) up to 12%. Between scenarios, S3 had the maximum potential to reduce the environmental impact, due to a lower impact per kg of feed and an increased body protein-to-lipid ratio of the pigs, resulting in a better feed conversion ratio. Optimization of the body protein-to-lipid ratio, therefore, might result in a reduced environmental impact of pig production. Furthermore, the impact of replacing SBM with RSM changed only marginally when emissions related to direct (up to 2.9%) and indirect LUC (up to 2.5%) were included. When we evaluated environmental impacts of feed production only, which implies excluding other processes along the chain as is generally found in the literature, GWP decreased up to 10%, including LUC, EU up to 5% and LU up to 16%.

Validation of an automated mite counter for Dermanyssus gallinae in experimental laying hen cages

For integrated pest management (IPM) programs to be maximally effective, monitoring of the growth and decline of the pest populations is essential. Here, we present the validation results of a new automated monitoring device for the poultry red mite (Dermanyssus gallinae), a serious pest in laying hen facilities world-wide. This monitoring device (called an "automated mite counter") was validated in experimental laying hen cages with live birds and a growing population of D. gallinae. This validation study resulted in 17 data points of 'number of mites counted' by the automated mite counter and the 'number of mites present' in the experimental laying hen cages. The study demonstrated that the automated mite counter was able to track the D. gallinae population effectively. A wider evaluation showed that this automated mite counter can become a useful tool in IPM of D. gallinae in laying hen facilities.

Distribution of anticoagulant rodenticide resistance in Rattus norvegicus in the Netherlands according to Vkorc1 mutations

BACKGROUND

Rodenticide resistance to anticoagulants in Rattus norvegicus will lead to increased difficulties in combating these pest animals. Here, the authors present the results of a survey in the Netherlands where tissue samples and droppings were tested using a newly developed TaqMan PCR test for genotypic variation at codon 139 in the Vkorc1 gene associated with anticoagulant rodenticide resistance. Test results are linked to results of a questionnaire that was conducted among pest controllers.

RESULTS

Genetic mutations at codon 139 of the Vkorc1 gene in R. norvegicus can be encountered in many parts of the Netherlands. In 34/61 rat tails, a genotype was found that is linked to anticoagulant rodenticide resistance (56%). In droppings, 42/169 samples (25%) showed a resistance-mediating genotype. In addition, indications of a clear genetic substructure in the Netherlands were found. In some regions, only resistance-mediating genotypes were found, corroborating results from the questionnaire in which pest controllers indicated they suspected resistance to anticoagulant rodenticides.

CONCLUSION

This is the first study to demonstrate the presence of multiple genetic mutations at codon 139 of the Vkorc1 gene in R. norvegicus in the Netherlands. As rodenticides should keep their efficacy because they are a last resort in rodent management, more studies are urgently needed that link specific genetic mutations to the efficacy of active substances.

Prevalence of Toxoplasma gondii in common moles (Talpa europaea)

Background

The prevalence of Toxoplasma gondii in common moles, Talpa europaea, was investigated in order to determine whether moles can serve as an indicator species for T. gondii infections in livestock.

Findings

In total, 86 moles were caught from 25 different sites in the Netherlands. Five different trapping habitats were distinguished: pasture, garden, forest, roadside, and recreation area. No positive samples (brain cysts) were found during microscopic detection (n = 70). Using the Latex Agglutination Test (LAT), sera of 70 moles were examined, whereby no sample reacted with T. gondii antigen. Real Time-PCR tests on brain tissue showed 2 positive samples (2.3%).

Conclusions

Because of the low number of positives in our study, the use of the common mole as an indicator species for livestock infections is currently not recommended.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-014-0048-0) contains supplementary material, which is available to authorized users.

