Showing papers by "Roger A. Baldwin published in 2016"

Cholecalciferol plus diphacinone baits for vole control: a novel approach to a historic problem

Abstract: Combination baits containing cholecalciferol plus an anticoagulant are effective against commensal ro- dents resistant to anticoagulants, and they likely pose less risk than anticoagulant-only rodenticides due to lower con- centrations of active ingredients and shorter time to death. However, these combination baits have not been tested for agricultural rodent pests. Therefore, we established a study to test the efficacy of cholecalciferol plus diphacinone arti- choke bract and pellet baits to determine their ability to manage California voles Microtus californicus in artichokes, where resistance to anticoagulants is known to occur. Field tests using radiocollared voles indicated that bract baits were highly efficacious (85 %), although pellet baits were less effective (60 %). Low observed efficacy of pellet baits may have resulted from poor weather following application during the second sampling period; further testing may yield more positive results. We observed a bimodal distribution in timing of death, with one group of voles dying between 4.3 and 5.8 days post-consumption; the other group died be- tween 9.0 and 14.5 days post-consumption. Deaths in the first group were attributed to cholecalciferol, while deaths in the second group were likely due to chronic anticoagulant exposure. Almost double the proportion of voles that died from bract consumption did so during the early period when compared to their pellet plot counterparts. This suggests that voles were consuming greater quantities of bract baits over a shorter period of time when compared to the pellet bait. Collectively, these findings indicate that baiting with cholecalciferol plus diphacinone coated bracts is an effective method for controlling vole populations in artichokes.

Gopherbusters? A Review of the Candidacy of Barn Owls as the Ultimate Natural Pest Control Option

Abstract: Author(s): Kross, Sara M.; Baldwin, Roger A. | Abstract: While many raptor species consume rodent pests, the behaviors and habits of barn owls make them particularly suitable candidates for consideration as a viable pest control strategy. As a cavity-nesting species, barn owls will readily nest in man-made structures including nest boxes. Barn owls are also less territorial than many other raptor species and will tolerate other pairs nesting nearby if prey is abundant. Barn owls preferentially consume rodents including voles (Microtus spp.) and pocket gophers (Thomomys spp.) in habitats where they occur, but will also switch to more abundant prey so they may be able to sustain populations even if preferred prey numbers fall. These life-history traits allow for people to inflate barn owl populations in target areas, and this has been a factor in the widespread popularity of encouraging barn owls to nest in agricultural areas to provide natural pest control of small nocturnal vertebrate pests. However, the ability of barn owls to control rodent pests has only been formally tested in Malaysian rice and palm oil agriculture, and whether barn owls are capable of controlling rodent pests to economically acceptable levels in areas such as California is as yet unknown. We extracted and combined data from field studies of barn owl nesting behavior and diet in California vineyards to predict that annually, a pair of nesting barn owls and their progeny will consume 97.85 kg of prey. We predicted that an average barn owl nest in a California vineyard will therefore consume 843 pocket gophers, 578 voles, and 1,540 other prey items, most of which are mice. At these values, a barn owl population density of one nest/10 ha may be able to offset the annual productivity of an average population of pocket gophers, but even the highest barn owl densities of one nest/2 ha would be unable to control pocket gopher populations at maximum densities and reproductive rates. While valuable for making initial predictions of the ability of owls to control small rodent pests, our prediction methods are crude, and accurately assessing the capability of barn owls to control rodent pests will require more field data and more sophisticated modeling techniques.

Burrow fumigation versus trapping for pocket gopher (Thomomys spp.) management: a comparison of efficacy and cost effectiveness

Abstract: Context. Pocket gophers (Geomyidae) cause extensive damage to many crops throughout western North America. A variety of methods are available to manage these populations, but data are often lacking on their efficacy and especially their cost effectiveness. Additionally, little peer-reviewed data are available that compare multiple methods simultaneously. Aims. We tested aluminum phosphide and pressurised exhaust using the Pressurised Exhaust Rodent Controller (PERC) as burrow fumigants, and compared them to trapping to determine which approach was most efficacious and cost effective. Methods. We assessed the efficacy of aluminum phosphide, the PERC machine, and trapping through the use of the open-hole monitoring method after single and multiple treatments over multiple years. We determined material and labour costs for each treatment type and amortised this cost over 1250 days of application to determine which treatment type was most cost effective. Key results. Aluminum phosphide had the shorte...

