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RNA interference (RNAi) is a sequence-specific gene silencing mechanism triggered by double-stranded RNA (dsRNA). Exploiting the RNAi mechanism to silence essential genes in insects has emerged as a promising new pest control strategy, and RNAi-based products are being developed for plant protection. RNAi has proven effective in silencing genes and causing mortality in the highly invasive emerald ash borer (EAB) (Agrilus planipennis) (Coleoptera: Buprestidae); however, a practical delivery method remains a barrier to its deployment. In this study, we evaluate the systemic distribution and retention of exogenously applied dsRNA in green ash (Fraxinus pennsylvanica) tissues to investigate the feasibility of dsRNA delivery through the host plant. To evaluate the distribution and persistence of dsRNA, seedings are exposed to EAB-specific dsRNA as a root soak, sampled 3, 7, 14, 21, and 30 d after exposure, and sectioned into root, woody-stem, soft-stem, and leaf tissues. Total RNA is extracted and evaluated by RT-PCR. Gel images and Sanger sequencing confirm the presence of exogenously applied dsRNAs, demonstrating successful uptake and translocation of dsRNAs throughout plant tissues. Our findings demonstrate that root application represents a viable delivery method for dsRNA in ash seedlings, supporting the potential of this technology in providing ash protection against EAB. [ABSTRACT FROM AUTHOR]

Exogenously applied double-stranded RNA (dsRNA) can induce potent host specific gene knockdown and mortality in insects. The deployment of RNA-interference (RNAi) technologies for pest suppression is gaining traction in both agriculture and horticulture, but its implementation in forest systems is lagging. While numerous forest pests have demonstrated susceptibility to RNAi mediated gene silencing, including the southern pine beetle (SPB), Dendroctonus frontalis, multiple barriers stand between laboratory screening and real-world deployment. One such barrier is dsRNA delivery. One possible delivery method is through host plants, but an understanding of exogenous dsRNA movement through plant tissues is essential. Therefore, we sought to understand the translocation and persistence of dsRNAs designed for SPB throughout woody plant tissues after hydroponic exposure. Loblolly pine, Pinus taeda, seedlings were exposed to dsRNAs as a root soak, followed by destructive sampling. Total RNA was extracted from different tissue types including root, stem, crown, needle, and meristem, after which gel electrophoresis confirmed the recovery of the exogenous dsRNAs, which were further verified using Sanger sequencing. Both techniques confirmed the presence of the exogenously applied target dsRNAs in each tissue type after 1, 3, 5, and 7 d of dsRNA exposure. These findings suggest that root drench applications of exogenous dsRNAs could provide a viable delivery route for RNAi technology designed to combat tree feeding pests. [ABSTRACT FROM AUTHOR]

The efficacy and high specificity of the RNA interference pathway has prompted its exploration as a potential molecular management tool for many insect pests, including the destructive southern pine beetle, Dendroctonus frontalis Zimmermann, in which gene knockdown and mortality via double-stranded RNAs (dsRNAs) have already been demonstrated in the laboratory. The nucleotide sequence of dsRNAs requires an exact match of at least 16 nucleotides with the targeted messenger RNA to trigger knockdown of that gene. This allows vital genes in a target pest to be silenced and mortality induced while reducing the probability of adverse effects in nontarget organisms. However, prior to utilization in forest ecosystems, demonstration of the specificity of dsRNAs through laboratory bioassays evaluating potential nontarget effects on model insects is required for proper risk assessment analyses. Consequently, we evaluated three SPB-specific dsRNAs for lethal effects, sublethal effects (larval growth rate, adult emergence or adult fecundity), and relative gene expression in three model nontarget insects representing key functional guilds, including a predator, herbivore, and pollinator. The SPB-specific dsRNAs had no effect on survival of our nontarget insects. Additionally, no sublethal effects were found and the gene expression analyses corroborated bioinformatic analyses in finding no gene knockdown. Our findings support the high specificity of RNAi technology and provide support for its development and deployment for protection of conifer forests against SPB with minimal nontarget concerns. [ABSTRACT FROM AUTHOR]

