|GOBLE, TARRYN - Cornell University - New York|
|HAJEK, ANN - Cornell University - New York|
|GARDESCU, SANA - Cornell University - New York|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2015
Publication Date: 3/2/2015
Publication URL: http://handle.nal.usda.gov/10113/62367
Citation: Goble, T.A., Hajek, A.E., Jackson, M.A., Gardescu, S. 2015. Microsclerotia of Metarhizium brunneum F52 applied in hydromulch for control of Asian longhorned beetles (Coleoptera: Cerambycidae). Journal of Economic Entomology. 108(2):433-443. DOI: http://dx.doi.org/10.1093/jee/tov013.
Interpretive Summary: The Asian longhorned beetle (ALB) is an introduced insect pest of numerous trees including maple, birch, chestnut and poplar trees. Trees infested with ALB larvae eventually die due to the larvae’s habit of feeding on the bark of the tree, eventually girdling the tree. The insect-killing fungus Metarhizium brunneum (Mb) produces spores that can infect and kill the ALB. We have developed a method for mass-producing a stable, dry granular form of Mb that produces infective spores when rehydrated. In this study, we evaluated the use of hydromulch, a straw-based sprayable material used in the grass seeding industry to stick Mb granules to tree trunks. The application of hydromulch containing Mb granules to trees provided sufficient moisture so that the Mb granules could rehydrate and produce spores. Initial results suggest that a sprayable hydromulch – Mb granule formulation has potential for delivering this bioinsecticide onto trees for control of the ALB. The development of an effective management tool for ALB will benefit landowners, forest managers, and urban pest control operators by providing a safe, non-chemical control tool for this invasive insect pest.
Technical Abstract: The entomopathogenic fungus Metarhizium brunneum (Petch), strain F52 (Hypocreales: Clavicipitaceae) is able to produce environmentally persistent microsclerotia. Incorporating these desiccation-tolerant M. brunneum F52 microsclerotia (Mb MS) granules into hydromulch [a mixture of water + wheat straw mulch + psyllium tackifier], may represent a novel, easy-to-use and environmentally-friendly mycoinsecticide that can be sprayed onto the trunks of forest or orchard trees to control insect pests. The premise is that hydromulch holds moisture that provides more time for Mb MS to germinate and produce conidia. We tested this formulation against Asian longhorned beetle adults, Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae). To test how quickly beetles could be killed, moist and dry bark pieces or filter paper were sprayed with a low dose (~9 Mb MS/cm2) of Mb MS-containing hydromulch. Median survival times of beetles exposed to moist bark and filter paper were 17.5 d and 19.5 d, respectively. Beetles exposed to dry bark, which had a lower measured water activity compared to the aforementioned substrates, died significantly slower but median survival time was significantly different from the untreated control. In an attempt to kill beetles faster, moist bark pieces were sprayed with one of three doses of Mb MS-containing hydromulch: low (6-9 Mb MS/cm2); medium (10-19 Mb MS/cm2) and high (20-30 Mb MS/cm2). At high doses, 50% of beetles died in 12.5 d but at lower doses time to death was significantly longer (16.5 d-17.5 d). Mb MS-containing hydromulch sprayed onto striped maple bolts could reduce the overall fecundity of beetles compared with controls. In a two week oviposition period, total beetle fecundity was highest in high-humidity controls in which females produced 18.3 viable offspring compared to 3.9 viable offspring for beetles exposed to Mb MS-containing hydromulch at high humidity. Fecundity in the high-humidity hydromulch treatment however, was not significantly different from the low-humidity Mb MS-containing hydromulch treatment (6.6 viable offspring) or its associated control (8.8 viable offspring). This paper represents the first evaluation of the arboreal application of Mb MS formulated within hydromulch.