Are Cholecalciferol plus Anticoagulant Rodenticides a Viable Option for Field Rodents

Abstract: Author(s): Baldwin, Roger A.; Meinerz, Ryan; Witmer, Gary W. | Abstract: Burrowing rodents, such as pocket gophers (Geomyidae) and voles (Microtus spp.), often cause extensive damage in agricultural, urban/residential, and natural resource areas. Effective management of burrowing rodents typically follows an integrated pest management (IPM) approach that involves a number of tools including rodenticide baiting. However, some of the more commonly used rodenticides have limitations including the development of resistance (e.g., first-generation anticoagulants and strychnine), secondary-toxicity concerns (e.g., anticoagulants), and limited availability (e.g., strychnine). Initial research with combination cholecalciferol plus anticoagulant rodenticides has indicated potential promise at overcoming some of these limitations. As such, we tested the efficacy of several different cholecalciferol plus anticoagulant combinations to determine if they were efficacious in managing Botta’s pocket gophers and California voles in both cage and field trials. Two-choice cage trials for California voles indicated that both pelletized (0.03% cholecalciferol plus 0.005% diphacinone, efficacy = 80%) and bract baits (0.012% cholecalciferol plus 0.002% diphacinone, efficacy = 70%) containing cholecalciferol plus diphacinone (C+D) were efficacious. Further field testing indicated that C+D-coated bract baits (0.014% cholecalciferol plus 0.003% diphacinone) were highly efficacious for vole control (efficacy = 85%), while pelletized baits were less promising (efficacy = 60%). Cage trials indicated that both C+D (0.03% cholecalciferol plus 0.005% diphacinone, efficacy = 80%) and two concentrations of cholecalciferol plus brodifacoum (C+B1 = 0.015% cholecalciferol plus 0.0025% brodifacoum, efficacy = 100%; C+B2 = 0.03% cholecalciferol plus 0.0025% brodifacoum, efficacy = 100%) pelleted baits showed promise as pocket gopher rodenticides. Further field testing of C+D and C+B2 resulted in efficacy significantly g70% (efficacy = 83% and 75%, respectively), although strychnine (0.5%) applications were the most efficacious (efficacy = 100%). Collectively, these results suggest that cholecalciferol plus anticoagulant rodenticides are effective options for managing burrowing rodent populations; they deserve further consideration for registration against these potentially damaging species.

User-Friendly Resource Design: Providing Accessible Ground Squirrel Extension for the Web

Abstract: Author(s): Dimson, Monica; Baldwin, Roger A.; Quinn, Niamh | Abstract: In terms of internet access, California farmers are some of the most well-connected in the country. According to the USDA, 70% of farms in the U.S. have access to the web as of 2015. In California, 93% of counties exceed that national average. This prompts us to take advantage of the opportunity to employ passive extension approaches, such as websites, which can save both time and resources for Extension audiences and personnel alike. Because digital media can be distributed without the expenses associated with static print resources, this allows us to update our information platforms with greater ease and frequency. Our goal is not to replace print publications, but to adapt Extension resources for a web context and thus connect with a large and geographically extensive audience, especially those who may not customarily seek or have access to more traditional Extension services. A website allows homeowners, landowners, and pest-control professionals to consult this resource freely, at their leisure, and to adopt best management practices more quickly. However, the movement toward cloud-based resources comes with greater web familiarity and thus greater expectations for the websites people use. We are currently developing a ground squirrel best management practices website. In order to provide a user-oriented experience comparable to that of other digital media resources, we need to consider the specific needs and behaviors of a web-based audience. We aim to achieve this by synthesizing new and existing resources into consumable, approachable content on a website that focuses on usability, clarity, visual impact, and site-wide cohesion. We will discuss these goals and how we achieved them.

An Evaluation of Potential Repellents for Botta's Pocket Gopher

Abstract: Author(s): Witmer, Gary W.; Moulton, Rachael S.; Baldwin, Roger A. | Abstract: Pocket gophers are fossorial rodents that cause substantial damage to crops, reforestation, and property. We tested potential repellents to identify candidates to reduce irrigation tubing damage. We dipped carrot chunks in the test materials, using mineral oil as the solvent. Gophers prefer tuberous roots and, when kept in captivity, are often fed carrots as part of their maintenance diet. None of the materials tested proved effective as repellents, even at concentrations as high as 20% active ingredient or in combinations. Wood blocks soaked in a few of the repellents received nearly significantly less damage than the control blocks and could be looked at further as repellents. However, it appears that the quest for an effective gopher repellent will continue to elude researchers.