The six-spined ips, Ips calligraphus, is a North American bark beetle that can exploit most eastern North American Pinus species and can cause mortality. Biotic and abiotic disturbances weaken trees, creating breeding substrate that promotes rapid population growth. Management historically relied on silvicultural practices, but as forests become increasingly stressed, innovative management is needed. Manipulation of the cellular RNA interference (RNAi) pathway to induce gene silencing is an emerging means of insect suppression, and is effective for some bark beetles. Quantitative PCR (qPCR) is a powerful tool for analysis of gene expression, and is essential for examining RNAi. To compare gene expression among individuals, stably expressed reference genes must be validated for qPCR. We evaluated six candidate reference genes (18s, 16s, 28s, ef1a, cad, coi) for stability under biotic (beetle sex, developmental stage, and host plant), and abiotic (temperature, photoperiod, and dsRNA exposure) conditions. We used the comprehensive RefFinder tool to compare stability rankings across four algorithms. These algorithms identified 18s, 16s, and 28s as the most stably expressed. Overall, 16s and 28s were selected as reference genes due to their stability and moderate expression levels, and can be used for I. calligraphus gene expression studies using qPCR, including those evaluating RNAi. [ABSTRACT FROM AUTHOR]

Emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), is rapidly invading North America and has inflicted extensive ash, Fraxinus spp., mortality in affected areas, altering composition and structure of wildland and urban forests. Insecticides can effectively protect ash on a small scale and classical biological control efforts have been implemented. In the U.S. emerald ash borer kills native ash so quickly, and populations are so mobile, that establishing an effective biological control program is challenging. Consequently, we assessed the compatibility of using reduced rates of the insecticide imidacloprid applied as a soil drench coupled with releases of three species of parasitic wasps. In this way we hope to slow the process of ash decline and prolong the window of opportunity to allow biological control agents to become established. We compared the efficacy and effects of i) full strength imidacloprid applications, ii) reduced rates of imidacloprid coupled with classical biological control, iii) classical biological control alone, and iv) untreated controls. We monitored emerald ash borer adult activity through trapping and destructive sampling for larvae, evaluated larval parasitization rates, and also assessed the native hymenopteran communities. Chemical treatments were not adequate to prevent ash canopy decline, but they also did not impede parasitization of emerald ash borer eggs or larvae. Two of the three classical biological control agents, Oobius agrili and Tetrastichus planipennisi , were recovered from trees treated with imidacloprid, demonstrating that they were successfully reproducing and indicating the compatibility of the two management strategies. Non-target hymenopterans appeared unaffected by the insecticide applications. Importantly we found no negative effects of the imidacloprid applications on native pollinators. Collectively these data suggest that judicious use of insecticides coupled with classical biological control may be an effective and potentially sustainable approach to managing invading populations of emerald ash borer. [ABSTRACT FROM AUTHOR]

We investigate a plant-microbe-insect interaction where a plant pathogenic microorganism is utilizing an invasive insect herbivore as an alternate resource, and test the hypothesis that the microorganism is affecting the population dynamics of the herbivore on its woody host plant., We investigated the presence of necrotic lesions formed by an unknown microbe on galls induced by the Asian chestnut gall wasp Dryocosmus kuriphilus Yasumatsu ( Hymenoptera: Cynipidae), a global pest on Castanea hosts. We hypothesize that colonization by this plant-associated microbe impacts survival and invasiveness of the gallmaker and, using Koch's postulates, we evaluate its effects on the gallmaker and on the gallmaker's primary natural enemy., Morphologically identical colonies were isolated from galls and insects, and DNA sequences matched with the fungal genus Colletotrichum, a causal agent of plant-pathogenic anthracnose. Inoculations generated comparable symptoms. After the formation of superficial lesions, the pathogen rapidly penetrates galls, colonizing insect tissue in gall chambers and causing extensive larval mortality. Minimal effects were evident on the associated parasitoid Torymus sinensis Kamijo ( Hymenoptera: Torymidae)., We report a plant pathogen utilizing a gall-inducing arthropod at the same time as sparing its parasite and expand reports of Colletotrichum impacting insects. We shed light on a complex of interactions influencing an important invader. [ABSTRACT FROM AUTHOR]

