Progress 09/01/16 to 09/30/17
Outputs
Target Audience: US Forest Service research and forest health protection entomologists. Other federal state and local governmental agency forest land managers Private land managers Private pesticide application companies Potential investors in Montana BioAgriculture Inc. Changes/Problems:Results were promising with one compound in particular showing boring deterrence in both Ips pini and spruce beetle. However, the project was hampered by limited supply of beetle for both the Ips and spruce beetle work. We were unable to conduct enough log bolt assys for definitive results. Unseasonable heavy rains in Arizona affected Ips pini populations and availability for testing. Spruce beetle infested spruce logs collected from the field and held for later emergence of adult beetles produced were affected by abnormally war fall in 2016 which limited cold diapause required for adult development. These logs produced very few beetles. The project used field collected spruce beetles shipped from Utah to Montana. Beetles are stressed with resulting high mortality in controls. What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest?In addition to conference presentations MBAI has engaged in continuing discussions of forestry mycoinsecticide development with: USFS research and Forest Health Protections entomologists in the Western US Other USFS personnel Entomologists in State Forestry agencies Collaborators at Northern Arizona University, Colorado State University and the University of Montana Managers potential customers at several ski resorts What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Accomplishments Phase 1 proof of concept; selection of one or more compounds that deter boring behavior of spruce beetle and or pine engraver and which have commercial potential for enhancing efficacy of a mycoinsecticide. Phase 1 met objectives of selecting one or more compounds which delayed boring of spruce beetle and Ips pini. The most promising of the 19 compounds tested would be compatible with B. bassiana application. Compounds: did not affect spores at effective concentrations, were miscible in water or ethanol/water solution, are commercially available and would not pose significant regulatory issues. Results for each objective and task are summarized below. Compounds were first screened in a bark disc bioassay, beetles place on treated discs cut from fresh logs and observed for time to bore through the disc. Compounds which delayed boring for at least 48 hours compared to controls were selected for log bolt bioassays, compounds combined with B. bassiana spores applied to fresh log bolts, placed in a screen cage with beetles released onto the bolt. Assay assessed for beetle mortality outside and inside of bolt and length of tunneling in treatments compared to B. bassiana alone and untreated controls. Results Objective 1 Deter boring Ips pini Three sets of bark disc assays were conducted at the Hofstetter Lab Northern Arizona University per contract subaward. These showed promising results with three of the 19 compounds screened, two showing a majority of beetles remaining on top of the disc at 48 hours and the third 30% at 24 hours in experiments where controls had all bored at less than 24 hours. The three compounds were tested in combination with the most virulent of the conifer Beauveria isolates strain 14B in log bolt assays. Assays also included a new Beauveria labelled strain labeled as 447 isolated from infected spruce beetle larvae in galleries of a spruce log. Bolts were sprayed with dilutions of spores mixed with compound at a spore concentration to deliver an approximate mid-range beetle mortality mixed with compounds at concentrations found effective in disc assay. Results from one assay shown in table 3 below, are expressed as percentage of beetles deterred that is remaining outside of the log bolt at 48 hours and the percentage of beetles which attacked or bored into the bolt. In the first bolt assay an attempt was made to peel logs and soccer for dead and live beetles under the bark. This technique works well for spruce log bolts as discussed in task 2. However, ponderosa bolts collected from the NAU experimental forest proved very difficult to peel and that peeling damaged a variable number of beetles in each bolt. These assays were inconclusive showing no significant difference between treatments and controls. A final bolt assay testing combinations of selected compounds with B. bassiana for Ips pini was set up at the NAU lab in October. These will be held for approximately sixty days and monitored for beetle reproduction by counting emerging adults. Objective 2 Deter boring of spruce beetle MBAI conducted spruce beetle assays at the company's lab in Montana with beetles from summer collections and supplied by the USFS region 4 and later from fall collected beetles. Very few beetles were obtained from beetle infested logs collected in the fall and held in the cold. comparing efficacy