Bait Stations Research Articles

The use of anticoagulants for rodent control in a mixed-use urban environmefent in Singapore: A controlled interrupted time series analysis.

Vector control remains an important strategy in preventing rodent-borne diseases. Studies quantifying the impact of anticoagulant bait use on rodent populations are scarce in tropical settings. This study examined the impact of anticoagulant bait use on three measures of rodent activity in Singapore to inform rodent-borne disease control strategies. Using a controlled interrupted time-series analytical design with negative binomial and linear regression models, the average rodent activity levels were compared in the pre- and post-intervention periods. There was a 62.7% (Incidence Rate Ratio (IRR): 0.373, 95% CI: [0.224, 0.620]) reduction in the number of rodents caught, a 25.8-unit (coefficient = -25.829, 95% CI: [-29.855, -21.804]) reduction in the number of 30 g/unit baits consumed and a 61.9% (IRR: 0.381, 95% CI: [0.218, 0.665]) reduction in the number of marred bait stations relative to the pre-intervention period. There was a rise in all three outcome measures within four months after the post-intervention period. This study provided strong evidence that anticoagulant baits substantially reduces rodent activity. The population resurgence after the post-intervention period reinforces the importance of timing the resumption of control measures aimed at reducing rodent-borne disease transmission.

Occurrence patterns of wild turkeys altered by wild pigs

Eastern wild turkeys (Meleagris gallopavo silvestris) are an important game bird in the United States, particularly in the Southeast. The introduction of wild pigs (Sus scrofa) can negatively affect native wildlife, habitat quality, and ecosystem functions. To explore the potential effects that pig presence, through habitat degradation and interspecific competition, may have on wild turkeys, we evaluated changes in occupancy of co-occurring wild pigs and wild turkeys.We deployed camera-monitored bait stations on 3 wildlife management areas in Arkansas during January–April 2017–2019 and collected >680,000 images to determine turkey and wild pig occurrence. We evaluated presence/absence of turkeys and wild pigs in camera trap images using Timelapse2 image analyzer software® and then used program MARK to create 2-species occupancy models and determine the effect of wild pig presence and various landscape covariates on the occupancy and detectability of wild turkeys. The occupancy rate of wild pigs was 50.4% (95% CI = 46.9%–54.0%) and included positive relationships with the percent cover of deciduous forest and the number of wildlife openings within 500 m. The occupancy rate of turkeys increased from 45.5% (95% CI = 39.3%–51.6%) when wild pigs were not present to 59.4% (95% CI = 45.2%–73.5%, 95%) when wild pigs were present, indicating a tendency of the 2 species to select for similar environmental conditions (Species Interaction Factor = 1.13). Detectability of turkeys decreased when wild pigs occupied a site at any point during the season, regardless of whether or not the wild pigs were detected during the same trapping occasion. The decrease in detectability suggests a possible short-term displacement of turkeys by wild pigs. This displacement can have indirect effects through alteration of breeding behaviors and altered habitat use patterns, and these indirect effects represent an important topic for research moving forward.

Installation Season May Significantly Impact Time Required for Subterranean Termites to Find and Feed on In-Ground Baits.