Agrilus planipennis Fainnaire (Coleoptera: Buprestidae) is a wood-boring pest of Asian origin that has caused widespread mortality of ash, Fraxinus spp., in North America since its accidental introduction in the 1990s. Studies conducted at the epicenter of the infestation in the Great Lakes region have discovered several species of native parasitoids capable of utilizing A. planipennis-, however, little is known of how these natural enemy complexes vary across the shifting forest types and habitats encompassed by the expanding infestation. We characterized the assemblage of native natural enemies being recruited to A. planipennis at five sites in north-central Kentucky, where infestations have been documented since 2009. Through destructive sampling, dissection, and rearing of infested ash material, 12 native parasitoid morpho-species were found being recruited to A. planipennis, nine of which have not been reported previously. Catogenus rufus (F.) (Coleopter: Passandridae), Phasgonophora sulcata Westwood (Hymenoptera: Chalcididae), and Leluthia asgtigma (Ashmead) (Hymenoptera: Braconidae) have been discovered utilizing A. planipennis in more northerly infested regions of North America and were present in our study. Native hymenopteran parasitoid responses to A. planipennis presence and associated ash decline, measured using visual assessments of canopy decline, revealed a positive correlation between parasitoid guilds and ash decline. [ABSTRACT FROM AUTHOR]

The invasive emerald ash borer (Agrilus planipennis - EAB) is causing rapid and widespread ash (Fraxinus spp.) mortality in eastern North America, has established populations near Moscow, Russia, and is threatening ash resources in Europe. Given the prevalence of susceptible hosts these post-invasion forests will clearly differ from their pre-invasion counterparts. Understanding these changes is key to mitigating the impacts of invasion and developing sound management strategies. We evaluated short term changes in a forest stand invaded by EAB, and examined if the southern variant of the Forest Vegetation Simulator (FVS) could accurately predict those changes. Through simulation, managers can gain a clearer understanding of how pest invasions impact and alter future forest dynamics. However, many simulators are designed to achieve long-term predictions and thus do not align with the short term changes associated with rapid EAB-induced ash mortality. Woody vegetation was surveyed in 2010 and used to project impacts of EAB invasion into 2012 by simulating a 50% ash mortality rate. The same plots were then re-surveyed in 2012, allowing us to evaluate: (1) changes in actual forest composition and structure; and (2) simulation accuracy. Within our forest stand, FVS accurately estimated short term changes in stem density and basal area parameters, thus demonstrating its value as a short-term simulator for EAB-induced changes within the southern region of the United States. EAB-induced ash mortality is quickly changing these forests and will ultimately alter how stakeholders manage their lands. We discuss the potential usefulness of FVS as a tool for aiding management decisions in response to EAB invasion. [ABSTRACT FROM AUTHOR]

Sleeve cages for enclosing or excluding arthropods are essential components of field studies evaluating trophic interactions. Microclimatic variation in sleeve cages was evaluated to characterize its potential effects on subsequent long-term experiments. Two sleeve cage materials, polyester and nylon, and two cage sizes, 400 and 6000 cm2, were tested on eastern hemlock, Tsuga canadensis (L.) Carrière. Temperature and relative humidity inside and outside cages, and the cost and durability of the cage materials, were compared. Long-term effects of the sleeve cages were observed by measuring new growth on T. canadensis branches. The ultimate goal was to identify a material that minimizes bag-induced microclimatic variation. Bagged branches whose microclimates mimic those of surrounding unbagged branches should have minimal effects on plant growth and may prove ideal venues for assessing herbivore and predator behavior under natural conditions. No differences were found in temperature or humidity between caging materials. Small cages had higher average temperatures than large cages, especially in the winter, but this difference was confounded by the fact that small cages were positioned higher in trees than large cages. Differences in plant growth were detected. Eastern hemlock branches enclosed within polyester cages produced fewer new growth tips than uncaged controls. Both polyester and nylon cages reduced the length of new shoot growth relative to uncaged branches. In spite of higher costs, nylon cages were superior to polyester with respect to durability and ease of handling. [ABSTRACT FROM AUTHOR]

Highlights: [•] T. sinensis is a parasite used for biological control of D. kuriphilus. [•] Behavior of T. sinensis adult females was tested in a Y-tube olfactometer. [•] Insects were not attracted to gall odor presented alone. [•] T. sinensis responded negatively to a gall image presented alone. [•] Wasps responded positively to olfactory and visual cues when presented together. [Copyright &y& Elsevier]

