Inverse density dependence of parity rates in the onchocerciasis vectorSimulium damnosum s.l.

2015 ◽  
Vol 30 (1) ◽  
pp. 85-88 ◽  
Author(s):  
R. A. CHEKE ◽  
S. YOUNG ◽  
R. GARMS
Keyword(s):  
Density Dependence ◽  
Inverse Density Dependence

Regulation of nematode fecundity in the ring-necked pheasant (Phasianus colchicus): not just density dependence

Parasitology ◽  
1999 ◽  
Vol 118 (4) ◽  
pp. 417-423 ◽  
Author(s):  
D. M. TOMPKINS ◽  
P. J. HUDSON
Keyword(s):  
Density Dependence ◽  
Good Predictor ◽  
Phasianus Colchicus ◽  
Common Pattern ◽  
Infection Experiment ◽  
Stunted Growth ◽  
Heterakis Gallinarum ◽  
Parasite Intensity ◽  
Inverse Density Dependence ◽  
The Common

Patterns of nematode fecundity were investigated for infections of the caecal worm Heterakis gallinarum in the ring-necked pheasant (Phasianus colchicus). Worm length was a good predictor of parasite fecundity. After controlling for worm length no other factors, including parasite intensity, were related to worm fecundity. Density dependence in worm size was detected in natural infections at parasite intensities above a threshold of 96 worms (worm size decreased with increasing parasite intensity). However, below this threshold, worm size actually decreased with decreasing parasite intensity (inverse density dependence). The interaction between density dependence and inverse density dependence in regulating the development and subsequent fecundity of H. gallinarum worms in ring-necked pheasants was demonstrated in an infection experiment. Density dependence was observed in the stunted growth of worms in heavily infected hosts, relative to worms in lightly infected hosts. Inverse density dependence in worm size was the common pattern across hosts by the end of the experiment, when parasite intensities were below the density dependence threshold. This is the first study to document both density dependence and inverse density dependence in parasite fecundity in the same host–helminth system.

scholarly journals Influence of distance from adjacent forest fragments on aphids (Hemiptera: Aphididae) parasitoidism in wheat fields in Parana State, Brazil

2016 ◽  
Vol 42 (1) ◽  
pp. 1 ◽  
Author(s):  
Orcial Ceolin Bortolotto ◽  
Ayres De Oliveira Menezes Jr. ◽  
Adriano Thibes Hoshino ◽  
Hugo Reis Medeiros
Keyword(s):  
Density Dependence ◽  
Natural Enemies ◽  
Neotropical Region ◽  
Agricultural Landscapes ◽  
Clear Relationship ◽  
Forest Fragments ◽  
The North ◽  
Inverse Density Dependence ◽  
Planting Season ◽  
Aphid Abundance

In agricultural landscapes, non-crop habitats, such as forest fragments, may not only play an important role for natural enemies, but may also favor some pests. However, there is a lack of studies in Neotropical regions about these interactions. Thus, the aim of this study was to investigate aphid parasitoidism at two distances (25 m and 525 m) from edges of forest fragments adjacent to wheat crops. This research was carried out in four wheat fields in the north of the Parana state, Brazil, during the planting season of 2009. In total, 8,392 aphids were counted, representing two species. There were 589 total aphid-parasitized (“mummies”), represented by six species. In all four areas, aphid abundance and parasitoidism showed no clear relationship to distance from forest fragments (25 m and 525 m). In addition, inverse density dependence between aphids and parasitoidism was observed. In summary, this study does not support the hypothesis of higher parasitoidism of aphids near edges of forest fragments. However, this is the first study in the Neotropical region and more research must be done to better understand this tritrophic interaction.

Inverse density dependence and the Allee effect

1999 ◽  
Vol 14 (10) ◽  
pp. 405-410 ◽  
Author(s):  
Franck Courchamp ◽  
Tim Clutton-Brock ◽  
Bryan Grenfell
Keyword(s):  
Density Dependence ◽  
Allee Effect ◽  
Inverse Density Dependence

Delayed and inverse density dependence in a chamois population of the Italian Alps

Ecography ◽  
1997 ◽  
Vol 20 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Angel F. Capurro ◽  
Marino Gatto ◽  
Guido Tosi
Keyword(s):  
Density Dependence ◽  
Italian Alps ◽  
Inverse Density Dependence

Joint effects of inverse density-dependence and extreme environmental variation on the viability of a social bird species

Ecoscience ◽  
2010 ◽  
Vol 17 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Aggeliki Doxa ◽  
Konstantinos Theodorou ◽  
Dionyssia Hatzilacou ◽  
Alain Crivelli ◽  
Alexandre Robert
Keyword(s):  
Density Dependence ◽  
Bird Species ◽  
Environmental Variation ◽  
Joint Effects ◽  
Inverse Density Dependence
Sign in / Sign up

Export Citation Format

Share Document