Simple SummaryInsecticide baits for use against subterranean termites have been shown to be highly effective, but the time required for termites to find and feed on baits may be a barrier to adoption in some areas. One explanation for this “time-to-attack” problem is that termite foraging near the soil surface may be limited during inhospitable periods. In California, characterized by a hot-summer Mediterranean climate, western subterranean termites have mostly been observed near the surface during the wet season, suggesting that baits installed in summer may sit uninvestigated for many months. To test this hypothesis, we established research plots in areas of known termite incidence, installing baits on four different dates over a one-year period and then recording termite activity every 60 days for two years. As expected, most foraging in these stations was observed in winter and spring. Time-to-attack for stations installed at the beginning of winter was significantly less than for stations installed at the beginning of summer (194 d vs. 296 d). These findings may help pest control operators in regions with pronounced dry periods to optimize their use of bait station systems by targeting specific installation seasons.Rhinotermitid termites, serious pests of wooden structures throughout the world, are commonly controlled with chitin synthesis inhibitor bait systems. Seasonal termite foraging patterns in some regions may prolong bait interception time, however, significantly decreasing colony elimination speed. We hypothesized that installing baits immediately prior to the season of highest foraging activity will minimize interception time when baiting for Reticulitermes spp. in California, a region characterized by a hot-summer Mediterranean climate. To test this theory, we installed three different bait systems on four dates corresponding to the major seasons (spring, summer, autumn, winter) at five field locations known to harbor the target species. We then recorded initial termite discovery events every 60 days for two years, considering effects of installation season, bait system, site, and distance from previously observed termite incidence on bait interception time. Observed foraging activity in bait stations was highest during late winter and spring. Baits installed during winter exhibited interception times more than 100 days shorter than those of baits installed during summer. From these findings, we conclude that colony elimination speed and perceived CSI bait utility may be increased in Mediterranean climate regions when baits are installed immediately prior to the wet season.

Testing the Short-Term Effectiveness of Various Deterrents for Reducing Crop Foraging by Primates

Crop foraging by wildlife is a major driver of negative interactions between farmers and wildlife, and yet there are few published examples of effective solutions to deter wildlife from crops. Here we investigate the effectiveness of six different methods to deter primates from crop foraging on commercial farms in South Africa. Model snakes and bioacoustic sounds had no effect on chacma baboons (Papio ursinus). A leopard model and the sound of bees reduced the foraging duration at bait stations of vervet monkeys (Chlorocebus pygerythrus) and baboons, respectively. Human sounds appeared to reduce the number of days baboons visited a bait station, but not their foraging duration. Only an electric fence was effective at keeping both baboons and vervets out of a crop field. We encourage modifications to electric fence designs to avoid electrocution of smaller animals and make recommendations for other deterrent methods that require further investigation.

White-Tailed Deer Spatial Distribution in Relation to '4-Poster' Tick Control Devices in Suburbia.

Deer are keystone hosts for adult ticks and have enabled the spread of tick distributions. The ‘4-Poster’ deer bait station was developed by the United States Department of Agriculture to control ticks feeding on free-ranging deer. Although effective in certain scenarios, ‘4-Poster’ deer treatment stations require the use of bait to attract deer to one location, which may cause increased deer disease transmission rates and habitat damage. To better understand and manage the impact of baited ‘4-Poster’ stations on deer movements, we captured and GPS-monitored 35 deer as part of an integrated pest management project. Fifteen ‘4-Poster’ stations were deployed among three suburban county parks to control ticks. To quantify the effects of ‘4-Poster’ stations, we calculated deer movement metrics before and after feeders were filled with whole kernel corn, and we gathered information on visitation rates to feeders. Overall, 83.3% of collared deer visited a feeder and revisited approximately every 5 days. After feeders were refilled, collared deer were ~5% closer to feeders and conspecifics than before filling. Males used a higher percentage of available feeders and visited them more throughout the deployment periods. Although these nuanced alterations in behavior may not be strong enough to increase local deer abundance, in light of infectious diseases affecting deer populations and effective ‘4-Poster’ densities, the core range shifts and clustering after refilling bait may be a cause for concern. As such, trade-offs between conflicting management goals should be carefully considered when deploying ‘4-Poster’ stations.

Assessing colony elimination in multicolonial ants: Estimating field efficacy of insecticidal baits against the invasive dark rover ant (Brachymyrmex patagonicus).

