Biology subjects

Hinds, L. A.

Publications and source records attributed to Hinds, L. A..

4 recordsLinked to original sources

bioRxiv2024

Background food influences rate of encounter and efficacy of rodenticides in wild house mice

O_LIBaiting is widely used in wildlife management for various purposes, including lethal control, fertility control, disease and parasite control, and conditioned aversion programs for many invasive vertebrate species. The efficacy of baiting programs relies on the likelihood that target animals will encounter the bait, consume it, and receive an appropriate dose of the active ingredient. However, there has been little focus on encounter rate of toxic baits combined with behavioural aversion, which are likely to be significant factors affecting efficacy. C_LIO_LIThe likelihood of an animal encountering and consuming a toxic grain bait should theoretically increase in proportion to its availability relative to background food quantity if it is neither more or less detectable or palatable. Furthermore, the probability of consuming toxic baits might also be influenced by bait aversion following ingestion of a non-lethal dose of toxin. C_LIO_LIUsing a model system of wild house mice (Mus musculus L.) in mouse-proof enclosures in Australia, we manipulated background food, applied zinc phosphide (ZnP) baits and measured the mortality of mice. When background food was scarce, mouse mortality was high, whereas an increasing abundance of background food led to reduced mortality. A scenario modelling random encounters and including bait aversion explained 78% of the variation in observed mortality outcomes and achieved a closer fit to the data. Mortality rates were predicted to be higher with a higher strength bait which overcomes behavioural aversion. C_LIO_LIEnsuring that animals locate and consume a lethal dose of toxic bait is a critical factor for successful bait delivery and efficacy. This is particularly significant in toxic baiting programs, where sublethal doses can make animals feel sick, leading to a negative association with the bait, and the development of aversion. C_LIO_LISynthesis and applications: Our findings explain why some toxic baiting programs might fail. To achieve successful control, efforts should be directed at reducing the availability of background food to increase the probability of encounter and uptake of toxic baits. It is important to measure and understand the role of background food on toxic baiting programs to explain variable outcomes and inform strategies for successful bait delivery. C_LI Graphical abstractOur findings explain why some toxic baiting programs might fail. To achieve successful control, efforts should be directed at reducing the availability of background food to increase the probability of encounter and uptake of toxic baits. It is important to measure and understand the role of background food on toxic baiting programs to explain variable outcomes and inform strategies for successful bait delivery. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/573962v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@df4b66org.highwire.dtl.DTLVardef@1cf1910org.highwire.dtl.DTLVardef@17680eeorg.highwire.dtl.DTLVardef@10ac688_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2023

Improving radio transmitter attachment methods for small mammals through captive trials and field studies

Radio tracking can be used to collect information about animal movement, home range, behaviour and habitat use. Many field studies have fitted radio transmitters to small rodents using permanent nylon cable tie collars and successfully collected movement and fate data. The approach to animal welfare within the context of scientific research prioritises minimising adverse effects on the research animals. While a range of electronically activated release mechanisms exist in radio tracking collars for larger mammals, weight and size restrictions make these unsuitable for smaller animals (< 30 g). Our aim was to identify a radio transmitter model and attachment method of an appropriate size and weight, which would remain attached to a house mouse (Mus musculus) for >20 days to collect movement data and then detach or show signs of detaching after 30 days. Laboratory and field trials established that cable ties with a cotton thread weak-link, using heat shrink to attach a customised radio transmitter worked for wild house mice in agricultural fields. Glue-on methods did not stay attached for long enough to obtain more than a few days tracking data. Short summaryCollecting meaningful radio tracking data for small mammals weighing <30 grams relies on selecting radio transmitter attachment methods suitable for the target species while prioritising animal welfare. Developing a non-permanent radio transmitter attachment for house mice is challenging due to size and weight constraints however, by trialling methods in the laboratory and field we developed a suitable radio collar with an in-built weak-link. Our non-permanent weak-link radio collar is an important improvement on existing permanent radio collars for small mammals.

ecology↗

bioRxiv2021

Acute oral toxicity of zinc phosphide: an assessment for wild house mice in Australia

BACKGROUNDThe efficacy of zinc phosphide (ZnP) for broadacre control of wild house mice in Australia is being reported by growers as increasingly variable. Have mice become less sensitive over time or are they taking a sub-lethal dose and developing aversion? In this laboratory study the sensitivity of groups of wild caught and an outbred laboratory strain of mice was assessed using oral gavage of a range of ZnP concentrations. The willingness of mice to consume ZnP-coated grains was then determined. RESULTSEach mouse group had very similar LD50 values (72 to 79 mg ZnP per kg body weight) which are significantly higher than previously reported. Time to death post-gavage ranged between 2.5 to 48 h. ZnP coated grains (50 g ZnP per kg grain) presented in the absence of alternative food were consumed and 94 percent of wild mice died. Mice provided with alternative food and ZnP coated wheat grains (either 25 or 50 g ZnP per kg grain) consumed toxic and non-toxic grains, and mortality was lower (33 to 55 percent). If a sublethal amount of ZnP coated grain was consumed, aversion occurred mostly in the presence of alternative food. CONCLUSIONSThe sensitivity of wild house mice to ZnP in Australia is significantly lower than previously assumed. Under laboratory conditions ZnP coated grains coated with a new higher dose (50 g ZnP per kg grain) were readily consumed. Consumption of toxic grain occurred when alternative food was available but was decreased. It is important to assess the efficacy of the higher ZnP dose per grain under natural field conditions, especially when background food is low.

ecology↗

bioRxiv2021

Effects of background food on alternative grain uptake and zinc phosphide efficacy in wild house mice

BACKGROUNDHouse mice (Mus musculus) cause significant, ongoing losses to grain crops in Australia, particularly during mouse plagues. Zinc phosphide (ZnP) coated grain is used for control, but with variable success. In a laboratory setting, we tested if mice would (1) switch from consumption of one grain type to another when presented with an alternative, and (2) consume ZnP-treated grains when presented as a choice with a different grain. RESULTSMice readily switched from their background grain to an alternative grain, preferring cereals (wheat or barley) over lentils. Mice readily consumed ZnP-coated barley grains. Their mortality rate was significantly higher (86%, n=30) in the presence of a less-favoured grain (lentils) compared to their mortality rate (47%, n=29; and 53%, n=30) in the presence of a more-favoured grain (wheat and barley, respectively). Mice died between 4-112 h (median = 18 h) after consuming one or more toxic grains. Independent analysis of ZnP-coated grains showed variable toxin loading indicating that consumption of a single grain would not guarantee intake of a lethal dose. There was also a strong and rapid behavioural aversion if mice did not consume a lethal dose on the first night. CONCLUSIONSThe registered dose rate of 25 g ZnP/kg wheat; [~] 1 mg ZnP/grain in Australia needs to be re-evaluated to determine what factors may be contributing to variation in efficacy. Further field research is also required to understand the complex association between ZnP dose, and quantity and quality of background food on efficacy of ZnP baits.

ecology↗