Effectiveness of Sterile Boll Weevils (Coleoptera: Curculionidae) Against a Low-Density Population in Commercially Grown Cotton in Northcentral Mississippi

1989 ◽  
Vol 82 (2) ◽  
pp. 472-476 ◽  
Author(s):  
E. J. Villavaso ◽  
J. L. Roberson ◽  
R. W. Seward
Keyword(s):  
Low Density ◽  
Density Population

scholarly journals Ability of Spalangia endius (Hymenoptera: Pteromalidae) to Parasitize Bactrocera dorsalis (Diptera: Tephritidae) after Switching Hosts

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 613
Author(s):  
Yuan Zheng ◽  
Zi-Wei Song ◽  
Yu-Ping Zhang ◽  
Dun-Song Li
Keyword(s):  
Bactrocera Dorsalis ◽  
Low Density ◽  
Type Ii ◽  
Emergence Time ◽  
Functional Responses ◽  
Parasitism Rate ◽  
Spalangia Endius ◽  
Pupal Parasite ◽  
Density Population

We studied the parasitism capacity of Spalangia endius as a pupal parasite of Bactocera dorsalis after switching hosts. We used pupae of B. dorsalis and M. domestica as the hosts and studied parasitism by S. endius in the laboratory. The parasitism capacities were compared at different host densities and different parasitoid ages. The two functional responses of S. endius fitted a Holling Type II equation. More M. domestica were parasitized than B. dorsalis at all the densities. The ability of S. endius to control M. domestica was α/Th (parasitism capacity) = 32.1950, which was much stronger than that of control B. dorsalis, which was α/Th = 4.7380. The parasitism rate of wasps that had parasitized B. dorsalis had decreased by the emergence time of parasitoids. These results suggest that the parasitoid-pest ratio should be 1:25 to maintain a relatively stable parasitism rate for control of B. dorsalis. The S. endius colony reared on M. domestica successfully controlled a low-density population of B. dorsalis in the lab. We provide evidence suggesting that the parasitism capacity of S. endius needs to be improved.

scholarly journals A fencing experiment on a high-density population of Microtus townsendii

1977 ◽  
Vol 55 (7) ◽  
pp. 1166-1175 ◽  
Author(s):  
Rudy Boonstra ◽  
Charles J. Krebs
Keyword(s):  
Survival Rate ◽  
Breeding Season ◽  
Population Regulation ◽  
Control Area ◽  
High Density ◽  
Low Density ◽  
Vole Population ◽  
Sharp Decline ◽  
Density Population ◽  
Microtus Townsendii

If dispersal is prevented, a low-density vole population will increase to unusually high densities. A mouse-proof fence was constructed around a vole population that had already reached high density and both this population and one on a control area were live-trapped from January 1975 to November 1975. The population on the control remained at peak densities. The enclosed population increased to even higher density once the breeding season had started and had a higher survival rate than the control population. By midsummer the enclosed population had severely overgrazed the vegetation and went into a sharp decline. Dispersal losses from the control were estimated at 32% for males and 31% for females in these high-density populations. Microtus townsendii populations thus responded to a fence in a manner similar to that of other species that have been studied. This experiment indicates the importance of dispersal to population regulation in voles even at peak densities.

scholarly journals Anatomy and physiology of Cattail as related to different population densities

2015 ◽  
Vol 33 (1) ◽  
pp. 01-12 ◽  
Author(s):  
F.F. CORRÊA ◽  
R.H. MADAIL ◽  
S. BARBOSA ◽  
M.P. PEREIRA ◽  
E.M. CASTRO ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Density ◽  
Root Anatomy ◽  
Low Density ◽  
Typha Angustifolia ◽  
Anatomy And Physiology ◽  
Shoot Ratio ◽  
Root Shoot Ratio ◽  
Apoplastic Barriers ◽  
Density Population

The objective of this work was to evaluate the effects of the population density of Typha angustifolia plants in the anatomical and physiological characteristics. Plants were collected from populations of high density (over 50% of colonization capacity) and low density (less than 50% of colonization capacity) and cultivated under controlled greenhouse conditions. Plants from both populations were grown in plastic trays containing 4 L of nutritive solution for 60 days. At the end of this period, the relative growth rate, leaf area ratio, net assimilatory rate, root/shoot ratio, leaf anatomy, root anatomy, and catalase and ascorbate peroxidase activities were evaluated. Plants from high density populations showed increased growth rate and root/shoot ratio. Low density populations showed higher values of stomatal index and density in leaves, as well as increased palisade parenchyma thickness. Root epidermis and exodermis thickness as well as the aerenchyma proportion of high density populations were reduced, these plants also showed increased vascular cylinder proportion. Only catalase activity was modified between the high and low density populations, showing increased values in low density populations. Therefore, different Typha angustifolia plants show differences in its anatomy and physiology related to its origins on high and low density conditions. High density population plants shows increased growth capacity related to lower apoplastic barriers in root and this may be related to increased nutrient uptake capacity.