A frequent goal of pest management strategies targeting social insects is total colony elimination. Insecticidal baits are highly effective at controlling social insect pests, although their ability to provide total colony elimination has only been well studied in a few species. Genetically testing colony elimination in many urban pest ants can be challenging due to indistinct colony boundaries observed in unicolonial, invasive species; however, some pest ants, such as the dark rover ant (Brachymyrmex patagonicus), maintain strict colony borders through aggression towards non-nestmates. Each of these distinct colonies can be identified using molecular markers, allowing for the tracking of individual colonies pre- and post-treatment to measure colony density. While counting the number of foraging workers to assess treatment efficacy may suffice in some cases, it offers little insight into the colony-level impacts of a treatment. Using microsatellite markers, distinct rover ant colonies were identified and tracked around residential structures before and after the application of an imidacloprid bait. The number of foraging ants at the treated structures was reduced by an average of 83.0% over a 28-day observation period. Baiting also significantly reduced the total number of colonies present. At the treatment structures, only ~25% of the original colonies remained at the end of the study. Colonies with foraging trails <1.5m from a bait station had a higher chance of being eliminated. Using insecticidal baits against B. patagonicus can be highly effective at colony elimination; however, with such small foraging ranges and high colony densities, proper placement is required to ensure enough bait is properly positioned to treat all colonies affecting a structure. © 2022 Society of Chemical Industry.

Method for Nest Detection of the Yellow-Legged Hornet in High Density Areas.

The Asian hornet Vespa velutina is a social predator that has invaded several countries of Europe and Asia, impacting pollinators, apiculture and human health. One of the few effective control methods developed so far is the early destruction of nests. However, they are often built within dense vegetation, being difficult to detect. The aim of the method described here is to detect nests with a simple procedure, utilizing readily available materials, for widespread use in infested areas. The method has two phases, the first phase involves capturing and marking hornets, lured to a protein bait, and recording the flight directions of individuals to the nest and the time needed to complete a bait-nest-bait round trip, to estimate the distance. Collecting this information from two (or more) bait stations allows to delineate the approximate location of the nest. The second phase aims to determine the precise location of the nest, using sugary baits in the vicinity of the nest and conspicuous marks attached to the released hornets, to visually follow them up to their nest. This method is an alternative to other methods that are either ineffective in areas with high nest density or require expensive equipment and specialized training.

The Spatial Distribution of the House Mouse, Mus musculus domesticus, in Multi-Family Dwellings.

Simple SummaryThe management of house mice, Mus musculus domesticus, in low-income high-rise multi-family dwellings (MFDs) is often frustrated by the limited resources available through low-bid contracting. An improved understanding of the small-scale distribution of this important public health pest could allow the pest management industry to better allocate its limited time and resources to better managing infestations. This study utilized data from two research projects that measured house mouse infestation rates from four urban low-income MFDs to determine if a significant correlation between neighboring units exists in their infestation status. Results show that such a correlation exists whereby apartments that share a wall, ceiling or floor with a neighboring apartment that has a current infestation are more likely to have existing house mouse activity. This information can be utilized by the pest management industry to design monitoring strategies, during integrated pest management activities, to better ensure the elimination of house mice in low-income high-rise MFDs.The house mouse, Mus musculus domesticus, creates significant public health risks for residents in low-income multi-family dwellings (MFDs). This study was designed to evaluate the spatial distribution of house mice in MFDs. Four low-income high-rise apartment buildings in three cities in New Jersey were selected for building-wide monitoring on two occasions with approximately one year between the monitoring events. The presence of a house mouse infestation was determined by placing mouse bait stations with three different non-toxic baits for a one-week period in all accessible units as well as common areas. Permutation tests were conducted to evaluate house mouse infestation spatial patterns. All four analyzed buildings exhibited a significant correlation between apartments with house mouse infestations and whether they share a common wall or ceiling/floor at both sampling periods except one building during the second inspection, which contained a high number of isolated apartments. Foraging ranges, speed of locomotion, and dispersal behavior of house mice are relatively larger, faster, and more common, respectively, compared to common urban arthropod pests. This could lead to the conclusion that house mice are as likely to infest non-neighboring apartments as those that share a wall or floor/ceiling. However, these results demonstrate that house mouse infestations tend to occur among apartments that share common walls or ceilings/floors. This spatial distribution pattern can be utilized in rodent management plans to improve the efficiency of house mouse management programs in MFDs.