Remote sensing and spatial analysis represent useful tools for modeling species' dispersal, characterizing the spread of invasions and the invasability of a region, and thus allowing more accurate predictions for developing mitigation strategies. American chestnut, Castanea dentata, was historically a dominant forest species in North America, but occurs only sporadically today after its functional elimination by an exotic fungal pathogen in the early 1900's. In recent decades Castanea resources have increased due to restoration efforts, commercial chestnut plantations, and horticultural uses. This resurgence is threatened by an additional exotic species, the globally invasive Asian chestnut gall wasp, Dryocosmus kuriphilus. The gall wasp was first discovered in Lexington, Kentucky (USA) in 2010. We used remotely sensed data and Geographic Information Systems to describe the local distribution of the Castanea hosts, and the occurrence and dispersal of the gall wasp. We tested the hypotheses that geomorphology, Castanea occurrence, and prevailing winds influence local proliferation. We found that gall wasp spread may be attributable to host plant distribution and to the effects of prevailing winds occurring during a brief period of adult insect emergence, and is influenced by topography. Our results suggest that weather data and topographic features can be used to delineate currently infested areas and predict future gall wasp infestations. [ABSTRACT FROM AUTHOR]

The article focuses on a research conducted in order to identify the effects of jasmonic acid (JA) and a JA-inhibitor, diethyldithiocarbamic acid on the growth and defense of the Asian chestnut gall wasp, Dryocosmus kuriphilus galls formed on American chestnut, Castanea dentata. It discusses the importance of JA in defenses against insects and pathogens as well as the regulation of nutrient partitioning. The study revealed the importance of JA treatments on gall wasps.

Environmental conditions associated with climate change are exacerbating pine mortality caused by the southern pine beetle (SPB) (Dendroctonus frontalis), prompting investigations into innovative management strategies.Triggering the RNA interference (RNAi) pathway using species‐specific double‐stranded RNA (dsRNA) to silence genes and cause mortality is effective in SPB and is an emerging technology for pest management, but specificity and safety must be demonstrated.We evaluated three pine‐associates (the scolytine six‐spined ips, Ips calligraphus, a foliage feeding pine sawfly, Neodiprion lecontei, and the detritivorous eastern subterranean termite, Reticulitermes flavipes), for transcriptome sequence overlap with the SPB dsRNA and performed bioassays to evaluate lethal and sublethal effects after dsRNA ingestion.Genetic analyses revealed little overlap between dsRNA sequences and target gene orthologs, with only two matches found in I. calligraphus, the most closely related phylogenetically.No lethal or sublethal effects were observed in any of the nontarget organisms evaluated, and changes in gene expression occurred only in I. calligraphus, but with no discernible effects on adult survival.Our findings build on previous nontarget evaluations for SPB‐specific dsRNA in model insects and demonstrate that the use of RNAi as a component of an IPM strategy would not directly compromise commonly occurring non‐congeneric pine associates. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) is a naturally occurring process inhibiting gene expression, and recent advances in our understanding of the mechanism have allowed its development as a tool against insect pests. A major challenge for deployment in the field is the development of convenient and efficient methods for production of double stranded RNA (dsRNA). We assessed the potential for deploying bacterially produced dsRNA as a bio-pesticide against an invasive forest pest, the emerald ash borer (EAB). EAB feeds on the cambial tissue of ash trees (Fraxinus spp.), causing rapid death. EAB has killed millions of trees in North America since its discovery in 2002, prompting the need for innovative management strategies. In our study, bacterial expression and synthesis of dsRNA were performed with E. coli strain HT115 using the L4440 expression vector. EAB-specific dsRNAs (shi and hsp) over-expressed in E. coli were toxic to neonate EAB after oral administration, successfully triggering gene silencing and subsequent mortality; however, a non-specific dsRNA control was not included. Our results suggest that ingestion of transformed E. coli expressing dsRNAs can induce an RNAi response in EAB. To our knowledge, this is the first example of an effective RNAi response induced by feeding dsRNA-expressing bacteria in a forest pest. [ABSTRACT FROM AUTHOR]

