par Raffa, Kenneth Francis;Grégoire, Jean-Claude ;Lindgren, Staffan B.S.
Référence Bark Beetles: Biology and Ecology of Native and Invasive Species, Elsevier Inc., page (1-40)
Publication Publié, 2015-01
Partie d'ouvrage collectif
Résumé : Scolytine beetles show enormous diversity in their mating behaviors, host plant associations, chemical and acoustic signaling, symbiotic relationships, and other critical aspects of their life histories. They can be monogamous or polygamous, solitary or gregarious, and employ levels of parental care that range from gallery maintenance in many tribes to eusociality in some ambrosia beetles. Within this complexity, however, scolytines display some generalities that arise from reproducing within plants, such as sophisticated host location systems, morphological adaptations that facilitate tunneling, advanced communication systems that provide very specific information about plants, and close associations with microbial symbionts. Bark beetles produce pheromones that both attract mates and serve additional functions that vary with the beetles' host-plant relationships. Some species use aggregation pheromones to coordinate cooperative resource procurement, a behavior needed to overcome the sophisticated defenses of live trees. A broad array of microbial symbionts is associated with bark beetles, and these fungi and bacteria vary in their degrees of association, impacts, mechanisms, and functional substitutabilities. Some symbionts contribute to acquisition, utilization, and defense of the host plant resource, and some provide a direct food base. A wide array of predators, competitors, and parasites exploit bark beetles. Many of these natural enemies utilize chemical signals emanating from the beetles or their symbionts in host location, depending on the stage they attack. The habitat in which bark beetles reside poses significant challenges to predators and parasites, so their effects on population dynamics are often limited. Some behavioral, reproductive, and landscape patterns emerge when bark beetle species are functionally categorized by the physiological condition of host plants they colonize. Bark beetles play important and varied roles in ecosystem processes, contributing to biodiversity, nutrient cycling, and heterogeneity. They also pose challenges to resource management in both native and commercial ecosystems. The scale at which beetles exert impacts varies markedly among functional groups, with most species having very localized effects. A few species exert landscape-scale effects, and these ecosystem engineers are among the most pronounced disturbance agents of the biomes they help shape. Their population dynamics are characterized by cross-scale interactions, density-dependent feedbacks, plasticity in host selection decisions, critical thresholds at multiple levels of interaction, and multi-equilibria. A variety of anthropogenic inputs, specifically transport into new regions, habitat manipulations that homogenize forest structure or impede predators, and climatic changes such as elevated temperature and increased drought, increase the socioeconomic losses caused by both eruptive and historically noneruptive species.