Forest restoration treatments indirectly diversify pollination networks via floral- and temperature-mediated effects

In North American conifer forests, a variety of federally initiated thinning programs are implemented to restore pre-European settlement forest structures, but these changes may impact ecosystem function via impacts on sensitive biotic communities. Across the wildland-urban interface of the Front Range region of Colorado, agencies associated with the Collaborative Forest Landscape Restoration Program (CFLRP) have implemented thinning treatments across thousands of hectares of ponderosa pine forest; here we leverage these treatments as an experimental framework to examine thinning effects on a pollinator community. We measured variation in forest structure and sampled bee community assemblages using multiple methods (trapping and netting) to compare bee biodiversity and patterns of floral visitation by bees (bee-flower networks) between mechanically thinned stands that were 3-10 years after treatment and nonthinned stands. Three key findings emerged: (1) Native bee abundance, richness, and diversity were 120%, 53%, and 37% greater, respectively, in thinned stands. In addition, nestedness, richness, and abundance of bee-flower interactions were all substantially higher in thinned stands, and there was increased functional redundancy in bee assemblages after thinning. (2) Structural equation modeling indicated that variation in temperature and floral abundance were mediated by canopy openness and correlated with bee richness and abundance, thereby indirectly driving variation in bee-flower interactions. (3) Four floral species (Penstemon virens, Cerastium arvense, Erysimum capitatum, and Geranium caespitosum) were identified as key connectors in bee-flower interaction networks, though these were not necessarily the most abundant flowering plants. Our analyses indicate that native bee α-diversity and bee-flower interactions positively responded to thinning treatments, and these effects were indirectly driven by canopy removal. We conclude that CFLRP treatments have conservation value for native bee communities. Further monitoring is warranted to evaluate the longevity of these effects.

The effect of natural disturbances on forest biodiversity: an ecological synthesis

Disturbances alter biodiversity via their specific characteristics, including severity and extent in the landscape, which act at different temporal and spatial scales. Biodiversity response to disturbance also depends on the community characteristics and habitat requirements of species. Untangling the mechanistic interplay of these factors has guided disturbance ecology for decades, generating mixed scientific evidence of biodiversity responses to disturbance. Understanding the impact of natural disturbances on biodiversity is increasingly important due to human-induced changes in natural disturbance regimes. In many areas, major natural forest disturbances, such as wildfires, windstorms, and insect outbreaks, are becoming more frequent, intense, severe, and widespread due to climate change and land-use change. Conversely, the suppression of natural disturbances threatens disturbance-dependent biota. Using a meta-analytic approach, we analysed a global data set (with most sampling concentrated in temperate and boreal secondary forests) of species assemblages of 26 taxonomic groups, including plants, animals, and fungi collected from forests affected by wildfires, windstorms, and insect outbreaks. The overall effect of natural disturbances on α-diversity did not differ significantly from zero, but some taxonomic groups responded positively to disturbance, while others tended to respond negatively. Disturbance was beneficial for taxonomic groups preferring conditions associated with open canopies (e.g. hymenopterans and hoverflies), whereas ground-dwelling groups and/or groups typically associated with shady conditions (e.g. epigeic lichens and mycorrhizal fungi) were more likely to be negatively impacted by disturbance. Across all taxonomic groups, the highest α-diversity in disturbed forest patches occurred under moderate disturbance severity, i.e. with approximately 55% of trees killed by disturbance. We further extended our meta-analysis by applying a unified diversity concept based on Hill numbers to estimate α-diversity changes in different taxonomic groups across a gradient of disturbance severity measured at the stand scale and incorporating other disturbance features. We found that disturbance severity negatively affected diversity for Hill number q = 0 but not for q = 1 and q = 2, indicating that diversity-disturbance relationships are shaped by species relative abundances. Our synthesis of α-diversity was extended by a synthesis of disturbance-induced change in species assemblages, and revealed that disturbance changes the β-diversity of multiple taxonomic groups, including some groups that were not affected at the α-diversity level (birds and woody plants). Finally, we used mixed rarefaction/extrapolation to estimate biodiversity change as a function of the proportion of forests that were disturbed, i.e. the disturbance extent measured at the landscape scale. The comparison of intact and naturally disturbed forests revealed that both types of forests provide habitat for unique species assemblages, whereas species diversity in the mixture of disturbed and undisturbed forests peaked at intermediate values of disturbance extent in the simulated landscape. Hence, the relationship between α-diversity and disturbance severity in disturbed forest stands was strikingly similar to the relationship between species richness and disturbance extent in a landscape consisting of both disturbed and undisturbed forest habitats. This result suggests that both moderate disturbance severity and moderate disturbance extent support the highest levels of biodiversity in contemporary forest landscapes.

Bumblebee (Hymenoptera: Apidae) Visitation Frequency Drives Seed Yields and Interacts with Site-Level Species Richness to Drive Pollination Services in Sunflower

Understanding whether pollinator behaviors and species richness drive crop yields is a key area of investigation in pollination ecology. Using sunflower as a study species we describe variation in mean floral visitation times among bee taxa and test how interactions between bee richness and the proportion of bumblebees in localized communities impact seed yield. Seven bee genera commonly visited sunflower including Agapostemon, Bombus, Halictus, Lasioglossum, Megachile, Melissodes, and Svastra. Mean visitation times to sunflower varied across genera and Bombus and Halictus spp. spent the most time foraging on inflorescences, but the number of visits by Bombus spp. was the only parameter associated with increased yields. Experimental pollination deficit reduced seed development and yields, and these effects were stronger in stands of wild-type sunflower in the field compared to a confection variety grown in the greenhouse. Relationships between bee richness and pollination services differed for potted and wild sunflower: when bees had short-term access to potted sunflower, bee richness and relative Bombus abundances were not associated with pollination quotients. When bees had long-term access to wild sunflower, relative Bombus abundances predicted pollination services but were modified by site-level bee richness: as richness increased, the effects of Bombus abundance decreased. Our studies demonstrate that bee species richness is not always a clear predictor of pollination services; instead, our results underscore the importance of specific taxa when species richness is low (here, bumblebees), and show that the effects of bee functional groups important for pollination may be modified by changes in site-level species richness.