The need and potential of biosensors to detect dioxins and dioxin-like polychlorinated biphenyls along the milk, eggs and meat food chain

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are hazardous toxic, ubiquitous and persistent chemical compounds, which can enter the food chain and accumulate up to higher trophic levels. Their determination requires sophisticated methods, expensive facilities and instruments, well-trained personnel and expensive chemical reagents. Ideally, real-time monitoring using rapid detection methods should be applied to detect possible contamination along the food chain in order to prevent human exposure. Sensor technology may be promising in this respect. This review gives the state of the art for detecting possible contamination with dioxins and DL-PCBs along the food chain of animal-source foods. The main detection methods applied (i.e., high resolution gas-chromatography combined with high resolution mass-spectrometry (HRGC/HRMS) and the chemical activated luciferase gene expression method (CALUX bioassay)), each have their limitations. Biosensors for detecting dioxins and related compounds, although still under development, show potential to overcome these limitations. Immunosensors and biomimetic-based biosensors potentially offer increased selectivity and sensitivity for dioxin and DL-PCB detection, while whole cell-based biosensors present interpretable biological results. The main shortcoming of current biosensors, however, is their detection level: this may be insufficient as limits for dioxins and DL-PCBs for food and feedstuffs are in pg per gram level. In addition, these contaminants are normally present in fat, a difficult matrix for biosensor detection. Therefore, simple and efficient extraction and clean-up procedures are required which may enable biosensors to detect dioxins and DL-PCBs contamination along the food chain.

Escherichia coli concentrations in feces of geese, coots, and gulls residing on recreational water in The Netherlands

Contamination of recreational water by bird feces is a main concern of water managers. It is important to understand the sources of Escherichia coli contamination since the organism is frequently used as a water hygiene parameter. Here, we address presence and levels of E. coli in fecal shedding from several waterfowl (25 geese, 20 coots, and 40 gulls) and demonstrate that there is a bird species variation. Results indicate that gull feces contain a greater average concentration of E. coli per gram than do geese or coot feces. However, contamination risks also depends on bird abundance. These are important aspects for effective water bird management.

The role of wild rodents in spread and transmission of Coxiella burnetii needs further elucidation

Rodents are known to cause massive food losses, but are also implicated as reservoirs for a wide variety of zoonotic pathogens. This review discusses the contribution of rodents in the spread and transmission of Coxiella burnetii, the causative agent of Q-fever. We found that rodents have been implicated as reservoirs for Q-fever, but their role in pathogen maintenance, geographic spread and transmission still remains to be clarified. As there are indications for a role of rodents in Q-fever epidemiology, including during the 2007–10 outbreak in the Netherlands, the overall lack of knowledge on the role of rodents warrants studies into their contribution in transmission of C. burnetii from the sylvatic cycle to the domestic cycle, in within-herd transmission, in transmission to surrounding farms and in direct transmission to humans. Although the basic sylvatic and domestic cycles of C. burnetii infection can operate independently, they will overlap in many instances as many areas in the world are occupied by both domestic and wild animals. This area of Q-fever ecology is of interest and research should focus on this aspect of Q-fever epidemiology and, in particular, on the role of rodents therein. More studies are needed that elicit the exact role of rodents in epidemiology of C. burnetii to further optimise disease control.

Food safety in free-range and organic livestock systems: risk management and responsibility

Animal production systems that offer outdoor access to the animals have become increasingly popular in the Western world due to the growing general discontent of consumers with conventional bioindustrial farming practices. These open production systems offer improved animal welfare but may create new problems for animal health, resulting in increased food safety risks from bacterial, viral, or parasitic infections or environmental contaminants. Examples of these new problems include increased Toxoplasma gondii infections in pigs and high dioxin levels in eggs from free-range hens. In this review, the relation between positive and negative points of free-range and organic livestock production systems is discussed with reference to production in The Netherlands. We investigated how proponents of more animal welfare friendly systems deal with potential negative issues in public and whether any risk communication is used. Generally, we found that the existence of a dilemma is disputed or avoided in communication with the consumer. This avoidance could be detrimental for public trust in alternative animal production systems, should problems occur. To prevent future problems, it will be necessary to communicate about the relevant types and sources of the food safety risks to the consumers. The responsibility for protecting food safety should be properly divided among the various parties involved: producers, processors, governments, nongovernmental organizations, and consumers.

