scholarly journals Evaluation of Two Decades of Cryphonectria parasitica Hypovirus Introduction in an American Chestnut Stand in Wisconsin

2018 ◽  
Vol 108 (6) ◽  
pp. 702-710 ◽  
Author(s):  
Mark L. Double ◽  
Andrew M. Jarosz ◽  
Dennis W. Fulbright ◽  
Anita Davelos Baines ◽  
William L. MacDonald
Keyword(s):  
Biological Control ◽  
Large Diameter ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
American Chestnut ◽  
Biological Control Agents ◽  
History Of Disease ◽  
History Of

Hypovirus-infected Cryphonectria parasitica strains were introduced in a large stand of American chestnut (>4,000 individuals) in western Wisconsin (USA) to evaluate whether hypoviruses can serve as biological control agents. They were deployed by treating cankers from 1992 to 1997 and again from 2004 to 2014. After 17 years of hypovirus introductions within an area of the stand with the longest history of disease, isolation of hypovirus-infected strains increased from 55% in 1994 to 86% in 2014 from cankers that were treated. During the same period, isolation from cankers that arose on trees with treated cankers increased from 29 to 72% and from 15 to 84% for cankers on nearby trees that received no treatment. Tree survivorship over the 23-year study period for trees with treated cankers was 51% compared with 31% for trees that were not treated. Introduction of hypovirus has resulted in the regrowth of the crowns of many large-diameter trees. Putative recovery of American chestnut in this stand provides evidence that prolonged hypovirus treatment can act as a biological control when limited numbers of vegetative compatibility types of C. parasitica exist.

scholarly journals 75 years of the chestnut blight fungus Cryphonectria parasitica (Murr.) Barr in Europe

2014 ◽  
pp. 82-85
Author(s):  
László Radócz ◽  
Gábor Görcsös ◽  
Gábor Tarcali ◽  
Gabriella Kovács ◽  
Qin Ling
Keyword(s):  
Biological Control ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
European Chestnut ◽  
High Prevalence ◽  
History Of ◽  
Short Time ◽  
High Diversity

The chestnut blight fungus Cryphonectria parasitica is a native pathogen in East Asia and has been introduced into North America and Europe. Historical records and population genetic studies revealed at least three major introduction events from Asia into Europe. Nowadays, chestnut blight is present in almost the entire distribution range of European chestnut, i.e. from the Iberian Peninsula to the Caucasus. The C. parasitica population in most countries has been studied in respect to the diversity of vegetative compatibility (vc) types and the occurrence of hypovirulence. The vc type diversity of the different populations varied considerably. Typically, a high diversity of vc types has been found in areas with a long history of chestnut blight and where sexual recombination between divergent genotypes commonly has occurred. On the other hand, newly established populations often showed a low diversity with only one, or a few vc types present. Hypovirulence, i.e. the occurrence of C. parasitica isolates infected by Cryphonectria hypovirus 1 has been found widespread in Europe. Natural dissemination and active biological control applications have lead to a high prevalence of the hypovirus and to the recovery of many chestnut stands. Virulent cankers became hypovirus-infected within a short time and ceased expansion. There is concern that the diversity of vegetative compatibility types could increase in Europe through sexual reproduction between C. parasitica genotypes originating from different introductions. A higher level of vegetative incompatibility would not only hamper hypovirus spread within a population but could also select for lower virulence in CHV-1 and subsequently lead to an erosion of biological control. Recent studies, however, indicate that the vc type barriers are not so restrictive than previously assumed and that so far no evidence for an erosion of biological control system in high diversity populations can be observed.

scholarly journals A history of biological control in Canadian forests, 1882–2014

2016 ◽  
Vol 148 (S1) ◽  
pp. S239-S269 ◽  
Author(s):  
Chris J.K. MacQuarrie ◽  
D.B. Lyons ◽  
M. Lukas Seehausen ◽  
Sandy M. Smith
Keyword(s):  
Biological Control ◽  
Significant Influence ◽  
Native Species ◽  
Historical Data ◽  
Pest Species ◽  
Biological Control Agents ◽  
Forest Pests ◽  
Control Programmes ◽  
Strategic Implementation ◽  
History Of

AbstractBiological control has been an important tactic in the management of Canadian forests for over a century, but one that has had varied success. Here, we review the history of biological control programmes using vertebrate and invertebrate parasitoids and predators against insects in Canadian forests. Since roughly 1882, 41 insect species have been the target of biological control, with approximately equal numbers of both native and non-native species targeted. A total of 161 species of biological control agents have been released in Canadian forests, spanning most major orders of insects, as well as mites and mammals. Biological control has resulted in the successful suppression of nine pest species, and aided in the control of an additional six species. In this review, we outline the chronological history of major projects across Canadian forests, focussing on those that have had significant influence for the development of biological control. The historical data clearly illustrate a rise and fall in the use of biological control as a tactic for managing forest pests, from its dominance in the 1940s and 1950s to its current low level. The strategic implementation of these biological control programmes, their degree of success, and the challenges faced are discussed, along with the discipline’s shifting relationship to basic science and the environmental viewpoints surrounding its use.

