Vertebrate Pest Research Articles

Damage impact of vertebrate pests on different crops and stored food items

Damage impact of vertebrate pests on different crops and stored food items

Feral horse impacts: The Kosciuszko Science Conference, Thursday 8 November 2018, Shine Dome, Australian Academy of Science, Canberra

Feral horse impacts: The Kosciuszko Science Conference, Thursday 8 November 2018, Shine Dome, Australian Academy of Science, Canberra

Distribution and Abundance of Vertebrate Pests of Cultivated Maize and their Eco-Friendly Management in District Bagh, Azad Jammu and Kashmir, Pakistan

Distribution and Abundance of Vertebrate Pests of Cultivated Maize and their Eco-Friendly Management in District Bagh, Azad Jammu and Kashmir, Pakistan

The Institutionalisation of Poison: A historical review of vertebrate pest control in Australia, 1814 to 2018

ABSTRACT This paper provides a chronological record of the history of poison in vertebrate species control in south-east Australia, since the first instance was recorded to target dingoes in 1814. ...

Special Topic: Commensal Vertebrate Pests

Special Topic: Commensal Vertebrate Pests

Put a (clear, goal-oriented, flexible and focused) contract on them! Some thoughts on selecting your pest contractors

In the last 20 years, IPM (Integrated Pest Management) has become an increasingly important discipline within the area of Preventive Conservation. Incorporating an IPM program is a complex task even for a small sized institution, so when facing the challenge of starting a monitoring, recording, quarantine and identification scheme whilst ensuring that IPM protocols and best practices cascading from a comprehensive IPM Policy are followed throughout the institution, most IPM professionals tend to focus on the invertebrate pest problem while relaying entirely on external pest control companies to deal with the parallel issue of vertebrate pest. This talk will present a case study to show an example of the well-known correlation between vertebrate and invertebrate pest activity and their complex relations, providing a few tips for those new to IPM on how to spot potential infestation sources, identifying points of entry and following the clues to find the origin of infestations, demonstrating how the detective work is an essential part of the role of an IPM professional. Following up on the case study the talk will lead on to discuss the importance of stablishing secure and long-lasting relationships with key position holders in your institution in order to influence key contracts. The talk will provide advice on how to help your colleagues in Building/Estates Management Departments (those usually being in charge of managing pest control contracts), select the best candidate for an institution that have chosen the IPM strategy of prevention and investment on investigation over the traditional methods of pest control. The talk will also discuss issues of reaction versus prevention, legalities, preventive strategies, raising awareness of IPM in your institution, the importance of education and outreach and many other areas of IPM you always wanted to know about but were afraid to ask…

A STUDY OF RAT SPECIES, THEIR POPULATIONS AND CROP DAMAGE IN MATURE OIL PALM PLANTATIONS IN CENTRAL KALIMANTAN

Rats are the most important amongst the many vertebrate pests of oil palm. They occur in nurseries, immature and mature oilpalm plantation areas and can cause substantial economic loses to the plantations. A study was conducted to determine the species and population of the rats as well as to assess the crop damage in a mature oil palm area in Central Kalimantan province. Five study plots were established at randomly selected fields in five oil palm estates and the rat populations were estimated using the 'catch, marked and recapture' (CMR) technique. The house rat, Rattus rattus diardii, was the only rat species found from live-trapping using wire mesh drop door traps. Using the CMR technique, the population of the Rattus rattus diardii was estimated; it ranged from 185 to 718 rats per hectare among the five trapping plots. The average rat population was 384 rats per hectare over the five estates. The percentage of palms with fresh rat damage on fresh fruit bunches (FFB), ranged from low to moderate, i.e. 5 -15 per cent. Generally, it was observed that high rat population amounted to high number of palms with fresh damage on FFB. The potential crop losses were calculated for the five estates and it ranged from USD 201.48 to USD 779.64 per hectare per year. At the average potential crop loss of USD 417.42 per hectare per year, the combined potential loss for the five estates with a total area of about 20 000 ha amounted to USD 8.35 million. This study also indicated that the house rat, Rattus rattus diardii, was the sole rat species found to be well established in the mature oil palm plantation areas of Central Kalimantan. Side observation from this study indicated that barn owl population augmentation did not result in the desired level of rat control. Hence, the need for a pragmatic integrated approach incorporating both judicious rat baiting together with biological control of rats using barn owls. Keywords: Oil palm, rat species, rat population, catch, marked and recapture (CMR), Rattus rattus diardii, crop losses.