Interspecific variation in spruce constitutive and induced defenses in response to a bark beetle-fungal symbiont provides insight into traits associated with resistance

Differences in defensive traits of tree species may predict why some conifers are susceptible to bark beetle-fungal complexes and others are not. A symbiotic fungus (Leptographium abietinum (Peck) M.J. Wingf.) associated with the tree-killing bark beetle (Dendroctonus rufipennis Kirby) is phytopathogenic to host trees and may hasten tree decline during colonization by beetles, but defense responses of mature trees to the fungus have not been experimentally examined. To test the hypothesis that interspecific variation in spruce resistance is explained by defense traits we compared constitutive (bark thickness and constitutive resin ducts) and induced defenses (resin flow, monoterpene composition, concentration, phloem lesion formation and traumatic resin ducts) between two sympatric spruces: Engelmann spruce (Picea engelmannii Parry ex Engelm.-a susceptible host) and blue spruce (Picea pungens Engelm.-a resistant host) in response to fungal inoculation. Four central findings emerged: (i) blue spruce has thicker outer bark and thinner phloem than Engelmann spruce, which may restrict fungal access to phloem and result in less beetle-available resource overall; (ii) both spruce species induce monoterpenes in response to inoculation but blue spruce has higher constitutive monoterpene levels, induces monoterpenes more rapidly, and induces higher concentrations over a period of time consistent with spruce beetle attack duration; (iii) Engelmann and blue spruce differed in the monoterpenes they upregulated in response to fungal inoculation: blue spruce upregulated α-pinene, terpinolene and γ-terpinene, but Engelmann spruce upregulated 3-carene and linalool; and (iv) blue spruce has a higher frequency of constitutive resin ducts and produces more traumatic resin ducts in annual growth increments than Engelmann spruce, though Engelmann spruce produces more resin following aseptic wounding or fungal inoculation. These findings suggest that higher constitutive resin duct densities and monoterpene concentrations, as well as the ability to rapidly induce specific monoterpenes in response to L. abietinum inoculation, are phenotypic traits associated with hosts resistant to spruce beetle colonization.

Livestock grazing is associated with seasonal reduction in pollinator biodiversity and functional dispersion but cheatgrass invasion is not: Variation in bee assemblages in a multi-use shortgrass prairie

Livestock grazing and non-native plant species affect rangeland habitats globally. These factors may have important effects on ecosystem services including pollination, yet, interactions between pollinators, grazing, and invasive plants are poorly understood. To address this, we tested the hypothesis that cattle grazing and site colonization by cheatgrass (Bromus tectorum) impact bee foraging and nesting habitats, and the biodiversity of wild bee communities, in a shortgrass prairie system. Bee nesting habitats (litter and wood cover) were marginally improved in non-grazed sites with low cheatgrass cover, though foraging habitat (floral cover and richness, bare soil) did not differ among cattle-grazed sites or non-grazed sites with low or high cheatgrass cover. However, floral cover was a good predictor of bee abundance and functional dispersion. Mean bee abundance, richness, diversity and functional diversity were significantly lower in cattle-grazed habitats than in non-grazed habitats. Differences in bee diversity among habitats were pronounced early in the growing season (May) but by late-season (August) these differences eroded as Melissodes spp. and Bombus spp. became more abundant at study sites. Fourth-corner analysis revealed that sites with high floral cover tended to support large, social, polylectic bees; sites with high grass cover tended to support oligolectic solitary bees. Both cattle-grazed sites and sites with high cheatgrass cover were associated with lower abundances of above-ground nesting bees but higher abundance of below-ground nesters than non-grazed sites with low cheatgrass cover. We conclude that high cheatgrass cover is not associated with reduced bee biodiversity or abundance, but cattle grazing was negatively associated with bee abundances and altered species composition. Although floral cover is an important predictor of bee assemblages, this was not impacted by cattle grazing and our study suggests that cattle likely impact bee communities through effects other than those mediated by forbs, including soil disturbance or nest destruction. Efforts aimed at pollinator conservation in prairie habitats should focus on managing cattle impacts early in the growing season to benefit sensitive bee species.

Bark beetle outbreak enhances biodiversity and foraging habitat of native bees in alpine landscapes of the southern Rocky Mountains

Landscape-scale bark beetle outbreaks alter forest structure with direct and indirect effects on plants and animals in forest ecosystems. Using alpine spruce forest and a native bee community as a study system, we tested how tree mortality from bark beetles impacts bee foraging habitats and populations. Bees were collected across the growing season (early-, middle-, and late-season) for two years using passive trapping methods, and collections were used to analyze patterns in species abundances and diversity. Three important findings emerged: (1) forest stands that were post-outbreak had 62% higher floral density and 68% more floral species during peak bloom, respectively, than non-affected stands; (2) bee captures were highest early-season (June) and were not strongly affected by bark beetle outbreak; however, mean number of bee species and Shannon–Weiner diversity were significantly higher in post-outbreak stands and this effect was pronounced early in the growing season. Corresponding analysis of β-diversity indicated higher accumulation of bee biodiversity in post-outbreak stands and a turnover in the ratio of Bombus: Osmia; (3) bee captures were linked to variation in foraging habitat, but number of bee species and diversity were more strongly predicted by forest structure. Our results provide evidence of increased alpine bee biodiversity in post-outbreak stands and increased availability of floral resources. We conclude that large-scale disturbance from bark beetle outbreaks may drive shifts in pollinator community composition through cascading effects on floral resources, mediated via mortality of overstory trees.

