Scholarly Works, Entomology
Permanent URI for this collection
Research articles, presentations, and other scholarship
Browse
Browsing Scholarly Works, Entomology by Subject "06 Biological Sciences"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Establishment of the predator Laricobius nigrinus, introduced as a biological control agent for hemlock woolly adelgid in Virginia, USAJubb, Carrie S.; McAvoy, Thomas J.; Stanley, Kari E.; Heminger, Ariel R.; Salom, Scott M. (Springer, 2021-01-05)Laricobius nigrinus Fender (Coleoptera: Derodontidae), a predatory beetle native to western North America, has been released since 2003 for management of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), a non-native pest killing hemlocks in eastern North America. Over 420,000 L. nigrinus have been released in the eastern USA from field and lab-reared sources, 14,000 of which were deployed in the Commonwealth of Virginia, USA. In order to determine the establishment rates of L. nigrinus in Virginia, surveys were conducted in 2017 and 2018 at all release sites within this state. During the study, stand-level HWA densities were estimated, and hemlock tree health and predator–prey ratios were quantified. The identification of Laricobius spp. recoveries were made using microsatellite analysis. During the period of the study, L. nigrinus were found to have established at 82% of Virginia release sites and were the primary species recovered (80%). Both Laricobius rubidus (18%) and hybrids (2%) were also recovered. Stand-level HWA densities varied greatly over sites and years but showed a general decline in year two of the study. Establishment at such a high percentage of release sites suggests that the climate in Virginia is suitable for the predator and the insect is adaptable to the wide variety of site conditions where hemlocks typically grow.
- The invasive tree, Ailanthus altissima, impacts understory nativity, not seedbank nativityBrooks, Rachel K.; Barney, Jacob; Salom, Scott M. (Elsevier, 2021-06-01)Ailanthus altissima, the invasive forest tree commonly known as the tree-of-heaven, has been associated with decreased levels of plant species richness and native species diversity. However, this relationship with resident plants has been inconsistently found and the tree's influence on the seedbank has yet to be studied. To further understand the long-term impact of this tree, ten paired invaded-uninvaded sites were identified in Virginia, USA in a variety of different-aged stands. The herbaceous and woody understories for each plot were inventoried and soil samples were collected and grown out for 34 weeks in a greenhouse. All plants were identified to the most detailed taxonomic level possible. In total, 35 woody understory species, 62 herbaceous understory taxa, and 77 seedbank taxa were identified. The relationship between A. altissima presence and i) the proportion of individual plants that are native, ii) the proportion of species that are native, iii) the native diversity, and iv) the nonnative diversity were analyzed. In addition, models including the invasion age were also considered. We show that A. altissima invasions were associated with a decrease in the proportion of native plants and species in the understory, but not in the seedbank. Nonnative woody diversity also increased with A. altissima presence. Additionally, the impact on the nativity of the woody understory became more extreme over time. We end by discussing the benefits of both managing A. altissima invasions early to limit its overall impact and including the management of other nonnative plants in A. altissima restoration plans.
- Large scale complete genome sequencing and phylodynamic analysis of eastern equine encephalitis virus reveal source-sink transmission dynamics in the United StatesTan, Yi; Lam, Tommy Tsan-Yuk; Heberlein-Larson, Lea A.; Smole, Sandra C.; Auguste, A. Jonathan; Hennigan, Scott; Halpin, Rebecca A.; Fedorova, Nadia; Puri, Vinita; Stockwell, Timothy B.; Shilts, Meghan H.; Andreadis, Theodore G.; Armstrong, Philip M.; Tesh, Robert B.; Weaver, Scott C.; Unnasch, Thomas R.; Ciota, Alexander T.; Kramer, Laura D.; Das, Suman R. (American Society for Microbiology, 2018-04-04)Eastern equine encephalitis virus (EEEV) has a high case-fatality rate in horses and humans, and Florida has been hypothesized to be the source of EEEV epidemics for the northeastern United States. To test this hypothesis, we sequenced complete genomes of 433 EEEV strains collected within the United States from 1934 to 2014. Phylogenetic analysis suggested EEEV evolves relatively slowly and that transmission is enzootic in Florida, characterized by higher genetic diversity and long-term local persistence. In contrast, EEEV strains in New York and Massachusetts were characterized by lower genetic diversity, multiple introductions, and shorter local persistence. Our phylogeographic analysis supported a source-sink model in which Florida is the major source of EEEV compared to the other localities sampled. In sum, this study revealed the complex epidemiological dynamics of EEEV in different geographic regions in the United States and provided general insights into the evolution and transmission of other avian mosquito-borne viruses in this region.
- Plant essential oils synergize various pyrethroid insecticides and antagonize malathion in Aedes aegyptiNorris, Edmund J.; Gross, Aaron D.; Bartholomay, Lyric C.; Coats, J. R. (Wiley, 2019-12-01)Pyrethroid resistance is a significant threat to agricultural, urban and public health pest control activities. Because economic incentives for the production of novel active ingredients for the control of public health pests are lacking, this field is particularly affected by the potential failure of pyrethroid-based insecticides brought about by increasing pyrethroid resistance. As a result, innovative approaches are desperately needed to overcome insecticide resistance, particularly in mosquitoes that transmit deadly and debilitating pathogens. Numerous studies have demonstrated the potential of plant essential oils to enhance the efficacy of pyrethroids. The toxicity of pyrethroids combined with plant oils is significantly greater than the baseline toxicity of either oils or pyrethroids applied alone, which suggests there are synergistic interactions between components of these mixtures. The present study examined the potential of eight plant essential oils applied in one of two concentrations (1% and 5%) to enhance the toxicity of various pyrethroids (permethrin, natural pyrethrins, deltamethrin and β-cyfluthrin). The various plant essential oils enhanced the pyrethroids to differing degrees. The levels of enhancement provided by combinations of plant essential oils and pyrethroids in comparison with pyrethroids alone were calculated and synergistic outcomes characterized. Numerous plant essential oils significantly synergized a variety of pyrethroids; type I pyrethroids were synergized to a greater degree than type II pyrethroids. Eight plant essential oils significantly enhanced 24-h mortality rates provided by permethrin and six plant essential oils enhanced 24-h mortality rates obtained with natural pyrethrins. By contrast, only three plant essential plants significantly enhanced the toxicity of deltamethrin and β-cyfluthrin. Of the plant essential oils that enhanced the toxicity of these pyrethroids, some produced varying levels of synergism and antagonism. Geranium, patchouli and Texas cedarwood oils produced the highest levels of synergism, displaying co-toxicity factors of > 100 in some combinations. To assess the levels of enhancement and synergism of other classes of insecticide, malathion was also applied in combination with the plant oils. Significant antagonism was provided by a majority of the plant essential oils applied in combination with this insecticide, which suggests that plant essential oils may act to inhibit the oxidative activation processes within exposed adult mosquitoes.