Evaluation of oral baits and distribution methods for Tasmanian devils (Sarcophilus harrisii)†

Context Diseases are increasingly contributing to wildlife population declines. Tasmanian devil (Sarcophilus harrisii) populations have locally declined by 82%, largely owing to the morbidity and mortality associated with two independent transmissible devil facial tumours (DFT1 and DFT2). Toxic baits are often used as a management tool for controlling vertebrate pest populations in Australia, but in other areas of the world, oral baits are also used to deliver vaccines or pharmaceuticals to wildlife. Aim Our goal was to evaluate the potential use of edible baits as vehicles for vaccine delivery to Tasmanian devils. Method We first tested bait palatability with captive devils. Bait interactions were recorded, and consumption and bait interaction behaviours were quantified. We next trialled baits containing inert capsules as potential vaccine containers in captivity. After confirming bait palatability in captivity, ground baiting was trialled at six field sites and monitored using camera traps. Finally, an automated bait dispenser was trialled at field sites to attempt to limit bait consumption by non-target species. Key results Captive devils consumed all types of placebo baits, but consumed a higher percentage of ruminant- and fish-based baits than cereal-based baits. Captive devils also consumed inert capsules inserted into placebo baits. Ground-baiting trials in the field showed that 53% of baits were removed from bait stations, with 76% of the removals occurring on the first night. Devils were suspected or confirmed to remove about 7% of baits compared with 93% by non-target species. We also evaluated an automated bait dispenser, which reduced bait removal by non-target species and resulted in over 50% of the baits being removed by devils. Conclusions This study demonstrated that captive and wild devils will accept and consume placebo versions of commercial baits. Bait dispensers or modified baits or baiting strategies are needed to increase bait uptake by devils. Implications Bait dispensers can be used at a regional scale to deliver baits to devils. These could potentially be used as vaccine-delivery vehicles to mitigate the impacts of disease on devil populations.

Evidence that predator satiation drives reproductive synchrony in the desert masting grass, soft spinifex (Triodia pungens)

AbstractThe predator satiation (PS) hypothesis of masting holds that seeding periodicity among plant populations enhances seed survival by starving granivores during low‐output periods and satiating reduced consumer populations during mast (high‐output) years. Although well‐studied in the northern hemisphere and in New Zealand, the PS hypothesis has received scant research attention in Australia. This is despite vegetation communities across nearly half the continent being dominated by masting species subject to high levels of seed predation (e.g. mulga [Acacia aneura] shrublands and spinifex [Triodia spp.] grasslands). Here, phenological monitoring and experimental testing of the PS hypothesis in the desert masting grass Triodia pungens (soft spinifex) occurred over 10 years at Deep Well station, central Australia. Field evidence supported the hypothesis that masting enhances seed escape from predators, as mean proportion seed survival at experimental bait stations was significantly greater during mast years (0.38 in 2012 and 0.33 in 2017) than during inter‐mast years (0.01 in 2016 and 2018). The possibility that seed decay as opposed to consumption affected results was controlled for by a deterioration experiment that indicated no significant loss of seed viability after 6‐months burial. The results support the hypothesis that masting in T. pungens is an adaptive trait related to the satiation of seed predators. However, whether masting enhances seed escape because predators are satiated at higher seed densities (i.e. masting causes a predator functional response) and/or because frequent low‐output periods reduce predator populations and make satiation more likely (i.e. a numerical predator masting response), remains unresolved. Aside from T. pungens, there are numerous other plants of the Australian arid zone that experience high levels of granivory and display masting. Seed predation may be a more important selective force acting on arid Australian plant reproduction than previously thought.

