scholarly journals Comparison of Field Population Growths of Three Cereal Aphid Species on Winter Wheat

2011 ◽  
Vol 39 (No. 2) ◽  
pp. 61-64 ◽  
Author(s):  
V. Jarošík ◽  
A. Honěk ◽  
A. Tichopád
Keyword(s):  
Winter Wheat ◽  
Rhopalosiphum Padi ◽  
Intrinsic Rate ◽  
Aphid Species ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Aphid Density ◽  
Rate Of Increase

Population growths of three aphid species colonising winter wheat stands, Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae, were analysed by regression method. The calculations were based on counts in 268 winter wheat plots at 3 or 7 day intervals over 10 (leaves) or 6 (ears) years. The population dynamics of a particular species differed widely between years. Density independent exponential growth of the population was most common, but its rate differed significantly between species, and for S. avenae also between populations on leaves and ears, on which the populations grew fastest. Field estimates of the intrinsic rate of increase derived from the exponential growths ranged between 0.010–0.026 in M. dirhodum, 0.0071–0.011 in R. padi, and between 0.00078–0.0061 and 0.0015–0.13 in S. avenae on leaves and ears, respectively. In the populations with the most vigorous population growth, S. avenae on ears and M. dirhodum on leaves, the rate of population increase significantly decreased with increasing aphid density.  

Potential Rates of Increase of a Harbour Porpoise (Phocoena phocoena) Population Subjected to Incidental Mortality in Commercial Fisheries

1991 ◽  
Vol 48 (12) ◽  
pp. 2429-2435 ◽  
Author(s):  
Thomas H. Woodley ◽  
Andrew J. Read
Keyword(s):  
Gulf Of Maine ◽  
Intrinsic Rate ◽  
Frequency Equation ◽  
Harbour Porpoise ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Natural Mortality ◽  
Phocoena Phocoena ◽  
Rate Of Increase ◽  
Incidental Mortality

We estimated the potential intrinsic rate of increase (r) of the harbour porpoise (Phocoena phocoena) population in the Bay of Fundy and Gulf of Maine using empirical data on reproductive rates (mx) and several hypothetical survival (Ix) schedules. Schedules of Ix, to maximum ages of 12 and 15 yr, were calculated from two potential natural mortality (nx) schedules combined with several schedules of incidental mortality (hx) estimates. The most realistic results were obtained when nx of non-calves were calculated from Caugley's (1966. Ecology 47: 906–918) smoothed age-frequency equation for Himalayan thar (Hemitragus jemlahicus) and applied in conjunction with a range of calf natural mortality estimates, this model indicates that harbour porpoises have a limited capacity for population increase, and populations are unlikely to sustain even moderate levels of incidental mortality (4% of the population per year). Extending the maximum age used in the models from 12 to 15 yr does little to increase estimates of r for the harbour porpoise population, and hence their susceptibility to incidental mortality.

scholarly journals Influence of Plant Diversity on the Numerical Response ofEriopis connexa(Coleoptera: Coccinellidae) to Changes in Cereal Aphid Density in Wheat Crops

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
María C. Tulli ◽  
Dora M. Carmona ◽  
Ana M. Vincini
Keyword(s):  
Plant Diversity ◽  
Aphid Species ◽  
Linear Increase ◽  
Numerical Response ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Higher Plant ◽  
Metopolophium Dirhodum ◽  
Aphid Density ◽  
Eriopis Connexa

Cereal aphids cause economic injury to wheat crops. In Argentina,Eriopis connexais an indigenous ladybird. In the present study, the numerical response ofE. connexato changes in aphid density on wheat crops with high and low plant diversity was investigated. The study was carried out in Balcarce, Buenos Aires, Argentina, from September to December 2007 and 2008, on two wheat crops with either a higher plant diversity (HPD) with refuge strips or a lower plant diversity (LPD) without refuge strips. Crops were sampled every week and the abundance of aphids andE. connexawas recorded. The dominant aphid species wereSchizaphis graminum, Metopolophium dirhodum,andSitobion avenae.Eriopis connexashowed a linear increase in the numerical response to an increase in aphid density, which varied in space and time. The abundance ofE. connexaincreased in relation to the crop development and aphid population and was higher in the HPD than in the LPD system. This predator increased its reproductive numerical response only in 2008, with a significant liner response in the HPD system. This suggests that the potential ofE. connexaas a predator of cereal aphids also increases directly in proportion to landscape vegetal diversity.

