Effects of Visual Silhouette, Leaf Size and Host Species on Feeding Preference by Adult Emerald Ash Borer, \u3ci\u3eAgrilus Planipennis\u3c/i\u3e Fairmaire (Coleoptera: Buprestidae)

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive species recently established in North America. In large arena bioassays, when given a choice among live green ash, Fraxinus pennsylvanica Marsh and artificial ash saplings that were hidden or exposed from view, beetles preferred live trees (either visible or hidden) compared to artificial trees that had similar visual silhouettes, confirming that olfactory cues are used to locate hosts. Examination of the effect of leaf size revealed that large leaves attracted more beetles than medium-sized leaves that in turn attracted more beetles than small leaves of the same age. Beetles also consumed more of the large leaves in terms of total leaf area than either medium or small leaves, but the proportion of foliage that beetles consumed relative to total available leaf area, did not differ. When newly emerged adults were fed on green and Manchurian ash, Fraxinus mandshurica Rupr., foliage in a no- choice assay, beetles that were given green ash consumed significantly more foliage compared to those that fed on Manchurian ash, but neither longevity nor beetle body weight differed. Our results suggest that while beetles might use olfactory cues to identify suitable hosts, visual cues also play a role in landing and feeding behavior. Manchurian ash might have greater nutritive value or resistance than green ash, necessitating lower consumption and therefore less damage in nature

Effects of Visual Silhouette, Leaf Size and Host Species on Feeding Preference by Adult Emerald Ash Borer, \u3ci\u3eAgrilus Planipennis\u3c/i\u3e Fairmaire (Coleoptera: Buprestidae)

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive species recently established in North America. In large arena bioassays, when given a choice among live green ash, Fraxinus pennsylvanica Marsh and artificial ash saplings that were hidden or exposed from view, beetles preferred live trees (either visible or hidden) compared to artificial trees that had similar visual silhouettes, confirming that olfactory cues are used to locate hosts. Examination of the effect of leaf size revealed that large leaves attracted more beetles than medium-sized leaves that in turn attracted more beetles than small leaves of the same age. Beetles also consumed more of the large leaves in terms of total leaf area than either medium or small leaves, but the proportion of foliage that beetles consumed relative to total available leaf area, did not differ. When newly emerged adults were fed on green and Manchurian ash, Fraxinus mandshurica Rupr., foliage in a no- choice assay, beetles that were given green ash consumed significantly more foliage compared to those that fed on Manchurian ash, but neither longevity nor beetle body weight differed. Our results suggest that while beetles might use olfactory cues to identify suitable hosts, visual cues also play a role in landing and feeding behavior. Manchurian ash might have greater nutritive value or resistance than green ash, necessitating lower consumption and therefore less damage in nature

Evaluation of two repellent semiochemicals for disruption of attack by the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae)

When released from attractant-baited multiple-funnel traps, 3-methyl-2-cyclohexen-1- one (MCH) reduced catches of male and female mountain pine beetles, Dendroctonus ponderosae Hopkins, by 67.4% and 71.8%, respectively. 2-Phenyl ethanol reduced the respective catches by 96.6% and 95.1%, but only verbenone and all three compounds together reduced catches to levels no different from those in unbaited control traps. In another experiment, all three binary combinations of the above compounds, plus the ternary combination, reduced catches of both sexes by >96%. In comparable tree protection experiments near Princeton BC, MCH and 2-phenyl ethanol alone and together significantly reduced the percentages of pheromone-baited lodgepole pines that were attacked by 16.0%, 33.3% and 40.0%, respectively, but verbenone alone totally protected baited trees, and many trees within 5 m of them, from attack. In identical experiments near Prince George BC, where mountain pine beetle populations were much higher, adding MCH, 2-phenyl ethanol or both together to verbenone did not cause attack to be reduced significantly beyond that achieved by verbenone alone. Our results confirm that 2-phenyl ethanol is an antiaggregation pheromone for the mountain pine beetle, and that MCH is an interspecific synomone. However, because neither was as effective as verbenone in protecting pheromone-baited trees from attack, and adding either or both to verbenone did not improve protection, neither compound warrants further consideration as a potential tool for operational disruption of attack

Invasion disharmony in the global biogeography of native and non‐native beetle species

