Browsing by Author "Shrader, Meredith Edana"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Bean leaf beetle (Coleoptera: Chrysomelidae) preference for two Phaseolus beans over soybean
    Shrader, Meredith Edana; Kuhar, Thomas P.; Schultz, Peter B.; Pfeiffer, Douglas G.; Kamminga, Katherine (2014)
    In the eastern and central U.S., bean leaf beetle, Cerotoma trifurcata (Förster) (Coleoptera: Chrysomelidae), is a pest of legume crops, on which adults chew holes in leaves, can destroy seedlings, and can injure pods (Smelser and Pedigo 1992a, J. Econ. Entomol. 85: 2408 - 2412; Smelser and Pedigo 1992b, J. Econ. Entomol. 85: 2399 - 2403; Koch et al. 2005, Crop Prot. 24: 734 - 742). The beetle is also a primary vector of bean pod mottle virus, which can further reduce yield and seed quality in soybeans (Giesler et al. 2002, Plant Dis. 86: 1280 - 1289). On the Delmarva Peninsula, snap beans (Phaseolus vulgaris L.), lima beans (Phaseolus lunatus L.), and soybeans (Glycine max (L.) Merr.), are each important crops, and relatively high populations of C. trifurcata occur. To better understand the potential intercrop movement of the beetle and its implications for pest management, we conducted beetle host plant preference experiments...
  • Thumbnail Image
    Drosophila suzukii (Diptera: Drosophilidae) oviposition and adult emergence in six wine grape varieties grown in Virginia
    Shrader, Meredith Edana; Burrack, Hannah J.; Pfeiffer, Douglas G. (2018-10-01)
    Drosophila suzukii (Matsumura) is a pest of small fruits and grapes in the United States and in its home range of Japan. Physiological and morphological laboratory testing was performed on six commonly grown wine grape varieties in Virginia. Skin thickness, penetration force, and ºBrix were analyzed to determine ovipositional preferences. Experiments were performed for three consecutive years from grapes collected at one Virginia vineyard. More eggs were laid in intact Viognier grapes than any other variety. Oviposition into intact grapes was not affected by skin thickness or ºBrix; however, oviposition increased when penetration force decreased. An ovipositional choice test determined no varietal preferences. Survivorship from egg to adulthood using uninjured and injured grapes was also assessed to determine varietal suitability as D. suzukii hosts, with more flies emerging from injured grapes than uninjured. However, D. suzukii adults did emerge from intact grapes and at higher percentages than previously recorded in other wine grape studies. All varieties had eggs oviposited into them when injured. Determining the time at which each grape variety became susceptible to oviposition was determined using a D. suzukii bioassay spanning 12 wk using grapes from the green pea stage until ripe. Susceptibility to D. suzukii oviposition was based upon ripening period and penetration force. Early ripening varieties may be more susceptible to D. suzukii oviposition in the field with later maturing, harder fleshed-varieties which may escape D. suzukii oviposition.
  • Thumbnail Image
    Drosophila suzukii (Matsumura) (Diptera: Drosphilidae): Risk Assessment For An Invasive Vinegar Fly In Virginia Vineyards
    Shrader, Meredith Edana (Virginia Tech, 2017-06-22)
    Drosophila suzukii (Matsumura) (Diptera: Drosophila) is an invasive frugivore and has become a significant pest of small fruit, cherry and grape throughout the United States. It may be possible to determine if a Virginia vineyard is at risk of D. suzukii infestation by analyzing the biotic and abiotic factors around each vineyard. This pest is known to utilize a wide range of cultivated and wild host plants. A host plant survey was conducted at four vineyards in the Piedmont Region of Virginia to identify hosts used by D. suzukii around vineyards. The seasonal availability of host plants and adult emergence from them were tracked. Six host plant species of D. suzukii were identified, some available season-long. Monitoring D. suzukii in cultivated crops is crucial for the timing of spray applications. Homemade and commercially available baits and traps were deployed in two vineyards to determine the efficacy and selectivity towards D. suzukii. The homemade and commercially available baits that contained red wine caught the most D. suzukii, but none were exclusively attractive to D. suzukii. Wine grape susceptibility was assessed in laboratory choice and no-choice ovipositional bioassays. Ovipositional susceptibility was determined by measuring the physiological and morphological parameters using six wine grape varieties. More eggs were laid in grapes as penetration force decreased. Penetration force and not skin thickness was the limiting factor for oviposition. Survivorship of eggs laid in intact grapes was analyzed and survivorship to adulthood was dependent upon variety and survivorship usually exceeded 9% survival seen in previous studies. Larval developmental parameters of D. suzukii were affected by grape variety and the density of Z. indianus. D. suzukii mortality was increased in most cases when in competition with Z. indianus, but was less pronounced when reared in Viognier grapes. My Z. indianus oviposition study demonstrated that they will follow injury created by D. suzukii, and then the Z. indianus larvae may outcompete D. suzukii within the berries. These studies greatly improved our understanding of D. suzukii biology and ecology in Virginia vineyards.