Effects of predator exclusion on nest and hatchling survival in the gopher tortoise

Lora L. Smith; David A. Steen; L. Mike Conner; Jessica C. Rutledge

doi:10.1002/jwmg.449

The Gopher Tortoise in Florida 2007

Turtle and Tortoise Newsletter ◽

10.2744/1526-3096(2008)12[30:tgtif]2.0.co;2 ◽

2008 ◽

Vol 12 (1) ◽

pp. 30

Author(s):

Joan Berish

Keyword(s):

Gopher Tortoise

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Comprehensive health assessment and blood analyte reference intervals of gopher tortoises (Gopherus polyphemus) in southeastern FL, USA

Conservation Physiology ◽

10.1093/conphys/coab015 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Annie Page-Karjian ◽

Kathleen Rafferty ◽

Clerson Xavier ◽

Nicole I Stacy ◽

Jon A Moore ◽

...

Keyword(s):

Plasma Protein ◽

Health Assessment ◽

Clinical Signs ◽

Keystone Species ◽

Reference Intervals ◽

Upper Respiratory Tract ◽

Gopher Tortoise ◽

Gopherus Polyphemus ◽

Baseline Information ◽

Mycoplasma Spp

Abstract The gopher tortoise (Gopherus polyphemus), a keystone species, is declining throughout its geographic range. Lack of knowledge with respect to the potential infectious diseases present within wild populations creates a dilemma for wildlife biologists, conservationists and public policy makers. The objective of this study was to conduct a health assessment of two previously unstudied gopher tortoise aggregations located at two sites in southeastern FL. Samples were collected from 91 tortoises (48 adults, 35 juveniles, 8 hatchlings) captured at Florida Atlantic University’s Harbor Branch Oceanographic Institute, in Fort Pierce, FL, USA in 2019, and Loggerhead Park in Juno Beach, FL, USA, during 2018–2019. Samples of blood, nasal swabs and oral/cloacal swabs were analyzed for hematology, plasma protein electrophoretic profiles and infectious disease testing including Mycoplasma spp. serology and polymerase chain reaction (PCR) assays for Ranavirus, Herpesvirus and Anaplasma spp. Hematological and plasma protein electrophoresis reference intervals are presented for adult and juvenile tortoises from both sites combined. Clinical signs consistent with upper respiratory tract disease (URTD) were observed in 18/91 (20%) tortoises, and antibodies to Mycoplasma agassizii were detected in 33/77 (42.9%) tortoises. Adult tortoises were significantly more likely than juveniles to have URTD clinical signs, and statistically significant, positive relationships were observed between the presence of antibodies to Mycoplasma spp. and carapace length, packed cell volume and plasma globulin concentrations. Anaplasma spp. inclusions were observed in 8/82 (10%) tortoises, but PCR detected Anaplasma sp. in 21/83 (25%) tortoises. Herpesvirus and Ranavirus were not detected in any blood or swab samples. This work contributes important baseline information on the health of gopher tortoises toward the southern end of the species’ range.

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Assessing the role of generalist predators in the biological control of alfalfa weevil (Coleoptera: Curculionidae)

The Canadian Entomologist ◽

10.4039/tce.2017.9 ◽

2017 ◽

Vol 149 (4) ◽

pp. 525-533 ◽

Cited By ~ 1

Author(s):

Tatyana A. Rand

Keyword(s):

United States ◽

Biological Control ◽

Experimental Work ◽

United States Of America ◽

Acyrthosiphon Pisum ◽

The United States ◽

Generalist Predators ◽

Alfalfa Weevil ◽

Exclusion Experiment ◽

Predator Exclusion

AbstractAlfalfa weevil (Coleoptera:Curculionidae) is a major pest of alfalfa throughout the United States of America. Biological control research has disproportionately focussed on introduced parasitoids. Generalist predators may also be important, but experimental work evaluating their impacts is lacking. I combined a cross-site survey with a predator exclusion experiment to identify key predators, and test for impacts on weevil survival and plant defoliation levels in Montana and North Dakota, United States of America. Spiders (Araneae) dominated the complex, followed by Nabidae (Hemiptera) and Coccinellidae (Coleoptera). None of the dominant predators showed aggregative responses to weevil (Hypera postica (Gyllenhal); Coleoptera: Curculionidae) or pea aphid (Acyrthosiphon pisum (Harris); Hemiptera: Aphididae) densities across 10 sites surveyed. However, weevil densities were positively correlated with both coccinellid and nabid densities across transects at the experimental site. Thus, predator groups traditionally associated with aphids can show strong aggregative numerical responses to alfalfa weevil larvae at smaller scales. Predator exclusion revealed no significant predator effects on larval survival or alfalfa damage. However, final densities of pea aphids were significantly higher in exclusion treatments relative to controls. The results suggest that even under conditions where predators exert significant pressure on aphids, they may still have minimal impacts on weevils. Additional experimental work is necessary to determine the broader potential of generalist predators as alfalfa weevil control agents.