Effects of Site Thermal Variation and Physiography on Flight Synchrony and Phenology of the North American Spruce Beetle (Coleoptera: Curculionidae, Scolytinae) and Associated Species in Colorado

Spruce beetle, Dendroctonus rufipennis Kirby, is associated with forest mortality in Colorado and across western North America, yet it is not well understood how thermal variability affects basic population processes such as flight phenology. However, phenology-temperature relationships are important for understanding patterns of ecosystem disturbance, especially under projected climate warming. Here, we use a multiyear trapping study to test the hypothesis that spruce beetle flight synchrony, timing, and fitness traits (body size) are affected by variation in regional temperature and physiography. Large quantities of co-colonizing scolytines (Polygraphus convexifrons) (Coleoptera: Curculionidae, Scolytinae) and predatory beetles (Thanasimus undulatus) (Coleoptera: Cleridae) that may affect D. rufipennis populations also responded to spruce beetle synthetic pheromone lures. Relationships between flight patterns and environmental conditions were also analyzed for these species. The winter of 2018 was warmer and drier than winter 2017 and was associated with earlier flight for both scolytine species across most sites. The most important environmental factor driving D. rufipennis flight phenology was accumulated growing degree-days, with delayed flight cessation under warmer conditions and larger beetles following a warm winter. Flight was consistently more synchronous under colder growing season conditions for all species, but synchrony was not associated with winter temperatures. Warmer-than-average years promoted earlier flight of D. rufipennis and associated species, and less synchronous, prolonged flight across the region. Consequently, climate warming may be associated with earlier and potentially extended biotic pressure for spruce trees in the Rocky Mountain region, and flight phenology of multiple scolytines is plastic in response to thermal conditions.

Biomimetic sensory feedback through peripheral nerve stimulation improves dexterous use of a bionic hand

We describe use of a bidirectional neuromyoelectric prosthetic hand that conveys biomimetic sensory feedback. Electromyographic recordings from residual arm muscles were decoded to provide independent and proportional control of a six-DOF prosthetic hand and wrist-the DEKA LUKE arm. Activation of contact sensors on the prosthesis resulted in intraneural microstimulation of residual sensory nerve fibers through chronically implanted Utah Slanted Electrode Arrays, thereby evoking tactile percepts on the phantom hand. With sensory feedback enabled, the participant exhibited greater precision in grip force and was better able to handle fragile objects. With active exploration, the participant was also able to distinguish between small and large objects and between soft and hard ones. When the sensory feedback was biomimetic-designed to mimic natural sensory signals-the participant was able to identify the objects significantly faster than with the use of traditional encoding algorithms that depended on only the present stimulus intensity. Thus, artificial touch can be sculpted by patterning the sensory feedback, and biologically inspired patterns elicit more interpretable and useful percepts.

Laboratory and Field Evaluation of the Entomopathogenic Fungus Beauveria bassiana (Deuteromycotina: Hyphomycetes) for Population Management of Spruce Beetle, Dendroctonus rufipennis (Coleoptera: Scolytinae), in Felled Trees and Factors Limiting Pathogen Success

An isolate of the entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) was tested for its ability to reduce survival and reproduction of spruce beetle, Dendroctonus rufipennis (Kirby) (Coleoptera: Scolytinae), under laboratory and field conditions. Conidial suspension applied directly to adults or to filter papers that adults contacted had a median survival time of 3-4 d in laboratory assays and beetles died more rapidly when exposed to conidial suspension than when treated with surfactant solution only. In the field, conidial suspension was applied to the surface of felled and pheromone-baited Engelmann spruce (Picea engelmannii) trees using a backpack sprayer. Mortality of colonizing parent beetles (F0), reproduction (abundance of F1 offspring in logs), and emergence of F1 beetles from logs was compared between treated and nontreated logs. Application of spore suspension increased mortality of F0 adults by 36% on average. Total F1 reproduction was reduced by 17% and emergence from logs was reduced by 13% in treated logs, but considerable variability in reproduction and emergence was observed. Viable spores were re-isolated from treated logs up to 90 d after application, indicating that spores are capable of long-term persistence on the tree bole microhabitat. Subsequent in vitro tests revealed that temperatures below 15°C and exposure to spruce monoterpenes likely limit performance of B. bassiana under field conditions, but exposure to low-intensity light or interactions with spruce beetle symbiotic fungi were not strongly inhibitory. It is concluded that matching environmental tolerances of biocontrol fungi to field conditions can likely improve their usefulness for control of spruce beetle in windthrown trees.

Plant Water Stress Affects Interactions Between an Invasive and a Naturalized Aphid Species on Cereal Crops

In cereal cropping systems of the Pacific Northwestern United States (PNW), climate change is projected to increase the frequency of drought during summer months, which could increase water stress for crop plants. Yet, it remains uncertain how interactions between herbivore species are affected by drought stress. Here, interactions between two cereal aphids present in PNW cereal systems, Metopolophium festucae (Theobald) subsp. cerealium (a newly invasive species) and Rhopalosiphum padi L. (a naturalized species), were tested relative to wheat water stress. When aphids were confined in leaf cages on wheat, asymmetrical facilitation occurred; per capita fecundity of R. padi was increased by 46% when M. festucae cerealium was also present, compared to when only R. padi was present. Imposed water stress did not influence this interaction. When aphids were confined on whole wheat plants, asymmetrical competition occurred; cocolonization inhibited M. festucae cerealium population growth but did not affect R. padi population growth. Under conditions of plant water stress, however, the inhibitory effect of R. padi on M. festucae cerealium was not observed. We conclude that beneficial effects of cocolonization on R. padi are due to a localized plant response to M. festucae cerealium feeding, and that cocolonization of plants is likely to suppress M. festucae cerealium populations under ample water conditions, but not when plants are water stressed. This suggests that plant responses to water stress alter the outcome of competition between herbivore species, with implications for the structure of pest communities on wheat during periods of drought.

