scholarly journals Effect ofAmblyseius largoensis(Acari: Phytoseiidae) onRaoiella Indica(Acari: Tenuipalpidae) by Predator Exclusion and Predator Release Techniques

2014 ◽  
Vol 97 (1) ◽  
pp. 256-261 ◽  
Author(s):  
Daniel Carrillo ◽  
Marjorie A. Hoy ◽  
Jorge E. Peña
Keyword(s):  
Predator Exclusion ◽  
Predator Release

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

2017 ◽  
Vol 149 (4) ◽  
pp. 525-533 ◽  
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.

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

2015 ◽  
Vol 157 (3) ◽  
pp. 360-364 ◽  
Author(s):  
Ignacio Castellanos ◽  
Pedro Barbosa ◽  
Iriana Zuria ◽  
Astrid Caldas
Keyword(s):  
Antipredator Behavior ◽  
Predator Exclusion ◽  
Insect Predation

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

2017 ◽  
Vol 44 (7) ◽  
pp. 484 ◽  
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.

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

2014 ◽  
Vol 104 (5) ◽  
pp. 576-585 ◽  
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.

Choosing cost-effective locations for conservation fences in the local landscape

2012 ◽  
Vol 39 (3) ◽  
pp. 192 ◽  
Author(s):  
Michael Bode ◽  
Karl E. C. Brennan ◽  
Keith Morris ◽  
Neil Burrows ◽  
Neville Hague
Keyword(s):  
Systematic Approach ◽  
Decision Support Tool ◽  
Cost Effective ◽  
Small Scale ◽  
Decision Making Process ◽  
Large Set ◽  
Expected Return ◽  
Support Tool ◽  
Funding Sources ◽  
Predator Exclusion

Context Exclosure fences are widely used to reintroduce locally extinct animals. These fences function either as permanent landscape-scale areas free from most predators, or as small-scale temporary acclimatisation areas for newly translocated individuals to be ‘soft released’ into the wider landscape. Existing research can help managers identify the best design for their exclosure fence, but there are currently no methods available to help identify the optimal location for these exclosures in the local landscape (e.g. within a property). Aims We outline a flexible decision-support tool that can help managers choose the best location for a proposed exclosure fence. We applied this method to choose the site of a predator-exclusion fence within the proposed Lorna Glen (Matuwa) Conservation Park in the rangelands of central Western Australia. Methods The decision was subject to a set of economic, ecological and political constraints that were applied sequentially. The final exclosure fence location, chosen from among those sites that satisfied the constraints, optimised conservation outcomes by maximising the area enclosed. Key results From a prohibitively large set of potential exclosure locations, the series of constraints reduced the number of candidates down to 32. When ranked by the total area enclosed, one exclosure location was clearly superior. Conclusions By describing the decision-making process explicitly and quantitatively, and systematically considering each of the candidate solutions, our approach identifies an efficient exclosure fence location via a repeatable and transparent process. Implications The construction of an exclusion fence is an expensive management option, and therefore needs to convincingly demonstrate a high expected return-on-investment. A systematic approach for choosing the location of an exclosure fence provides managers with a decision that can be justified to funding sources and stakeholders.

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

2012 ◽  
Vol 77 (2) ◽  
pp. 352-358 ◽  
Author(s):  
Lora L. Smith ◽  
David A. Steen ◽  
L. Mike Conner ◽  
Jessica C. Rutledge
Keyword(s):  
Gopher Tortoise ◽  
Predator Exclusion

scholarly journals Breeding Success in the Western Gull × Glaucous-Winged Gull Complex: The Influence of Habitat and Nest-Site Characteristics

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 353-365 ◽  
Author(s):  
Thomas P. Good
Keyword(s):  
Breeding Success ◽  
Nearest Neighbor ◽  
Physical Structure ◽  
Breeding Performance ◽  
Nesting Ecology ◽  
Larus Occidentalis ◽  
Western Gull ◽  
Hybrid Complex ◽  
Predator Exclusion ◽  
Para Determinar

AbstractThe nesting ecology of breeding pairs of the Western Gull × Glaucous-winged Gull (Larus occidentalis × glaucescens) hybrid complex was investigated at two locations in coastal Washington. In Grays Harbor, breeding performance (clutch size, hatching and fledging success) was highest in vegetated habitat where nests were most dense and where natural screens blocked the nearest neighbor. Egg loss, presumably from gull predators, was common except in areas of dense vegetation. At Tatoosh Island, egg loss was rare, and breeding performance was similar in vegetated and rock habitats. To test if physical structure around open-area nests influenced egg loss in Grays Harbor, predator-exclusion fences were erected around nests on a sandbar island lacking vegetation. Excluding predators reduced egg loss and increased hatching success relative to nests with adjacent natural screens (driftwood logs >30 cm tall) or nests lacking natural screens. Pairs that nest in habitats with adequate habitat structure appear to benefit in terms of lower egg loss and higher nesting success, especially in Grays Harbor. Increasing structure around individual nests may increase breeding success of gulls or other seabirds that experience extensive nest predation.Éxito Reproductivo en el Complejo Larus occidentalis × glaucescens: Influencia del Hábitat y las Características del Sitio de AnidaciónResumen. La ecología de anidación de parejas reproductivas del complejo híbrido Larus occidentalis × glaucescens fue investigada en dos localidades en la costa de Washington. En Grays Harbor, el desempeño reproductivo (en términos del tamaño de la nidada y el éxito de eclosión y emplumamiento) fue máximo en ambientes con vegetación donde los nidos estaban a mayor densidad y donde el vecino más cercano estaba separado por barreras naturales. La pérdida de huevos (presumiblemente ante gaviotas depredadoras) fue común excepto en áreas con vegetación densa. En la isla Tatoosh, la pérdida de huevos fue poco frecuente y el desempeño reproductivo fue similar en ambientes con vegetación y ambientes rocosos. Para determinar si la estructura física alrededor de los nidos en áreas abiertas influenciaba la pérdida de huevos en Grays Harbor, se construyeron cercas para excluir a los depredadores alrededor de nidos en una isla arenosa carente de vegetación. La exclusión de depredadores redujo la pérdida de huevos e incrementó el éxito de eclosión con relación a nidos con barreras naturales adyacentes (troncos de >30 cm de alto) y a nidos sin barreras naturales. Las parejas que anidan en ambientes con estructura de hábitat adecuada parecen beneficiarse en términos de una menor pérdida de huevos y un mayor éxito de anidación, especialmente en Grays Harbor. Incrementar la estructura alrededor de nidos individuales podría aumentar el éxito reproductivo de gaviotas u otras aves marinas sujetas a altos niveles de depredación de nidos.

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