Browsing by Author "Frank, Steven D."

Now showing 1 - 4 of 4
  • Thumbnail Image
    Biology, Ecology, and Management of Nonnative Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) in Ornamental Plant Nurseries
    Ranger, Christopher M.; Reding, Michael E.; Schultz, Peter B.; Oliver, Jason B.; Frank, Steven D.; Addesso, Karla M.; Chong, Juang Hong; Sampson, Blair J.; Werle, Christopher T.; Gill, Stanton; Krause, Charles (Entomological Society of America, 2016-01)
    Xylosandrus germanus (Blandford) and Xylosandrus crassiusculus (Motschulsky) (Coleoptera: Curculionidae: Scolytinae) are two of the most damaging nonnative ambrosia beetle pests in ornamental plant nurseries. Adult females tunnel into the stems and branches of host plants to create galleries with brood chambers. Hosts are infected with symbiotic Ambrosiella spp. fungi that serve as food for the larvae and adults. Plants can also become infected with secondary opportunistic pathogens, including Fusarium spp. Both X. germanus and X. crassiusculus have broad host ranges, and infestations can result in "toothpicks" of extruded chewed wood and sap flow associated with gallery entrances, canopy dieback, stem and trunk cankers, and plant death. Beetles efficiently locate and preferentially attack living, weakened plants, especially those physiologically stressed by flooding, inadequate drainage, frost injury, or winter injury and low temperature. Maintaining plant health is the foundation of a management plan. Vulnerable hosts can be partially protected with preventive pyrethroid applications in the spring before peak flight and attack, which are monitored using ethanol-based trapping tactics.
  • Thumbnail Image
    Flood Stress as a Technique to Assess Preventive Insecticide and Fungicide Treatments for Protecting Trees against Ambrosia Beetles
    Ranger, Christopher M.; Schultz, Peter B.; Reding, Michael E.; Frank, Steven D.; Palmquist, Debra E. (MDPI, 2016-08-18)
    Ambrosia beetles tunnel into the heartwood of trees where they cultivate and feed upon a symbiotic fungus. We assessed the effectiveness of flood stress for making Cercis canadensis L. and Cornus florida L. trees attractive to attack as part of insecticide and fungicide efficacy trials conducted in Ohio and Virginia. Since female ambrosia beetles will not begin ovipositing until their symbiotic fungus is established within the host, we also assessed pre-treatment of trees with permethrin, azoxystrobin, and potassium phosphite on fungal establishment and beetle colonization success. Permethrin reduced attacks on flooded trees, yet no attacks occurred on any of the non-flooded trees. Fewer galleries created within flooded trees pre-treated with permethrin, azoxystrobin, and potassium phosphite contained the purported symbiotic fungus; foundress’ eggs were only detected in flooded but untreated trees. While pre-treatment with permethrin, azoxystrobin, and potassium phosphite can disrupt colonization success, maintaining tree health continues to be the most effective and sustainable management strategy.
  • Thumbnail Image
    Freeze stress of deciduous trees induces attacks by opportunistic ambrosia beetles
    Ranger, Christopher M.; Schultz, Peter B.; Frank, Steven D.; Reding, Michael E. (2019-05)
    A broad host range and the utilization of living but weakened trees contribute, in part, to the invasion success of ambrosia beetles (Curculionidae: Scolytinae). The present study assessed the capability of freeze stress to induce attacks by ambrosia beetles. Freeze stress predisposed Cercis canadensis L., Cornus florida L., Malus pumila Mill. and Styrax japonicus Sieb. to attack under field conditions, although no attacks occurred on untreated trees. More attacks occurred on freeze-stressed versus flood-stressed M. pumila in Virginia but not for S. japonicus in Ohio. Attacks on flooded trees were skewed towards the base of the trunk, whereas attacks on freeze-stressed trees mainly occurred around the upper regions of the trunk and into the branches. The predominant species recovered were Anisandrus maiche Stark and Xylosandrus germanus (Blandford) in Ohio, and Xylosandrus crassiusculus (Motschulsky) in Virginia. Ethanol emissions from trunks of S. japonicus were detected by solid phase microextraction-gas chromatography-mass spectrometry at 1 day after imposing freeze stress, peaking 4 days after injury. Trees with an intolerance of freeze stress are predicted to be vulnerable to attack, especially when subjected to mild winter temperatures followed by late-spring freezes. Freeze stress could thereby facilitate the destructiveness of exotic ambrosia beetles.
  • Thumbnail Image
    Non-Native Ambrosia Beetles as Opportunistic Exploiters of Living but Weakened Trees
    Ranger, Christopher M.; Schultz, Peter B.; Frank, Steven D.; Chong, Juang H.; Reding, Michael E. (PLOS, 2015-07-02)
    Exotic Xylosandrus spp. ambrosia beetles established in non-native habitats have been associated with sudden and extensive attacks on a diverse range of living trees, but factors driving their shift from dying/dead hosts to living and healthy ones are not well understood. We sought to characterize the role of host physiological condition on preference and colonization by two invaders, Xylosandrus germanus and Xylosandrus crassiusculus. When given free-choice under field conditions among flooded and non-flooded deciduous tree species of varying intolerance to flooding, beetles attacked flood-intolerant tree species over more tolerant species within 3 days of initiating flood stress. In particular, flood-intolerant flowering dogwood (Cornus florida) sustained more attacks than flood-tolerant species, including silver maple (Acer saccharinum) and swamp white oak (Quercus bicolor). Ethanol, a key host-derived attractant, was detected at higher concentrations 3 days after initiating flooding within stems of flood intolerant species compared to tolerant and non-flooded species. A positive correlation was also detected between ethanol concentrations in stem tissue and cumulative ambrosia beetle attacks. When adult X. germanus and X. crassiusculus were confined with no-choice to stems of flood-stressed and non-flooded C. florida, more ejected sawdust resulting from tunneling activity was associated with the flood-stressed trees. Furthermore, living foundresses, eggs, larvae, and pupae were only detected within galleries created in stems of flood-stressed trees. Despite a capability to attack diverse tree genera, X. germanus and X. crassiusculus efficiently distinguished among varying host qualities and preferentially targeted trees based on their intolerance of flood stress. Non-flooded trees were not preferred or successfully colonized. This study demonstrates the host-selection strategy exhibited by X. germanus and X. crassiusculus in non-native habitats involves detection of stress-induced ethanol emission and early colonization of living but weakened trees.