Low predation rates on the larvae of three species of barnacles by the ctenophore Pleurobrachia pileus

2015 ◽  
Vol 541 ◽  
pp. 105-122 ◽  
Author(s):  
KA Sorochan ◽  
A Metaxas
Keyword(s):  
Pleurobrachia Pileus ◽  
Predation Rates

Occurrence of hydromedusae in the plankton off Northumberland (western central North Sea) and the role of planktonic predators

1999 ◽  
Vol 79 (6) ◽  
pp. 979-992 ◽  
Author(s):  
K.R. Nicholas ◽  
C.L.J. Frid
Keyword(s):  
North Sea ◽  
East Coast ◽  
North East ◽  
The North ◽  
Pleurobrachia Pileus ◽  
Predatory Impact ◽  
Meganyctiphanes Norvegica ◽  
Central North Sea ◽  
Predation Rates

The pattern of occurrence of medusae off the north-east coast of England are described for the period 1990–1996. The predatory role of the medusae, Aglantha digitale, was examined by comparison of estimated predation rates with those of other planktonic predators. Aglanthe digitale was found to have the potential to considerably reduce copepod abundances, particularly in winter. Other important predators were the amphipod Themisto compressa and the chaetognath Sagitta elegans. There was a great deal of seasonal and interannual variability in predatory impact, with predators such as Pleurobrachia pileus and Meganyctiphanes norvegica occasionally exerting a high predatory impact. Previous studies have identified an important community structuring role for predation in winter in this area, this study shows that planktonic predators can influence copepod abundances throughout the year.

Effects of Predation and Trophic Conditions on the Reproduction of Tylototriton verrucosus (Caudata: Salamandridae) in Darjeeling

2011 ◽  
Vol 4 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Ritwik Dasgupta
Keyword(s):  
Frequency Distribution ◽  
Primary Productivity ◽  
Egg Size ◽  
Zooplankton Abundance ◽  
Trophic Conditions ◽  
Size Frequency Distribution ◽  
Size Frequency ◽  
High Predation ◽  
Hatchling Size ◽  
Predation Rates

The facts that small hatchlings emerged from small eggs laid under high predation levels prevailing at the lower altitudes of distribution of this species in Darjeeling while larger hatchlings emerged from larger eggs laid under lower levels of predation at higher altitudes, show that predation is not selected for large egg and initial hatchling size in this salamandrid species. Metamorphic size was small under high predation rates because this species relied on crypsis for evading predators. Egg and hatchling size are related inversely to levels of primary productivity and zooplankton abundance in lentic habitats. Hatchling sizes are related positively to egg size and size frequency distribution of zooplankton. Small egg and small hatchling size have been selected for at the lower altitudes of distribution of this salamandrid in Darjeeling because predation rates increased in step with improvement in trophic conditions at the lower altitudes.

Background matching

2018 ◽  
Author(s):  
Graeme D. Ruxton ◽  
William L. Allen ◽  
Thomas N. Sherratt ◽  
Michael P. Speed
Keyword(s):  
Evolutionary Biology ◽  
Complex Environment ◽  
Background Matching ◽  
Highly Effective ◽  
Predation Rates

Background matching is perhaps the most obvious phenomenon that falls under the label of crypsis. Stevens & Merilaita (2011) describe background matching as situations where ‘the appearance generally matches the colour, lightness and pattern of one (specialized) or several (compromise) background types’. There are fascinating examples of species that behaviourally select their microhabitat and orientation so as to enhance similarity to features of the background, and species that change aspects of their appearance in ways that enhance background matching. The degree of background matching is often imperfect; this is thought to commonly reflect the fact that organisms are viewed against a range of different backgrounds, and so they have evolved appearance traits that offer some degree of matching against several of these. Understanding background matching addresses important issues in evolutionary biology, such as the maintenance of polymorphisms. We discuss how predation rates that depend on the frequency of morphs in the environment may be a common explanation for polymorphic crypsis, and the role search images might play in this process. Achieving highly effective background matching in a complex environment is difficult and this may create room for other types of crypsis.

scholarly journals Organic Farming and Cover-Crop Management Reduce Pest Predation in Austrian Vineyards

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 220
Author(s):  
Jo Marie Reiff ◽  
Sebastian Kolb ◽  
Martin H. Entling ◽  
Thomas Herndl ◽  
Stefan Möth ◽  
...  
Keyword(s):  
Organic Farming ◽  
Pest Control ◽  
Cover Crops ◽  
Cover Crop ◽  
Management Practices ◽  
Integrated Management ◽  
Lobesia Botrana ◽  
Management Options ◽  
Natural Pest Control ◽  
Predation Rates