of the fungal pathogen strain alone and in combination with the most effective boring deterrent compounds. Multiple sets of compound disc assay screens were conducted. Control mortality in disc assays was high, however from repeated tests six compounds showed delayed boring and were selected for log bolt assays. Control mortality in transported beetles was again high in bolt assys, the best results are shown in table 4 below. In these assays duplicate log bolts were used for each treatment. B. bassiana strain 14B was used at a dose rate from previous bioassays targeting about 50% mortality. Compounds were diluted into spore suspensions at concentrations determined from disc assays. Twenty beetles without sorting for male and female were released onto each bolt. Log bolts we processed at 7 days post treatment with counts of: dead beetles outside if log (dd out), dead beetles inside log (dd in), live beetles inside (lv in), the length of bore tracks (cm) total number of beetles collected, total number of beetles collected, 5 dead in each bolt, total % dead in both bolts and % of dead beetles with infection confirmed by B. bassiana sporulation on cadavers placed in humidity. Table 4, Spruce beetle log bolt Beauveria compound boring deterrence bioassay dd out dd in liv in Bore length cm Total beetles % dead Total % dead % spore Control 1 5 2 10 59 17 41 48 11 Control 2 6 3 7 31 16 56 14B 1 5 7 6 78 18 67 61 54 14B 2 8 2 8 62 18 56 MD 1 9 2 5 29 16 69 82 67 MD 2 9 8/2sp 1 31 18 94 CT 1 4 3/2sp 9 63 16 44 50 46 CT 2 1 9/1sp 8 77 18 56 CN 1 8 3 4 15 73 61 55 CN 2 2 6/3sp 8 49 16 50 GE 1 4 8/1sp 6 92 18 67 59 59 GE 2 8 0 8 42 16 50 HX 10 4 5 19 74 53 39 447 1 5 5 6 51 16 63 59 31 447 2 6/1live 3 7 54 16 50 Control mortality was high however Beauveria infection in controls was limited and much less than in treatments. Variability between duplicate bolts was also high however limited numbers of beetles limited the number of replications for each treatment. Mortality with strain 14B without compound was 61% with 54% confirmed infection. Strain 14B plus compound MD was promising. This combination had the highest mortality, the highest mortality of beetles outside of the log, highest percentage of confirmed infection, and shortest length of bore track where this could be measured. This experiment was repeated with fall 2017 collected beetles however control mortalities were too high to obtain a result. Compound MD was one of the most effective with Ips pini disc assays. Objective 3 Compounds are compatible with Beauveria Deterrent compounds may be mixed with fungal pathogen spores in formulations or mixed in water at the time of application. Tests for effects of compound on spore viability were conducted to replicate spray tank mix of water, spores and compound at concentrations anticipated for field trials with 4 hours exposure. Compounds which delayed boring of either beetle species did not affect B. bassiana spore viability. Objective 4 Compounds can be applied in water solution or emulsion Effective compounds were found miscible in water or ethanol in water. At concentrations tested compounds dissolved in ethanol would remain miscible when ethanol solution was mixed on water for application. Objective 5 Compounds are available in commercially feasible supply from fermentation or from commercial sources Compounds showing boring deterrence are available from commercial sources as fragrances, flavorings, synthetic intermediate or solvents. Economics appear favorable; amounts applied to trees would be very small. The dose rate used in the spruce beetle bolt assay would apply 40 to 60mg of compound to a large spruce tree. Objective 6 Compounds Have no obvious barriers to EPA approval as a formulation adjuvant or registration as a semiochemical EPA may regulate a selected deterrent compound as either a formulation adjuvant or as a semiochemical requiring registration as a biochemical agent. Compounds showing boring deterrence in bioassays are not registered with EPA as pesticides or pesticide formulation additives. Approval from EPA as tank mix additive would be necessary. In addition, use on public lands by the US Forest Service or other agencies would be subject to approval. However, such approvals should not require any toxicology studies or other data requirements. All of the effective compounds have commercial uses with human exposure and approvals of such uses by EPA and or FDA.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2017
Citation:
Bradley, C.; Malesky D.; Davis, S.; Jankowski, E.; Bradley, J. Spruce beetle mycoinsecticide. Western Forest Insect Work Conference, May 2017 Jackson Wyoming
Thomas Seth Davis1*, Danielle Malesky2, Andrew J. Mann1, and Clifford Bradley3Laboratory and field evaluation of the entomopathogenic fungus Beauvaria bassiana for population suppression of spruce beetle, Dendroctonus rufipennis Kirby (Coleoptera: Scolytinae). Environmental Entomology In press
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