Showing papers by "Robert C. Venette published in 2010"

Pest Risk Maps for Invasive Alien Species: A Roadmap for Improvement

Abstract: Pest risk maps are powerful visual communication tools to describe where invasive alien species might arrive, establish, spread, or cause harmful impacts. These maps inform strategic and tactical pest management decisions, such as potential restrictions on international trade or the design of pest surveys and domestic quarantines. Diverse methods are available to create pest risk maps, and can potentially yield different depictions of risk for the same species. Inherent uncertainties about the biology of the invader, future climate conditions, and species interactions further complicate map interpretation. If multiple maps are available, risk managers must choose how to incorporate the various representations of risk into their decisionmaking process, and may make significant errors if they misunderstand what each map portrays. This article describes the need for pest risk maps, compares pest risk mapping methods, and recommends future research to improve such important decision-support tools.

Acceptance and suitability of novel trees for Orthotomicus erosus, an exotic bark beetle in North America

Abstract: To predict whether an herbivorous pest insect will establish in a new area, the potential host plants must be known. For invading bark beetles, adults must recognize and accept trees suitable for larval development. The preference-performance hypothesis predicts that adults will select host species that maximize the fitness of their offspring. We tested five species of North American conifers and one angiosperm for adult acceptance and suitability for reproduction of the Mediterranean pine engraver, Orthotomicus erosus (Wollaston). Red pine, Pinus resinosa Aiton, and white spruce, Picea glauca (Moench) Voss, were accepted by adult beetles and suitable for reproduction to the extent of adult replacement. Others, such as balsam fir, Abies balsamea (L.) Mill., eastern hemlock, Tsuga canagensis (L.) Carriere, and tamarack, Larix laricina (Du Roi) Koch, were acceptable but unsuitable. The presence of tree species that are acceptable to adults but unsuitable for reproduction may affect the ability of O. erosus to establish across North America.

Cold hardiness of emerald ash borer, Agrilus planipennis: a new perspective

Abstract: This study was designed to assess the cold hardiness of emerald ash borer larvae, the overwintering stage of the insect. We began by measuring larval supercooling points, the temperatures at which larvae freeze. We found that larvae collected from naturally infested trees in St. Paul, MN between late October and early December had an average supercooling point of -25°C (-13°F). Research elsewhere indicates that when these insects freeze, they die. Our laboratory assessments of cold hardiness were confirmed during field tests. Naturally infested logs were held outdoors in St. Paul, MN (low winter air temp=-28°C) and near Grand Rapids, MN (-34°C) for ca. 5.5 weeks. Approximately 40% of larvae from logs in St. Paul were inactive or brown, both evidence of death; approximately 90% of larvae from logs near Grand Rapids were inactive or brown, compared with the approximately 10% that showed evidence of death prior to exposure or after being held under cool, non-lethal conditions. Overwintering mortality may help to minimize the damage caused by emerald ash borer in areas with extremely cold winter climates.

Boring in Response to Bark and Phloem Extracts From North American Trees Does Not Explain Host Acceptance Behavior of Orthotomicus erosus (Coleoptera: Scolytidae)

Abstract: When invasive herbivorous insects encounter novel plant species, they must determine whether the novel plants are hosts. The Mediterranean pine engraver, Orthotomicus erosus (Wollaston), an exotic bark beetle poised to expand its range in North America, accepts hosts after contacting the bark. To test the hypothesis that O. erosus accepts hosts on the basis of gustatory cues, we prepared bark and phloem extracts from logs of four North American tree species that we had used in previous host acceptance experiments. Water, methanol, and hexane extracts of red pine, tamarack, balsam fir, and paper birch were presented alone and in combination on a neutral filter paper substrate in a section of a plastic drinking straw. Boring behavior in response to the three-extract combinations differed from the pattern of acceptance previously observed among species when the beetles were in contact with the bark surface. Only the aqueous extracts of tamarack, Larix laricina, increased the initiation and the extent of boring by O. erosus on the filter paper substrate. We conclude that the effects of extracted chemicals do not match the behavior of the beetles observed when penetrating excised bark and phloem discs, indicating that host selection by O. erosus may not be predictable from bark and phloem chemistry alone. Instead, host acceptance may be determined by nongustatory stimuli or by a combination of stimuli including gustatory and nongustatory cues.

Walking Response of the Mediterranean Pine Engraver, Orthotomicus erosus, to Novel Plant Odors in a Laboratory Olfactometer

Abstract: When an herbivorous insect enters a new geographic area, it will select host plants based on short and long distance cues. A conifer-feeding bark beetle that has been recently introduced to North America, the Mediterranean pine engraver, Orthotomicus erosus (Wollaston), has a potentially wide host range, especially among members of the Pinaceae. The long-distance response of the beetles to tree odors may be a key feature of the mechanism of host recognition and selection. We used a laboratory olfactometer to study the walking response of 1,440 O. erosus to odor cues from the bark and phloem of six North American tree species. The beetle moved toward the angiosperm non-host Betula papyrifera more than would be expected by chance, but had a neutral response to odors of two tree species that support reproduction and three species that do not. These results suggest that tree odors alone may not be adequate for O. erosus to recognize novel hosts.

Invasive forest pathogens: Summary of issues, critical needs, and future goals for Forest Service Research and Development

Abstract: Invasive pathogens have caused immeasurable ecological and economic damage to forest ecosystems. Damage will undoubtedly increase over time due to increased introductions and evolution of invasive pathogens in concert with complex environmental disturbances, such as climate change. Forest Service Research and Development must fulfill critical roles and responsibilities to address issues related to invasive forest pathogens. This paper identifies critical, long-term research needs in four key areas: (1) prediction and prevention, (2) early detection and rapid response, (3) management and mitigation, and (4) restoration and rehabilitation. The paper also addresses issues related to national and international collaboration, scientific applications, and communication.