Lopholeucaspis japonica (Cockerell) (Hemiptera: Diaspididae), commonly known as Japanese maple scale (JMS), is an invasive pest established in the United States in 1914. Over the past decade, JMS infestations have escalated, posing a significant threat to the nursery industry, and resulting in economic losses from unsellable infested plants. The limited understanding of JMS hampers the development of effective management strategies, intensifying the financial impact of this destructive pest. To contribute to the development of a sustainable pest management program, it is crucial to acquire knowledge of JMS's natural history, biology, and dispersal capabilities. Management costs can be reduced by determining the optimal timing for scouting and spraying through peak crawler emergence and the identification of overwintering life stages. Understanding JMS dispersal patterns within tree canopies can lead to the refinement of scouting methods, such as strategically placing the tape method (for monitoring crawlers). A two-year study took place at two separate locations and on boxwoods (2022-2023) and red maples (2023). Our phenology findings indicated that there were two generations and prolonged crawler presence which can extend over a period of 34 weeks (March-October) during the growing season. The first generation of crawler emergence on boxwoods started as early as the second week of March [110-114 Growing Degree Days in base 50°F (GDD50)], with the first peak occurring in mid-June [1179-1514 GDD50]. The second generation depending on the year began in July and peaked between early September and mid-August due to overlapping from prolonged presence of crawlers. Crawler emergence on maples indicated the first peak during the second week of July, followed by the second peak during the third week of August. Management practices, including monitoring and chemical control and based on phenology data, could be suggested to begin early March and continue throughout the season putting high pressure on crawlers during the peaks of activity. Overwintering studies from this project suggested JMS could be developing throughout winter with immatures found in January and February while in March the highest population was adults. Using horticultural oil during the winter months may help with JMS infestations. To investigate dispersal patterns, the canopy of experimental plants of maples and boxwoods were divided into top, middle, and bottom sections based on plant height. Comparative analysis of JMS crawler densities within the canopies of maples indicated that the middle canopy sections exhibited higher crawler densities compared to the top sections. However, when evaluating all three sections (top, middle, and bottom), the bottom sections displayed the highest crawler densities. Examination of cardinal points within the top and middle canopies of maples revealed a widespread distribution pattern. In contrast, no significant differences in crawler densities were observed between the various canopy sections of boxwoods, indicating a uniform distribution across the plant. / Master of Science in Life Sciences / Japanese maple scale (JMS), scientifically known as Lopholeucaspis japonica, is an invasive pest damaging ornamental plants in the United States since 1914, particularly affecting the nursery industry in the Southeast, including Virginia. This study aimed to enhance the understanding of JMS phenology, overwintering biology, and dispersal patterns. A two-year study took place at two separate locations and on boxwoods (2022-2023) and maples (2023). Phenology and dispersal patterns were monitored using the tape method to count crawlers per cm². Over two years, 100 JMS specimens were inspected monthly for three consecutive winter months to record overwintering life stages. Across both years and crops there were two peaks of activity with the first peak being between June and July and the second falling in between August and September. For overwintering, higher numbers of JMS immatures were found in January and February, and adults in March. To investigate dispersal patterns, the canopy of experimental plants of maples and boxwoods were divided into top, middle, and bottom sections based on plant height. Comparing JMS crawler densities in maples between the top and middle canopy sections revealed higher densities in the middle. However, when all three sections in maples were compared, the bottom had the highest density of crawlers. Cardinal points within the top and middle canopies were investigated for maples only and showed a widespread distribution when examining those points. For boxwoods, no significant difference was found in crawler densities between plant sections. This knowledge will empower nursery growers to make informed decisions, optimize their efforts in monitoring and control, and minimize the economic impact caused by JMS infestations.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/119277 |
| Date | 04 June 2024 |
| Creators | Wyatt, Mollie McDonnell |
| Contributors | Entomology, Del Pozo-Valdivia, Alejandro, Kuhar, Thomas P., Kring, Timothy Joseph, Kunkel, Brian |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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