Efficacy of repellent-treated structural barriers for Richardson’s ground squirrels (Urocitellus richardsonii (Sabine)) and house mice (Mus musculus L.)

The worldwide presence of vertebrate pests such as rodents has created a need for non-lethal control methods that can be applied to integrated pest management plans. Chemical repellents are often a useful wildlife management tool as they can be directly applied to a commodity or structure to prevent infringement and damage. We assessed the efficacy of an anthraquinone (AQ)-based repellent in a structural barrier model against Richardson’s ground squirrels (Urocitellus richardsonii (Sabine)) (RGS) and house mice (Mus musculus L.). The AQ-based repellent was applied to pieces of burlap which were secured over each end of a small section of PVC pipe. Unadulterated enrichment food was then offered within the enclosed PVC pipe to motivate interactions with repellent-treated and untreated burlap barriers. Defeat of the barrier was defined as a physical breach by means of chewing the burlap or burlap/repellent barrier such that the test animal was able to gain entry to the hide and the enrichment food. RGS defeated 55% (±7.9) of untreated barriers, 25% (±6.8) of barriers treated with 50% dilution AQ-based repellent, and 27.5% (±5.6) of barriers treated with 0% dilution AQ-based repellent. House mice defeated 100% (±0.0) of untreated barriers, 20.5% (±6.4) of barriers treated with 50% dilution AQ-based repellent, and 45.5% (±7.8) of barriers treated with 0% dilution AQ-based repellent. Relative to untreated barriers, AQ treatments reduced defeat of the barrier by 50–55% for RGS and 55–80% for house mice. RGS showed a marked decrease in consumption of enrichment food after exposure to AQ. The 0% dilution of AQ-treated structural barrier had more individuals of both RGS and house mice chew through the structural barrier than the 50% dilution despite the increased concentration of AQ. We hypothesized that the additional water in the 50% dilution may have allowed for greater absorption of the repellent throughout the burlap fibers, thus enabling greater interaction with the AQ-treated barriers. Our results indicate that AQ-based repellents show promise as structural barriers for RGS and house mice.

3-Monochloropropane-1,2-diol (alpha-chlorohydrin) disrupts spermatogenesis and causes spermatotoxicity in males of the Egyptian fruit-bat (Rousettus aegyptiacus)

We evaluated the sterilizing effect of 3-monochloropropane-1, 2-diol (3-MCPD) in male Egyptian fruit bats (Rousettus aegyptiacus). We used three groups. One was treated with 70 mg/kg 3-MCPD for 4 days. The second group was treated with 3-MCPD as a bait formulation (known concentration of 3-MCPD mixed with a known amount of food). The third group was untreated controls. We compared the weights of the reproductive organs, histology of the testes, occurrence of spermatogenesis, and the count, motility and abnormalities of epididymal sperm of treated males with those of the untreated control group. 3-MCPD caused significantly decreased weights of reproductive organs, several testicular histological alterations and spermatogenic arrest accompanied by significant decreases in sperm count and motility, and significantly increased number of abnormal sperm. 3-MCPD bait was readily accepted by the animals. 3-MCPD, even in low doses and after limited exposure, disrupted spermatogenesis in males of the Egyptian fruit bat. Our findings have potential value for public health and agricultural authorities, and for vertebrate pest managers. 3-MCPD may have application for control of this pest.