Habitat simplification and intensive use of pesticides are main drivers of global arthropod declines and are, thus, decreasing natural pest control. Organic farming, complex landscapes, and local vineyard management practices such as implementation of flower-rich cover-crop mixtures may be a promising approach to enhance predator abundance and, therefore, natural pest control. We examined the effect of organic versus integrated management, cover-crop diversity in the vineyard inter-rows, and landscape composition on the natural pest control of Lobesia botrana eggs and pupae. Predation of L. botrana pupae was reduced by organic farming and species-poor cover-crops by about 10%. Predation rates of L. botrana eggs did not differ significantly in any of the studied management options. Dominant predators were earwigs (Forficulidae), bush crickets (Tettigoniidae), and ants (Formicidae). Negative effects of organic viticulture are most likely related to the negative nontarget effects on arthropods related to the frequent sulfur and copper applications in combination with the avoidance of strongly damaging insecticides by integrated winegrowers. While a 10% difference in predation rates on a single pest stage is unlikely to have strong practical implications, our results show that the assumed effectiveness of environmentally friendly agriculture needs to be evaluated for specific crops and regions.

scholarly journals Invertebrate and vertebrate predation rates in a hyperarid ecosystem following an oil spill

2021 ◽  
Author(s):  
Marco Ferrante ◽  
Daniella Möller ◽  
Gabriella Möller ◽  
Esteban Menares ◽  
Yael Lubin ◽  
...  
Keyword(s):  
Oil Spill ◽  
Predation Rates

scholarly journals Do Repugnant Scents Increase Survival of Ground Nests? A Test with Artificial and Natural Duck Nests

2007 ◽  
Vol 121 (2) ◽  
pp. 150
Author(s):  
Vanessa B. Harriman ◽  
Justin A. Pitt ◽  
Serge Larivière
Keyword(s):  
Human Hair ◽  
Nest Predation ◽  
Survival Rates ◽  
Olfactory Cues ◽  
Artificial Nests ◽  
Treatment Groups ◽  
Mammalian Predators ◽  
High Predation ◽  
Ground Nesting ◽  
Predation Rates

Ground-nesting birds typically experience high predation rates on their nests, often by mammalian predators. As such, researchers and wildlife managers have employed numerous techniques to mitigate nest predation. We investigated the use of scents as repellents to deter predators from both artificial and natural ground nests. Survival rates of artificial nests did not differ among six groups of substances (Wald ?2 df = 5 = 4.53, P < 0.48); however the chronology of predation among groups differed. A commercial Coyote urine based deterrent (DEER-D-TERTM), human hair, and Worcestershire sauce were depredated faster than the control (F4,5 = 40.3, P < 0.001). Nest survival of natural nests differed among those groups tested (Wald ?2 df = 2 = 11.8, P < 0.005); the eight mothball treatment decreased survival (Wald ?2 df = 1 = 11.5, P < 0.005), which indicated that novel smells may attract predators or result in duck nest abandonment when coupled with natural duck scent. Chronologies of predation events among treatment groups were not different for natural nests (F2,3 = 1.9, P = 0.22). These findings indicate an interaction between novel scents and predator olfactory cues.

Bad news for bobtails: understanding predatory behaviour of a resource-subsidised corvid towards an island endemic reptile

2018 ◽  
Vol 45 (7) ◽  
pp. 595
Author(s):  
W. Oversby ◽  
S. M. Ferguson ◽  
R. A. Davis ◽  
P. W. Bateman
Keyword(s):  
Human Activity ◽  
Large Population ◽  
Camera Traps ◽  
Bad News ◽  
Human Settlement ◽  
Tourism Impacts ◽  
Predatory Behaviour ◽  
Predator Prey ◽  
Island Endemic ◽  
Predation Rates

Context Resource subsidisation as a result of urbanisation and other human activity can have positive impacts for some opportunistic predators. Many species of corvid have benefitted from the expansion of human-dominated habitats; however, their impacts on co-occurring prey fauna are generally poorly understood. Aims We aimed to test the hypothesis that urbanisation associated with tourism impacts the predator–prey relationship between Australian ravens, or wardongs (Corvus coronoides), a ubiquitous corvid of southern Australia, and Rottnest Island bobtails (Tiliqua rugosa konowi), a subspecies of bobtail lizard isolated to a small (19km2) island off the coast of Western Australia. Methods Using clay model lizards and camera traps, we assessed the wardongs’ attack rates by distance from the settlement and by whether the model was in closed or open habitat. Key Results We found that while wardongs preyed upon Rottnest Island bobtails, predation was not affected by proximity to human settlement despite the highest number of wardongs being found there. Models in closed vegetation were attacked by wardong significantly more than were those in open vegetation. Implications Increased predation rates in closed vegetation suggests that current revegetation efforts on the island may be increasing the availability of preferred hunting habitat for the wardong. This finding may influence decisions by management on whether to control the large population of wardongs on the island.

scholarly journals Land-use components, abundance of predatory arthropods, and vegetation height affect predation rates in grasslands

2019 ◽  
Vol 270-271 ◽  
pp. 84-92 ◽  
Author(s):  
Sebastian T. Meyer ◽  
Lisa Heuss ◽  
Heike Feldhaar ◽  
Wolfgang W. Weisser ◽  
Martin M. Gossner
Keyword(s):  
Land Use ◽  
Vegetation Height ◽  
Predatory Arthropods ◽  
Predation Rates
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