The spotted lanternfly (Lycorma delicatula) overwinters in egg masses for approximately eight months a year, representing the longest individual life stage. The immobile egg mass life stage constitutes a good candidate for management practices. Many insecticides and biopesticides have been demonstrated to provide control of nymphal and adult L. delicatula, but more research is needed on managing SLF egg masses. I conducted bioassays across three years (2021–2023) utilizing various insecticides and biopesticides against untreated and water checks at different application timings on SLF egg masses. Furthermore, in 2023, field trials of malathion and Beauveria bassiana biopesticides were investigated. I found substantial hatch reduction from malathion in all bioassays and field trials. Other pesticides tested in laboratory bioassays demonstrated varying hatch reductions across application timings and years. Laboratory bioassays suggested a single commercially available application of B. bassiana made directly on overwintering L. delicatula egg masses could subsequently infect hatching neonates. In laboratory studies, the optimal timing of spray applications on L. delicatula egg masses was approximately two weeks before hatch. Both field trials demonstrated that infection in hatching L. delicatula nymphs was greater than in laboratory bioassays. The intention of this research is to provide stakeholders with additional environmentally friendly tools to manage spotted lanternfly. In separate studies, I report the first detections of Aculops ailanthi, an exotic mite on tree-of-heaven, Ailanthus altissima, from Montgomery County, Virginia, and Wayne County, Michigan, USA. Samples from both states were sent to USDA-ARS for identification, and scanning electron microscopy confirmed the species as A. ailanthi based on the morphological features. Moreover, I describe the impacts that high populations of A. ailanthi can have on Ai. altissima, in greenhouse settings, and its potential use as a biological control agent. I investigated the efficacy of various foliar insecticide treatments against A. ailanthi on potted Ai. altissima saplings to produce additional management recommendations for researchers struggling to cultivate Ai. altissima in greenhouse conditions due to the overwhelming injury produced by A. ailanthi. All pesticide treatments significantly reduced A. ailanthi populations and provided residual control for two weeks. / Doctor of Philosophy / The invasive spotted lanternfly has spread to many States since it was introduced into the USA in 2014. Spotted lanternfly negatively influences many economic sectors, disrupting the distribution of commerce and requiring stakeholders to implement management options to reduce impacts on valuable commodities. Grapevines, a preferred host of spotted lanternfly, are at the greatest risk from spotted lanternfly. Currently, most spotted lanternfly management in vineyards targets the adult life stage as the adults aggregate in dense populations, feeding and excreting honeydew on vines. While many insecticides and biopesticides are effective at managing spotted lanternfly to some degree, commercial vineyards have reported an increase in the frequency of pesticide applications against spotted lanternfly. Spotted lanternfly survive the winter in egg masses, and despite remaining in egg masses for a large portion of the year, little research has been conducted on the management of spotted lanternfly egg masses. Here, I examined insecticide and biopesticide applications for spotted lanternfly egg masses. I applied a single application of pesticides to spotted lanternfly egg masses at various times during the overwinter life stage. I found many insecticidal treatments resulted in a reduction in the hatch of the spotted lanternfly. Furthermore, I observed signs of infection in recently emerged spotted lanternfly when egg masses were exposed to biopesticide treatments. In laboratory studies, I found that commercial insect pathogenic fungus applications made two weeks before hatch resulted in the most significant hatch reduction and infection. Field trials of pesticides against overwintering spotted lanternfly egg masses demonstrated similar effects as those observed in laboratory studies. Finally, while growing tree-of-heaven for SLF research, I documented the presence of a mite, Aculops ailanthi, reporting multiple new state records and observations of potential biological control utility against tree-of-heaven.

Quand deux espèces exploitent la même niche écologique, elles entrent en compétition. Cette compétition interspécifique peut conduire à l’exclusion de l’une d’entre elles. Toutefois, il est possible qu’un équilibre s’installe et que les deux espèces coexistent en sympatrie. Eupelmus vuilleti et Dinarmus basalis sont deux espèces de parasitoïdes solitaires, exploitant la même niche écologique, les larves et les nymphes de Callosobruchus maculatus un coléoptère séminivore. En situation de compétition par exploitation, E. vuilleti présente les caractéristiques d’une espèce dominante, potentiellement capable d’exclure D. basalis. Aussi, nous nous sommes demandés comment D. basalis peut se maintenir dans la même niche écologique qu’E. vuilleti, comme cela est observé dans certaines zones africaines ? Nos résultats montrent qu’en présence de compétitrices (compétition par interférence), les femelles des deux espèces expriment des comportements agonistiques et la résolution des conflits est principalement influencée par la valeur que les femelles placent dans la ressource. Nous montrons finalement que dans les conditions de compétition interspécifique directe, les femelles de D. basalis sont plus agressives et font du self-suparparasitisme pour augmenter leur gain en fitness. Au contraire, les femelles d’E. vuilleti s’éloignent et attendent pour finalement revenir multiparasiter après le départ de cette dernière. En conséquence, la coexistence de ces deux espèces est le résultat d’un équilibre entre les stratégies adoptées par les femelles dans ces deux situations de compétition. / When two species exploit the same ecological niche, interspecific competition may lead to the exclusion of one of them. For the two species to co-exist, resource exploitation strategies developed by both species must somehow counter-balance each other. Eupelmus vuilleti and Dinarmus basalis are two solitary parasitoid species exploiting the same hosts, larvae and pupae of Callosobruchus maculatus. When confronted to already parasitized hosts (i.e. exploitative competition), Eupelmus vuilleti seems to be dominant and potentially able to exclude D. basalis. Here, we aim at understanding how E. vuilleti and D. basalis can coexist when in sympatry. More particularly, we investigate the behavioral strategies adopted by females of both species when exploiting the resource (i.e. host) in presence of a competitor female (conspecific or interspecific) (i.e. interference competition). Our study reveals that in presence of a competitor female, E. vuilleti and D. basalis females display agonistic behaviors and the contest resolution is mainly influenced by the value that contestants place on the resource. Finally, under interspecific direct competition, D. basalis females tend to outcompete E. vuilleti females: they are more aggressive. In contrast, E. vuilleti females adopt a waiting strategy, waiting for the opponent female’s departure to multiparasitize hosts after committing an ovicide. Thus, both species seem to show counterbalancing strategies which could promote their coexistence in nature and granaries.