Non-Trapping, Non-Invasive, Rapid Surveillance Sampling Using Tracking Tunnels, Trail Cameras, and eDNA to Determine Presence of Pest Predator Species

A common challenge for land managers is knowing which vertebrate pest species are present in areas they manage, especially if such areas are remote like isolated habitats, rugged terrain, or infrequently traveled islands. Most invasive predator species, such as feral dogs, cats, mongoose, and commensal rodents pose great threat to human health and key resources such as native species. Animal trapping to determine the presence of a pest species can be expensive and dangerous, requiring permits, experienced personnel, multiple days, and multiple trapping methods. Furthermore, many invasive pest species may go unnoticed because they are nocturnal, secretive, or leave little evidence of their presence. Tracking tunnels, trail cameras, and environmental DNA (eDNA) are non-trapping methods that can be used to rapidly assess if vertebrate pest species are present in a given habitat or ecosystem, including before, during, and after pest suppression techniques are implemented. We share tracking tunnel dimensions and specifications so readers can make their own tracking tunnels for rodent and other small mammal sampling, and we provide some common distributers where tracking tunnels can be purchased. A brief overview of trail camera technology and eDNA forensic uses are described, as well as their applications for vertebrate pest identification, surveillance, and damage management. To demonstrate these methods, we share example case studies from the Caribbean, including first time records of house mouse presence at Sandy Point National Wildlife Refuge in St. Croix (US Virgin Islands) and along a rainforest elevation gradient in the Luquillo National Forest, Puerto Rico. Additionally, we describe case studies of trail camera use on Desecheo Island (Puerto Rico) to determine brodifacoum bait consumption, and eDNA use in Wyoming to determine native bird depredation events. Tracking tunnels and trail cameras are recommended as quick and inexpensive ways to reveal the vertebrate pest species that are present at a site or habitat. These non-trapping, non-invasive techniques can provide quick and efficient methods of surveillance, detection, and monitoring of vertebrate pests, and otherwise may be used as effective tools to aid in wildlife damage management.

Your Children Mite Not be Safe at School: An Outbreak of Biting Rat Mites at a Southern California Elementary School Campus

During May, 2017, the Orange County Mosquito and Vector Control District (OCMVCD) received anonymous calls from distressed school staff and parents of children attending an elementary school (Villa Park Elementary School, VPES) in Orange County, California, about an outbreak of pruritic dermatitis that was believed to be caused by biting arthropods. The incident received intense media coverage and led to a partial closure of the campus. With no identified culprit, OCMVCD interviewed VPES staff and surveyed the school property for vertebrate pests and their ectoparasites to determine the source of the outbreak. After thorough inspections of the exterior and interior of classrooms and a carefully-placed, glue-board trap survey, OCMVCD detected signs of significant roof rat activity (feces, rub marks, and harborage sites) throughout the campus and the presence of rat mites inside multiple classrooms. OCMVCD worked with other governmental agencies (Orange County Health Care’s Environmental Health, California Department of Pesticide Regulation’s School Integrated Pest Management Program, local city officials) and the VPES administration to educate parents about the vertebrate pests on the school grounds and the complexities of controlling the rat mite infestation during the school year. OCMVCD also identified deficiencies in the school’s pest control program and developed an integrated vector management plan to address the immediate and long-term health threats to prevent rodent and rat mite outbreaks in the future. This report details the investigation and methodology used to locate and eradicate the vertebrate and ectoparasite threats on the VPES campus and the challenges encountered during the process.

Detection and Circulation of a Novel Rabbit Hemorrhagic Disease Virus in Australia.

