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Recolonization by native species following removal of invasive plant species can often be uneven and lead to the rapid increase of one or a few native plant species. This can result in the formation of a significant resource pulse that may consequently affect populations of herbivorous species and their natural enemies. Here we present results from observations of parasitism rates during a localized outbreak of the Asimina webworm moth, Omphalocera munroei, a locally monophagous herbivore of the common paw-paw. Asimina triloba. This outbreak initiated from locations of increased understory growth of A. triloba, following the removal of Amur Honeysuckle (Lonicera maackii). Parasitism rates during the outbreak reached 50%, with higher parasitism rates observed in larvae collected at the end of the local outbreak relative to those the year following the peak of the outbreak. Parasitism rates remained high 3 y after the end of the local O. munroei outbreak, indicating >7 y of high parasitoid densities. O. munroei emerges late in the growing season, making it fairly inaccessible as a host or prey to many generalist predators/parasitoids, which emerge earlier the following year. This suggests the O. munroei outbreak potentially contributed to an increase in natural enemy pressure of other native species in the community., INTRODUCTION Invasive plant species can have extensive negative impacts on diversity, species interactions, community composition, ecosystem function, socioeconomic conditions, and human health (Vila et al, 2011; Rai and Singh, 2020). [...]

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a devastating, invasive insect pest of ash trees, Fraxinus spp., in North America. Using a simulation model, we evaluated three potential management options to slow the spread of A. planipennis in discrete outlier sites: (i) removing ash trees to reduce available host phloem resource, (ii) girdling ash trees to attract ovipositing female beetles and destroying the trees before larvae complete development, and (Hi) applying a highly effective systemic insecticide. Simulations indicate that systemic insecticide applications provided the greatest reduction in the radial spread of A. planipennis. In simulations in which management options were applied only within a 300 m radius from the origin of the infestation, insecticide applications reduced the radial spread by 30% and larval consumption of ash phloem by 40% beyond the treated area. In contrast, girdling ash trees reduced the radial spread by 15% and larval consumption of ash phloem by 20% beyond the treated area. Both of these management options significantly reduced the spread of A. planipennis when treatments were applied 1 to 4 years after infestations were initiated. Reducing ash phloem by removing ash trees decreased population size within treated areas but did not reduce the radial spread, population size, or larval consumption of ash phloem beyond treated areas. Resume: L'agrile du frene, Agrilus plenipennis Fairmaire (coleoptere, buprestides), est un insecte nuisible envahissant qui est devastateur pour le frene, Fraxinus spp., en Amerique du Nord. A l'aide d'un modele de simulation, nous avons evalue trois options potentielles de lutte pour ralentir la propagation d'A. plenipennis dans differents sites enclaves: (i) l'elimi-nation des frenes pour reduire la ressource disponible que constitue le phloeme de l'hote, (ii) l'annelation des frenes pour attirer les insectes femelles durant la periode d'oviposition et eliminer les arbres avant que les larves completent leur deve-loppement et (Hi) l'application d'un insecticide systemique tres efficace. Les simulations indiquent que les applications d'insecticide systemique reduisent le plus la propagation radiale d'A. plenipennis. Dans les simulations ou les options de lutte ont ete appliquees seulement a l'interieur d'un rayon de 300 m du point d'origine de l'infestation, les applications d'insecticide ont reduit la propagation radiale de 30 % et l'alimentation dans le phloeme du frene par les larves de 40 % au-dela de la zone traitee. Par contre, l'annelation des tiges de frene a reduit la propagation radiale de 15 % et l'alimen-tation dans le phloeme du frene par les larves de 20 % au-dela de la zone traitee. Ces deux options de lutte ont significati-vement reduit la propagation d'A. plenipennis lorsque les traitements etaient appliques un a quatre ans apres le debut des infestations. L'elimination des frenes pour reduire la quantite de phloeme disponible a diminue la taille de la population a l'interieur des zones traitees mais n'a pas reduit la propagation radiale, la taille de la population, ni l'alimentation dans le phloeme du frene au-dela des zones traitees. [Traduit par la Redaction], Introduction Nonindigenous invaders threaten biodiversity (Mack et al. 2000) and may profoundly affect evolutionary (e.g., Strauss et al. 2006) and community-ecosystem processes (e.g., Krushelnycky and Gillespie 2008). Invasive pests in [...]

Detection of newly established populations of Agrilus planipennis Fairmaire, the most destructive forest insect to invade the United States, remains challenging. Regulatory agencies currently rely on artificial traps, consisting of baited three-sided panels suspended in the canopy of ash (Fraxinus spp.) trees. Detection trees represent another survey option. Ash trees are girdled in spring to attract ovipositing A. planipennis females then debarked in fall to assess larval presence and density. From 2008-2010, systematic grids of detection trees and artificial traps were established across a 390-km2 area for the SLow Ash Mortality pilot project. We compared probabilities of detection associated with detection trees and artificial traps along varying A. planipennis density proxies estimated as distance-weighted averages of larval counts (detection trees) or adult captures (traps) within 800 m of each detection tree or trap. Detection trees were consistently more likely to be positive, that is, detect A. planipennis, than traps in all three years, even when traps were placed in canopies of detection trees. Probability of detection with a single detection tree was >50% when density proxies for the area were <5 larvae per detection tree, while the probability of detection with an artificial trap placed in the same area was <35%, even when density proxies exceeded 25 larvae per detection tree. At very low densities of <5 larvae per detection tree, using three detection trees would increase detection probabilities to 90%, while five artificial traps would increase the detection probability only to 40%. [ABSTRACT FROM AUTHOR]

1 Emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive forest insect pest threatening more than 8 billion ash ( Fraxinus spp.) trees in North America. Development of effective survey methods and strategies to slow the spread of A. planipennis requires an understanding of dispersal, particularly in recently established satellite populations. 2 We assessed the dispersal of A. planipennis beetles over a single generation at two sites by intensively sampling ash trees at known distances from infested ash logs, the point source of the infestations. Larval density was recorded from more than 100 trees at each site. 3 Density of A. planipennis larvae by distance for one site was fit to the Ricker function, inverse power function, and the negative exponential function using a maximum likelihood approach. The prediction of the best model, a negative exponential function, was compared with the results from both sites. 4 The present study demonstrates that larval densities rapidly declined with distance, and that most larvae (88.9 and 90.3%) were on trees within 100 m of the emergence point of the adults at each site. The larval distribution pattern observed at both sites was adequately described by the negative exponential function. [ABSTRACT FROM AUTHOR]