Academic literature on the topic 'Bait acceptance'

Predation by introduced house mice Mus musculus on islands is one cause of decline in native birds and has deleterious impacts on other ecological aspects. Eradication of rats (Rattus spp.) from islands of up to >10000 ha has been achieved, but for mice scale is still an issue with the largest island cleared being only 710 ha. The feasibility of eradicating mice from larger islands is being considered, and to support these assessments, we undertook a field study on Gough Island (6400 ha) to determine whether all mice would be likely to accept toxic bait. We replicated a toxic bait operation as closely as possible, in timing, probable bait density and distribution, using a bait formulation used commonly in rodent eradication operations. Baits lacked toxin but were coated with the fluorescent dye rhodamine B. Mice trapped in and around the baited areas were inspected under ultraviolet light for fluorescent marking indicative of bait consumption. Of 434 mice, 97% tested positive, including mice trapped on assessment lines up to 90 m from the closest bait. There was no difference in the proportions of unstained mice from assessment lines outside baited sites compared with mice trapped in the core baited sites, suggesting large-scale foraging movements over relatively large distances into the baited sites from surrounding, non-baited habitat. Despite the high bait densities (15.7 kg ha−1 at initial application and 7.9 kg ha−1 at second application), bait consumption rates of ~4 kg ha−1 day−1 occurred after both applications. This was much higher than expected (probably the result of large-scale movements) and meant that all baits were consumed before trapping began. Thus the 13 unstained mice trapped in the core of the baited area may have moved there after bait was consumed. Further trials are required to assess whether all unmarked mice were false negatives (not exposed to bait) or if any were true negatives (rejected bait). A separate experiment found that all 11 mice trapped in a cave had eaten bait applied aboveground around the cave’s entrances, suggesting that caves do not serve as refugia for mice and are thus unlikely to compromise an eradication attempt.

The aim of our study was to investigate the possibility of application of essential oils as additives in cereal-based rodenticide baits, at rates which prevent mould development and are applicable in humane medicine. Also, the purpose of these oils would be to extend the utility value of baits and reduce the use of antifungal ingredients that usually affect bait acceptance. The effects of essential oils of ten different plant species, applied at rates of one and two ml per kg of plain bait, on bait acceptance and palatability in choice feeding tests for Swiss mice were studied under controlled laboratory conditions. Baits were prepared according to relevant EPPO standards (2004). The effects of essential oils on bait acceptance and palatability for Swiss mice were determined in choice feeding tests using a formula by Johnson and Prescott (1994). There was no significant statistical difference in effects between groups and sexes regarding weight change in the experiment. During the experiment and recovery period, neither change in mice behavior no deaths were observed. Cinnamon and anise essential oils, commonly used as attractants, and clove oil, were most effective because they had no negative effect on bait acceptance and palatability, while fenchel and bergamot oils showed repellent activity that grew as the oil content in baits increased.

The development of bait types, additives such as synthetic flavours, and attractants for use in fox control and rabies vaccination programmes is briefly reviewed. A captive colony was used to establish bait preferences for foxes. A variety of bait types and additives were screened for this purpose. The potential of chemical attractants to enhance the discovery of baits by foxes was also examined. Gustatory additives, such as beef flavour and sugar, enhanced bait acceptance, and olfactory attractants such as synthetic fermented egg showed promise. Trials using captive animals allow for observations impossible under field conditions. However, field trials are also needed to determine whether behavioural responses of free-ranging animals are similar to those observed in captive individuals.

We examined the acceptance and palatability of baits containing different contents of sodium selenite as a rodenticide, in Swiss mice under laboratory conditions. In a no-choice and choice feeding test, the animals were exposed to baits containing 0.1, 0.05, 0.025 and 0.0125% of sodium selenite. The total bait consumption by Swiss mice in the no-choice feeding test was highly negatively correlated, while total sodium selenite intake was medium-positively correlated to the sodium selenite content in the bait. In the same test, daily intakes significantly depended on the content of sodium selenite in the bait, while the exposure and associated interactions of contents of sodium selenite and exposure had no statistically significant impact. Baits with sodium selenite contents of 0.05 and 0.1% had the most lethal effects. The negative impact of the sodium selenite content on bait acceptance and palatability was confirmed in choice feeding tests. Baits containing 0.05 and 0.1% of sodium selenite displayed the biological potential to be used as a rodenticide. It is necessary to improve its insufficient acceptability and palatability by adding adequate additives to the bait. The results of this study should be verified in experiments with wild rodents.