The highly virulent rabbit hemorrhagic disease virus (RHDV) has been widely used in Australia and New Zealand since the mid-1990s to control wild rabbits, an invasive vertebrate pest in these countries. In January 2014, an exotic RHDV was detected in Australia, and 8 additional outbreaks were reported in both domestic and wild rabbits in the 15 months following its detection. Full-length genomic analysis revealed that this virus is a recombinant containing an RHDVa capsid gene and nonstructural genes most closely related to nonpathogenic rabbit caliciviruses. Nationwide monitoring efforts need to be expanded to assess if the increasing number of different RHDV variants circulating in the Australian environment will affect biological control of rabbits. At the same time, updated vaccines and vaccination protocols are urgently needed to protect pet and farmed rabbits from these novel rabbit caliciviruses.

Wild dog management in Australia: An interactional approach to case studies of community-led action

ABSTRACTWild dogs are a widespread, established pest in Australia and have economic, environmental, and social impacts. Best practice management recommends coordinated community-led action as a key strategy to reduce this vertebrate pest. This research increased understanding of how citizens organize to collectively manage wild dogs in three case studies from Australia, with attention to the interaction of cultural, structural, and interactional domains of group action. Information asymmetry and changing demographic profiles emerge as challenges to effective group development. Visible community leaders and strong group identity are important, as is peer recognition of community efforts to develop collective action norms. This article complements and extends existing quantitative data sets with qualitative analysis and contextual understanding, while also reflecting on the implications of collective action for wild dog management more broadly. This research is relevant for those concerned with community action and complex issues of vertebrate pest management.

Efficiency of different spatial and temporal strategies for reducing vertebrate pest populations

Understanding effectiveness of control strategies of pest species is fundamental for planning efficient and cost-effective management programs. In addition to culling rates, there are many potential factors that can determine efficiency of different management strategies, including demographic processes such as immigration rates, birth dynamics, and spatial ecology. We developed a stochastic, data-based simulation model of feral swine population dynamics which accounted for social dynamics in space. We tested the impacts of different spatio-temporal management strategies (i.e., culling rates, timing of culling during the year, spatial pattern of culling and strength of a barrier to immigration) on population response and efficiency. The spatial culling strategy dramatically impacted efficiency of control – using zonation required removal of fewer pigs (up to 46% less) to achieve similar reductions compared with other spatial strategies. Also, our spatially-explicit model predicted that lower culling intensities could be used to achieve population reductions when zonation was applied relative to predictions from harvesting theory based on simple logistic models. As culling intensity increased (≥50% of target population annually) and the target population reached low density (<5% of original density), effects of spatial strategy became less pronounced relative to immigration barrier effects. Lastly, for the same level of moderate culling effort, prioritization of culling during the low-birthing period generally resulted in faster population reduction to near zero abundance relative to prioritization during the high-birthing period, or spreading the work over a year period, but the significance of this effect depended on the spatial culling strategy and culling intensity. Our results imply that continually updating knowledge of current abundance during management may not only be important for determining culling quotas, but also for updating and optimizing management strategies. When the management goal is maximum population control, consideration of birth and spatial dynamics can increase return on management effort and bring to light management inefficiencies.

Organic Fertilizer Deters Vertebrate Pests from White Grub‐Infested Turf

Soil‐dwelling white grubs cause damage by feeding on turf roots, but vertebrate predation of grubs can cause extensive damage, even at low population densities. As a result, golf course superintendents may use insecticides to reduce white grub populations regardless of population densities. This research explores the potential to deter vertebrates from white grub‐infested areas by applying Milorganite, a turf fertilizer derived from human biosolids. The study was conducted on rough‐height Kentucky bluegrass (Poa pratensis L.) at two different golf courses in Wisconsin in 2008. The fertilizer was applied once at 16.1 or 48.8 kg N ha−1, and vertebrate damage was rated weekly for 4 wk. All control plots received some damage from vertebrate predation. The high and low rates of Milorganite reduced damage from vertebrate predation compared with the nontreated control, but there were minimal differences between rates. These findings suggest that biosolid‐based fertilizers may deter vertebrate predators of white grubs and could provide an alternative to insecticide treatment. The feasibility of this practice remains unclear and would depend on the residual efficacy and required reapplication interval of the products applied.

