European Fire Ants on Mount Desert Island, Maine: Population Structure, Mechanisms of Competition and Community Impacts of \u3cem\u3eMyrmica Rubra L.\u3c/em\u3e (Hymenoptera: Formicidae)

In the early to mid-201h century, Mvrmica rubra Latreille established in various communities in Maine, mostly along the coast. Since its establishment, the ant has spread both locally via vegetative colony budding and regionally via human commerce to no fewer than 30 Maine communities, including one inland site. Studies were undertaken in the summer of 2002 to address questions of the ants\u27 population structure in its introduced range by testing for intercolony aggression within and between local infestations. Using captive nests maintained in their original nest soil, M. rubra was tested against its close neighbors, neighbors of lorn within the same infestation, and at two locations within a distinct infestation elsewhere on the island. Aggressive behaviors were quantified, and results suggest a multicolonial population structure, with ants tolerating their close neighbors (perhaps fragments of their own colony), showing measurable aggression toward their 1Om neighbors, and significantly more aggression again toward distant neighbors from which they were separated geographically at the outset. Pitfall and Berlese funnel sampling in four paired sites in Acadia National Park in 2002 showed little impact of M. rubra on the resident (non-ant) arthropod community, with the exception of a significant increase in isopod abundance. Impacts on the native ant fauna were severe, reflecting almost complete displacement and a significant reduction in species richness and diversity. Independent sampling of the homopteran community (tended by M. rubra and native ants for their honeydew exudates) showed an enhanced richness and abundance of several groups where M. rubra was present. Proportionally fewer homopterans were left untended within invaded habitat, suggesting that these insects are ant-limited and confirming our results that M. rubra may enhance such populations. Finally, a total of 27 aggression assays against nativelresident ants in Acadia National Park were performed in an attempt to quantify and characterize behavioral interactions between M. rubra and the native ant community. On average, M. rubra was able to quickly dominate the native foragers and displace them from baits, though some species were more adept at defense, generally by virtue of a well developed sting or chemical spray. A separate experiment testing discovery time and recruitment at the boundary of a local infestation showed that M. rubra foragers discover and recruit more quickly to a food resource. Taken together, these findings suggest that M. rubra, by virtue of its numerical dominance, has broken the dominance-discovery trade-off that serves to partition food resources, allowing native ant coexistence (Fellers, 1987)

Assessing trap and lure effectiveness for the monitoring of Sirex noctilio

1. Lure-baited traps are an important tool for monitoring the spread and establishment of the Sirex woodwasp Sirex noctilio. The utility of these traps, however, is limited in areas with low wasp populations due to the reliance on a plant volatile (kairomone) lure in the absence of an identified pheromone. Knowledge of the optimal trap type and deployment strategy is also lacking. 2. We tested the effectiveness of a putative pheromone in baited traps, by means of a series of field trials in South Africa over a three-year period. We also examined the influence of lure type, trap type and trap height on capture success. 3. The pheromone was found to be ineffective as an attractant under South African field conditions for both male and female wasps. Lure type, trap type and trap height were found to have little to no effect on female wasp catch. Given moderately strong responses to the blend in wind tunnel and laboratory conditions, we suggest possible aspects of the biology and life history of S. noctilio that may influence lure effectiveness. 4. The traditional black intercept panel traps with kairomone lure remains the best trap for S. noctilio, at least where populations are high.USDA APHIS PPQ CPHSThttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1461-95632015-09-30hb201