The history of, and prospects for, the biological control of Chromolaena odorata (Compositae) by Pareuchaetes pseudoinsulata Rego Barros and allies (Lepidoptera: Arctiidae)

1982 ◽  
Vol 72 (2) ◽  
pp. 193-205 ◽  
Author(s):  
M. J. W. Cock ◽  
J. D. Holloway
Keyword(s):  
Biological Control ◽  
Previous Literature ◽  
New Combination ◽  
Biological Control Agents ◽  
Chromolaena Odorata ◽  
Arctiid Moth ◽  
New Synonyms ◽  
Pareuchaetes Pseudoinsulata ◽  
History Of ◽  
The Tropics

AbstractChromolaena odorata is a tropical American species of the Compositae that has become a serious problem in plantations in the tropics of Asia and Africa. The history of attempts to control it using the arctiid moth Pareuchaetes pseudoinsulata Rego Barros (misidentified in previous literature as Ammalo insulata (Wlk.)) is summarised. The taxonomy and distributions of the five species in Pareuchaetes are presented, together with keys based on genitalic characters, three new synonyms and one new combination. Information on the biogeography and ecology of the Pareuchaetes species is used to assess their potential as biological control agents.

scholarly journals Relationship Between Biological Control, Incidence of Hypovirulence, and Diversity of Vegetative Compatibility Types of Cryphonectria parasitica in France

2000 ◽  
Vol 90 (7) ◽  
pp. 730-737 ◽  
Author(s):  
Cécile Robin ◽  
Carole Anziani ◽  
Paolo Cortesi
Keyword(s):  
Biological Control ◽  
Allelic Diversity ◽  
Background Level ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Natural Background ◽  
Vegetative Incompatibility ◽  
Natural Background Level ◽  
Two Parameters

In France, chestnut blight, caused by Cryphonectria parasitica, has been controlled since 1974 in orchards, but never in coppice forests, by releasing hypovirulent strains infected with CHV1 hypovirus. We tested the hypothesis that this biological control (BC) has lead to a decrease in blight severity, spread of hypovirulence, and change in C. parasitica populations. The low severity of chestnut blight was confirmed in the six regions studied (subdivided into zones). The remission of cankers was associated with the presence of white isolates presumed to be hypovirulent. These two parameters were also correlated, at the zonal level, to the frequency of sites where BC was used. However, the estimates of the natural background level of hypovirulence, independent of BC, ranged from 4% in forests in Dordogne to 60% in orchards in Lozère. Differences in the rate of hypovirulent isolates among regions were consistent with the diversity of vegetative compatibility (VC) types in populations of C. parasitica. The highest VC-type diversity and mean allelic diversity for known vegetative incompatibility (vic) genes were observed in Dordogne. We showed that the current diversity of VC types in populations of C. parasitica was lower than in 1981. We found 30 VC types among 1,113 isolates of C. parasitica. Ten VC types were incompatible with known EU testers, suggesting that one additional vic gene or allele at one of the six vic loci known should be present in Europe.

scholarly journals Biologische Bekämpfung des Kastanienrindenkrebses auf der Alpennordseite der Schweiz|Biological control of chestnut blight north of the Swiss Alps

2007 ◽  
Vol 158 (11) ◽  
pp. 342-348
Author(s):  
Ursula Heiniger
Keyword(s):  
Biological Control ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Swiss Alps ◽  
Chestnut Blight ◽  
Biologische Bekämpfung ◽  
Chestnut Blight Fungus ◽  
Low Rate

Since 1986 several isolated stands of chestnut (Castanea sativa) located north of the Swiss Alps have been infected with the chestnut blight fungus (Cryphonectria parasitica). At all sites (1–3), the diversity of the vegetative compatibility types was low. To control the disease, the hypovirus CHV1 was introduced at seventeen sites in five cantons. In total, 571 cankers were treated with local C. parasitica isolates containing CHV1. Re-inspection of the cankers one to two years after treatment demonstrated that the percentage of active cankers was significantly reduced in three cantons. Re-isolations of C. parasitica showed that the hypovirus persisted in 33% to 75% of the treated cankers and was disseminated to new cankers at a low rate. The difficulties and the potential of hypovirus treatment of small chestnut stands are discussed.

Movement of cytoplasmic hypovirulence agents in chestnut blight cankers

1992 ◽  
Vol 70 (3) ◽  
pp. 557-561 ◽  
Author(s):  
L. Shain ◽  
J. B. Miller
Keyword(s):  
Biological Control ◽  
Key Words ◽  
Cryphonectria Parasitica ◽  
Castanea Dentata ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Typical Morphology ◽  
Natural Range ◽  
Hypovirulent Strain ◽  
Endothia Parasitica

Chestnut blight cankers, initiated with virulent methionine auxotrophic strains of Cryphonectria parasitica, were challenged by placing one or two discs of agar and mycelium of prototrophic hypovirulent strains at their base. Movement of hypovirulence agents was confirmed by recovery of an isolate that exhibited the typical morphology of the introduced hypovirulent strain on media with methionine but little or no growth on media without methionine. Cultures from bark showed that the hypovirulent agent moved through mycelium around the circumference of cankers within 3 weeks when the virulent and challenging hypovirulent were vegetatively compatible. Conversion of the mycelium in the canker interior proceeded more slowly. Conversion of mycelium also was delayed, but eventually occurred, when virulent and hypovirulent inocula differed in vegetative compatibility. Conidia, however, continued to yield virulent, methionine-requiring cultures up to 65 weeks after challenge, even though underlying bark frequently yielded hypovirulent, methionine-requiring cultures. This disinclination of hypovirulent agents to enter the asexual apparatus in cankers may contribute substantially to the observed ineffective dissemination of hypovirulence in the natural range of American chestnut. Exploitation of those hypovirulent agents that can enter conidia in cankers may enhance the biological control of chestnut blight by hypovirulence. Key words: biological control, Cryphonectria parasitica, Endothia parasitica, Castanea dentata.

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