Intraspecific genetic variation underpins many evolutionary processes and phenomena. For species considered pests, the dynamics of how genetic variation is distributed geographically take on a greater importance, because they can impact pest-management strategies directly. This is particularly true when management strategies are genetic in nature, such as population manipulation via RNA interference (RNAi; a naturally occurring antiviral response that disrupts translation of messenger RNAs into proteins to silence genes). Using RNAi for gene silencing is highly species specific; however, the efficacy of this approach in geographically distinct populations of widespread pest species has not been evaluated comprehensively. Here, we present a preliminary study evaluating differential susceptibility of geographically disparate populations of southern pine beetle, Dendroctonus frontalis , to RNAi. Although the efficacy of RNAi has been demonstrated in localized populations, D. frontalis has a broad distribution across North and Central America and is expanding its range owing to climate change. We observe differences in response between and within geographically distinct populations from its core range and recently expanded range. Our findings have broad implications for the use of RNAi as a management tool in widely distributed species and highlight the need for a deeper understanding of intraspecific genetic variation in this species and others. [ABSTRACT FROM AUTHOR]

Fall webworm, Hyphantria cunea Drury (Lepidoptera: Arctiidae) is extremely adaptable and highly invasive in China as a defoliator of ornamental and forest trees. Both voltinism and diapause strategies of fall webworm in China are variable, and this variability contributes to it invasiveness. Little is known about molecular regulation of diapause in fall webworm. To gain insight into possible mechanisms of diapause induction, high-throughput RNA-seq data were generated from non-diapause pupae (NDP) and diapause pupae (DP). A total of 58,151 unigenes were assembled and researched against nine public databases. In total, 29,013 up-regulated and 3451 down-regulated unigenes were differentially expressed by DP when compared with those of NDP. Genes encoding proteins such as UDP-glycosyl transferase (UGT), cytochrome P450 and Hsp70 were predicted to be involved in diapause. Moreover, GO function and KEGG pathway enrichments were performed on all differentially expressed genes (DEGs) and showed that cell cycle and insulin signaling pathways may be related to the diapause of the fall webworm. This study provides valuable information about the fall webworm transcriptome for future gene function research, especially as it relates to diapause. [ABSTRACT FROM AUTHOR]

Micromechanical properties that help mediate herbivore access may be particularly important when considering herbivorous insects that feed with piercing-sucking stylets. We used microindentation to quantify the micromechanical properties of hemlock, Tsuga spp., to quantify the hardness of the feeding site of the invasive hemlock woolly adelgid, Adelges tsugae. We measured hardness of the hemlock leaf cushion, the stylet insertion point of the adelgid, across four seasons in a 1 y period for four hemlock species growing in a common garden, including eastern, western, mountain, and northern Japanese hemlocks. Leaf cushion hardness was highest in the fall and winter and lowest in summer for all species. Northern Japanese hemlock had relatively greater hardness than the remaining species. Our data contributes an additional perspective to the existing framework within which greater susceptibility and subsequent mortality of eastern hemlocks is observed. The potential application of microindentation to understanding the nature and relevance of plant mechanical defenses in plant-herbivore interactions is also demonstrated and highlighted. [ABSTRACT FROM AUTHOR]

In the eastern United States, eastern hemlock Tusga canadensis (L.) Carriere forests are threatened by the invasive hemlock woolly adelgid, Adelges tsugae, a pest that is causing widespread hemlock mortality. Eastern hemlock is an essential component of forested communities. Adelgid-induced hemlock mortality is causing a shift in forest composition and structure, altering ecosystem function and thereby influencing the arthropod community. Using pitfall traps at three sites, we monitored ground-dwelling arthropods at 30-d intervals in hemlock-dominated and deciduous-dominated forests in central Appalachia over 2 yr. Here, we focus on the ant community (Hymenoptera: Formicidae) collected in the summer months. Ants form a ubiquitous and integral component of the invertebrate community, functioning at various trophic levels as predators, herbivores, and omnivores, and fulfilling important roles in forest ecosystems. We found no difference in overall ant abundance between hemlock-dominated and deciduous-dominated forests but did detect significant differences in the genera Prenolepis between forest types (P < 0.01) and Aphaenogaster across study locations (P¼0.02). Three genera were unique to deciduous forests; one was unique to hemlock forests. Not surprisingly, total formicids and several genera demonstrated temporal differences in abundance, with greater numbers captured in July than in August. As hemlock woolly adelgid-induced mortality of eastern hemlock becomes more pervasive, changes in forest composition and structure are imminent, accompanied by shifts in hemlock associates. [ABSTRACT FROM AUTHOR]

Abstract: Recent work suggests that germination inhibition via allelopathy may be an important component of some species’ invasion ecology. We conducted four germination assays to test the inhibitory potential of Amur honeysuckle (Lonicera maackii), a problematic invasive shrub. The subject species in the first assay, Festuca arundinacea, exhibited a significant delay in germination when treated with extract from ground honeysuckle foliage. In the second assay, two concentrations of L. maackii extract were created by soaking foliage. F. arundinacea germination was not significantly influenced by the treatments while germination in Impatiens wallerana was substantially decreased. The third assay compared the impact of foliar extract from honeysuckle, with the native shrubs Lindera benzoin and Asimina triloba using F. arundinaceae, I. wallerana, Coreopsis lanceolata and Poa pratensis as subject species. In this assay, I. wallerana was strongly inhibited by L. maackii foliage; however, none of the other species were significantly influenced by the treatments. In the fourth assay, fruit extracts from L. maackii and L. benzoin were applied to the same four subject species. L. maackii fruit extract had an inhibitory influence on seed germination of all subject species, and inhibition from L. benzoin was also noted. Across all assays, there was a mixed reaction to extract from L. maackii and co-occurring native species that was species-specific and dependent upon the extract source. Our findings provide support for the idea that L. maackii has allelopathic activity, but further work is needed to (i) understand how broad the impact may be across the wide variety of species that are found in its invasion range and (ii) substantiate that the allelopathic effect has relevance in field environments. [Copyright &y& Elsevier]

1. Bark beetles and their predators are useful systems for addressing questions concerning diet breadth and prey preference in arthropod natural enemies. These predators use bark beetle pheromones to locate their prey, and the response to different pheromones is a measure of prey preference. 2. Trapping experiments were conducted to examine geographic variation in the response to prey pheromones by two bark beetle predators, Thanasimus dubius and Temnochila virescens. The experiments used pheromones for several Dendroctonus and Ips prey species (frontalin, ipsdienol, and ipsenol) and manipulated visual cues involved in prey location (black vs. white traps). The study sites included regions where the frontalin-emitter Dendroctonus frontalis was in outbreak vs. endemic or absent. 3. There was significant geographic variation in pheromone preference for T. dubius. This predator strongly preferred a pheromone (frontalin) associated with D. frontalis at outbreak sites, while preference was more even at endemic and absent sites. No geographic variation was found in the response by T. virescens. White traps caught fewer insects than black traps for both predators, suggesting that visual cues are also important in prey location. 4. The overall pattern for T. dubius is consistent with switching or optimal foraging theory, assuming D. frontalis is a higher quality prey than Ips. The two predator species partition the prey pheromones in areas where D. frontalis is abundant, possibly to minimise competition and intraguild predation. [ABSTRACT FROM AUTHOR]

Double-stranded RNA (dsRNA)-mediated gene silencing, or RNA interference (RNAi), is an emerging biotechnology that has been a breakthrough tool for crop protection. Exogenous dsRNA triggers the RNAi pathway, silences genes, disrupts protein function, and can cause insect mortality. However, effective delivery of the dsRNA is problematic, particularly in systems with long-lived, endophagous insects such as the emerald ash borer (EAB), Agrilus planipennis, a tree-killing nonnative invader that attacks ash, Fraxinus spp. Larvae feed on cambial tissue causing rapid tree death. EAB is susceptible to RNAi, but we lack a practical means of delivery. Here we evaluated delivery of dsRNA to green, F. pennsylvanica, and tropical ash, F. uhdei, through root and/or petiole absorption, and also demonstrated dsRNA absorption through the EAB egg chorion. We labeled exogenous dsRNA using a fluorescing label and then used confocal microscopy and RT-qPCR to evaluate its distribution in plant and insect tissues. Labeled dsRNAs are detectable in root, stem, and leaf tissues 48-h postapplication. In excised ash branches, labeled dsRNA is detectable in the inner bark and in recovered EAB neonates 8-day postapplication. Eggs and larvae emerging from treated eggs also presented fluorescing dsRNA under confocal imaging. Adult EAB-fed tropical ash leaves treated with in vitro synthesized EAB-specific dsSHI through petiole absorption experience a significant knockdown of the shi gene and a significant mortality. Our findings provide a proof of concept that delivery of dsRNAs through topical or systemic application methods is a feasible means of suppressing EAB, providing hope for future tree protection. [ABSTRACT FROM AUTHOR]

Emerald ash borer (EAB, Agrilus planipennis) is an invasive phloem feeder from East Asia that has killed millions of ash trees in North America. Currently, effective options for individual tree protection are limited to systemic insecticides, in particular neonicotinoids, which have come under increased scrutiny for their nontarget effects. In this study, green ash (Fraxinus pennsylvanica) trees were treated with two neonicotinoid insecticides, imidacloprid and dinotefuran, at full and half label rates based on trunk diameter to evaluate residues and efficacy. Analyzing the leaf, stem, and root tissues, there was no difference in insecticide residues between application rates within each tissue type. However, there were significantly higher residues of imidacloprid in root tissue compared to other plant tissues, and dinotefuran applied at the full label rate resulted in lower residues in stem phloem tissue. Additionally, insecticide-treated stems were artificially infested with EAB eggs to measure larval success (survival and growth). EAB larvae consumed less phloem in treated trees compared to untreated controls. These findings suggest that, in small-diameter ash, lower than label-recommended doses may be a viable component of an integrated management plan for EAB. [ABSTRACT FROM AUTHOR]

Recent study has shown that RNA interference (RNAi) is efficient in emerald ash borer (EAB), Agrilus planipennis, and that ingestion of double-stranded RNA (dsRNA) targeting specific genes causes gene silencing and mortality in neonates. Here, we report on the identification of highly effective target genes for RNAi-mediated control of EAB. We screened 13 candidate genes in neonate larvae and selected the most effective target genes for further investigation, including their effect on EAB adults and on a non-target organism, Tribolium castaneum. The two most efficient target genes selected, hsp(heat shock 70-kDa protein cognate 3) and shi (shibire), caused up to 90% mortality of larvae and adults. In EAB eggs, larvae, and adults, the hsp is expressed at higher levels when compared to that of shi. Ingestion of dsHSP and dsSHI caused mortality in both neonate larvae and adults. Administration of a mixture of both dsRNAs worked better than either dsRNA by itself. In contrast, injection of EAB.dsHSP and EAB.dsSHI did not cause mortality in T. castaneum. Thus, the two genes identified cause high mortality in the EAB with no apparent phenotype effects in a non-target organism, the red flour beetle, and could be used in RNAi-mediated control of this invasive pest. [ABSTRACT FROM AUTHOR]

Bats in the genus Corynorhinus possess a suite of morphological characters that permit them to effectively use both gleaning and aerial-hawking foraging strategies to capture Lepidoptera. Consequently, they occupy a specialized feeding niche within North American bat assemblages and are of particular interest for dietary studies. We collected fecal pellets from a colony of C. rafinesquii (Rafinesque's Big-Eared Bat) at Mammoth Cave National Park during August-October 2011 and amplified cytochrome-c oxidase subunit 1 fragments of prey from these pellets. We used the Barcode of Life Database to identify prey, and evaluated the size of prey species based on published values. The mean wingspan of prey we recorded from our samples was smaller than average values reported for Rafinesque's Big-Eared Bat using traditional methods (P ≤ 0.01), suggesting that surveys of culled insect parts beneath roosting sites may lead to biased estimates of the size and breadth of prey species eaten by gleaning bats. Mean wingspan of lepidopteran prey consumed by Rafinesque's Big-Eared Bat in our study was larger (P ≤ 0.01) than values reported for the Myotis septentrionalis (Northern Long-Eared Bat), which is a smaller, sympatric gleaner in eastern North America. Further, comparisons of our diet data with abundance of prey suggest macrolepidopteran taxa are consistently consumed by Rafinesque's Big-Eared Bat to greater degree than microlepidotera. Our findings suggest that North American Corynorhinus consume a wider range of sizes and species of Lepidoptera than previously reported in studies based solely on identification of culled prey-wings b eneath feeding roosts. [ABSTRACT FROM AUTHOR]