Homopterans and an invasive red ant, Myrmica rubra (L.), in Maine

Myrmica rubra (L.), is an invasive ant that is spreading across eastern North America. It is presently found in over 40 communities in Maine and areas in Vermont, New Hampshire, Massachusetts, New York, and several provinces in the Canadian Maritimes and Ontario. In addition to disrupting native ant faunas, invasive ants also have been shown to influence homopteran abundance and species composition. We conducted surveys of Homoptera in infested and noninfested sites and conducted manipulative experiments to quantify the effects of M. rubra on homopteran abundance and composition in the summers of 2003, 2006, and 2007 on Mount Desert Island, ME. In 2003, Homoptera family-level richness was higher in infested sites compared with noninfested sites with two out of three sampling methods. Homopteran abundance in infested compared with noninfested sites depended upon the site. The sites with the highest population of M. rubra were associated with significant differences in Homoptera population abundance. In 2006 and 2007, two out of three host plants sampled had significantly higher abundances of the aphids, Aphis spiraephila Patch and Prociphilus tessellatus Fitch. An ant exclusion field experiment on the native plant, meadowsweet (Spiraea alba Du Roi), resulted in higher abundances of A. spiraephila with M. rubra tending compared with native ant tending. A predator exclusion field experiment was conducted on meadowsweet using adult ladybeetles, Hippodamia convergens Guérin-Méneville, larval green lacewings, Chyrsoperla carnea Stephens, and no predators. Predator impacts on aphid populations were reduced in the presence of M. rubra with C. carnea and moderately reduced with H. convergens.We thank Bruce Hazen-Connery and David Manski, biologists with the National Park Service at Acadia National Park, for their support and assistance with the logistics of conducting research in Acadia National Park. In addition, we want to thank two anonymous reviewers for their invaluable comments. This research was supported by several entities: the Maine Agriculture and Forestry Experiment Station, the University of Maine Graduate School, the National Park Service at Acadia National Park, and the L.L. Bean Acadia Research Fellowship Program run by the Friends of Acadia. This is Maine Agricultural and Forestry Experiment Station journal article no. 3245.http://www.entsoc.org/nf201

Mechanisms of competitive displacement of native ant fauna by invading Myrmica rubra (Hymenoptera : Formicidae) populations

Exotic ants have become invasive in many regions around the world, with variable ecological impacts. Post-invasion, native ant communities are often found to be depauperate, though the drivers of minimal coexistence are rarely well known. Myrmica rubra, a Palearctic Myrmecine ant, is currently expanding its range as an invasive in North America. This aggressive ant forms dense, patchy local infestations and appears to aggressively displace native ant fauna. We measured behavioral interactions and rates of recruitment in experimental field assays pitting native foragers against captive colonies of M. rubra at tuna-jelly or aphid baits in uninfested areas of Mt. Desert Island, Maine. Behavioral interactions were idiosyncratic with respect to the native opponent, but M. rubra generally showed significantly higher levels of recruitment, aggression and displacement of native foragers. Since the absence of a tradeoff between resource discovery rate and behavioral dominance appears to contribute to invasion success in other exotic ant species (the dominance-discovery hypothesis), we studied M. rubra and naturally co-occurring native ants at baits along the invasion front. Myrmica rubra was consistently faster to discover baits and disproportionately displaced native foragers, confirming a break in the dominance-discovery tradeoff and providing a plausible proximate mechanism for native ant exclusion. Finally, we surveyed ant recruitment at baits for 24 hours in August 2004 at four sites with varying M. rubra abundance but found little evidence of temporal niche partitioning. Taken together, these results indicate competitive superiority by M. rubra with respect to native ant communities of the northeastern North America and suggest direct aggression and competitive exclusion at food resources can lead to local native displacement.U.S. National Parks Service at Acadia National Park and the Maine Agricultural and Forestry Experiment Station. This is MAFES Publication No. 3384.http://www.entsoc.org/Pubs/Periodicals/EE2015-12-30hb201

Assessment of beetle diversity, community composition and potential threats to forestry using kairomone-baited traps