Dodging silver bullets: good CRISPR gene-drive design is critical for eradicating exotic vertebrates.

Self-replicating gene drives that can spread deleterious alleles through animal populations have been promoted as a much needed but controversial 'silver bullet' for controlling invasive alien species. Homing-based drives comprise an endonuclease and a guide RNA (gRNA) that are replicated during meiosis via homologous recombination. However, their efficacy for controlling wild populations is threatened by inherent polymorphic resistance and the creation of resistance alleles via non-homologous end-joining (NHEJ)-mediated DNA repair. We used stochastic individual-based models to identify realistic gene-drive strategies capable of eradicating vertebrate pest populations (mice, rats and rabbits) on islands. One popular strategy, a sex-reversing drive that converts heterozygous females into sterile males, failed to spread and required the ongoing deployment of gene-drive carriers to achieve eradication. Under alternative strategies, multiplexed gRNAs could overcome inherent polymorphic resistance and were required for eradication success even when the probability of NHEJ was low. Strategies causing homozygotic embryonic non-viability or homozygotic female sterility produced high probabilities of eradication and were robust to NHEJ-mediated deletion of the DNA sequence between multiplexed endonuclease recognition sites. The latter two strategies also purged the gene drive when eradication failed, therefore posing lower long-term risk should animals escape beyond target islands. Multiplexing gRNAs will be necessary if this technology is to be useful for insular extirpation attempts; however, precise knowledge of homing rates will be required to design low-risk gene drives with high probabilities of eradication success.

An assessment of the magnitudes and factors associated with postharvest losses in off-farm grain stores in Kenya

Off-farm grain storage is an important postharvest undertaking by government, traders and processors in Kenya. A survey was conducted in 2014/2015 to assess the kinds and magnitudes of perceived losses experienced in off-farm stores, and the factors associated with them. Store supervisors or key personnel charged with grain storage in 39 public and 74 private stores, spread across the six maize growing agro-ecological zones, were interviewed using a structured questionnaire. Total perceived losses averaged 17.6± 2.3%, and were attributed to insects (7.2± 1.0%), molds (5.7± 2.1%), moisture loss (3.4± 0.5%), rodents (2.0± 0.5%), spillage (0.50 ± 0.0%) and birds (0.10± 0.0%). Total losses experienced in public and privately owned stores were not significantly different. The losses attributed to insect and the vertebrate pests, moisture loss and spillage, were also not significantly different in the two storage systems. However, losses due to molds were significantly higher in the private stores. From regression analysis, higher losses were associated with the use of residual insecticides, purchasing low quality maize for storage, reuse of storage bags, untimely control of storage pests, and the agro-climatic conditions of the moist transitional, moist mid-altitude and dry mid-altitude zones. Relying on infestation reports to initiate pest control had the highest marginal effect (21.7%). Lower loss magnitudes were associated with cleaning and drying grain before storage, early pest control and storage periods shorter than two months. These findings provide important reasons for appraising current off-farm storage techniques with a view to taking possible actions for improvements. It is recommended that innovations to mitigate maize postharvest losses should also target off-farm storage, as the losses incurred are significant.

Benign Rabbit Calicivirus in New Zealand.