Spatial behaviour of little owls (Athene noctua) in a declining low-density population in Denmark

2009 ◽  
Vol 150 (3) ◽  
pp. 537-548 ◽  
Author(s):  
Peter Sunde ◽  
Kasper Thorup ◽  
Lars B. Jacobsen ◽  
Miriam H. Holsegård-Rasmussen ◽  
Nina Ottessen ◽  
...  
Keyword(s):  
Low Density ◽  
Spatial Behaviour ◽  
Athene Noctua ◽  
Density Population

Covey Membership and Size Dynamics in a Low Density Population of Northern Bobwhites

2013 ◽  
Vol 125 (4) ◽  
pp. 833-840 ◽  
Author(s):  
Adam K. Janke ◽  
Robert J. Gates ◽  
Mark J. Wiley
Keyword(s):  
Low Density ◽  
Northern Bobwhites ◽  
Density Population

Movement and spatial distribution of the Nile rat (Arvicanthis niloticus) in Kenya

1985 ◽  
Vol 1 (2) ◽  
pp. 111-130 ◽  
Author(s):  
M. J. Delany ◽  
R. H. Monro
Keyword(s):  
Spatial Distribution ◽  
Agricultural Practices ◽  
Population Cycle ◽  
Low Density ◽  
Density Population ◽  
Arvicanthis Niloticus ◽  
Growing Population

ABSTRACTThe movement and spatial distribution of marked Nile rats, Arvicanthis niloticus, was traced through phases of a low density population from January to August 1981, a rapidly growing population from September to January 1982, and a high and declining post-reproductive population from February to April 1982. Apart from late in the population cycle there was considerable movement, interchange and establishment of new ranges. As the population increased individual ranges became smaller. The rats apparently preferred field edges and did not favour the fields themselves. Females frequently established themselves at certain sites where they produced their litters; some of the offspring remained with the mother in the warren. There is also evidence that ousiders of both sexes joined these warrens. Males were generally more wide-ranging than females. Agricultural practices, e.g. mowing and trampling by cattle, influenced the rats preparedness to remain within a particular location. Exploitation of all the available habitat took several months to achieve.

An experimental study of the behavior of blue grouse (Dendragapus obscurus). I. Differences between the founders from three populations

1975 ◽  
Vol 53 (9) ◽  
pp. 1222-1237 ◽  
Author(s):  
Arthur T. Bergerud ◽  
H. Dennis Hemus
Keyword(s):  
Vancouver Island ◽  
Mirror Image ◽  
High Density ◽  
The Other ◽  
Low Density ◽  
Single Population ◽  
High Density Population ◽  
Dendragapus Obscurus ◽  
Field Workers ◽  
Density Population

In 1970 the authors compared the behavior of two low-density populations of blue grouse (Dendragapus obscurus) with the behavior of a high-density population on Vancouver Island. They then introduced individuals from these populations onto four islands and compared the behavior of these founders in 1971 and 1972.One island received founders from all three populations, while the other three islands each received founders from a single population. Birds from two low-density populations were quite observable, and displayed frequently when approached by field workers, both at their capture sites on Vancouver Island and in different habitats on the release sites on islands. The high-density population was much less observable, and displayed less frequently than did the two low-density populations, both at the capture sites and on the release islands. Male founders from the low-density populations were more aggressive in interacting with their mirror image than were males from the high-density population. Male founders from the high-density population dispersed less from the release sites, had smaller territories, and settled closer together than did males from the two low-density populations. These findings are consistent with the view that animals have a form of behavior that spaces them out as numbers rise, and so prevents unlimited increase in numbers.

Observations on the effects of rabbit calicivirus disease on low and medium density rabbit populations in western New South Wales

2001 ◽  
Vol 23 (2) ◽  
pp. 194 ◽  
Author(s):  
Andy Sharp ◽  
Kerry Holmes ◽  
Melinda Norton ◽  
Adam Marks
Keyword(s):  
Arid Zone ◽  
New South ◽  
New South Wales ◽  
Winter Period ◽  
Low Density ◽  
Medium Density ◽  
Management Actions ◽  
South Wales ◽  
Positive Growth ◽  
Density Population

Between winter 1995 and winter 1998, seasonal spotlight counts for rabbits were conducted along three transects in western New South Wales. Rabbit Calicivirus (RCV) arrived at the study site in spring 1996 and had an immediate marked effect on rabbit densities. Prior to the advent of Rabbit Calicivirus Disease (RCD), rabbit abundance followed the expected annual pattern of positive growth during the winter to summer period and negligible or negative growth during the summer to winter period. With the arrival of RCV, rabbit abundance was observed to decline by 47% and 75% within low density populations and by 84% within a medium density population. In the subsequent 21 months, the low density populations returned to levels approximating those prior to the arrival of RCV. In contrast, rabbit abundance within the medium density population remained at consistently lowered levels. These data suggest that RCD will have a minimal effect on semi-arid zone rabbit populations below a density of 0.4/ha and that additional management actions will be required to further reduce rabbit abundances.

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