The Effects of Bean Leafroll Virus on Life History Traits and Host Selection Behavior of Specialized Pea Aphid (Acyrthosiphon pisum, Hemiptera: Aphididae) Genotypes

Intraspecific specialization by insect herbivores on different host plant species contributes to the formation of genetically distinct "host races," but the effects of plant virus infection on interactions between specialized herbivores and their host plants have barely been investigated. Using three genetically and phenotypically divergent pea aphid clones (Acyrthosiphon pisum L.) adapted to either pea (Pisum sativum L.) or alfalfa (Medicago sativa L.), we tested how infection of these hosts by an insect-borne phytovirus (Bean leafroll virus; BLRV) affects aphid performance and preference. Four important findings emerged: 1) mean aphid survival rate and intrinsic rate of population growth (Rm) were increased by 15% and 14%, respectively, for aphids feeding on plants infected with BLRV; 2) 34% of variance in survival rate was attributable to clone × host plant interactions; 3) a three-way aphid clone × host plant species × virus treatment significantly affected intrinsic rates of population growth; and 4) each clone exhibited a preference for either pea or alfalfa when choosing between noninfected host plants, but for two of the three clones tested these preferences were modestly reduced when selecting among virus-infected host plants. Our studies show that colonizing BLRV-infected hosts increased A. pisum survival and rates of population growth, confirming that the virus benefits A. pisum. BLRV transmission affected aphid discrimination of host plant species in a genotype-specific fashion, and we detected three unique "virus-association phenotypes," with potential consequences for patterns of host plant use by aphid populations and crop virus epidemiology.

Restoring motor control and sensory feedback in people with upper extremity amputations using arrays of 96 microelectrodes implanted in the median and ulnar nerves

OBJECTIVE

An important goal of neuroprosthetic research is to establish bidirectional communication between the user and new prosthetic limbs that are capable of controlling >20 different movements. One strategy for achieving this goal is to interface the prosthetic limb directly with efferent and afferent fibres in the peripheral nervous system using an array of intrafascicular microelectrodes. This approach would provide access to a large number of independent neural pathways for controlling high degree-of-freedom prosthetic limbs, as well as evoking multiple-complex sensory percepts.

APPROACH

Utah Slanted Electrode Arrays (USEAs, 96 recording/stimulating electrodes) were implanted for 30 days into the median (Subject 1-M, 31 years post-amputation) or ulnar (Subject 2-U, 1.5 years post-amputation) nerves of two amputees. Neural activity was recorded during intended movements of the subject's phantom fingers and a linear Kalman filter was used to decode the neural data. Microelectrode stimulation of varying amplitudes and frequencies was delivered via single or multiple electrodes to investigate the number, size and quality of sensory percepts that could be evoked. Device performance over time was assessed by measuring: electrode impedances, signal-to-noise ratios (SNRs), stimulation thresholds, number and stability of evoked percepts.

MAIN RESULTS

The subjects were able to proportionally, control individual fingers of a virtual robotic hand, with 13 different movements decoded offline (r = 0.48) and two movements decoded online. Electrical stimulation across one USEA evoked >80 sensory percepts. Varying the stimulation parameters modulated percept quality. Devices remained intrafascicularly implanted for the duration of the study with no significant changes in the SNRs or percept thresholds.

SIGNIFICANCE

This study demonstrated that an array of 96 microelectrodes can be implanted into the human peripheral nervous system for up to 1 month durations. Such an array could provide intuitive control of a virtual prosthetic hand with broad sensory feedback.

The ecology of yeasts in the bark beetle holobiont: a century of research revisited

Yeasts are extremely common associates of scolytine bark beetles, yet the basic ecology of yeasts in the bark beetle holobiont remains poorly understood. Yeasts are present in all beetle life stages and consistently isolated from adult, larval, and pupal integuments and mycangial structures, but yeasts are also found in oviposition galleries, pupal chambers, larval and adult digestive tracts, as well as phloem and xylem tissues. Yeasts in the Saccharomycetaceae family are the most prevalent associates, and most individual beetles are associated with only one or several yeast species. Kuraishia capsulata and Ogataea pini are the most commonly encountered yeast species in surveys of Dendroctonus and Ips beetles; most beetles that have been surveyed are vectors for one or both yeasts. Yeasts have significant but often overlooked functional roles in bark beetle ecology. Infochemicals resulting from volatile production by yeast have wide-ranging bioactivity for arthropods: Yeast emissions attract beetles at low concentrations but repel beetles at high concentrations, and yeast emissions can also serve as cues to predators and parasites of bark beetles. In some cases, yeasts can modify tree chemistry over time or metabolize toxic terpenoids, though potential consequences for beetle performance or the growth of nutritional fungi remain to be demonstrated. Also, the presence of yeast species can restrict or promote the establishment and growth of filamentous fungi, including mutualists, entomopathogens, and opportunistic saprophytes. The role of yeasts as nutritional symbionts has received mixed support, though a nutritional hypothesis has not been extensively tested. Continued research on the functional ecology of bark beetle-yeast associations is needed to better understand the emergent properties of these complex symbiont assemblages.