Deterring non-target birds from toxic bait sites for wild pigs

Toxic baiting of wild pigs (Sus scrofa) is a potential new tool for population control and damage reduction in the US. Field trials testing a prototype toxic bait (HOGGONE 2 containing 5% sodium nitrite [SN]), though, revealed that wild pigs spilled small particles of toxic bait outside of bait stations which subsequently created hazards for non-target species that consumed those particles, primarily passerine birds. To deter non-target birds from consuming particles of spilled bait, we tested four deterrents at mock bait sites (i.e., baited with bird seed) in north-central Colorado, USA during April–May 2020. We found a programable, inflatable deterrent device (scare dancer) reduced bird visitation by an average of 96%. Then, we evaluated the deterrent devices at SN-toxic bait sites in north-central Texas, USA during July 2020, where the devices were activated the morning following deployment of SN-toxic bait. Overall, we found 139 dead wild pigs at 10 bait sites following one night of toxic baiting, which represented an average of 91% reduction in wild pigs visiting bait sites. We found that deterrent devices were 100% effective at deterring birds from toxic bait sites. We found two dead non-target mice at bait sites without deterrent devices. We noted that deploying toxic bait in mid-summer rather than late-winter/early-spring reduced hazards to migrating birds because they were not present in our study area during July. We recommend using deterrent devices (i.e., novel, programmable, battery operated, continuous and erratic movement, and snapping sounds) to reduce hazards to non-target birds at SN-toxic bait sites. We further recommend deploying SN-toxic bait during seasons when migrating birds are not as abundant until further research demonstrates minimal risks to migrating birds.

An overview of experimental Gray Wolf (&lt;i&gt;Canis lupus&lt;/i&gt;) poisoning programs in northern Ontario, 1956 to 1964

In the late 1950s, the Ontario Department of Lands and Forests commenced an experimental Gray Wolf (Canis lupus) poisoning program in northern Ontario, the results of which were documented in a series of unpublished reports. Most projects consisted of distributing baits poisoned with strychnine on frozen lakes in late winter; 12 were conducted by district staff and typically consisted of &lt;10 bait stations monitored for two to four months. An intensive three-year program was completed in the Allanwater area, about 250 km north of Thunder Bay, where up to 56 bait stations were distributed on a grid covering &gt;25 000 km2. Thirty eight wolf kills were reported in the district projects and 81 in the Allanwater study. In total, where sex was identified 56% were male and 44% female. Adults made up 51% of the kill in the Allanwater study, subadults (&lt;2 years old) 44%, and 5% were of unknown age. Two hundred and sixty five kills of species other than wolves were documented from all studies, comprising 10 mammal and nine bird species. Common Raven (Corvus corax) and Red Fox (Vulpes vulpes) made up 54% and 24% of the non-target mortality, respectively, and were recorded in most studies. Kills of wolves and non-target species were probably under-reported because animals left bait stations before dying, were buried by snow, were removed by bounty hunters, or monitoring for non-target species was poor. Although completed over 50 years ago, the studies summarized here provide context on the ecological impacts and ethics of poison use to control wolves.

Perspectives for Synergic Blends of Attractive Sources in South American Palm Weevil Mass Trapping: Waiting for the Red Palm Weevil Brazil Invasion.

Simple SummaryPalm weevils—both South American and red palm weevils—threaten economically relevant palms, affecting oil and fruit production with a corresponding social impact. The natural tendency of the red palm weevil to explore vast territories in combination with corridors of cultivated susceptible palm species drives pest expansion in new territories. Invasion still occurs westward, from Sundaland to Portugal and the West-African coast, including the Canary Archipelago. The red palm weevil menaces the South American oil palm plantations, opening a new double-pest scenario and consequential damages or a possible coexistence with reciprocal competitive exclusion phenomena opportunities. On the brink of the red palm weevil’s entrance into South America, we present available options for multiple lure-use in contaminating stations for the sustainable and effective management of both pests.Coupling several natural and synthetic lures with aggregation pheromones from the palm weevils Rhynchophorus palmarum and R. ferrugineus reveals a synergy that results in an increase in pest captures. The combined attraction of pure pheromones, ethyl acetate, and decaying sweet and starchy plant tissue increases the net total of mass-trapped weevils. The 2018 entrance of the red palm weevil (RPW) into South America has threatened palm-product income in Brazil and other neighboring countries. The presence of the new A1 quarantine pest necessitates the review of all available options for a sustainable mass-trapping, monitoring, and control strategy to ultimately target both weevils with the same device. The effective lure-blend set for the mass-trapping system will attract weevils in baiting and contaminating stations for entomopathogenic fungi that the same weevils will spread.