Management of cereal aphid (Hemiptera: Aphididae) populations and their natural enemies in winter wheat by alternate strip spraying with a selective insecticide

1987 ◽  
Vol 77 (4) ◽  
pp. 677-682 ◽  
Author(s):  
Nick Carter
Keyword(s):  
Winter Wheat ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Rhopalosiphum Padi ◽  
Population Development ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Peak Density ◽  
Selective Insecticide ◽  
Similar Peak

AbstractThe effect on aphid population development of creating natural enemy refuges by spraying only alternate strips of winter wheat with the aphid-specific insecticide pirimicarb at 140 g a.i./ha was compared with those in an unsprayed and a completely sprayed block in south-eastern England. The numbers of Sitobion avenae (F.), Metopolophium dirhodum (Walker) and Rhopalosiphum padi (L.) increased rapidly in the unsprayed block and in the unsprayed strips to reach similar peak densities in early August. Natural enemy activity was similar in these two areas, indicating negligible movement of predators and parasitoids from the sprayed strips to the unsprayed strips. Instead, aphids re-colonized the sprayed strips more quickly than the sprayed block, and the peak density in the former was similar to those in the unsprayed areas.

Comparing growth patterns among field populations of cereal aphids reveals factors limiting their maximum abundance

2006 ◽  
Vol 96 (3) ◽  
pp. 269-277 ◽  
Author(s):  
A. Honek ◽  
V. Jarosik ◽  
A.F.G. Dixon
Keyword(s):  
Exponential Growth ◽  
Rhopalosiphum Padi ◽  
Growth Patterns ◽  
Aphid Population ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Density Dependent ◽  
Maximum Abundance ◽  
Aphid Density

AbstractCereal stands in central Europe are commonly infested with three species of aphids that may become serious pests. With increasing abundance, the proportion of a particular species in the total aphid population may remain constant, suggesting a density-independent exponential growth, or the proportion can change, suggesting density-dependent constraints on growth. The constraints that affect particular species, and thus their relative abundance, were studied. The proportionality between maximum abundances of the cereal aphids was studied using a 10-year census of the numbers of aphids infesting 268 winter wheat plots. For two species their abundance on leaves and ears was compared. With increasing aphid density the maximum abundance of Rhopalosiphum padi (Linnaeus) remained proportional, but not that of Sitobion avenae (Fabricius), which was constrained by the smaller surface area of ears compared to leaves. There was no evidence of inter-specific competition. Maximum abundance of R. padi and Metopolophium dirhodum (Walker) on leaves did not change proportionally as the proportion of M. dirhodum decreased with increasing overall aphid density. This decrease was probably caused by the restricted distribution of M. dirhodum, which is confined to leaves, where space is limiting. No change in proportion between populations was detected when the average densities were below 0.54 aphids per leaf or ear. Non-proportional relationships between aphid populations appeared to be due to spatial constraints, acting upon the more abundant population. Detecting the limitation of population growth can help with the assessment of when density-independent exponential growth is limited by density-dependent factors. This information may help in the development of models of cereal aphid population dynamics.

scholarly journals Abundance of cereal aphids (Hemiptera: Aphididae) within wild Triticum and Aegi­lops spp., and cultivated wheat

1999 ◽  
Vol 35 (No. 2) ◽  
pp. 67-70
Author(s):  
H. Havlíčková ◽  
V. Holubec
Keyword(s):  
Rhopalosiphum Padi ◽  
Significant Negative Correlation ◽  
Aphid Species ◽  
Gene Bank ◽  
Cereal Aphids ◽  
Aegilops Species ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Triticum Species ◽  
The Individual

Accessions of the wild Triticum species: T. boeticum, T. dicoccoides, T. urartu, and the Aegilops species:  Ae. columnaris, Ae. geniculata, Ae. markgrafii, Ae. neglecta and Ae. triuncialis in the collection of the Gene Bank of RICP Prague-Ruzyně, with T.  aestivum cv. Sandra as control, were evaluated for cereal aphid occurrence in the open during 1995–1998 period. The cereal aphid species Rhopalosiphum  padi (RP), Metopolophium dirhodum (MD) and Sitobion avenae (SA) were predominant on the plants. Variations in the abundance of individual aphid species in each year were found. The results from 1997, the optimal year for aphid occurrence, showed differences between both aphid and plant species. RP significantly dominated in Triticum species, while SA preferred Aegilops accessions. A significant negative correlation was found between RP and MD densities in the Triti­ cum spp., while MD and SA occurrence showed a negative relation to that of RP and SA in the Aegilops accessions. The individual aphid species showed a similar pattern of infestation in several genomically close accessions.

