Diversity & Flight Periods of Jewel Beetles (Coleoptera: Buprestidae) in Alabama: A Focus on the Chrysobothris femorata Species Complex and a Common Host, Red Maple (Acer rubrum)

Abstract

Flatheaded borers in the Chrysobothris femorata species complex are important pests of tree crops throughout North America. These taxonomically unresolved borers are common pests of hardwood trees and shrubs grown in nurseries. The larval stages grow and feed internally on their hosts, which leaves behind tunnels called galleries. Larval damage is difficult to manage, especially when it is virtually undetectable until adults emerge from their hosts. Furthermore, management would benefit from knowledge of specific visual and/or olfactory cues involved in host location and choice. Although borers belonging to the C. femorata complex are well established in Alabama, their geographical distributions and flight periods are not well documented. Additionally, there is virtually no information on how effective insecticides like imidacloprid work to protect hosts, as direct toxicity assays have not been conducted on larvae or adults. Because imidacloprid can positively impact plant growth and drought tolerance, it may be protecting hosts from C. femorata attacks indirectly. The first objective of this study addresses the distribution and phenology of species in Alabama. The flight activity was monitored using purple traps at three locations (Alpine, Auburn, Mobile) in 2021, 2022, and 2023. Trapping in 2021 yielded only 1 beetle from all sites. In 2022, we collected 8 species of Chrysobothris at traps statewide, most of which were recorded in Mobile from May to July. In 2023, 12 species of Chrysobothris were collected statewide, with most recorded in Auburn from April to July. The second objective of this study focuses on changes in host physiology in response to the effects of imidacloprid treatment and drought. Twenty four 5-gallon red maple (Acer rubrum) trees grouped into 6 replicates were assessed for physiological responses to four treatments (-Drought/-imidacloprid, +Drought/-imidacloprid, -Drought/+imidacloprid, +Drought/+imidacloprid) via nitrogen analysis, maple spider mite inoculation, and spectral reflectance tests. Overall, maple spider mite mortality and fecundity were not significantly impacted by treatments, however, survival of adult mites was significantly reduced at the end of mite trials in +Drought/-imidacloprid plants. Additionally, general mite populations seemed to follow a consistent trend, with significantly more eggs, immatures, and adults on trees treated with imidacloprid, regardless of drought.