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Quantifying insect predation with predator exclusion cages: the role of prey antipredator behavior as a source of bias

Entomologia Experimentalis et Applicata ◽

10.1111/eea.12375 ◽

2015 ◽

Vol 157 (3) ◽

pp. 360-364 ◽

Cited By ~ 3

Author(s):

Ignacio Castellanos ◽

Pedro Barbosa ◽

Iriana Zuria ◽

Astrid Caldas

Keyword(s):

Antipredator Behavior ◽

Predator Exclusion ◽

Insect Predation

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Assisted colonisation trial of the eastern barred bandicoot (Perameles gunnii) to a fox-free island

Wildlife Research ◽

10.1071/wr16198 ◽

2017 ◽

Vol 44 (7) ◽

pp. 484 ◽

Cited By ~ 6

Author(s):

Rebecca Groenewegen ◽

Dan Harley ◽

Richard Hill ◽

Graeme Coulson

Keyword(s):

Habitat Use ◽

Body Condition ◽

Red Fox ◽

Suitable Habitat ◽

Viable Option ◽

Predator Exclusion ◽

In The Wild ◽

Radio Transmitters ◽

Release Group ◽

Small Sites

Context Assisted colonisation has the potential to protect species from intractable threats within their historical ranges. The Australian mainland subspecies of the eastern barred bandicoot (Perameles gunnii) is extinct in the wild, with surviving populations restricted to small sites protected by predator–barrier fences. PVA modelling shows that a self-sustaining bandicoot population would require an area free of the introduced red fox (Vulpes vulpes) of at least 2500ha. French Island is outside the historic range of the species, but is fox-free and contains around 9000ha of potentially suitable habitat. Aims This study will assess the suitability of French Island as a potential site for a self-sustaining eastern barred bandicoot population by conducting a 1-year assisted colonisation trial to assess habitat use, body condition and survival. Methods Between July and September 2012, 18 adult bandicoots were released. We radio-tracked bandicoots using intraperitoneal radio-transmitters for up to 122 days and trapped fortnightly. Key results The release group met the three measures of success: (1) appropriate habitat use; (2) recovery of post-release bodyweight; and (3) founder survival exceeding 100 days. Habitat use and body condition throughout the trial reflected that of mainland populations, and seven bandicoots survived longer than 100 days. Mortality was greatest in the first month, with veterinary investigations confirming two deaths due to cat predation, two deaths from toxoplasmosis and one unknown cause of death. Bandicoots that survived longer than 100 days occupied higher, drier ground than those that did not. Toxoplasmosis cases were associated with lower topographic position on the site. Conclusions Our results suggest that French Island provides suitable habitat for the establishment of a population of eastern barred bandicoots. On French Island, toxoplasmosis was identified as an important source of mortality in addition to cat predation, and warrants further investigation. Implications Given the costs and challenges of predator control and the maintenance of predator exclusion fences, assisted colonisation to one or more fox-free islands remains the most viable option to establish self-sustaining bandicoot populations. Our results highlight the value in conducting trial releases ahead of major translocations.

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Insecticide sprays, natural enemy assemblages and predation on Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae)

Bulletin of Entomological Research ◽

10.1017/s0007485314000315 ◽

2014 ◽

Vol 104 (5) ◽

pp. 576-585 ◽

Cited By ~ 29

Author(s):

C. Monzo ◽

J.A. Qureshi ◽

P.A. Stansly

Keyword(s):

Natural Enemy ◽

Early Spring ◽

Citrus Greening ◽

Asian Citrus Psyllid ◽

Late Winter ◽

Diaphorina Citri ◽

Citrus Groves ◽

Arthropod Fauna ◽

Predator Exclusion ◽

Insecticide Sprays

AbstractThe Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of ‘huanglongbing’ (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.

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