Changing climate-changing pathogens: Toxoplasma gondii in North-Western Europe

In this review, we describe the effects of global climate change for one specific pathogen: the parasite Toxoplasma gondii. It is postulated that an increase of T. gondii prevalence in humans can occur in some regions of North-Western Europe as a result of changing environmental conditions. Such a change can be predicted by using Global Climate Change models. We have elaborated such a prediction for one scenario (SRES A1) by using one specific model (CCSR/NRIES) as an example. Next to environmental factors, also anthropogenic factors may contribute to increased prevalence of T. gondii in this region. In order to counter the potential severe consequences of a potential increase resulting from the combination of climatic and anthropogenic factors, there is an urgent need for the development of a human vaccine. Until a vaccine that offers complete protection is developed, the emphasis should be on treatment optimization and prevention.

The Year of the Rat ends - time to fight hunger!

This paper investigates the importance of ecologically based rodent management in the light of the current food crisis, and the potential effects of this approach on the position of the undernourished. Hunger and food prices are on the rise owing to shortages that can be traced to reasons such as climatic extremes, use of crops for biofuels, reduced growth in yields which lag behind population growth, reduced world stocks and lack of sufficient investment in maintaining the irrigation infrastructure. For the undernourished this is problematic as they are most vulnerable to the rise in food prices. Very often, agricultural experts focus on an increase in agricultural production to reduce food prices. It is postulated in this article that almost 280 million undernourished could additionally benefit if more attention were paid to reducing pre- and post-harvest losses by rodents. Moreover, rodent-borne diseases would decrease, diseases that can be catastrophic to the livelihoods of the poorest of the poor.

The ethics of rodent control

Because western societies generally see animals as objects of moral concern, demands have been made on the way they are treated, e.g. during animal experimentation. In the case of rodent pests, however, inhumane control methods are often applied. This inconsistency in the human-animal relationship requires clarification. This paper analyses the criteria that must be met when judging the use of animals during experiments, and investigates whether these can be applied in rodent control. This is important, because, until now, animal welfare has been less of an issue in pest control: effectiveness, hygiene and cost efficiency have been leading principles. Two options are available to solve the inconsistency: the first is to abandon the criteria used in animal experimentation; the second is to apply these criteria to both animal experimentation and rodent control. This latter option implies that rodent control methods should not lead to intense pain or discomfort, and any discomfort should have a short duration and should allow escaped rodents to lead a natural life. Adherence to this option will, however, require a shift in the design of rodent control methods: effectiveness will no longer be the leading principle. It will have to share its position with animal welfare and humaneness.

Cats and goat whey associated with Toxoplasma gondii infection in pigs

In organic livestock production systems, farm-management factors are thought to play an important role in the on-farm prevalence of Toxoplasma gondii. Serological results and the results of an HACCP analysis were combined to determine important risk factors for the prevalence of this protozoan parasite. Mathematical analysis demonstrated that feeding goat whey to pigs and the presence of a high number of cats were positively correlated to T. gondii seroprevalence in pigs. Not covering roughage and the farmers' assumption that pigs can come into contact with cat feces also showed a positive relationship. In order to decrease the risk of T. gondii infecting their pigs, farmers should limit the access and number of cats on their farms and refrain from feeding goat whey to their pigs.

Presence of Salmonella and Campylobacter spp. in wild small mammals on organic farms

The presence of Salmonella and Campylobacter spp. in rodents and insectivores (n = 282) was investigated on organic farms. Infections were encountered in house mice (8 of 83 Campylobacter positive and 1 of 83 Salmonella sp. strain Livingstone positive) and brown rats (1 of 8 Campylobacter positive) but not in other species. No shared Campylobacter genotypes were found between rodent and pig manure isolates. Effective on-farm rodent management is recommended.