The Colletotrichum gloeosporioides species complex

Colletotrichum - current status and future directions.

The Colletotrichum acutatum species complex

Climate models project that by 2100, the northeastern US and eastern Canada will warm by approximately 3- 5 8C, with increased winter precipitation. These changes will affect trees directly and also indirectly through effects on ''nuisance'' species, such as insect pests, pathogens, and invasive plants. We review how basic ecological principles can be used to predict nuisance species' responses to climate change and how this is likely to impact northeastern forests. We then examine in detail the potential responses of two pest species (hemlock woolly adelgid (Adelges tsugae Annand) and forest tent caterpillar (Malacosoma disstria Hubner)), two pathogens (armillaria root rot (Armillaria spp.) and beech bark disease (Cryptococcus fagisuga Lind. + Neonectria spp.)), and two invasive plant species (glossy buckthorn (Frangula alnus Mill.) and oriental bittersweet (Celastrus orbiculatus Thunb.)). Several of these species are likely to have stronger or more widespread effects on forest composition and structure under the projected climate. However, uncertainty pervades our predictions because we lack adequate data on the species and because some species depend on complex, incompletely understood, unstable relationships. While targeted research will increase our confidence in making predictions, some un-

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Responses of insect pests, pathogens, and invasive plant species to climate change in the forests of northeastern North America: What can

This document is a part of the Synthesis and Assessment Products described in the U.S. Climate Change Science Program Strategic Plan. The report describes how climate affects the design, construction, safety, operations, and maintenance of transportation infrastructure and systems. The prospect of a changing climate raises critical questions regarding how alterations in temperature, precipitation, storm events, and other aspects of the climate could affect the nation's roads, airports, rail, transit systems, pipelines, ports, and waterways. Phase I of this regional assessment of climate change and its potential impacts on transportation systems addresses these questions for the region of the U.S. central Gulf Coast between Galveston, Texas and Mobile, Alabama.

The Effects of Climate Change on Agriculture, Land Resources, Water Resources, and Biodiversity in the United States

Hemlock woolly adelgid, Adelges tsugae Annand, is an exotic forest pest threatening the health of New England’s eastern hemlock, Tsuga canadensis (L.) Carriere. Research indicates that the northern spread of this insect may be slowed or prevented by cold temperature. We conducted laboratory studies to assess the coldhardiness of A. tsugae, collected at sites within plant hardiness zones 5a (Northern), 6a (Central), and 6b (Southern) in January, February, and March. Adelgids were exposed to −15, −20, −25, −30, and −35°C for 2, 4, or 8 h, and comparisons in survival were made with insects held at 0°C. For all months and sites, mortality increased as temperature decreased, and no survival occurred among those from the Central and Southern sites exposed to −30 and −35°C. In January and February, ≤3% of the adelgids collected from the Northern site survived −30°C, and none survived −35°C in January or March. Adelgids from all sites entered the winter with similar levels of coldhardiness, but those fro...

Regional Responses of Hemlock Woolly Adelgid (Homoptera: Adelgidae) to Low Temperatures

Entomopathogenic fungi of Eurygaster integriceps Puton (Hemiptera: Scutelleridae): collection and characterization for development

An epizootic has been reported in Fiorinia externa populations in New York, Connecticut, Penn- sylvania and New Jersey. Infected insects have profuse sclerotial masses enclosing their bodies. The most commonly isolated microorganism from infected F. externa was Colletotrichum sp. A morphological and molecular characterization of this fungus indicated that it is closely related to phytopathogenic C. acutatum isolates. Isolates of Colletotrichum sp. from F. externa in areas of the epizootic were similar genetically and were named Colletotrichum acutatum var. fioriniae var. nov. based on our findings. In vitro and in planta mating observed between isolates of C. acutatum var. fioriniae could serve as a possible source of genetic variation and might give rise to new biotypes with a propensity to infect insects. Only one other strain, C. gloeosporioides f. sp. ortheziidae, has been reported to show entomopathogenic activ- ity.

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Colletotrichum acutatum var. fioriniae (teleomorph: Glomerella acutata var. fioriniae var. nov.) infection of a scale insect.

The hemlock woolly adelgid, Adelges tsugae Annand, is not currently found in the U.S. Department of Agriculture plant coldhardiness zones colder than 5a in New England. Cold winter temperatures may be a factor limiting the northern expansion of this pest. Laboratory studies were conducted to determine the low lethal temperature of A. tsugae collected in January, February, and March 1997 from Holyoke, MA, located in plant coldhardiness zone 5a. Adelgids were exposed to temperatures of −20, −25, −30, −35, and −40°C for 2, 4, and 8 h. To correct for experimental mortality, comparisons in survival were made with untreated controls held at 0°C. For samples collected in January and February, a gradual decline in survival occurred as temperatures decreased. In March, differences in adelgid survival were not significant below −20°C. In this month, the percentage of live adelgids after cold treatment was ≤11% for −20°C and <2% for −25 and −30°C. In all months, no adelgids survived after exposure to −35 or −40°C. The minimum low temperature range for plant coldhardiness zone 4b, the next coldest zone north of the Mt. Tom infestation, is −28.9 to −31.6°C and further north in zone 4a it is −31.7 to −34.4°C. Therefore, the northerly spread and establishment of A. tsugae may be impeded or perhaps prevented by the cold climate of northern New England. However, our studies are laboratory based and may not completely reflect what occurs in nature and adelgids along the leading edge of the infestation may develop an ability to tolerate colder temperatures in the future.

Svetlana Gouli

Papers

Regional Responses of Hemlock Woolly Adelgid (Homoptera: Adelgidae) to Low Temperatures

Entomopathogenic fungi of Eurygaster integriceps Puton (Hemiptera: Scutelleridae): collection and characterization for development

Colletotrichum acutatum var. fioriniae (teleomorph: Glomerella acutata var. fioriniae var. nov.) infection of a scale insect.

Low Lethal Temperature for Hemlock Woolly Adelgid (Homoptera: Adelgidae)

Survival of hemlock woolly adelgid (Homoptera: Adelgidae) at low temperatures