Efficacy of low-dose fipronil bait against blacklegged tick (Ixodes scapularis) larvae feeding on white-footed mice (Peromyscus leucopus) under simulated field conditions

BackgroundLyme disease, caused primarily by Borrelia burgdorferi sensu stricto, is the most prevalent vector-borne disease in the United States. Treatment of rodent pathogen reservoirs with an oral acaricide may suppress the production of infected host-seeking ticks posing a risk for human infection. A previous study showed that an oral fipronil bait effectively controlled larval Ixodes scapularis ticks on white-footed mice (Peromyscus leucopus) up to 15 days post-bait exposure. The present study expands upon this finding by exposing group-housed white-footed mice to fipronil bait under simulated field conditions prior to tick infestation.MethodsMice (n = 80) were housed in groups of 10 within large enclosures and offered a choice between fipronil bait within a commercial bait station and an alternative diet. The mice were assigned to two treatment groups and two control groups to undergo bait exposure durations of either 24 h (reduced) or 168 h (extended). Groups were further differentiated by the time point post-bait exposure when larval ticks were applied to mice within feeding capsules (reduced day 1, day 15; extended day 21, day 35). For 4 days post-tick introduction, attached larvae were observed by microscopy and replete larvae were recovered. Replete larvae were monitored for molting success. Plasma was collected from all treatment group mice to obtain fipronil plasma concentrations (CP).ResultsThe fipronil bait (0.005% fipronil) was palatable and controlled larval ticks on white-footed mice when presented under simulated field conditions. Efficacy in preventing attached larvae from feeding to repletion was 100% (day 1), 89.0% (day 15), 85.8% (day 21), and 75.2% (day 35). When also considering molting success, the fipronil bait prevented 100% (day 1), 91.1% (day 15), 91.7% (day 21), and 82.5% (day 35) of larvae attaching to mice from molting. The mean CP per mouse was 191.5 ng/ml (day 1), 29.4 ng/ml (day 15), 10.6 ng/ml (day 21), and 1.0 ng/ml (day 35).ConclusionsThe results suggest that fipronil bait will be consumed by white-footed mice in the presence of an alternative diet, and effectively control larval ticks on treated mice. A field trial is needed to confirm the results of this study. Low-dose fipronil bait may provide a cost-effective means of controlling blacklegged ticks to be integrated into tick management programs.Graphical

Landscape Heterogeneity and Woody Encroachment Decrease Mesocarnivore Scavenging in a Savanna Agroecosystem

Increased agricultural intensification and extensive woody plant encroachment are having widespread effects on the functioning of grass-dominated systems at multiple spatial scales. Yet there is little understanding of how the provisioning of biodiversity-based ecosystem services might be altered by these ongoing changes. One fundamental ecosystem service that is decreasing globally, especially in human-altered landscapes, is scavenging that regulates disease processes, alters species distributions, and influences nutrient cycling. Accordingly, our goal was to understand how facultative scavenging, particularly that of mesocarnivores, was affected by landscape heterogeneity and woody encroachment in tropical-grassy savannas within an agricultural landscape mosaic. We baited (using chicken carcasses) plots across a gradient of land cover heterogeneity in areas with an open and closed canopy and subsequently measured scavenging rates. We found that scavenging efficiency of mesocarnivores and other small vertebrates was dependent on environmental variation at multiple spatial scales within our savanna agroecosystem. Mesocarnivores removed more bait when the overstory canopy at the plot (i.e., exact location of bait station) was more closed; in contrast, mesocarnivore scavenging was less efficient when patches (50 × 50 m area around the bait station) within the site had a higher density of shrubs. At the landscape scale, increased land cover fragmentation resulted in decreased amounts of scavenging by mesocarnivores. This study demonstrates that a relatively transformed agroecosystem can support the provision of important ecosystem services and offer an important buffer against loss of ecosystem services. Our results suggest that targeted woody encroachment control, protection of large trees, and management or mitigation of extreme levels of fragmentation can help maintain ecosystem service provision and biodiversity.