Host settling behavior, reproductive performance, and effects on plant growth of an exotic cereal aphid, Metopolophium festucae subsp. cerealium (Hemiptera: Aphididae)

The cereal aphid Metopolophium festucae subsp. cerealium (Stroyan) is a recent addition to North America, but little is known about this species in its exotic habitat. We surveyed aphid populations for 3 years (2011-2013) to investigate changes in aphid density in the Pacific Northwest United States. We tested aphid host settling preference and fecundity on eight grass species, four native grasses (bluebunch wheatgrass, blue wild rye, Idaho fescue, and rough fescue) and four cereal crops (corn, wheat, barley, and oat), and evaluated the effects of aphid feeding on plant biomass. Four important findings emerged: 1) aphid prevalence in sweep net samples increased from 2011 to 2012, but remained stable from 2012 to 2013; 2) aphids preferentially settled on wheat and avoided corn, but aphids did not discriminate between barley, oat, and native grasses; 3) aphid fecundity was high on wheat and barley, intermediate on oat and blue wild rye, low on Idaho fescue, rough fescue, and bluebunch wheatgrass, and aphids did not reproduce at all on corn; and 4) barley, corn, oats, Idaho fescue, and blue wild rye were not susceptible to aphid feeding damage, but wheat, rough fescue, and bluebunch wheatgrass were susceptible to aphid feeding damage. Our results suggest that wheat and barley are preferred by M. festucae cerealium, and that aphids reproduce most rapidly on these hosts and cause significant reductions in wheat but not barley growth. Also, M. festucae cerealium appears capable of surviving on native grasses, although only bluebunch wheatgrass and rough fescue were susceptible to aphid feeding damage.

Spatial and temporal characteristics of V1 microstimulation during chronic implantation of a microelectrode array in a behaving macaque

OBJECTIVE

It has been hypothesized that a vision prosthesis capable of evoking useful visual percepts can be based upon electrically stimulating the primary visual cortex (V1) of a blind human subject via penetrating microelectrode arrays. As a continuation of earlier work, we examined several spatial and temporal characteristics of V1 microstimulation.

APPROACH

An array of 100 penetrating microelectrodes was chronically implanted in V1 of a behaving macaque monkey. Microstimulation thresholds were measured using a two-alternative forced choice detection task. Relative locations of electrically-evoked percepts were measured using a memory saccade-to-target task.

MAIN RESULTS

The principal finding was that two years after implantation we were able to evoke behavioural responses to electric stimulation across the spatial extent of the array using groups of contiguous electrodes. Consistent responses to stimulation were evoked at an average threshold current per electrode of 204 ± 49 µA (mean ± std) for groups of four electrodes and 91 ± 25 µA for groups of nine electrodes. Saccades to electrically-evoked percepts using groups of nine electrodes showed that the animal could discriminate spatially distinct percepts with groups having an average separation of 1.6 ± 0.3 mm (mean ± std) in cortex and 1.0° ± 0.2° in visual space. Significance. These results demonstrate chronic perceptual functionality and provide evidence for the feasibility of a cortically-based vision prosthesis for the blind using penetrating microelectrodes.

Volatile emissions from an epiphytic fungus are semiochemicals for eusocial wasps

Microbes are ubiquitous on plant surfaces. However, interactions between epiphytic microbes and arthropods are rarely considered as a factor that affects arthropod behaviors. Here, volatile emissions from an epiphytic fungus were investigated as semiochemical attractants for two eusocial wasps. The fungus Aureobasidium pullulans was isolated from apples, and the volatile compounds emitted by fungal colonies were quantified. The attractiveness of fungal colonies and fungal volatiles to social wasps (Vespula spp.) were experimentally tested in the field. Three important findings emerged: (1) traps baited with A. pullulans caught 2750 % more wasps on average than unbaited control traps; (2) the major headspace volatiles emitted by A. pullulans were 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-phenylethyl alcohol; and (3) a synthetic blend of fungal volatiles attracted 4,933 % more wasps on average than unbaited controls. Wasps were most attracted to 2-methyl-1-butanol. The primary wasp species attracted to fungal volatiles were the western yellowjacket (Vespula pensylvanica) and the German yellowjacket (V. germanica), and both species externally vectored A. pullulans. This is the first study to link microbial volatile emissions with eusocial wasp behaviors, and these experiments indicate that volatile compounds emitted by an epiphytic fungus can be responsible for wasp attraction. This work implicates epiphytic microbes as important components in the community ecology of some eusocial hymenopterans, and fungal emissions may signal suitable nutrient sources to foraging wasps. Our experiments are suggestive of a potential symbiosis, but additional studies are needed to determine if eusocial wasp-fungal associations are widespread, and whether these associations are incidental, facultative, or obligate.

Multiple factors may influence the performance of a visual prosthesis based on intracortical microstimulation: nonhuman primate behavioural experimentation

We hypothesize that a visual prosthesis capable of evoking high-resolution visual perceptions can be produced using high-electrode-count arrays of penetrating microelectrodes implanted into the primary visual cortex of a blind human subject. To explore this hypothesis, and as a prelude to human psychophysical experiments, we have conducted a set of experiments in primary visual cortex (V1) of non-human primates using chronically implanted Utah Electrode Arrays (UEAs). The electrical and recording properties of implanted electrodes, the high-resolution visuotopic organization of V1, and the stimulation levels required to evoke behavioural responses were measured. The impedances of stimulated electrodes were found to drop significantly immediately following stimulation sessions, but these post-stimulation impedances returned to pre-stimulation values by the next experimental session. Two months of periodic microstimulation at currents of up to 96 µA did not impair the mapping of receptive fields from local field potentials or multi-unit activity, or impact behavioural visual thresholds of light stimuli that excited regions of V1 that were implanted with UEAs. These results demonstrate that microstimulation at the levels used did not cause functional impairment of the electrode array or the neural tissue. However, microstimulation with current levels ranging from 18 to 76 µA (46 ± 19 µA, mean ± std) was able to elicit behavioural responses on eight out of 82 systematically stimulated electrodes. We suggest that the ability of microstimulation to evoke phosphenes and elicit a subsequent behavioural response may depend on several factors: the location of the electrode tips within the cortical layers of V1, distance of the electrode tips to neuronal somata, and the inability of nonhuman primates to recognize and respond to a generalized set of evoked percepts.

