2012 Annual Report
1a.Objectives (from AD-416):
#1: Develop improved techniques for managing scarabs and ambrosia beetles in nurseries by determining the biology and ecology of exotic scarabs and ambrosia beetles in relation to the nursery ecosystem, the response of nursery crops to root herbivory by exotic scarabs and potential relationship to attacks by ambrosia beetles, and by examining interactions between exotic ambrosia beetles and the nursery ecosystem including factors leading to attacks on nursery trees by ambrosia beetles, especially as it relates to abiotic and biotic stress.
#2: Evaluate sustainable, environmentally-friendly alternatives to conventional insecticides, including reduced-risk chemicals, microbial products, and botanical extracts for control of ambrosia beetles and scarabs.
#3: Develop new application methods and strategies for ambrosia beetle and scarab control and to prevent their distribution to uninfested parts of the United States and abroad.
1b.Approach (from AD-416):
The development and survival of Anomala orientalis (oriental beetle, OB) larvae will be evaluated on a variety of woody ornamental species. The relationship between constitutive and induced defensive compounds in the roots, along with total carbon and nitrogen levels, and development and survival of OB will be determined. OB larvae have caused considerable damage to trees and shrubs in ornamental nurseries and in production of small fruits such as blueberries and cranberries. Despite the damage this species causes in woody nursery and small fruit crops, there has been very little research evaluating trees and shrubs as hosts for OB. Species and varieties of trees and shrubs that are poor or marginal hosts would either not need protection from OB or acceptable levels of protection might be achieved by lower rates of insecticides.
Data will be analyzed each season and adjustments will be made to experimental design if necessary. If we identify species that are especially good or poor hosts for OB, we will conduct additional testing on varieties within those species and closely related species to see if their quality as hosts is similar (good or poor). This information will be used to identify suites of characteristics (chemical compounds, nutritional, etc.) that make a woody plant a viable host for larval OB. This data could then be used by plant breeders to develop varieties resistant to OB.
In 2012, we continued research projects on interactions of oriental beetle larvae (invasive scarab) and ornamental nursery crops as hosts; growth-response of nursery trees to root-herbivory by scarab larvae; monitoring ambrosia beetles with ethanol-baited traps and ethanol-injected trap trees; evaluating response of ambrosia beetles to different tree species injected with ethanol; optimizing an odor-based trap-tree tactic for inducing attacks on trees by ambrosia beetles; evaluating synergism between ethanol in injected trees and volatiles emitted from those trees; identifying host-derived volatile cues used by Xylosandrus germanus to locate hosts; determining the influence of water-stress on tree attractiveness and susceptibility to ambrosia beetles; screening for compounds that act in synergism with ethanol for attracting ambrosia beetles; characterizing the spatial distribution of trees attacked by ambrosia beetles within ornamental nurseries. The previous activities are primarily related to Objective-1 of the project plan with some relative to Objective-3. Research was also conducted on evaluating verbenone as a repellent to ambrosia beetles in the field; and testing insecticides and entomopathogens for control of ambrosia beetles. Those projects are related to Objectives-2 and -3 of the project plan.
Ambrosia beetle responses to volatile emissions from ethanol-injected sweetbay magnolia. The responses of ambrosia beetles to ethanol-injected trees and bolts (stem sections) from injected trees were determined to develop a reliable monitoring system. Traps baited with bolts from injected trees were more attractive than traps baited with ethanol. Trees injected with ethanol were more attractive than trees drenched or baited with ethanol. The results show that ethanol-injected trees can aid monitoring of ambrosia beetles flight and attack activity in nurseries which will help growers synchronize their control treatments with ambrosia beetle activity and thus improve management of these pests.
Evaluating insecticides for preventing attacks by ambrosia beetles in nurseries. Xylosandrus crassiusculus and Xylosandrus germanus are the most problematic ambrosia beetles in ornamental nurseries in the Northeastern, Midwestern, Atlantic, and Southeastern states. The ethanol-injection technique we developed enabled us to conduct more realistic evaluations of insecticides against ambrosia beetles on nursery trees by attracting sufficient numbers of beetles to our experimental trees. Conventional and reduced-risk insecticides were evaluated as control agents against these species. Two conventional insecticides were the most effective, however, botanical formulations were also promising control agents. These materials were previously untested against the above ambrosia beetle species on nursery trees. Research involving water stress of trees revealed that physiologically-stressed trees are preferred for colonization. The research revealed that keeping trees as healthy as possible is an important component for managing ambrosia beetles. Especially stressed trees could not be protected by any of the tested materials.
Ranger, C.M., Reding, M.E., Oliver, J., Schultz, P., Moyseenko, J.J., Youssef, N. 2011. Comparative efficacy of plant-derived essential oils for managing Ambrosia beetles (Coleoptera: Curculionidae: Scolytiniae) and their corresponding mass spectral characterization. Journal of Economic Entomology. 104(5):1665-1674.
Reding, M.E., Schultz, P.B., Ranger, C.M., Oliver, J.B. 2011. Optimizing ethanol-baited traps for monitoring damaging ambrosia beetles (Coleoptera: Curculionidae, Scolytinae) in ornamental nurseries. Journal of Economic Entomology. 104:2017-2024.
Ranger, C.M., Reding, M.E., Schultz, P., Oliver, J. 2012. Ambrosia beetle (Coleoptera: Curculionidae) responses to volatile emissions associated with ethanol-injected Magnolia virginiana L. Environmental Entomology. 41(3):636-647.
Ranger, C.M., Reding, M.E., Schultz, P., Oliver, J. 2012. Influence of flood-stress on ambrosia beetle host-selection and implications for their management in a changing climate. Agricultural and Forest Entomology. DOI: 10.1111/j.1461-9563.2012.00591.x.