scholarly journals An Alternative Perspective for the Theory of Biological Control

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 131 ◽  
Author(s):  
Nicholas Mills
Keyword(s):  
Biological Control ◽  
Population Growth ◽  
Interaction Strength ◽  
Invasion Biology ◽  
Host Population ◽  
Invasive Pest ◽  
Future Directions ◽  
Relative Population ◽  
Population Growth Rates ◽  
Propagule Size

Importation biological control represents the planned introduction of a specialist natural enemy from the region of origin of an invasive pest or weed. For this study, the author considered why attempts to develop a predictive theory for biological control have been misguided and what future directions might be more promising and effective. Despite considerable interest in the theory of consumer–resource population dynamics, such theory has contributed little to improvements in the success of biological control due to a focus on persistence and equilibrium dynamics rather than establishment and impact. A broader consideration of invasion biology in addition to population ecology offers new opportunities for a more inclusive theory of biological control that incorporates the demographic and genetic processes that more specifically address the establishment and impact of introduced natural enemies. The importance of propagule size and genetic variance for successful establishment, and of contributions to host population growth, relative population growth rates, interaction strength, and coevolution for suppression of host abundance are discussed as promising future directions for a theory of biological control.

scholarly journals How Does Nutrient Availability Affect the Population Dynamics of the Invasive New Zealand Mud Snail (Potamopyrgus Antipodarum)?

2009 ◽  
Vol 32 ◽  
pp. 123-124
Author(s):  
Teresa Tibbets
Keyword(s):  
New Zealand ◽  
Population Growth ◽  
Invasion Biology ◽  
Potamopyrgus Antipodarum ◽  
Trophic Levels ◽  
Invasion Success ◽  
Population Growth Rates ◽  
Mud Snail ◽  
Introduced Range ◽  
New Zealand Mud Snail

A primary goal of invasion biology is to predict which introduced species become invasive and which systems are susceptible to invasion. Therefore it is vital to understand how invasive species sustain positive population growth rates in their introduced range and what environmental factors control population growth. The New Zealand mud snail (Potamopyrgus antipodarum) (Figure 1.) has spread throughout Europe, Australia, and North America, and has reached pest densities in many streams in the Greater Yellowstone Area (GYA) since their introduction in the 1980‘s. High rates of growth and secondary production have been documented for mud snails in its introduced range in the GYA, as have evidence of negative interactions between mud snails and native macroinvertebrates and higher trophic levels. However, little is known about how the availability of nutrients affects the invasion success of mud snails.

scholarly journals Estimates of regional annual abundance and population growth rates of white sharks off central California

2021 ◽  
Vol 257 ◽  
pp. 109104
Author(s):  
Paul E. Kanive ◽  
Jay J. Rotella ◽  
Taylor K. Chapple ◽  
Scot D. Anderson ◽  
Timothy D. White ◽  
...  
Keyword(s):  
Population Growth ◽  
Growth Rates ◽  
Central California ◽  
Population Growth Rates

Demography of Xenosaurus platyceps (Squamata: Xenosauridae): a comparison between tropical and temperate populations

2008 ◽  
Vol 29 (2) ◽  
pp. 245-256 ◽  
Author(s):  
Carissa Jones ◽  
Isaac Rojas-González ◽  
Julio Lemos-Espinal ◽  
Jaime Zúñiga-Vega
Keyword(s):  
Life History ◽  
Population Growth ◽  
Adult Mortality ◽  
Life History Strategies ◽  
Relative Importance ◽  
Theoretical Frameworks ◽  
Population Growth Rates ◽  
Relative Contribution ◽  
Two Populations ◽  
Average Fitness

Abstract There appears to be variation in life-history strategies even between populations of the same species. For ectothermic organisms such as lizards, it has been predicted that demographic and life-history traits should differ consistently between temperate and tropical populations. This study compares the demographic strategies of a temperate and a tropical population of the lizard Xenosaurus platyceps. Population growth rates in both types of environments indicated populations in numerical equilibrium. Of the two populations, we found that the temperate population experiences lower adult mortality. The relative importance (estimated as the relative contribution to population growth rate) of permanence and of the adult/reproductive size classes is higher in the temperate population. In contrast, the relative importance for average fitness of fecundity and growth is higher in the tropical population. These results are consistent with the theoretical frameworks about life-historical differences among tropical and temperate lizard populations.