Status of Gould’s Petrel Pterodroma leucoptera caledonica in New Caledonia: distribution, breeding biology, threats and conservation

ABSTRACT Pterodroma leucoptera caledonica is a subspecies of Gould’s Petrel endemic to New Caledonia. Its distribution, abundance and breeding biology are poorly known. Extensive surveys of New Caledonia between 1994 and 2014 located only two breeding colonies, and a further likely, but still unconfirmed; the total estimated size of the population could be of the order of 5000–7000 breeding pairs. Nesting burrows were situated either near streams or on slopes near ridges. The breeding phenology of caledonica was similar to that of the Australian leucoptera, but with a breeding calendar that lagged that of leucoptera by 2–4 weeks depending on year and breeding parameter. Breeding success was low, with evidence of a high level of predation of eggs, chicks and adults by rats, pigs and cats. Pigs also destroyed nesting burrows. Permanent bait stations installed to control rats at one colony appeared successful, but the control of pigs and cats is much more problematic. If, as expected, the level of predation observed at one colony extends across all breeding colonies, population decline is inevitable and extinction likely in the long term. With no populations of P. l. caledonica on predator-free offshore islands, translocation to such sites may be evaluated to safeguard this subspecies. In the meantime, we recommend that the global status of Gould’s Petrel Pterodroma leucoptera be upgraded from Vulnerable to Endangered.

The effect of COVID19 pandemic restrictions on an urban rodent population

Shortly after the enactment of restrictions aimed at limiting the spread of COVID-19, various local government and public health authorities around the world reported an increased sighting of rats. Such reports have yet to be empirically validated. Here we combined data from multi-catch rodent stations (providing data on rodent captures), rodent bait stations (providing data on rodent activity) and residents’ complaints to explore the effects of a six week lockdown period on rodent populations within the City of Sydney, Australia. The sampling interval encompassed October 2019 to July 2020 with lockdown defined as the interval from April 1st to May 15th, 2020. Rodent captures and activity (visits to bait stations) were stable prior to lockdown. Captures showed a rapid increase and then decline during the lockdown, while rodent visits to bait stations declined throughout this period. There were no changes in the frequency of complaints during lockdown relative to before and after lockdown. There was a non-directional change in the geographical distribution of indices of rodent abundance suggesting that rodents redistributed in response to resource scarcity. We hypothesize that lockdown measures initially resulted in increased rodent captures due to sudden shortage of human-derived food resources. Rodent visits to bait stations might not show this pattern due to the nature of the binary data collected, namely the presence or absence of a visit. Relocation of bait stations driven by pest management goals may also have affected the detection of any directional spatial effect. We conclude that the onset of COVID-19 may have disrupted commensal rodent populations, with possible implications for the future management of these ubiquitous urban indicator species.

Assessment of factors influencing visitation to rodent management devices at food distribution centers

Rodent management programs at food distribution centers in the United States and Canada often adhere to interval-based spacing of control devices, with traps spaced 6–12 m apart on the interior perimeter, and exterior bait stations spaced 15–30 m apart. However, this design is based only on rodent foraging ranges, and does not consider the influence of rodent behavior or biology on movement patterns. Therefore, this study evaluated characteristics of food distribution centers that influence rodent behavior to determine their impact on interior trap capture and exterior bait feeding by rodents. We found that rodent interactions with control devices was not uniform in facilities, and less than half (45.2%) of all interior devices trapped at least one mouse. Rodent feeding at exterior bait stations was similarly not uniform, with 56.1% of observations representing minor feeding (one corner of bait or less consumed). Furthermore, we found that certain ecological and structural characteristics of device location were associated with higher trap capture and/or bait consumption. Results of this investigation suggest that rodent management at food distribution centers can be improved with assessment-based placement of traps and bait stations. In addition to reducing food safety threats through improved trap capture, this approach can reduce the number of devices to service and redirect service time toward pro-active inspections, rather than trap checking. Finally, device locations that are assessment-based align with the 2011 Food Safety Modernization Act that mandates preventive controls to protect human food.