Effects of gallery density and species ratio on the fitness and fecundity of two sympatric bark beetles (Coleoptera: Curculionidae)

Interspecific interactions among tree-killing bark beetle species may have ecologically important consequences on beetle population dynamics. Using two tree-killing beetle species (Dendroctonus brevicomis and D. frontalis), we performed observational and experimental studies to verify cross-attraction and co-colonization under field conditions in northern Arizona and test the effects of gallery density and species ratio on response variables of average gallery length, offspring size (progeny fitness), and offspring production per centimeter gallery (fecundity). Our results show that both D. frontalis and D. brevicomis aggregate to pheromones synthesized de novo by D. brevicomis under field conditions and that galleries of both D. brevicomis and D. frontalis occurred together in the same region of a single host tree with significant frequency. In experimental manipulations of species ratios, the presence of conspecific beetles in the gallery environment strongly mediated fecundity, but D. frontalis was the only species that suffered negative impacts from the presence of heterospecific beetles in the gallery environment. Interactions did not result in any apparent fitness effects for progeny of either species, which suggests that multispecies aggregations and co-colonization may be a dominant ecological strategy in the region and result in niche sharing.

A minimally invasive approach to long-term head fixation in behaving nonhuman primates

We have designed a device for long-term head fixation for use in behaving nonhuman primates that is robust yet minimally invasive and simple to use. This device is a modified version of the halo system that is used in humans for cervical traction and stabilization after spinal column injuries. This device consists of an aluminum halo with four titanium skull pins offset from the halo by aluminum posts. The titanium pins insert onto small segments of cranially reinforcing titanium plate, which are attached to the skull with titanium cortex screws. The surgery involves four scalp incisions, placement of the reinforcing plates, insertion of the pins for attachment of the halo, and incision closure. After the halo is attached, the animal's head can be fixed to a primate chair using a custom-built attachment arm that provides three degrees of adjustability for proper positioning during behavioral tasks. We have installed this device on two Macaque monkeys weighing 7 and 10kg. The halos have been in place on these animals for up to 8 months without signs of discomfort or loss of fixation. Using this method of head fixation, we have been able to track the animals' eye positions with an accuracy of less than two visual degrees while they perform behavioral tasks.

Murder and assault arrests of White House cases: clinical and demographic correlates of violence subsequent to civil commitment

The authors studied arrest records and clinical data on 217 persons formerly hospitalized as "White House Cases" because they were psychotically preoccupied with prominent political figures. Prior arrest for violent crime was the variable most strongly associated with arrest for violent crime after hospital discharge. Male gender and a history of weapons possession were also correlated with future violence. For those with prior violent crime arrests, hospital incidents requiring seclusion were also associated with later violence. For those without prior arrests, subsequent violence was associated with threats, living outside Washington, and command hallucinations. For those previously arrested for nonviolent crimes, only persecutory delusions were associated with later violence.

Marked heterogeneity of aromatase activity in human malignant melanoma tissue

The prognosis from human malignant melanoma varies according to sex and to multiple histologic, biologic and cell kinetic parameters. Thus melanomas exhibit a major degree of heterogeneity in their biologic properties and further characterization of their biochemical heterogeneity should yield important information. The present study sought to demonstrate the activity of a biochemical marker of estrogen synthesis, the aromatase enzyme, in melanoma tissue and to determine its range of activity. Initially, we validated a highly sensitive radiometric assay for aromatase by comparing it with a direct product isolation method. We detected production of 417 pmol/g protein/h of estrone and 37.3 pmol/g protein/h of estradiol by direct product isolation in a human melanoma and 398 pmol estrone/g protein/h by the radiometric assay. The activity present was blocked by similar amounts of the aromatase inhibitor, aminoglutethimide, as were necessary to block placental, breast cancer, and rat brain aromatase activity. We then assayed aromatase radiometrically in 19 human melanomas and found measurable activity ranging from 9 to 398 pmol estrone/g protein/h in 15 tissues. No relationship with the patient's age or sex was demonstrated. The activity exceeded by 2-fold that previously detected in 49/61 human breast cancers. This study identified a marker enzyme in melanoma tissue which varied by 40-fold among human tumors. Correlation of aromatase activity with prognosis and response to various types of therapy is now necessary to establish the biologic relevance of this finding.

Soft-tissue expansion in the lower extremities

Soft-tissue expansion enjoys ever-wider use, but to date an experience using this technique in the lower extremity has never been presented. We reviewed our first 16 patients to describe the indications and contraindications for the use of tissue expansion in the lower extremity. Guidelines evolved from study of the data. Soft-tissue expansion merits consideration for coverage of problem wounds, in preparation for removal of large benign lesions, and for the repair of contour defects. The operator should know that an open wound below the knee predicts a complication if soft-tissue expansion is attempted in that location. In the thigh, incisions can be confidently placed at the edge of the defect. In every location, large expanders should be chosen so that they are as long as or longer than the adjacent defect. The increase in circumference of the limb should be followed. Simple designs for advancement flaps usually work well. As our experience has grown, reconstruction using soft-tissue expansion in the lower extremity has become safer and the results more predictable through better patient selection and diligent monitoring of intraluminal pressures, even if only by ensuring that the patient is always comfortable. Soft-tissue expansion has a role in reconstruction of the lower extremity.