scholarly journals Phenology and Synchrony of Scymnus coniferarum (Coleoptera: Coccinellidae) with Multiple Adelgid Species in the Puget Sound, WA, USA

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 558
Author(s):  
Molly Darr ◽  
Rachel Brooks ◽  
Nathan Havill ◽  
E. Hoebeke ◽  
Scott Salom
Keyword(s):  
Biological Control ◽  
Puget Sound ◽  
Dna Barcode ◽  
Sequence Divergence ◽  
Adelges Tsugae ◽  
Tsuga Heterophylla ◽  
Seasonal Abundance ◽  
Invasive Pest ◽  
Pinus Monticola ◽  
Conifer Species

The hemlock woolly adelgid (HWA), Adelges tsugae, is an invasive pest of Tsuga spp. in eastern North America. Scymnus coniferarum is a predaceous beetle that was collected from HWA in the western United States. Limited knowledge of this insect in its native habitat led to studies to evaluate its potential for biological control of HWA. Seasonal abundance was sampled at six sites in Tacoma, WA, twice monthly, for one year on different host trees of potential adelgid prey. Tree species included Pseudotsuga menziesii, Pinus contorta, Pinus monticola, and Tsuga heterophylla. Scymnus coniferarum adults were found on all conifer species, except P. menziesii. Each conifer species supported a different adelgid species, suggesting S. coniferarum feeds on multiple adelgid species. More S. coniferarum were found on pine than hemlock. DNA barcoding of S. coniferarum found two distinct clusters that differed by 6% divergence. Beetles in each cluster were co-habiting the same conifer species, and they could not be distinguished morphologically. Further taxonomic studies are needed to understand the significance of DNA barcode sequence divergence. Because S. coniferarum was more frequently associated with pine adelgids than HWA, and because of remaining taxonomic uncertainty, S. coniferarum may not be suitable for HWA biological control.

Assessment of invasive rodent impacts on island avifauna: methods, limitations and the way forward

2015 ◽  
Vol 42 (2) ◽  
pp. 185 ◽  
Author(s):  
Lise Ruffino ◽  
Diane Zarzoso-Lacoste ◽  
Eric Vidal
Keyword(s):  
Population Growth ◽  
Population Level ◽  
Bird Conservation ◽  
Bird Population ◽  
Breeding Parameters ◽  
Population Growth Rates ◽  
Bird Populations ◽  
Field Evidence ◽  
Bird Breeding

Bird conservation is nowadays a strong driving force for prioritising rodent eradications, but robust quantitative estimates of impacts are needed to ensure cost-effectiveness of management operations. Here, we review the published literature to investigate on what methodological basis rodent effects on island bird communities have been evaluated for the past six decades. We then discuss the advantages and limitations of each category of methods for the detection and quantification of impacts, and end with some recommendations on how to strengthen current approaches and extend our knowledge on the mechanisms of impacts. Impact studies (152 studies considered) emphasised seabirds (67%), black rats (63%) and the Pacific Ocean (57%). Among the most commonly used methods to study rodent impacts on birds were the observation of dead eggs or empty nests while monitoring bird breeding success, and the analyses of rodent diets, which can both lead to misleading conclusions if the data are not supported by direct field evidence of rodent predation. Direct observations of rodent–bird interactions (19% of studies) are still poorly considered despite their potential to reveal cryptic behaviours and shed light on the mechanisms of impacts. Rodent effects on birds were most often measured as a change or difference in bird breeding parameters (74% of studies), while estimates of bird population growth rates (4%) are lacking. Based on the outcomes of this literature review, we highlight the need for collecting unbiased population-level estimates of rodent impacts, which are essential prerequisites for predicting bird population growth scenarios and prioritising their conservation needs. This could be achieved by a more systematic integration of long-term monitoring of bird populations into rodent management operations and modelling bird population dynamics. We also strongly recommend including various complementary methods in impact assessment strategies to unravel complex interactions between rodents and birds and avoid faulty evidence. Finally, more research should be devoted to a better understanding of the cases of non-impacts (i.e. long-term coexistence) and those impacts mediated by mechanisms other than predation and ecosystem-level processes.

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