ABSTRACT
BACKGROUND: Snap traps and electronic traps are the main devices for nonchemical management of rodent pests. Traps should be efficient and should not cause unnecessary suffering of animals. Harmonized, systematic test methods are required to make sure that mechanical forces or electrical parameters are optimal to achieve swift unconsciousness and death. This study aimed to describe technical trap properties that can be used to facilitate future improvements in trap efficacy and humaneness. METHODS: We constructed a device to assess spring energy, triggering force, impulse and clamping force, and developed an arrangement to assess effective voltage, current, effective current and effective energy taking effect on rodent bodies in electronic traps - all without the use of animals. Descriptive data of trap characteristics were collated. RESULTS: All factors showed variability among snap trap models and trigger types, and there was considerable overlap between mouse and rat traps. For most trap models, there was no difference among new snap traps and traps that had been trigged 20 times. Effective current and effective energy decreased with lower voltage input, but the traps indicated weak battery by LED lights, and one model switched off automatically when voltage was insufficient. CONCLUSION: With the device and the electronic arrangement, the majority of snap trap models and electronic traps available on the market can be assessed in a standardized and repeatable way. Matching the data generated in this study with data on time for trapped target animals to reach irreversible unconsciousness, and experiences from pest control practitioners, should allow relating properties of traps to efficacy and animal welfare issues. This can support further development and optimization of traps for nonchemical rodent pest control. © 2024 Julius Kuehn-Institut and The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
ABSTRACT
Commensal rodent species cause damage to crops and stored products, they transmit pathogens to people, livestock and pets and threaten native flora and fauna. To minimize such adverse effects, commensal rodents are predominantly managed with anticoagulant rodenticides (AR) that can be transferred along the food chain. We tested the effect of the uptake of the AR brodifacoum (BR) by Norway rats (Rattus norvegicus) on spatial behavior because this helps to assess the availability of dead rats and residual BR to predators and scavengers. BR was delivered by oral gavage or free-fed bait presented in bait stations. Rats were radio-collared to monitor spatial behavior. BR residues in rat liver tissue were analyzed using liquid chromatography coupled with tandem mass spectrometry. Norway rats that had consumed BR decreased distances moved and had reduced home range size. Treatment effects on spatial behavior seemed to set in rapidly. However, there was no effect on habitat preference. Ninety-two percent of rats that succumbed to BR died in well-hidden locations, where removal by scavenging birds and large mammalian scavengers is unlikely. Rats that ingested bait from bait stations had 65% higher residue concentrations than rats that died from dosing with two-fold LD50. This suggests an overdosing in rats that are managed with 0.0025% BR. None of the 70 BR-loaded rats was caught/removed by wild predators/scavengers before collection of carcasses within 5-29 h. Therefore, and because almost all dead rats died in well-hidden locations, they do not seem to pose a significant risk of AR exposure to large predators/scavengers at livestock farms. Exposure of large predators may originate from AR-poisoned non-target small mammals. The few rats that died in the open are accessible and should be removed in routine searches during and after the application of AR bait to minimize transfer of AR into the wider environment.
