Invasive stink bug favors naïve plants: Testing the role of plant geographic origin in diverse, managed environments.

With the introduction and establishment of exotic species, most ecosystems now contain both native and exotic plants and herbivores. Recent research identifies several factors that govern how specialist herbivores switch host plants upon introduction. Predicting the feeding ecology and impacts of introduced generalist species, however, remains difficult. Here, we examine how plant geographic origin, an indicator of shared co-evolutionary history, influences patterns of host use by a generalist, invasive herbivore, while accounting for variation in plant availability. The brown marmorated stink bug, Halyomorpha halys, is a highly polyphagous Asian herbivore and an economically important invasive pest in North America and Europe. In visual surveys of 220 plant taxa in commercial nurseries in Maryland, USA, H. halys was more abundant on non-Asian plants and selected these over Asian plants. The relationship between the relative use of plants and their availability was strongly positive but depended also on plant origin at two of our three sites, where the higher relative use of non-Asian plants was greatest for highly abundant taxa. These results highlight the importance of considering both plant origin and relative abundance in understanding the selection of host plants by invasive generalist herbivores in diverse, natural and urban forests.

Host Plant Use by the Invasive Halyomorpha halys (Stål) on Woody Ornamental Trees and Shrubs.

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive plant-feeding insect native to eastern Asia. This herbivore is highly polyphagous, feeding on and damaging diverse plants, including field crops, vegetables, tree fruits, and ornamentals. Woody ornamental plants provide early- and late-season resources for adults emerging from and returning to overwintering sites, as well as feeding and breeding sites for H. halys throughout the growing season. In this study, we quantify the use of diverse plants by H. halys in two commercial nurseries in Maryland, recording data on the abundance of egg masses, early and late instar nymphs, and adults over a three-year study period. Our specific goals were to provide a quantitative comparison of the use of diverse plant species and cultivated varieties, identify non-hosts that could be used to create landscapes refractory to H. halys, and determine whether the use of plants varied across life stages of H. halys or the taxonomic status of plants. We found broad use of diverse plants in this study, identifying 88 host plants used by all life stages of H. halys. We also highlight the 43 plant taxa that did not support any life stage of H. halys and are thus classified as non-hosts. Interestingly, some of these plants were congeners of highly-used plants, underscoring high intrageneric and intraspecific variation in the use of plants by this polyphagous herbivore. We discuss how the selective planting of non-hosts, especially gymnosperms, may aid in reducing the agricultural and nuisance pest status of this invasive insect.

Edge Effects Influence the Abundance of the Invasive Halyomorpha halys (Hemiptera: Pentatomidae) in Woody Plant Nurseries.

The invasive brown marmorated stink bug, Halyomorpha halys (Stål), has caused severe economic losses in the United States and is also a major nuisance pest invading homes. In diverse woody plant nurseries, favored host plants may be attacked at different times of the season and in different locations in the field. Knowledge of factors influencing H. halys abundance and simple methods to predict where H. halys are found and cause damage are needed to develop effective management strategies. In this study, we examined H. halys abundance on plants in tree nurseries as a function of distance from field edges (edge and core samples) and documented the abundance in tree nurseries adjoining different habitat types (corn, soybean, residential areas, and production sod). We conducted timed counts for H. halys on 2,016 individual trees belonging to 146 unique woody plant cultivars at two commercial tree nurseries in Maryland. Across three years of sampling, we found that H. halys nymphs and adults were more abundant at field edges (0-5 m from edges) than in the core of fields (15-20 m from edges). Proximity of soybean fields was associated with high nymph and adult abundance. Results indicate that monitoring efforts and intervention tactics for this invasive pest could be restricted to field edges, especially those close to soybean fields. We show clearly that spatial factors, especially distance from edge, strongly influence H. halys abundance in nurseries. This information may greatly simplify the development of any future management strategies.

Trophic disruption: a meta-analysis of how habitat fragmentation affects resource consumption in terrestrial arthropod systems.

Habitat fragmentation is a complex process that affects ecological systems in diverse ways, altering everything from population persistence to ecosystem function. Despite widespread recognition that habitat fragmentation can influence food web interactions, consensus on the factors underlying variation in the impacts of fragmentation across systems remains elusive. In this study, we conduct a systematic review and meta-analysis to quantify the effects of habitat fragmentation and spatial habitat structure on resource consumption in terrestrial arthropod food webs. Across 419 studies, we found a negative overall effect of fragmentation on resource consumption. Variation in effect size was extensive but predictable. Specifically, resource consumption was reduced on small, isolated habitat fragments, higher at patch edges, and neutral with respect to landscape-scale spatial variables. In general, resource consumption increased in fragmented settings for habitat generalist consumers but decreased for specialist consumers. Our study demonstrates widespread disruption of trophic interactions in fragmented habitats and describes variation among studies that is largely predictable based on the ecological traits of the interacting species. We highlight future prospects for understanding how changes in spatial habitat structure may influence trophic modules and food webs.

Traps and trap placement may affect location of brown marmorated stink bug (Hemiptera: Pentatomidae) and increase injury to tomato fruits in home gardens.

