INFLUENCE OF GENETIC CHANGES AND OTHER VARIABLES ON THE ENCAPSULATION OF PARASITES BY HYPHANTRIA CUNEA

1976 ◽  
Vol 108 (7) ◽  
pp. 673-684 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Biological Control ◽  
New Brunswick ◽  
Laboratory Experiments ◽  
Natural Populations ◽  
Host Population ◽  
Genetic Constitution ◽  
Short Term ◽  
Hyphantria Cunea ◽  
Genetic Changes ◽  
Insect Parasites

AbstractThe percentage encapsulation of its common insect parasites by Hyphantria cunea Drury was measured in natural populations in New Brunswick and Nova Scotia over a period of 17 years, and the variables affecting encapsulation were studied in laboratory experiments. Percentage encapsulation varied with the species, stage, and activity of the parasite, and the stage and genetic strain of the host. Differences in encapsulation from area to area and particularly from year to year were closely related to short-term changes in the genetic constitution of the host population resulting from natural selection pressures. The application of these results to biological control and to population modeling is discussed briefly.

OBSERVED AND SIMULATED CHANGES IN GENETIC QUALITY IN NATURAL POPULATIONS OF HYPHANTRIA CUNEA

1971 ◽  
Vol 103 (6) ◽  
pp. 893-906 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Experimental Data ◽  
Natural Selection ◽  
New Brunswick ◽  
Selection Pressure ◽  
Natural Populations ◽  
Hyphantria Cunea ◽  
Genetic Changes ◽  
Genetic Quality ◽  
Natural Regulation ◽  
Annual Changes

AbstractAnnual changes in genetic quality were measured in natural populations of Hyphantria cunea Drury for 12 years in New Brunswick and Nova Scotia. Models for heritability and natural selection pressure, derived independently from experimental data, are used to simulate the changes in quality over the same period. In seven of eight areas, observed and simulated trends are significantly correlated. Regressions between observed and calculated values, examined with respect to both means and slopes, suggest how these preliminary models may be refined. The influence of genetic changes on the natural regulation of population density is discussed briefly, but analysis is deferred to a later paper in this series on H. cunea.

RELATION OF MORTALITY CAUSED BY PARASITES TO THE POPULATION DENSITY OF HYPHANTRIA CUNEA

1976 ◽  
Vol 108 (11) ◽  
pp. 1291-1294 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Nova Scotia ◽  
Population Density ◽  
New Brunswick ◽  
Parasite Species ◽  
Natural Populations ◽  
Host Density ◽  
Delayed Response ◽  
Hyphantria Cunea ◽  
Cent Mortality ◽  
The Relationship

AbstractParasitism in natural populations of Hyphantria cunea Drury was measured in New Brunswick and Nova Scotia, 1957–1973. Thirteen parasite species were recovered during this period but only a few caused an appreciable degree of mortality. The per cent mortality showed an immediate rather than a delayed response to host density, the relationship being direct up to a density of about 10 host colonies per mile, then inverse. Possible reasons for this sort of relationship are discussed.

Studies of Predators of the Balsam Woolly Aphid, Adelges piceae (Ratz.) (Homoptera: Adelgidae): XI. Cremifania nigrocellulata Cz. (Diptera: Chamaemyiidae), An Introduced Predator in Eastern Canada

1962 ◽  
Vol 94 (11) ◽  
pp. 1171-1175 ◽  
Author(s):  
R. C. Clark ◽  
N. R. Brown
Keyword(s):  
Biological Control ◽  
New Brunswick ◽  
Eastern Canada ◽  
Introduced Predator ◽  
Woolly Aphid ◽  
Commonwealth Institute ◽  
Adelges Piceae ◽  
Research Institute

Cremifania nigrocellulata Cz. is one of the complex of predators that attacks A. piceae (Ratz.) in Europe. After studies on its morphology, biology, and distribution were made by Delucchi and Pschorn-Walcher (1954), C. nigrocellulata was reared in Europe by the Commonwealth Institute of Biological Control and introduced into New Brunswick via the Entomology Research Institute for Biological Control, Belleville, Ontario.

Life History Changes in Eastern Mosquitofish (Gambusia holbrooki) Induced by Thermal Elevation

1991 ◽  
Vol 48 (1) ◽  
pp. 60-66 ◽  
Author(s):  
Gary K. Meffe
Keyword(s):  
South Carolina ◽  
Life History ◽  
Nuclear Reactor ◽  
Natural Populations ◽  
Life History Evolution ◽  
Gambusia Holbrooki ◽  
Genetic Changes ◽  
Thermal Death ◽  
Reproductive Biomass ◽  
Eastern Mosquitofish

Much light can be shed on life history evolution through study of responses of organisms to chronic exposure to a novel or perturbed environment. To determine the influence of 28 yr of temporally unpredictable thermal elevation on their life history patterns, I sampled eastern mosquitofish (Gambusia holbrooki) from a thermally elevated (outflow from a nuclear reactor) and an ambient (farm pond) habitat in South Carolina every month for 2 yr. Fish from the artificially heated environment reproduced all year, had higher reproductive investments (higher clutch sizes and reproductive biomass), and smaller offspring than did fish from the ambient environment, which ceased reproduction from October through March, typical for natural populations of the region. Likely environmental factors responsible for these differences include unpredictable food resources, higher mortality from thermal death, and higher predation by fishes and birds in the heated waters. The extent to which these life history alterations are the result of adaptive genetic changes versus phenotypically plastic responses remains to be tested.

PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

1972 ◽  
Vol 104 (8) ◽  
pp. 1197-1207 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Nova Scotia ◽  
North America ◽  
Population Density ◽  
New Brunswick ◽  
Numerical Response ◽  
Initial Number ◽  
Hyphantria Cunea ◽  
The North ◽  
The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

scholarly journals Rethinking earthquake-related DC-ULF electromagnetic phenomena: towards a physics-based approach

2011 ◽  
Vol 11 (11) ◽  
pp. 2941-2949 ◽  
Author(s):  
Q. Huang
Keyword(s):  
Laboratory Experiments ◽  
Physical Models ◽  
Short Term ◽  
Integrated Research ◽  
Weak Earthquake ◽  
Electromagnetic Signals ◽  
Short Term Prediction ◽  
Noisy Background ◽  
Theoretical Analyses ◽  
Physical Quantities

Abstract. Numerous electromagnetic changes possibly related with earthquakes have been independently reported and have even been attempted to apply to short-term prediction of earthquakes. However, there are active debates on the above issue because the seismogenic process is rather complicated and the studies have been mainly empirical (i.e. a kind of experience-based approach). Thus, a physics-based study would be helpful for understanding earthquake-related electromagnetic phenomena and strengthening their applications. As a potential physics-based approach, I present an integrated research scheme, taking into account the interaction among observation, methodology, and physical model. For simplicity, this work focuses only on the earthquake-related DC-ULF electromagnetic phenomena. The main approach includes the following key problems: (1) how to perform a reliable and appropriate observation with some clear physical quantities; (2) how to develop a robust methodology to reveal weak earthquake-related electromagnetic signals from noisy background; and (3) how to develop plausible physical models based on theoretical analyses and/or laboratory experiments for the explanation of the earthquake-related electromagnetic signals observed in the field conditions.

scholarly journals Naturalized Dolichogenidea gelechiidivoris Marsh (Hymenoptera: Braconidae) complement the resident parasitoid complex of Tuta absoluta (Meyrick) (Lepidopera:Gelechiidae) in Spain

2021 ◽  
Author(s):  
Carmen Denis ◽  
JORDI RIUDAVETS ◽  
OSCAR ALOMAR ◽  
NURIA AGUSTI ◽  
HELENA GONZALEZ-VALERO ◽  
...  
Keyword(s):  
Biological Control ◽  
Biocontrol Agent ◽  
Natural Populations ◽  
Tuta Absoluta ◽  
Parasitoid Complex ◽  
Parasitism Rates ◽  
Production Area ◽  
Side Walls ◽  
Predatory Mirid ◽  
First Time

Our study aimed to assess the contribution of natural parasitism due to Necremnus tutae Ribes & Bernardo (Hymenoptera: Eulophidae) to the biological control of Tuta absoluta (Meyrick) (Lepidopera:Gelechiidae) in commercial plots where an IPM program based on the use of predatory mirid bugs was implemented. During the samplings, the presence of another parasitoid was detected and, therefore, a second part of our study intended to identify this species and to evaluate the importance of its natural populations in the biological control of the pest. Leaflets with T. absoluta galleries were collected during 2017-2020 from commercial tomato plots in the horticultural production area of Catalonia (Northeast Spain), including greenhouses, open fields, and roof covered tunnels that lack side walls. In the laboratory, T. absoluta larvae were classified as ectoparasitized, alive, or dead. Reared parasitoids from ectoparasitized larvae were mostly morphologically identified as Necremnus sp. with parasitism rates that peaked in summer months with values between 9 and 15%. Some of these ectoparasitized larvae also yielded another parasitoid identified as Dolichogenidea gelechiidivoris Marsh (Hymenoptera: Braconidae) by both morphological and molecular-DNA barcoding methods. In 2020, parasitism rates due to D. gelechiidivoris that increased with season up to 22%. Our work reports for the first time in Europe the presence of the neotropical species D. gelechiidivoris adding this biocontrol agent to the resident parasitoid complex of T. absoluta in Spain.

Is Phasmarhabditis papillosa (Nematoda: Rhabditidae) a possible biological control agent against the Spanish slug, Arion vulgaris (Gastropoda: Arionidae)?

Nematology ◽  
2020 ◽  
pp. 1-9
Author(s):  
Žiga Laznik ◽  
Ivana Majić ◽  
Stanislav Trdan ◽  
Antoinette P. Malan ◽  
Annika Pieterse ◽  
...  
Keyword(s):  
Biological Control ◽  
Laboratory Experiments ◽  
Biological Control Agent ◽  
First Record ◽  
Control Agent ◽  
Molecular Techniques ◽  
Parasitic Nematodes ◽  
Arion Vulgaris ◽  
Potential Use

Summary In the period from August to October 2018, 140 specimens of the Spanish slug, Arion vulgaris, were collected from Podbrezje, Slovenia. Slugs were dissected and examined for the presence of parasitic nematodes within the cadavers. Identification of the nematodes was conducted using morphological and molecular techniques and confirmed the presence of Phasmarhabditis papillosa. This is the first record of P. papillosa from the mollusc host, A. vulgaris. Laboratory experiments aimed at testing the efficacy of P. papillosa against A. vulgaris were conducted using nematodes grown in vivo. Nematodes were applied at concentration rates of 50, 100 and 200 nematodes slug−1, respectively. Three weeks following treatment, the mortality of slugs was confirmed in all treatments (50 nematodes slug−1, 37.4 ± 2.7%; 100 nematodes slug−1, 48.4 ± 2.7%; 200 nematodes slug−1, 50.6 ± 2.7%). However, the pathogenesis of P. papillosa was observed first in the treatments with the lowest nematode dose at 4 days after treatments, while a decrease in the feeding behaviour of slugs was noted first in the treatments with the highest nematode dose. Future opportunities for the potential use of P. papillosa as a biological control agent against slugs are discussed. This is the first report of P. papillosa from Slovenia, and of its virulence against A. vulgaris.

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