Predictability of Invasive Argentine Ant Distribution Across Mediterranean Ecoregions of Southern California

The invasiveness of nonnative taxa can vary across a landscape due to environmental gradients, suggesting that location-dependent management strategies may be more effective at reducing spread compared to a “one size fits all” approach across the entire introduced range. Using bait stations placed along linear transects within habitat preserves, we tested for effects of ecoregion, vegetation, soil moisture, habitat edge type (i.e., moisture source), and distance from edges on the presence of the invasive Argentine ant Linepithema humile in San Diego County, California, a region with high indigenous biodiversity and numerous rare and protected species. Our results showed an inverse relationship between the presence of native ant species and the presence of the Argentine ant across ecoregions, with the latter reaching peak abundance in the coastal terrace. Argentine ant presence was negatively associated with distance from all edge types regardless of location, but the magnitude of this effect varied among ecoregions. In the xeric foothill and inland valleys, the probability of occurrence was nearly 0 at distances of 200 m and 750 m from moisture edges, respectively, whereas in the coastal terrace, the probability remained above 0.80 at distances up to 1.25 km. When compared to previous studies at different spatial scales, these findings provide an alternative perspective on the invasiveness of the Argentine ant at the landscape level. Our results further suggest that efforts to control spread in regions with a Mediterranean climate may be more successful in inland areas, where the ant is likely to have lower environmental tolerance and native ant species may be better able to generate biotic resistance. In contrast, different tactics and expectations may be necessary for coastal areas, where the same constraints are diminished or absent.

Activation of Anopheles stephensi Pantothenate Kinase and Coenzyme A Biosynthesis Reduces Infection with Diverse Plasmodium Species in the Mosquito Host.

Malaria parasites require pantothenate from both human and mosquito hosts to synthesize coenzyme A (CoA). Specifically, mosquito-stage parasites cannot synthesize pantothenate de novo or take up preformed CoA from the mosquito host, making it essential for the parasite to obtain pantothenate from mosquito stores. This makes pantothenate utilization an attractive target for controlling sexual stage malaria parasites in the mosquito. CoA is synthesized from pantothenate in a multi-step pathway initiated by the enzyme pantothenate kinase (PanK). In this work, we manipulated A. stephensi PanK activity and assessed the impact of mosquito PanK activity on the development of two malaria parasite species with distinct genetics and life cycles: the human parasite Plasmodium falciparum and the mouse parasite Plasmodium yoelii yoelii 17XNL. We identified two putative A. stephensi PanK isoforms encoded by a single gene and expressed in the mosquito midgut. Using both RNAi and small molecules with reported activity against human PanK, we confirmed that A. stephensi PanK manipulation was associated with corresponding changes in midgut CoA levels. Based on these findings, we used two small molecule modulators of human PanK activity (PZ-2891, compound 7) at reported and ten-fold EC50 doses to examine the effects of manipulating A. stephensi PanK on malaria parasite infection success. Our data showed that oral provisioning of 1.3 nM and 13 nM PZ-2891 increased midgut CoA levels and significantly decreased infection success for both Plasmodium species. In contrast, oral provisioning of 62 nM and 620 nM compound 7 decreased CoA levels and significantly increased infection success for both Plasmodium species. This work establishes the A. stephensi CoA biosynthesis pathway as a potential target for broadly blocking malaria parasite development in anopheline hosts. We envision this strategy, with small molecule PanK modulators delivered to mosquitoes via attractive bait stations, working in concert with deployment of parasite-directed novel pantothenamide drugs to block parasite infection in the human host. In mosquitoes, depletion of pantothenate through manipulation to increase CoA biosynthesis is expected to negatively impact Plasmodium survival by starving the parasite of this essential nutrient. This has the potential to kill both wild type parasites and pantothenamide-resistant parasites that could develop under pantothenamide drug pressure if these compounds are used as future therapeutics for human malaria.