International audienceAim The concept of "island disharmony" has been widely applied to describe the systematic over- and under-representation of taxa on islands compared to mainland regions. Here, we explore an extension of that concept to biological invasions. We compare biogeographical patterns in native and non-native beetle (Coleoptera) assemblages from around the world to test whether beetle invasions represent a random sample of species or whether some families are more prone to invade than others. Location Global. Methods Numbers of non-native beetle species established in ten regions worldwide were compared with the land area of each region. The distribution of species among families was compared with the distribution among families for all species native to the same region and with the distribution among families for the global pool of all known beetle species. Ordination analysis was used to characterize differences among native and non-native assemblages based upon the distribution of species among families. Results We report a total of 1,967 non-native beetle species across all ten regions, and a classic log-log relationship between numbers of species per region and land area though relationships are generally stronger for native assemblages. Some families (e.g., Dermestidae and Bostrichidae) are over-represented and others (e.g., Carabidae, Scarabaeidae and Buprestidae) are under-represented in non-native assemblages. The distribution of species among families is generally similar among native assemblages with greatest similarities among nearby regions. In contrast, non-native species assemblages are more similar to each other than to native species assemblages. Main conclusions Certain families are over-represented, and others are under-represented in non-native beetle assemblages compared to native assemblages, indicating "invasion disharmony" in the global representation of beetle families. Similarities in composition among non-native assemblages may reflect unobserved associations with invasion pathways and life-history traits that shape invasion success of different insect groups

Globally consistent climate sensitivity of natural disturbances across boreal and temperate forest ecosystems

Disturbance regimes are changing in forests across the world in response to global climate change. Despite the profound impacts of disturbances on ecosystem services and biodiversity, assessments of disturbances at the global scale remain scarce. Here, we analyzed natural disturbances in boreal and temperate forest ecosystems for the period 2001-2014, aiming to 1) quantify their within- and between-biome variation and 2) compare the climate sensitivity of disturbances across biomes. We studied 103 unmanaged forest landscapes with a total land area of 28.2 x 10(6) ha, distributed across five continents. A consistent and comprehensive quantification of disturbances was derived by combining satellite-based disturbance maps with local expert knowledge of disturbance agents. We used Gaussian finite mixture models to identify clusters of landscapes with similar disturbance activity as indicated by the percent forest area disturbed as well as the size, edge density and perimeter-area-ratio of disturbed patches. The climate sensitivity of disturbances was analyzed using Bayesian generalized linear mixed effect models and a globally consistent climate dataset. Within-biome variation in natural disturbances was high in both boreal and temperate biomes, and disturbance patterns did not vary systematically with latitude or biome. The emergent clusters of disturbance activity in the boreal zone were similar to those in the temperate zone, but boreal landscapes were more likely to experience high disturbance activity than their temperate counterparts. Across both biomes high disturbance activity was particularly associated with wildfire, and was consistently linked to years with warmer and drier than average conditions. Natural disturbances are a key driver of variability in boreal and temperate forest ecosystems, with high similarity in the disturbance patterns between both biomes. The universally high climate sensitivity of disturbances across boreal and temperate ecosystems indicates that future climate change could substantially increase disturbance activity.Peer reviewe

Forest Insects and Climate Change

Purpose of Review Climate change affects populations of forest insect pests in a number of ways. We reviewed the most recent literature (2013-2017) on this subject including previous reviews on the topic. We provide a comprehensive discussion of the subject, with special attention to insect range expansion, insect abundance, impacts on forest ecosystems, and effects on forest insect communities. We considered forest insects according to their major guilds and biomes. Recent Findings Effects of climate change on forest insects are demonstrated for a number of species and guilds, although generalizations of results available so far are difficult because of species-specific responses to climate change. In addition, disentangling direct and indirect effects of climate change is complex due to the large number of variables affected. Modeling based on climate projections is useful when combined with mechanistic explanations. Summary Expansion of either the true range or the outbreak range is observed in several model species/groups of major insect guilds in boreal and temperate biomes. Mechanistic explanations are provided for a few species and are mainly based on increase in winter temperatures. In relation to insect abundance, climate change can either promote outbreaks or disrupt trophic interactions and decrease the severity of outbreaks. There is good evidence that some recent outbreaks of bark beetles and defoliating insects are influenced by climate change and are having a large impact on ecosystems as well as on communities of forest insects