Reproductive potential in the parasitoid Eupelmus orientalis (Hymenoptera: Eupelmidae)

1994 ◽  
Vol 84 (2) ◽  
pp. 199-206 ◽  
Author(s):  
G. Doury ◽  
D. Rojas-Rousse
Keyword(s):  
Life Cycle ◽  
Callosobruchus Maculatus ◽  
Reproductive Potential ◽  
Intrinsic Rate ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Net Reproductive Rate ◽  
Offspring Production ◽  
Rate Of Increase ◽  
Age Dependent

AbstractEupelmus orientalis (Crawford) (Hymenoptera: Eupelmidae) is a solitary ectoparasitoid of the larvae and pupae of West African bruchids. Since the biology of this species was unknown, studies were carried out on its reproductive biology. The age-dependent fecundity and offspring production of virgin and mated females of E. orientalis were determined under laboratory conditions at 33°C:23°C, 50%:80% r.h., L:D 12:12 on its host Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) during the first 15 days of the life cycle. No differences were found between virgin and mated females for any parameter. A study of the age-dependent fecundity and offspring production was also carried out under the same conditions over the entire life cycle of mated females. The resulting data were used to determine the longevity and reproductive potential of the species, particularly through the calculated life tables and estimation of the intrinsic rate of increase. With ten hosts per female per day, E. orientalis females had a mean longevity of 45.75±5.09 days. They laid an average of 219.91±39.08 eggs, parasitized 154.27±26.17 hosts, and produced 166.77±9.41 offspring, consisting of 80.46±14.10 males and 86.31±10.04 females. The total mean developmental time was 18.58±0.22 days for males and 20.03±0.21 days for females. The net reproductive rate (Ro) was 62.33 female progeny per adult female, and the intrinsic rate of population increase (rm) was 0.1389 per day. The generation time (G) was 29.76 days and the doubling time (DT) 4.99 days. These results constitute the first step to determine the potential of E. orientalis as an agent for the biological control of bruchidae, especially C. maculatus.

A comparison of sexual competitiveness and demographic traits of Anastrepha obliqua (Macquart) (Diptera: Tephritidae) among fruit-associated populations

2018 ◽  
Vol 109 (3) ◽  
pp. 333-341
Author(s):  
E. Hernández ◽  
L. Ruiz-Montoya ◽  
J. Toledo ◽  
P. Montoya ◽  
P. Liedo ◽  
...  
Keyword(s):  
Mangifera Indica ◽  
Field Performance ◽  
Intrinsic Rate ◽  
Population Increase ◽  
Intrinsic Rate Of Increase ◽  
Reproduction Rate ◽  
Demographic Traits ◽  
Rate Of Increase ◽  
Anastrepha Obliqua ◽  
Spondias Purpurea

AbstractThe control of Anastrepha obliqua includes the sterilization of mass-reared insects grown in isolation in a constantly controlled environment. Through time, laboratory mass-reared colonies may produce flies with lower field performance. To recover the genetic variation and aptitude of mass-reared populations, wild insects are introduced into mass-reared colonies. Our aim in this study was to determine whether the host species from two localities influence the life history traits of A. obliqua. We collected flies as larvae from infested fruits of Spondias purpurea, S. mombin, Mangifera indica cv. ‘piña’, and M. indica cv. ‘coche’ from two localities in Chiapas, Mexico. There were significant differences in the mating competitiveness of males collected from mango cv. ‘coche’ compared with mass-reared males. There were no differences in the mating propensity between flies from the two localities, even in the number of matings, when weight was considered as a covariable. The mass-reared strain showed the earliest age at first oviposition. The locality affected the longevity and oviposition period, and these influenced the birth rate, intrinsic rate of increase, finite rate of population increase, mean generation time, and doubling time. According to the demographic parameters, the population of S. mombin would allow artificial colonization in less time, considering that it has a high reproduction rate starting at an early age. Even in the propensity test, it had the highest number of matings. However, males with greater sexual competitiveness and longevity for colonization corresponded to those collected from S. purpurea.