Traps designed to capture insects during normal movement/dispersal, or via attraction to non-specific (plant) volatile lures, yield by-catch that carries valuable information about patterns of community diversity and composition. In order to identify potential native/introduced pests and detect predictors of colonization of non-native pines, we examined beetle assemblages captured in intercept panel traps baited with kairomone lures used during a national monitoring of the woodwasp, Sirex noctilio, in Southern Africa. We identified 50 families and 436 morphospecies of beetles from nine sites sampled in both 2008 and 2009 and six areas in 2007 (trap catch pooled by region) across a latitudinal and elevational gradient. The most diverse groups were mainly those strongly associated with trees, known to include damaging pests. While native species dominated the samples in terms of richness, the dominant species was the introduced bark beetle Orthotomicus erosus (Curculionidae: Scolytinae) (22 ± 34 individuals/site). Four Scolytinae species without previous records in South Africa, namely Coccotrypes niger, Hypocryphalus robustus (formerly Hypocryphalus mangiferae), Hypothenemus birmanus and Xyleborus perforans, were captured in low abundances. Communities showed temporal stability within sites and strong biogeographic patterns across the landscape. The strongest single predictors of community composition were potential evaporation, latitude and maximum relative humidity, while the strongest multifactor model contained elevation, potential evaporation and maximum relative humidity. Temperature, land use variables and distance to natural areas did not significantly correlate with community composition. Non-phytophagous beetles were also captured and were highly diverse (32 families) perhaps representing important beneficial insects.The DST-NRF Centre of Excellence in Tree Health Biotechnology and the Tree Protection Cooperative Programme.http://journals.cambridge.org/action/displayJournal?jid=BER2017-08-31hb2017Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Biological control of forest plantation pests in an interconnected world requires greater international focus

The worldwide homogenization of genetic resources used in plantation forestry (primarily Pinus, Eucalypus, Populus and Acacia spp.) together with accelerating rates of human-aided dispersal of exotic pests, is resulting in plantation pests becoming broadly distributed extremely quickly, sometimes reaching a global distribution within a decade. This unprecedented rate of establishment and spread means that the risk associated with new and emerging pests is shared globally. Biological control represents a major component of the strategy to mitigate such risk, but the current efforts and scope for developing such controls are woefully inadequate for dealing with the increasing rates of pest spread. Given the global nature of the problem, biological control would benefit enormously from an international, collaborative focus. Though inherent difficulties and potential pitfalls exist, opportunities for costsharing, growth and maintenance of resources and capacity, and more comprehensive research programmes are critical to the long-term success of biological control. Governments and industries will need to increase their strategic investment in structures specifically designed to promote such focus if they are to successfully protect their forest resources.The Tree Protection Co-operative Programme (TPCP), the THRIP initiative of the Department of Trade and Industry and the National Research Foundation, South Africa.http://www.tandfonline.com/loi/ttpm20ab201

Disease ontogeny overshadows effects of climate and species interactions on population dynamics in a nonnative forest disease complex

Biotic threats to trees often arise from interactions among two or more species, frequency insects and fungi, that function together to defeat host defenses, secure resources and colonize new hosts. Feedbacks among plant enemies can have large positive feedbacks that can destabilize populations and permit outbreaks. Feedbacks can be rapid and direct (e.g. within trees or among years) or can arise from slowly developing changes in host resource quantity or quality at the scale of forest stands or landscapes. Climate may also influence system dynamics by altering feedbacks within or among species or through density independent effects. We evaluated major drivers of population dynamics of beech bark disease (BBD), an important forest disease in eastern deciduous forests of North America, using data from 28 study sites in the eastern United States monitored for up to 14 yr between 1979 and 1992. Both primary causal agents of BBD – the introduced felted beech scale. Cryptococcus fagisuga and native fungi Neonectria spp. – Showed strong simple density dependence in all study populations. Surprisingly, densities of scale insects and fungi had little or no effects on population growth rates of the other, despite their habit of living in close physical relationships. For both insects and fungi, ecologically important features of the density dependent functions (slope, carrying capacity and density independent variance ) were variable across sites. Climatic effects on density-dependent functions (and scatter around them) were evident but generally weak and variable. The most striking predictor of patterns in density dependence was duration since establishment of BBD in the region. Apparently BBD alters forests over decades in ways that strengthen self-regulation among causal agents without eliminating or even dramatically reducing host populations.This work was partially supported by the USDA Forest Service Northeastern Research Station, grant 04-JV-11242328- 122.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1600-0587ab201

