Trap Trees for Control of Dutch Elm Disease

Estimating populations of both pest and natural enemy species is important in the planning and implementation of biological control. For example, synthetic pheromone lures are used to sample bark beetles, and sometimes their predators, in forest ecosystems. However, insect attraction to natural pheromone sources may differ from attraction to synthetic pheromone lures. Moreover, these differences may vary systematically between the target pest and some important natural enemies. Thus, the accuracy of both absolute and relative abundances of bark beetles and predators could vary with lure selection. We evaluated a series of synthetic lures to determine which lure gave the closest approximation to actual numbers of Ips pini (Say) and predators arriving at hosts infested with I. pini in Wisconsin. We deployed synthetic lures containing various ratios of the (ϩ) and (Ϫ) enantiomers of the principal I. pini pheromone component, ipsdienol, with or without an additional component, lanierone. I. pini showed strong preferences for speciÞc enantiomeric ratios of ipsdienol, and these responses were synergized by lanierone. Predators showed equally strong attraction to ipsdienol, but preferred different ratios of the stereoisomers. The addition of lanierone had no effect on predators. The most abundant predator, Thanasimus dubius (F.), showed greater preference for host material infested with I. pini than any synthetic lure. These disparities in responses, combined with strong disparities in seasonal ßight patterns, provided estimates of pest to predator ratios that varied by as little as 12% to as much as 12 times, from pest:predator ratios arriving at host material infested with I. pini. These results suggest that variation between herbivores and their natural enemies in their phenology, preferred pheromone blends, and infested host material should be considered when developing estimates of relative pest and predator densities for subsequent management options.

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Molecular and cellular aspects of Dutch elm disease

Sticklen¹,

Bolyard²,

Hajela³

et al. 2005

phyto

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Cet article de synthèse présente une revue des recherches concernant les interactions moléculaires et cellulaires de la maladie hollandaise de l'orme. Cette maladie, causée par le champignon Ophiostoma ulmi, provoque un flétrissement vasculaire et elle est transmise d'ormes infectés à des ormes sains par des scolytes. Des toxines fongiques sont décrites en relation avec la pathogénèse, l'une d'elles, la cérato-ulmine, étant sous investigation au niveau moléculaire, plus particulièrement en ce qui concerne son mode d 'action et sa localisation. Le champignon a aussi été examiné au niveau moléculaire pour différencier des isolats agressifs et non agressifs sur la base de profils protéiques et d'acides nucléiques. Des cartes de lien génétique sont en développement afin de corréler la perturbation de certains gènes avec la perte du pouvoir pathogène. Des antagonistes viraux et bactériens du champignon, qui peuvent être utilisés comme mécanisme de lutte biologique contre la maladie hollandaise de l'orme, ont été caractérisés ainsi que plusieurs des molécules actives intervenant dans cette lutte. Les réponses de l'hôte sont discutées aux niveaux moléculaire et biochimique, incluant les phy toalexines et les éliciteurs des mécanismes de défense. Plusieurs avenues de recherche sont discutées afin de fournir une revue des approches moléculaires visant à comprendre et à manipuler les organismes impliqués en vue du but ultime de lutter contre la maladie hollandaise de l'orme.The folio wing review gives an overview of current research in the area of molecular and cellular interactions in Dutch elm disease. This vascular wilt disease is caused by the fungus Ophiostoma ulmi and is transmitted from diseased to healthy trees by the elm bark beetles. Fungal toxins are described which are associated with pathogenesis, one of which, ceratoulmin, is under investigation at the molecular level, particularly regarding its mode of action and localization. The fungus has also been examined at the molecular level to differentiate between aggressive and non-aggressive isolates on the basis of protein and nucleic acid profiles. Genetic linkage maps are being developed to correlate disruption of certain genes with the loss of pathogenicity. Viral and bacterial antagonists of the fungus, which may serve as biological control mechanisms for Dutch elm disease, have been characterized, as have several of the active molecules responsible for control. Host responses are also discussed at the molecular and biochemical level, including phytoalexins and defense mechanism elicitors. Several Unes of investigation are discussed to provide an overview of molecular approaches to understanding and manipulating the organisms involved with the ultimate goal of controlling Dutch elm disease

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Trap Trees for Control of Dutch Elm Disease

Cited by 3 publications

References 13 publications

Scolytus scolytus (large elm bark beetle)

Scolytus scolytus (large elm bark beetle)

Improved Population Monitoring of Bark Beetles and Predators by Incorporating Disparate Behavioral Responses to Semiochemicals

Molecular and cellular aspects of Dutch elm disease

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