Electrophoretic study of enzymes from cereal aphid populations. I. Electrophoretic techniques and staining systems for characterising isoenzymes from six species of cereal aphids (Hemiptera: Aphididae)

1983 ◽  
Vol 73 (4) ◽  
pp. 645-657 ◽  
Author(s):  
H. D. Loxdale ◽  
P. Castañera ◽  
C. P. Brookes
Keyword(s):  
Rhopalosiphum Padi ◽  
Aphid Species ◽  
Individual Species ◽  
Cereal Aphids ◽  
Cereal Aphid ◽  
Metopolophium Dirhodum ◽  
Electrophoretic Study ◽  
Banding Patterns ◽  
Glycerophosphate Dehydrogenase ◽  
Electrophoretic Techniques

AbstractOne–dimensional slab polyacrylamide gel electrophoretic techniques, staining systems and isoenzyme banding patterns for 14 soluble enzymes separated from crude homogenates of individuals of six species of cereal aphids (Sitobion avenae (F.), S. fragariae (Wlk.), Metopolophium dirhodum (Wlk.), M. festucae (Theo.), Rhopalosiphum padi (L.) and R. maidis (Fitch)) are described. The value of the techniques and banding patterns to taxonomic and population genetic studies of these and other aphid species are briefly discussed. With the six species, it was possible to separate the different genera as well as individual species within genera. The enzymes found to be most useful for inter–generic and/or -specific separations were adenylate kinase (AK), esterase (EST), glucose-6-phosphate dehydrogenase (G-6-PDH), hexokinase (HK), malate dehydrogenase (MDH), peptidase (PEP), phosphatase (PHOS), phosphoglucomutase (PMG), 6-phosphogluconate dehydrogenase (6-PGD) and sorbitol dehydrogenase (SORDH), whilst glutamate oxaloacetate transaminase (GOT), α-glycerophosphate dehydrogenase (α-GPD), malic enzyme (ME) and peroxidase (POD) were of relatively little taxonomic use. There were no banding pattern differences between the various morphs of S. avenae (first to fourth-instar nymphs, apterous and alate adults using the 14 enzymes.

Seed treatments with thiamine reduce the performance of generalist and specialist aphids on crop plants

2017 ◽  
Vol 108 (1) ◽  
pp. 84-92 ◽  
Author(s):  
A.M. Hamada ◽  
J. Fatehi ◽  
L.M.V. Jonsson
Keyword(s):  
Acyrthosiphon Pisum ◽  
Green Peach Aphid ◽  
Rhopalosiphum Padi ◽  
Plant Defence ◽  
Intrinsic Rate ◽  
Pea Aphid ◽  
Intrinsic Rate Of Increase ◽  
Host Acceptance ◽  
Seed Treatments ◽  
Rate Of Increase

AbstractThiamine is a vitamin that has been shown to act as a trigger to activate plant defence and reduce pathogen and nematode infection as well as aphid settling and reproduction. We have here investigated whether thiamine treatments of seeds (i.e. seed dressing) would increase plant resistance against aphids and whether this would have different effects on a generalist than on specialist aphids. Seeds of wheat, barley, oat and pea were treated with thiamine alone or in combination with the biocontrol bacteriaPseudomonas chlororaphisMA 342 (MA 342). Plants were grown in climate chambers. The effects of seed treatment on fecundity, host acceptance and life span were studied on specialist aphids bird cherry-oat aphid (Rhopalosiphum padiL.) and pea aphid (Acyrthosiphon pisumHarris) and on the generalist green peach aphid (Myzus persicae, Sulzer). Thiamine seed treatments reduced reproduction and host acceptance of all three aphid species. The number of days to reproduction, the length of the reproductive life, the fecundity and the intrinsic rate of increase were found reduced for bird cherry-oat aphid after thiamine treatment of the cereal seeds. MA 342 did not have any effect in any of the plant-aphid combinations, except a weak decrease of pea aphid reproduction on pea. The results show that there are no differential effects of either thiamine or MA 342 seed treatments on specialist and generalist aphids and suggest that seed treatments with thiamine has a potential in aphid pest management.

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