Elimination of lymphangioma circumscriptum by suction-assisted lipectomy

Lymphangioma circumscriptum presents as cutaneous vesicles or skin tags that drain lymphatic fluid. Deep, sequestered lymphatic cisterns encircled by smooth muscle are thought to be the cause of the skin manifestations, and selective resection of the deep cisterns, not the involved overlying skin, has been suggested as the treatment of choice. We report a successful treatment of lymphangioma circumscriptum using suction-assisted lipectomy to obliterate the deep lymphatic cisterns and their vertical channels communicating to the skin.

Multiple trichogenic adnexal tumors

A young girl developed multiple generalized subcutaneous nodules and two polypoid ear lesions between birth and 8 years of age. There was no family history or evidence of systemic disease. The subcutaneous nodules were trichogenic myxomas, consisting of vascular myxoid connective tissue, sometimes with islands of stratified squamous epithelium, keratinous cysts of epidermal type, or dermoid cysts with follicular and/or sebaceous differentiation. The polypoid lesions were trichofolliculomas, with areas similar to trichogenic myxomas. Our patient thus has multiple trichogenic tumors, the majority being pure hamartomas of the dermal papilla (trichogenic myxomas), others being a combined trichogenic myxoma and hamartoma of hair germ (trichofolliculoma).

White House Cases: psychiatric patients and the Secret Service

Delusional visitors to the White House or other government offices (often seeking a personal audience with the President) are interviewed by the Secret Service and then sent to Saint Elizabeths Hospital if they are considered mentally ill and potentially dangerous to themselves or others. A review of the demographic characteristics and diagnoses of 328 of these "White House Cases" treated at the hospital between 1970 and mid-1974 showed that these patients were most commonly unmarried, white, and male, and most had a diagnosis of paranoid schizophrenia. Although 22% of this group have threatened some prominent political figure, to date none of this study's patients has attempted to assassinate any such government official.

Soft-tissue expansion: concepts and complications

Soft-tissue expansion complements existing reconstructive techniques and provides new vistas for the plastic surgeon. The technique finds use for overcoming a shortage of tissue, for obtaining skin with special desirable qualities, for creation of flaps otherwise not possible because of the resultant donor site or limited vascularity, for creation of flaps with functioning muscle and overlying soft tissue, and for minimizing flap donor-site problems. Careful planning should include patient counseling, optimum incision placement, and time for a leisurely, complete expansion. The surgery can often be performed under local anesthesia and expansion is tolerated well. Patients should be counseled that the incidence of major complications in an unselected series is 1 in 4 patients. Major complications, however, typically result in a delay in reconstruction and not tissue loss.

Morbid obesity

Weight loss following surgical intervention for morbid obesity leaves a redundancy of loose, amorphous skin. Contour surgery should be delayed at least one year following stabilization of weight loss to allow maximum skin contracture. If more than one procedure is contemplated, a sequence should be outlined with the patient to maximize the use of operating room time and minimize exposure to general anesthesia.

Skin expansion to eliminate large scalp defects

In three children aged 3 to 8 years with large scalp defects temporary expanders of silicone elastomer were inserted under the scalp above the pericranium and under the galea through an incision at the junction of the defect and the normal scalp. Over the following six to eight weeks, the expanders were inflated weekly or semiweekly with injections of saline. During expansion, hair growth continued. When the scalp flap expansion was completed, the scalp margin was advanced. Two of the 3 patients required additional expansion, so a deflated expander was left under the scalp. The entire defect was covered in each case. This technique has wide application for a variety of reconstructive problems.

Wound coverage in the Achilles region

Skin loss over the distal Achilles region regardless of cause presents a problem in reconstruction. A variety of techniques have been employed. These procedures are critically reviewed and the technique which has proven helpful at our institution is discussed. The latter procedure employs a local random pattern rotation flap which has the advantages of simplicity, brief hospitalization, predictability of success, and coverage with sensate skin that is not bulky.

Efficacy of triamcinolone acetonide following neurorrhaphy-an electroneuromyographic evaluation

A primate model to test the effects of triamcinolone acetonide on reinnervation after neurorrhaphy was developed. Reinnervation was assessed in triamcinolone- and placebo-treated nerves. Twelve months after neurorrhaphy, nerves treated with triamcinolone had a faster conduction velocity; a greater amplitude in the evoked response; more and larger axons distally on cross-sectional histological examination; and an evoked response wave form closely resembling normal. We conclude that triamcinolone acetonide instilled locally about a neurorrhaphy immediately after the repair is beneficial for the regeneration of motor nerves in primates.

Effects of 5,6 benzo-alphapyrone on traumatic edema due to crush and burn injury

Benzopyrones are a class of drugs which have been used clinically and experimentally in Europe and Australia to reduce tissue swelling caused by high-protein edema states. These drugs are not available nor have they been investigated in the United States. This pilot experiment was designed to determine if one of these compounds, 5,6 benzo-alphapyrone, is effective in reducing traumatic edema from thermal and crush injury.

METHOD

One hind limb of 34 Sprague-Dawley rats was immersed for 30 seconds in 55 degrees C water and the animals divided into three groups as follows: Group I--no treatment; Group II--17 cc saline/kg body weight IP; Group III--25 mg 5,6 benzopyrone in 17 cc saline/kg body weight IP. In another 30 S-D rats, the soft tissue of the posterior aspect on one hind limb was crushed in a Servistor vise (jaws to within 1 mm of each other) for 5 minutes. They were divided into three groups and treated as in the thermal injury group. After 24 hours both limbs were amputated, weighed, dried, and reweighed. Crushed and burned rat hind limbs treated with benzopyrone after injury had significantly greater dry weights (less edema) than did untreated or saline treated limbs. Benzopyrone appears to be effective in reducing edema following crush and thermal injury in this experimental system. Further studies are being conducted to elucidate the mechanism of action of benzopyrones, their potential activity in other postinjury edema, and their effect on tissue survival.