Context. In New Zealand, the aerial application of toxic baits containing sodium fluoroacetate (1080) can consistently achieve significant reductions in populations of multiple vertebrate pest species including brushtail possums (Trichosurus vulpecula), ship rats (Rattus rattus) and stoats (Mustela erminea). Reductions in house mouse (Mus musculus) populations by 1080 baiting appear less consistent, possibly due to low acceptance of 1080 bait by mice in field conditions. Aims. We tested the effect of pre-feeding and 1080 concentration on the acceptance of pellet food by mice. Methods. Wild-caught mice were individually housed and presented with a series of two-choice laboratory feeding tests, using estimates of the daily amount eaten to indicate relative acceptance of different types of pellet food. Key results. Pre-feeding mice on non-toxic food did not increase their subsequent acceptance of the same food containing 0.15% 1080. Mice showed low acceptance of food containing 0.08 and 0.15% 1080 (by weight), with similar mortality (25%). Acceptance of food containing 1.5% 1080 was also very low in comparison with non-toxic food, although mortality in mice was higher (~66%). In comparison with other concentrations, mice ate comparatively more of food containing 0.001% 1080 with no mortality, although the non-toxic food was still significantly favoured. Presentation of a choice between non-toxic food and food containing 0.08, 0.15 or 1.5% 1080 to mice was followed by a significant decrease in average total daily food intake over the following 2 days. In surviving mice this ‘drop feed’ effect was followed by an increase in average daily intake of non-toxic food over the next 3 days until normal daily intake levels were again reached. Conclusions. We suggest that wild mice can rapidly identify food containing 1080 and subsequently will avoid it. Implications. This feeding response partly explains the variable success of 1080 baiting operations against wild mouse populations (M. musculus) in New Zealand.

Reticulitermids were significantly more likely to discover subterranean baits connected by physical guidelines than freestanding baits under both laboratory and field conditions. In the laboratory, subterranean termites built significantly longer tunnels adjacent to cellulosic guidelines than plastic guidelines. In the field, all guideline materials were equally effective at directing tunneling activity. Reticulitermes spp. workers were tested to determine their preferred substrate temperature. The preferred range for Reticulitermes spp. workers was found to be 18 to 27 degrees C. A laboratory bioassay was performed to determine if Reticulitermes spp. aggregates within thermal shadows. Significantly more Reticulitermes spp. workers aggregated within cool thermal shadows than control areas. In a multiple choice bioassay, mean consumption was higher for paper baits treated with fructose, galactose, glucose, raffinose, sucrose, trehalose and uric acid than for control baits. In a multiple choice bioassay, mean consumption was significantly lower for baits treated with arbutin, and most amino acids than for control baits. In the no-choice bioassay, the amount of paper bait consumed did not differ significantly for any of the treated baits tested and control baits.
Ph. D.

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.

Intellectualists argue that concern for the truth must be essential to belief if belief is to be distinguished from imagination, pretence, and acceptance for the sake of argument or inquiry. In response to these objections, the author utilizes the Aristotelian idea of potentiality that Bain deployed when framing his account of belief. Beliefs are “poised” to inform a wider range of behaviors than states of pretence or provisional assumption. But these are differences in degree, not kind. Delusions provide an interesting test case, and the author offers a “three factor” analysis of this syndrome. The typical Capgras patient believes that one of her family members has been replaced with an impostor. But if she fails to act or reason on that information in all of the contexts in which she acknowledges its relevance, the pragmatist definition classifies her belief as incomplete.

The sovereign debt crisis in Europe that started in early 2010 was the ground on which profound institutional reforms of the Economic Monetary Union (EMU) were put into place. It was triggered by the inability of Greece, Ireland, Portugal, and later on also Spain, to continue borrowing from the markets when fears increased that these Member States could default on their sovereign debt. The reasons why these Member States lost their access to the financial markets differed considerably, however. Greece had been suffering from a high level of indebtedness for many years, while rising sovereign debt in Ireland, Portugal and Spain was the result of public bail-outs of the national banking systems. The rescue measures in the latter countries had become necessary when, due to the financial crisis that preceded the debt crisis, a boom in the private housing markets came to a sudden halt. Common features of the development in all these countries were the high levels of sovereign debt and the strong dynamics of indebtedness, so that the governments lost their ability to borrow freely and at interest rates acceptable in the context of public budgetary systems.