The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an important pest of field crops, fruit orchards, commercial vegetables, ornamental plants, and home vegetable gardens. Pheromone-baited traps designed to attract, trap, and kill H. halys are marketed for use in home gardens to reduce damage to plants. To test this assertion, we conducted the following experiment: One group of 15 gardeners placed stink bug traps at the end of a row of tomatoes, Solanum lycopersicum (L.), in their vegetable garden and another group of 14 placed no traps in their garden and served as controls. Gardeners with traps were no more or less likely to have H. halys on tomato plants than those without traps, but the abundance of H. halys on tomato fruits was marginally greater in gardens with traps. However, tomato fruits grown in gardens with traps sustained significantly more injury than tomato fruits grown in gardens without traps. Furthermore, tomato fruits on plants near the trap housed more H. halys than tomato fruits on plants at the end of a row away from the trap. Traps may be useful in identifying gardens where H. halys is likely to be found and ones in which stink bug injury to tomatoes is likely. We found no evidence that stink bug traps protected tomatoes from H. halys, and it appears that the addition of traps to gardens may increase injury to tomato fruits.

GRASP [Genomic Resource Access for Stoichioproteomics]: comparative explorations of the atomic content of 12 Drosophila proteomes.

BACKGROUND: "Stoichioproteomics" relates the elemental composition of proteins and proteomes to variation in the physiological and ecological environment. To help harness and explore the wealth of hypotheses made possible under this framework, we introduce GRASP (http://www.graspdb.net), a public bioinformatic knowledgebase containing information on the frequencies of 20 amino acids and atomic composition of their side chains. GRASP integrates comparative protein composition data with annotation data from multiple public databases. Currently, GRASP includes information on proteins of 12 sequenced Drosophila (fruit fly) proteomes, which will be expanded to include increasingly diverse organisms over time. In this paper we illustrate the potential of GRASP for testing stoichioproteomic hypotheses by conducting an exploratory investigation into the composition of 12 Drosophila proteomes, testing the prediction that protein atomic content is associated with species ecology and with protein expression levels. RESULTS: Elements varied predictably along multivariate axes. Species were broadly similar, with the D. willistoni proteome a clear outlier. As expected, individual protein atomic content within proteomes was influenced by protein function and amino acid biochemistry. Evolution in elemental composition across the phylogeny followed less predictable patterns, but was associated with broad ecological variation in diet. Using expression data available for D. melanogaster, we found evidence consistent with selection for efficient usage of elements within the proteome: as expected, nitrogen content was reduced in highly expressed proteins in most tissues, most strongly in the gut, where nutrients are assimilated, and least strongly in the germline. CONCLUSIONS: The patterns identified here using GRASP provide a foundation on which to base future research into the evolution of atomic composition in Drosophila and other taxa.

Critical patch sizes for food-web modules.

Because patch size and connectivity may strongly impact the assemblage of species that occur on a patch, the types of food-web interactions that occur among those species may also depend on spatial structure. Here, we identify whether food-web interactions among salt-marsh-inhabiting arthropods vary with patch size and connectivity, and how such changes in trophic structure might feed back to influence the spatial distribution of prey. In a multiyear survey, patch-restricted predators exhibited steeper occupancy-patch-size relationships than herbivores, and species' critical patch sizes were correlated with overall rarity. As a result, the presence of food-web modules depended strongly on patch size: large and well-connected patches supported complex food-web modules, but only the simplest modules involving the most abundant species were found on small patches. Habitat-generalist spiders dominated on small patches, and predation pressure from such species may contribute to the observed lower densities of mesopredators on small patches. Overall, patch size and connectivity influenced the types of modules present on a patch through differential loss of rare, patch-restricted predators, but predation by generalist predators may be a key mechanism influencing the spatial structure of certain prey species.

Resource use efficiency and community effects of invasive Hypochaeris radicata (Asteraceae) during primary succession.

PREMISE OF THE STUDY: We sought to better understand the impacts and mechanisms underpinning a successful invasion of resource-poor sites by a nonnative plant on Mount St. Helens volcano (MSH). • METHODS: We investigated the short-term effects of the nonnative plant Hypochaeris radicata on growth of native species colonizing drought-prone primary successional surfaces under N-limited and N-augmented conditions. To understand the success of H. radicata, we compared its resource use efficiency to that of a closely related native colonist, Hieracium albiflorum, under the same conditions. • KEY RESULTS: Removing H. radicata did not affect growth of the most common colonists, but N addition demonstrated strong N limitation to growth in H. albiflorum, H. radicata, and Agrostis spp. Nonnative H. radicata exhibited lower water-use efficiency than H. albiflorum but did not differ in efficiency of N use. H. radicata biomass increased faster in response to an N pulse than did the native H. albiflorum, as did the pool of N held in H. radicata tissues. • CONCLUSIONS: Our findings contrast with results from Hawaiian volcanic sites, where higher short-term resource use efficiency was reported for invasive species, including H. radicata. Our results suggest that at MSH, the success of H. radicata relies on rapid uptake and utilization of N rather than on higher efficiency. This strategy is especially advantageous at MSH because N pulses commonly occur as a consequence of herbivore-induced mortality of Lupinus lepidus (Fabaceae).

Mutant epidermal growth factor receptor up-regulates molecular effectors of tumor invasion.

The gene most commonly altered in human glioblastomas is the epidermalgrowth factor receptor (EGFR). We profiled transcripts induced by mutantEGFR to better understand its role in tumor progression. The pattern found suggested enhanced tumor invasion. The highly induced genes included extracellular matrix components, metalloproteases, and a serine protease. We confirmed that mutant EGFR did make glioblastoma cells both more motile and invasive using in vitro assays. Furthermore, inhibitors of EGFR (OSI-774 and Tyrphostin AG1478) selectively down-regulated these molecular effectors in glioblastoma cells, eliminating enhanced invasion.