The Czech v351 strain of rabbit hemorrhagic disease virus (RHDV1) is used in Australia and New Zealand as a biological control agent for rabbits, which are important and damaging introduced vertebrate pests in these countries. However, nonpathogenic rabbit caliciviruses (RCVs) can provide partial immunological cross-protection against lethal RHDV infection and thus interfere with effective rabbit biocontrol. Antibodies that cross-reacted against RHDV antigens were found in wild rabbits before the release of RHDV1 in New Zealand in 1997, suggesting that nonpathogenic RCVs were already present in New Zealand. The aim of this study was to confirm the presence of nonpathogenic RCV in New Zealand and describe its geographical distribution. RCV and RHDV antibody assays were used to screen serum samples from 350 wild rabbits from 14 locations in New Zealand. The serological survey indicated that both RCV and RHDV are widespread in New Zealand wild rabbits, with antibodies detected in 10 out of 14 and 12 out of 14 populations, respectively. Two closely related RCV strains were identified in the duodenal tissue from a New Zealand wild rabbit (RCV Gore-425A and RCV Gore-425B). Both variants are most closely related to Australian RCV strains, but with 88% nucleotide identity, they are genetically distinct. Phylogenetic analysis revealed that the New Zealand RCV strains fall within the genetic diversity of the Australian RCV isolates, indicating a relatively recent movement of RCVs between Australia and New Zealand.IMPORTANCE Wild rabbits are important and damaging introduced vertebrate pests in Australia and New Zealand. Although RHDV1 is used as a biological control agent, some nonpathogenic RCVs can provide partial immunological cross-protection against lethal RHDV infection and thus interfere with its effectiveness for rabbit control. The presence of nonpathogenic RCVs in New Zealand wild rabbits has been long hypothesized, but earlier attempts to isolate a New Zealand RCV strain have been unsuccessful. Therefore, it is important to determine if such nonpathogenic viruses exist in New Zealand rabbits, especially considering the proposed introduction of new RHDV strains into New Zealand as biocontrols.

Farmer Perceptions and Behaviors Related to Wildlife and On‐Farm Conservation Actions

AbstractPolicy makers are increasingly encouraging farmers to protect or enhance habitat on their farms for wildlife conservation. However, a lack of knowledge of farmers’ opinions toward wildlife can lead to poor integration of conservation measures. We surveyed farmers to assess their perceptions of ecosystem services and disservices from perching birds, raptors, and bats—three taxa commonly targeted by conservation measures. The majority of farmers thought that perching birds and bats were beneficial for insect pest control and that raptors were beneficial for vertebrate pest control; however, fruit farmers viewed perching birds more negatively than did farmers growing other crops. Farmers using organic methods viewed all three wildlife groups more positively than conventional farmers. Farmer perception toward each wildlife group predicted their action to either attract or deter those taxa, suggesting the need to focus research and outreach on the effects of wildlife on farms for conservation programs to positively influence farmer perceptions.

Pandora’s box down-under: origins and numbers of mustelids transported to New Zealand for biological control of rabbits

This paper describes one of the world’s first large-scale experiments in biological control of a major vertebrate pest of agriculture, which was tried in New Zealand during the second half of the nineteenth century. Starting from the late 1860s, pasture damage in Southland and Otago by European rabbits was causing serious reductions in productivity of sheep (wool clip and lambing percentages) associated with malnutrition of the breeding ewes, and a consequent decline in the value of pastoral land. In response, and despite repeated local and international warnings, ferrets, stoats and weasels (Mustela furo, M. erminea and M. nivalis) were liberated on the worst of the rabbit-infested pastures. They were perceived as the ‘natural enemies of the rabbit’ but (unlike foxes) too small to threaten lambs. Over the 50 years after 1870, upwards of 75,000 ferrets, most imported from Australia or locally bred, were released in the South Island. Over the decade 1883–1892, at least 7838 stoats and weasels arrived from Britain. At least 25 shipments are known, with an average of only 10% mortality per shipment. Of the 3585 animals listed by species, 73% were weasels. The total cost of the ferret programme cannot now be estimated; that of stoats and weasels alone was at least £5441, probably twice that, or >$NZ 1–2 million in today’s money. Mustelids (and cats) killed many young rabbits, which was helpful because rates of change in rabbit populations are sensitive to variations in juvenile mortality, but in the most rabbit-prone semi-arid lands, mustelids could not remove enough rabbits to prevent the continuing damage to sheep pastures. The era of deliberate introductions of mustelids to control rabbits in New Zealand was short, expensive, and unsuccessful.