Systems such as robotic systems and systems with large input-output data tend to be difficult to model using mathematical techniques. These systems have typically high dimensionality and have degrees of uncertainty in many parameters. Artificial intelligence techniques such as neural networks, fuzzy logic, genetic algorithms and evolutionary algorithms have created new opportunities to solve complex systems. Application of fuzzy logic [Bai, Y., Zhuang H. and Wang, D. (2006)] in particular, to model and solve industrial problems is now wide spread and has universal acceptance. Fuzzy modelling or fuzzy identification has numerous practical applications in control, prediction and inference. It has been found useful when the system is either difficult to predict and or difficult to model by conventional methods. Fuzzy set theory provides a means for representing uncertainties. The underlying power of fuzzy logic is its ability to represent imprecise values in an understandable form. The majority of fuzzy logic systems to date have been static and based upon knowledge derived from imprecise heuristic knowledge of experienced operators, and where applicable also upon physical laws that governs the dynamics of the process. Although its application to industrial problems has often produced results superior to classical control, the design procedures are limited by the heuristic rules of the system. It is simply assumed that the rules for the system are readily available or can be obtained. This implicit assumption limits the application of fuzzy logic to the cases of the system with a few parameters. The number of parameters of a system could be large. The number of fuzzy rules of a system is directly dependent on these parameters. As the number of parameters increase, the number of fuzzy rules of the system grows exponentially. Genetic Algorithms can be used as a tool for the generation of fuzzy rules for a fuzzy logic system. This automatic generation of fuzzy rules, via genetic algorithms, can be categorised into two learning techniques, supervised and unsupervised. In this paper unsupervised learning of fuzzy rules of hierarchical and multi-layer fuzzy logic control systems are considered. In unsupervised learning there is no external teacher or critic to oversee the learning process. In other words, there are no specific examples of the function to be learned by the system. Rather, provision is made for a task-independent measure of the quality or representation that the system is required to learn. That is the system learns statistical regularities of the input data and it develops the ability to learn the feature of the input data and thereby create new classes automatically [Mohammadian, M., Nainar, I. and Kingham, M. (1997)]. To perform unsupervised learning, a competitive learning strategy may be used. The individual strings of genetic algorithms compete with each other for the “opportunity” to respond to features contained in the input data. In its simplest form, the system operates in accordance with the strategy that ‘the fittest wins and survives’. That is the individual chromosome in a population with greatest fitness ‘wins’ the competition and gets selected for the genetic algorithms operations (cross-over and mutation). The other individuals in the population then have to compete with fit individual to survive. The diversity of the learning tasks shown in this paper indicates genetic algorithm’s universality for concept learning in unsupervised manner. A hybrid integrated architecture incorporating fuzzy logic and genetic algorithm can generate fuzzy rules for problems requiring supervised or unsupervised learning. In this paper only unsupervised learning of fuzzy logic systems is considered. The learning of fuzzy rules and internal parameters in an unsupervised manner is performed using genetic algorithms. Simulations results have shown that the proposed system is capable of learning the control rules for hierarchical and multi-layer fuzzy logic systems. Application areas considered are, hierarchical control of a network of traffic light control and robotic systems. A first step in the construction of a fuzzy logic system is to determine which variables are fundamentally important. Any number of these decision variables may appear, but the more that are used, the larger the rule set that must be found. It is known [Raju, S., Zhou J. and Kisner, R. A. (1990), Raju G. V. S. and Zhou, J. (1993), Kingham, M., Mohammadian, M, and Stonier, R. J. (1998)], that the total number of rules in a system is an exponential function of the number of system variables. In order to design a fuzzy system with the required accuracy, the number of rules increases exponentially with the number of input variables and its associated fuzzy sets for the fuzzy logic system. A way to avoid the explosion of fuzzy rule bases in fuzzy logic systems is to consider Hierarchical Fuzzy Logic Control (HFLC) [Raju G. V. S. and Zhou, J. (1993)]. A learning approach based on genetic algorithms [Goldberg, D. (1989)] is discussed in this paper for the determination of the rule bases of hierarchical fuzzy logic systems.

Flowlines and risers can be submitted to plastic deformation, sometimes cyclically, due to the installation technique, or sometimes due to exceptional events. In this case, a specific evaluation of defect acceptance in the girth weld is necessary. The present study investigates the possibility to predict ductile tearing during installation when the performed fracture mechanics tests are only high triaxiality specimens and that the effective application requires cyclic loading. A classical analysis is performed using DNV RP F108 to determine the acceptable defect size of for the case in which a pipe is submitted to cyclic loading. In the present investigation, tearing resistance was characterized with SENB specimens. An engineering critical assessment (ECA) was performed considering the size of the expected defects and the amount of plastic deformation to which the pipeline would be submitted. A validation of the ECA was performed by segment tests. While the application of ECA based on the fracture tests would predict ductile tearing with the considered defect, the results of segment tests only revealed blunting for the considered plastic deformation. It confirms the effect that in lower constraint conditions (like in segment tests), SENB test results are overly conservative. The tearing phenomenon was then simulated by the finite element method using two different damage models (Gurson-Tvergard-Needlemann and the Bai-Wierzbicki model) and compared to the experimental results. As the deformation at the crack tip is typically very large, one needs to have knowledge about the hardening behavior in the post-necking region. As this behavior cannot be directly deduced from standard measurements, an automatic identification procedure was developed to determine the post-necking flow behavior of the weld metal and the base material transverse to the weld. As reported in the literature, simplified models like Rambord-Osgood are then inadequate and model including two hardening zones is necessary: one for small deformation and one for large deformation. The calibration of the damage models was only performed on the tearing curve obtained from the SENB experiments, and the segment tests were then “blindly” simulated.