A preliminary report on the use of Staphage Lysate for treatment of hidradenitis suppurativa

Eight patients, 7 with hidradenitis suppurativa and 1 with chronic recurrent staphylococcal abscess, all of whom failed to respond to antibiotic therapy, conservative therapeutic measures, and surgery, were experimentally placed on Staphage Lysate. Treatment after appropriate skin testing consisted of subcutaneous infections of 0.1 ml and intranasal installation of 0.3 ml of Staphage Lysate. Treatments were weekly for twelve weeks, biweekly for six months, and then monthly. Complications, which occurred early, were minimal and involved rash, vertigo, malaise, chills, nausea, fever, and headache. Six of the 8 patients reported noticeable improvement in odor, consistency, and amount of drainage and considerable decreases in pain. Seven of the 8 patients reported improvement in the ability of lesions to drain spontaneously, and a decrease in the frequency of inflammatory nodules. All 8 patients reported that the inflammatory periods were definitely shorter. Early data suggests that Staphage Lysate is a useful adjuvant in the treatment of hidradenitis suppurativa.

Effects of transient ischemia on nutrient flow and arteriovenous shunting in canine hindlimb

A canine model was developed to simulate use of a pneumatic tourniquet in the clinical setting in order to study the acute and delayed effects of transient ischemia on limb and tissue blood flow, using radioactive microspheres and electromagnetic flow probes. Experimental femoral artery flow rose markedly after tourniquet ischemia, and remained significantly elevated for 24 hours (p less than 0.01). Blood flow to the rectus femoris and anterior tibial muscles rose significantly (p less than 0.05) immediately after tourniquet ischemia, and the latter remained significantly elevated at 24 hours (p less than 0.05). Blood flow to the skin of the experimental limbs was elevated significantly (p less than 0.05), immediately ater tourniquet ischemia, and at no other time. Blood flow to the nerves did not increase to its maximum until 15 minutes after tourniquet deflation, and by 24 hours was normal. Tibial and femoral marrow blood flow remained significantly lower in the experimental limb throughout the 24-hour period. Ater tourniquet ischemia (300 mmhg; 2 hours), greatly increased femoral artery flow was related to reactive hyperemia in skin, muscle, and nerve. Twenty-four hours after tourniquet deflation, there was a significant increase in femoral artery and anterior tibial muscle blood flow, and significant arteriovenous shunting from the experimental limb. These data suggest that the hemodynamic response to a transient ischemic injury is more prolonged and of greater magnitude than previously believed.

Malignant tumors of the upper extremity: 1971 to 1976

A series of 31 patients who acquired malignancies of the upper extremity has been reviewed. Comments regarding suggested therapy are included.

The circular excision

A simple, practical alternative to the traditional method of excising small cutaneous lesions is described. It has the advantages of decreased length of final closure and flexibility in determining the orientation of final incisions in areas where it may be difficult to accurately determine skin tension lines.

Effects of tourniquet ischemia and postischemic edema on muscle metabolism

In vivo interstitial muscle pressures measured by wick catheter, tissue gas tensions measured by mass spectrometer, and glucose and high-energy phosphate metabolism measured fluorometrically were studied in the anterior tibial (AT) and vastus lateralis (VL) muscles of primate limbs during and following tourniquet ischemia (2.5 hours; 400 mm Hg) to elucidate postischemic edema and its metabolic consequences. During ischemia, interstitial pressure in the VL rose, while in the AT it decreased, but 24 hours later pressures in both experimental muscles were significantly greater than those in the controls. In both experimental muscles PO2 decreased significantly within 15 minutes of ischemia. PCO2 increased significantly in the AT at 30 minutes and at 75 minutes in the VL muscle. Twenty-four hours later only PO2 in the experimental AT was significantly different than its matched control. During ischemia glucose and phosphocreatine (CrP) decreased significantly, and G-6-P and lactate increased significantly in both muscles, but at 24 hours glucose levels were 25% lower and G-6-P 16.2% higher in the experimental AT and CrP 34% lower in the experimental VL. This study shows that there are significant acute and delayed alterations in primate muscle metabolism following tourniquet ischemia and suggests that these changes may be related to the anatomic location of the muscle studied and the type of trauma it has sustained.

Hemangioma of the temporalis muscle: a case report and review of the literature

Hemangiomas are the most common benign tumors of infancy and childhood. Most involve skin and subcutaneous tissues and are readily visible. Intramuscular hemangiomas are very uncommon, and rarely appear in the musculature of the head and neck. A 59-year-old woman who had had a lipoma excised from her left temporal region many years earlier underwent excision of a hemangioma of the left temporalis muscle. Intramuscular hemangiomas do not spontaneously involute and should be removed as soon as they are diagnosed, in order to obviate later destruction of the involved muscle and adjacent tissues. Preoperative embolization of the hemangioma may reduce intraoperative hemorrhaging.

In-home support for recovering alcoholic mothers and their families; the family rehabilitation coordinator project

A program is described for training paraprofessional workers to aid recovering alcoholic mothers and their families to improve household organization and communication and to use community services.

The team approach to treatment of the cleft lip and palate

The team consists of a family physician, plastic surgeon, orthodontist, prosthodontist, otolaryngologist, speech therapist, audiologist and social worker. A cleft lip is usually repaired when the child weighs 10 lb., is 10 weeks old and has 10 Gm. of hemoglobin. Defects of the secondary palate are repaired between one and two years of age; residual lip or nasal deformities are corrected before the child starts school. Further cosmetic surgery is delayed until adolescence, when facial growth has been completed.