Host specificity and diversity of Amylostereum associated with Japanese siricids

The mutualism between siricid woodwasps and Amylostereum fungal symbionts has long been considered to be species-specific. Recent studies from North America have challenged this assumption, where native siricids and the introduced Sirex noctilio are clearly swapping symbionts. Whether this pattern is a consequence of invasion or an underappreciated property of siricid biology is unknown. Here we show that the native Japanese siricid, Sirex nitobei, carries both Amylostereum areolatum and Amylostereum chailletii, rather than only A. areolatum as long assumed. Furthermore, all samples from a Urocerus sp. unexpectedly carried, A. chailletii and not Amylostereum laevigatum. Vegetative compatibility group tests revealed extensive clonality, with one VCG present amongst three A. areolatum isolates and six VCGs present amongst 61 A. chailletii isolates. These results contribute to the understanding of insect-fungal fidelity in the siricid-Amylostereum association and, together with other studies, suggest that host tree influences Amylostereum species occurrence, perhaps more strongly than wasps.The University of Pretoria and the Tree Protection Co-operative Programme .http:// www.elsevier.com/locate/funeco2017-12-31hb2016Forestry and Agricultural Biotechnology Institute (FABI)GeneticsZoology and Entomolog

Inferring controls on the epidemiology of beech bark disease from spatial patterning of disease organisms

1 Spatial pattern in the distribution and abundance of organisms is an emergent property of collective rates of reproduction, survival and movement of individuals in a heterogeneous environment. 2 The form, intensity and scale of spatial patterning can be used to test hypotheses regarding the relative importance of candidate processes to population dynamics. 3 Using 84 plots across eastern North America, we studied populations of two associated plant parasites, the invasive felted beech scale Cryptococcus fagisuga Lind. and the native Neonectria fungi, which together cause beech bark disease (BBD). 4 We evaluated spatial patterns at the scales of trees within stands, stands within the forest and forests within the landscape to examine four hypothetically important factors in the ecology of the disease: (i) local contagion within stands; (ii) regional contagion, or among patch infection–reinfection dynamics; (iii) variation in host susceptibility linked to genetic and/or environmental heterogeneity; and (iv) climate effects on population growth of BBD organisms. 5 Analyses revealed an unexpected lack of spatial aggregation in BBD populations among trees, stands and forests. This implies that propagule pressure is generally sufficiently high throughout the infested region of North America such that neither trees nor stands are spared from the disease by dispersal limitations of the disease agents. Furthermore, variation in tree and stand level susceptibility has minimal impact on BBD dynamics and climate is not a conspicuous driver of abundance within the core range of BBD.This work was partially supported by the USDA Forest Service Northeastern Research Station, grant 04-JV-11242328-122.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1461-9563/hb2013ab201

Predicted decrease in global climate suitability masks regional complexity of invasive fruit fly species response to climate change

Climate change affects the rate of insect invasions as well as the abundance, distribution and impacts of such invasions on a global scale. Among the principal analytical approaches to predicting and understanding future impacts of biological invasions are Species Distribution Models (SDMs), typically in the form of correlative Ecological Niche Models (ENMs). An underlying assumption of ENMs is that speciesenvironment relationships remain preserved during extrapolations in space and time, although this is widely criticised. The semi-mechanistic modelling platform, CLIMEX, employs a top-down approach using species ecophysiological traits and is able to avoid some of the issues of extrapolation, making it highly applicable to investigating biological invasions in the context of climate change. The tephritid fruit flies (Diptera: Tephritidae) comprise some of the most successful invasive species and serious economic pests around the world. Here we project 12 tephritid species CLIMEX models into future climate scenarios to examine overall patterns of climate suitability and forecast potential distributional changes for this group. We further compare the aggregate response of the group against species-specific responses. We then consider additional drivers of biological invasions to examine how invasion potential is influenced by climate, fruit production and trade indices. Considering the group of tephritid species examined here, climate change is predicted to decrease global climate suitability and to shift the cumulative distribution poleward. However, when examining species-level patterns, the predominant directionality of range shifts for 11 of the 12 species is eastward. Most notably, management will need to consider regional changes in fruit fly species invasion potential where high fruit production, trade indices and predicted distributions of these flies overlap.http://link.springer.com/journal/105302017-04-30hb2016Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog