Suitability of blue ash (fraxinus quadrangulata) and green ash (f. pennsylvanica) to emerald ash borer (agrilus planipennis) and its larval parasitoid tetrastichus planipennisi.

Emerald ash borer (EAB) (Agrilus planipennis ) is a primary pest that has killed tens of millions of North American ash (Fraxinus spp.) trees. The larval parasitoid Tetrastichus planipennisi was introduced from China as part of a classical biological control program for long-term EAB management. The high mortality rates of ash trees greatly reduce the number of EAB hosts and may make it difficult for parasitoids to persist. However, blue ash ( F. quadrangulata ) is relatively resistant and appears to be able to survive EAB infestation. If natural enemies can attack EAB in infested blue ash they may be better able to persist and protect regenerating ash trees. I compared the capacity of EAB larvae and its larval parasitoid to survive and develop in blue ash and the more susceptible green ash ( F. pennsylvanica ). Blue and green ash trees were infested with EAB eggs in the field and laboratory and their bark was peeled to determine larval survivorship and developmental stages. A subset of blue and green ash was exposed to T. planipennisi so that parasitism rates, brood sizes, sex ratios, and adult sizes could be determined. EAB larvae survivorship was high (\u3e96%) and mortality due to wound periderm formation was low (T. planipennisi brood sizes, sex ratios, and adult female sizes had no significant difference between ash species suggesting that hosts have no apparent affects. In the field, T. planipennisi was able to attack and develop on EAB larvae in caged blue and green ash trees. As such, if T. planipennisi can find blue ash trees, then they should readily attack and survive on living EAB. When joined with higher blue ash survival, it is possible that this ash species could serve as refuge for EAB and its parasitoids after susceptible ash are killed by this pest. Thus, blue ash presence may improve the capacity of parasitoids to parasitize, persist, and protect more susceptible ash species in forests

Evaluation of sample collection and storage protocols for surface eDNA surveys of an invasive terrestrial insect

Environmental DNA surveys have revolutionized monitoring of rare or cryptic species and species inhabiting areas where conventional sampling is difficult or dangerous. Recent advancements within terrestrial environments include the capture of eDNA deposited by animals on surfaces such as tree bark and foliage, hereafter “surface eDNA.” Notably, a technique which uses commercial paint rollers to aggregate surface eDNA has been deployed with success to detect the presence of forest insect pests providing a potentially powerful new management tool. However, before widespread adoption is feasible, the efficiency and logistics of roller sample collection and study design, especially relative to realistic survey conditions, must be evaluated. We compared the performance of two DNA preservation treatments—cold and ethanol—on their ability to reduce the loss of captured eDNA on rollers over time. Additionally, we evaluated how the detection probability of our target species, the spotted lanternfly (Lycorma delicatula), varied with sampling effort (time spent rolling per sample) and the initial quantity of eDNA present. Finally, we evaluated how the number of trees sampled per roller influenced the final concentrations of lanternfly eDNA remaining on the roller. We found storing rollers with ethanol or cold temperatures resulted in 3–10-fold greater concentrations of experimentally controlled eDNA relative to no treatment after 24 h. Detection probability declined as the amount of lanternfly eDNA decreased, but did not change in response to sampling effort over sample time (10–80 s/tree). Finally, recovered lanternfly eDNA decreased as more trees were sampled by a single roller—a 91% reduction after 7 trees—potentially due to captured DNA being transferred back from the roller onto the bark. Our results provide improved guidance for deploying roller surface eDNA methods for spotted lanternfly surveys, and for invasive insect pest surveillance and monitoring programs generally

Preference, performance, and selection of historic and novel hosts by emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)

North American and European ash trees are highly susceptible to emerald ash borer (EAB, Agrilus planipennis). This buprestid kills hosts via larva feeding on vascular tissue which eventually kills the host plant. Two new hosts have recently been found to support larval development of EAB. White fringetrees (Chionathus virginicus) were found attacked by EAB in 2014 and since then have been found to be attacked throughout other parts of the United States, while olive (Olea europaea) has only experimentally been found to support larvae to adulthood. Chemical profiles of these two plants were collected and analyzed to determine how their volatile emissions vary among susceptible and resistant ash trees. Additionally, larvae and adult beetles were tested for their performance on these novel plants. For white fringetree, wild populations were monitored to determine the impact of EAB during the attack wave. These studies find that white fringetree foliage supports adults, but when phloem is healthy it causes high larval morality in contrast to girdled or previously attacked by EAB where larvae survived by the end of assays. In the field, EAB began to use white fringetree quickly, within a couple of years after initial exposure. Female choice suggests white fringetree and susceptible ash are similarly preferred likely due to the similar volatile emissions. These chemicals likely caused host range expansion of EAB to this novel host. In contrast to ash, the impact of EAB on white fringetree is minimal. This plant mostly loses a branch or two from larval girdling, which in ornamentally planted fringetrees can be aesthetically displeasing. On olive, EAB is likely to be even less damaging because larvae take longer to develop than in ash and larvae die quickly in young, photosynthesizing stems. Adults did not perform well because oleuropein may cause them to compensatory feed and causing malnutrition. In North American forests, if EAB continues to destroy ash species at such high rates, EAB may be driven to use white fringetree more often. With continued use of this host, EAB is likely to adapt to better utilize white fringetree which could eventually lead to host switching

Preference, performance, and selection of historic and novel hosts by emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)

North American and European ash trees are highly susceptible to emerald ash borer (EAB, Agrilus planipennis). This buprestid kills hosts via larva feeding on vascular tissue which eventually kills the host plant. Two new hosts have recently been found to support larval development of EAB. White fringetrees (Chionathus virginicus) were found attacked by EAB in 2014 and since then have been found to be attacked throughout other parts of the United States, while olive (Olea europaea) has only experimentally been found to support larvae to adulthood. Chemical profiles of these two plants were collected and analyzed to determine how their volatile emissions vary among susceptible and resistant ash trees. Additionally, larvae and adult beetles were tested for their performance on these novel plants. For white fringetree, wild populations were monitored to determine the impact of EAB during the attack wave. These studies find that white fringetree foliage supports adults, but when phloem is healthy it causes high larval morality in contrast to girdled or previously attacked by EAB where larvae survived by the end of assays. In the field, EAB began to use white fringetree quickly, within a couple of years after initial exposure. Female choice suggests white fringetree and susceptible ash are similarly preferred likely due to the similar volatile emissions. These chemicals likely caused host range expansion of EAB to this novel host. In contrast to ash, the impact of EAB on white fringetree is minimal. This plant mostly loses a branch or two from larval girdling, which in ornamentally planted fringetrees can be aesthetically displeasing. On olive, EAB is likely to be even less damaging because larvae take longer to develop than in ash and larvae die quickly in young, photosynthesizing stems. Adults did not perform well because oleuropein may cause them to compensatory feed and causing malnutrition. In North American forests, if EAB continues to destroy ash species at such high rates, EAB may be driven to use white fringetree more often. With continued use of this host, EAB is likely to adapt to better utilize white fringetree which could eventually lead to host switching

Attack Dynamics and Impacts of Emerald Ash Borer on Wild White Fringetree Populations

North American forests have been heavily impacted from the loss of ash trees (Fraxinus spp.) due to emerald ash borer (EAB, Agrilus planipennis) invasion. Recently, white fringetree (Chionanthus virginicus), an ash relative, has been found to support the development of EAB in ornamental plantings, but interactions between EAB and this plant have never been examined in wild populations. We monitored two wild white fringetree populations in Ohio throughout the invasion wave of EAB to examine its impacts and factors that increased the likelihood of attack. Within 2 years of study initiation, the majority of white ash (F. americana) were attacked by EAB in these areas, in contrast to a few individual fringetrees. By the end of 5 years, however, EAB attacked up to 30% of white fringetrees and caused branch mortality in several individual plants. The percentage of white fringetrees attacked was significantly lower than in white ash trees, the majority of ash died due to EAB. Those fringetrees that were attacked displayed signs of stress, including epicormic branching and canopy thinning, both symptoms of larval damage by EAB. Our results provide the first reported findings of the dynamics and impact of EAB on wild white fringetree populations

Attack Dynamics and Impacts of Emerald Ash Borer on Wild White Fringetree Populations

North American forests have been heavily impacted from the loss of ash trees (Fraxinus spp.) due to emerald ash borer (EAB, Agrilus planipennis) invasion. Recently, white fringetree (Chionanthus virginicus), an ash relative, has been found to support the development of EAB in ornamental plantings, but interactions between EAB and this plant have never been examined in wild populations. We monitored two wild white fringetree populations in Ohio throughout the invasion wave of EAB to examine its impacts and factors that increased the likelihood of attack. Within 2 years of study initiation, the majority of white ash (F. americana) were attacked by EAB in these areas, in contrast to a few individual fringetrees. By the end of 5 years, however, EAB attacked up to 30% of white fringetrees and caused branch mortality in several individual plants. The percentage of white fringetrees attacked was significantly lower than in white ash trees, the majority of ash died due to EAB. Those fringetrees that were attacked displayed signs of stress, including epicormic branching and canopy thinning, both symptoms of larval damage by EAB. Our results provide the first reported findings of the dynamics and impact of EAB on wild white fringetree populations

Ecological Fitting: Chemical Profiles of Plant Hosts Provide Insights on Selection Cues and Preferences for a Major Buprestid Pest

Specific cues used by emerald ash borer (EAB, Agrilus planipennis) to select hosts are largely unknown. Attractants are likely general and the use of novel host plants provides an opportunity to investigate the commonality of these cues. We examined volatile profiles emitted by five plants that can host EAB and estimated their importance in explaining known oviposition preferences. Foliage volatiles were collected from potted black ash (Fraxinus nigra), Manchurian ash (F. mandshurica), blue ash (F. quadrangulata), white fringetree (Chionanthus virginicus), and olive (Olea europaea) and analyzed using GC-MS. Fifty-nine compounds were detected including eight green leaf volatiles (GLV), 12 monoterpenes, and 21 sesquiterpenes. Ordination plots show separation of species by full foliage profiles, monoterpenes, sesquiterpenes, and known antennally active compounds, but GLVs were similar across hosts. Random Forest (RF) analysis revealed eight compounds that separated plant species with an error rate of ~19%, consisting mostly of sesquiterpenes. Similarity of GLV profiles among known hosts suggests they serve as general cues for host selection. Manchurian ash, a resistant host, produced the highest quantities and variety of sesquiterpenes indicating that some of these chemicals may be antixenotic. All compounds identified by RF have been implicated as deterrents or attractants to woodborers in other studies and should be investigated for adult antennal activity and attraction

Ecological Fitting: Chemical Profiles of Plant Hosts Provide Insights on Selection Cues and Preferences for a Major Buprestid Pest

Specific cues used by emerald ash borer (EAB, Agrilus planipennis) to select hosts are largely unknown. Attractants are likely general and the use of novel host plants provides an opportunity to investigate the commonality of these cues. We examined volatile profiles emitted by five plants that can host EAB and estimated their importance in explaining known oviposition preferences. Foliage volatiles were collected from potted black ash (Fraxinus nigra), Manchurian ash (F. mandshurica), blue ash (F. quadrangulata), white fringetree (Chionanthus virginicus), and olive (Olea europaea) and analyzed using GC-MS. Fifty-nine compounds were detected including eight green leaf volatiles (GLV), 12 monoterpenes, and 21 sesquiterpenes. Ordination plots show separation of species by full foliage profiles, monoterpenes, sesquiterpenes, and known antennally active compounds, but GLVs were similar across hosts. Random Forest (RF) analysis revealed eight compounds that separated plant species with an error rate of ~19%, consisting mostly of sesquiterpenes. Similarity of GLV profiles among known hosts suggests they serve as general cues for host selection. Manchurian ash, a resistant host, produced the highest quantities and variety of sesquiterpenes indicating that some of these chemicals may be antixenotic. All compounds identified by RF have been implicated as deterrents or attractants to woodborers in other studies and should be investigated for adult antennal activity and attraction

Feeding, Survival, and Fecundity of Adult Emerald Ash Borer (Coleoptera: Buprestidae) on Foliage of Two Novel Hosts and Implications for Host Range Expansion

Insect herbivores are more likely to successfully use a novel host if the plant is closely related to the ancestral host and the insect is polyphagous. Emerald ash borer (EAB), Agrilus planipennis (Fairmaire) (Coleoptera: Buprestidae), is a specialist wood borer of ash (Fraxinus spp., Lamiales: Oleaceae) trees and one of the most destructive forest pests in North American forests. Recent studies have found that larvae can develop in stems of two ash relatives; white fringetree (Chionanthus virginicus (L.) [Laminales: Oleaceae]) and cultivated olive (Olea europaea (L.) [Laminales: Oleaceae]). For EAB adults, the ability to consume, successfully mate, and lay viable eggs on foliage of these hosts is unknown.Thus, we conducted two no-choice assays with adult EAB on foliage of white fringetree and olive paired with positive controls of susceptible ash. Larval performance was also examined in a reciprocal study with cut stems of white fringetree and green ash (Fraxinus pennsylvanica Marshall) to determine whether adult diet impacted the success of progeny. Longevity, consumption rates, and fecundity of adults were similar on white fringetree and ash foliage. In contrast, adults consuming olive died quickly, consumed more over time, and females laid far fewer eggs compared to those on ash. Adult diet did not impact larval success, but larvae in white fringetree stems grew slower. These results indicate that white fringetree is a suitable host for EAB to complete its lifecycle, although larvae perform more poorly on this host than in susceptible ash species. In contrast, the more distantly related olive appears to be a poor host for adult EAB, although some viable eggs were produced by females