Arboriculture & Urban Forestry 34(3): May 2008 47.27 to 79.45 ipsm, whereas the control group MED was 55.15 ipsm. The statistical analysis showed that only the Preventol treat- ments produced significant reductions in MED from treated logs (P0.0154). The borate dip treatment (P0.4863) and borate spray treatment (P0.7972) failed to produce statistically sig- nificant effects. Dunnett’s procedure showed that the MED of logs treated with Preventol solution concentrations of 0.01% and 0.02% were significantly different from the control, whereas the two lower concentrations were not. Figure 3 presents a side-by-side comparison of the indoor and outdoor rearing methods for each treatment. The figure shows that indoor rearing consistently produced higher reductions in MED compared with the corresponding outdoor treatments. When statistical tests were applied to the data, the borate dip (P < 0.0001) and borate spray (P0.0017) treatments showed that indoor rearing resulted in emergence levels that were sig- nificantly lower than those of outdoor rearing. The Preventol treatment test produced a P value of 0.1597. These are the ex- pected results considering the solubility of the two substances. We believe these data strongly support our hypothesis that ex- posure to rainfall and sunlight decreases the effectiveness of chemical log treatments. Protection against the weather is there- fore strongly recommended if any insecticide treatment applied to the bark is considered for sanitization. In a previous study, it was observed that a number EAB adults died while emerging from treated logs (Nzokou et al. 2006), suggesting that ingestion of the chemicals while burrowing out of the wood may be partially responsible for the insect mortality in both insecticides used. This phenomenon may have contrib- uted to the reduction in effectiveness of the outdoor rearing trials. If the chemicals are washed out or diluted by rain, higher MED values would be expected. A potential improvement could be to adjust the timing of applications to decrease the time gap between application and emergence. Repeated applications throughout the emergence period could be an improvement as well but would have the drawback of increasing labor and ma- terial costs. Another option that might increase the effectiveness of the chemical treatments is using a carrier that works as a bark penetrant. This way it may be possible to reach all larvae in the cambium and outer sapwood forgoing the need to depend on the residual chemical remaining in the outer bark. This may also increase the level of chemicals in the bark and increase the mortality resulting from ingestion while exiting. In a previous study, a surfactant, Pentra, was used for this purpose and was shown to significantly increase imidacloprid residue in xylem sap (Cappaert et al. 2004b). Survival Longevity Table 3 displays the survival longevity data collected. Preven- tol failed to cause significant reductions in the survival longev- ity of adult EAB once they had emerged (P 0.5261). The borate spray treatment, on the other hand, seemed to result in a noticeable and highly significant result (P < 0.0001), indicating that borate chemicals applied to larval EAB may have a lasting effect on the vigor and health of surviving adults. The Tukey- Kramer test found that all concentrations used except the second highest, 10% BAE, were significantly different from the control. This experiment was not set up to thoroughly study the chemi- cal’s effects on surviving adults. Survival data could not be gathered from logs reared outdoors for comparison. The data 177 Table 3. Survival longevity of adult Emerald Ash Borers (with standard errors in parentheses), in number of days, after emerging from logs treated chemically to eliminate infestation.z Treatment Preventol Concentration Sample size Control 0.005% 0.008% 0.01% 0.02% Borate spray Control 5% (6.2%)y 8% (9.6%) 10% (12.5%) 31 0 5 0 0 34 23 16 3 16.5% (20.8%) 6 cance level of 0.017 are marked with an asterisk (*). y Mean survival period (no. of days) 10.55 (1.06) — 8.80 (1.62) — — 10.76 (0.82) 4.74 (0.56)* 6.69 (0.86)* 7.00 (0.82) 3.67 (1.56)* zMean survival periods that are significantly lower than their control at a signifi- Borate spray concentrations displayed as percent boric acid equivalent with per- cent disodium octoborate tetrahydrate in parentheses. presented here indicate a potential effect and needs to be inves- tigated further before any conclusions can be made. CONCLUSIONS Borate and imidacloprid formulations were tested for the saniti- zation of logs infested by the EAB. Results obtained confirmed previous findings that a technical grade of imidacloprid insecti- cide (Preventol) is a very effective chemical treatment for the sanitization of EAB-infested logs. However, Results suggest that solution concentrations above 0.02% by weight are required. Levels of 0.04% and 0.05% are suggested to allow for a safety factor. Borate treatments at concentrations up to 16.5% BAE were not successful in controlling EAB. Results also showed that treating logs and subsequently rearing them outdoors results in reduced effectiveness for all chemical treatments used, indicat- ing that treated logs will have to be protected against rainfall when chemicals are used by applying them to the bark. Acknowledgments. This research project was funded by a grant from the USDA Forest Service, Wood Education & Resource Center through the Southeast Michigan Research and Development Council (SEMIRCD). We acknowledge support from the Michigan Department of Natural Resources and the Department of Forestry at Michigan State University. LITERATURE CITED Anonymous. 2004. Tim-bor Professional. Material Safety Data Sheet. The Nisus Corp., Rockford, TN. 1 pp. Bauer, L.S., R.A. Haack, D.L. Miller, T.R. Petrice, and L. Houping. 2003. Emerald Ash Borer life cycle. In Masto, V., and R. Reardon (Eds.). Proceeding of the Emerald Ash Borer Research and Technol- ogy Development Meeting. FHTET-2004-02, USDA USFS APHIS, Morgantown, WV. Cappaert, D.L., D.G. McCullough, and T.M. Poland. 2004a. Emerald Ash Borer life cycle: A reassessment. In Masto, V., and R. Reardon (Eds.). Proceeding of the Emerald Ash Borer Research and Technol- ogy Development Meeting. FHTET-2004-16, USDA USFS APHIS, Morgantown, WV. Cappaert, D.L., D.G. McCullough, T.M. Poland, and L.P. Molongoski. 2004b. Non-invasive neonicotinoids: Treatments for ash logs and trees. In Masto, V., and R. Reardon (Eds.). Proceeding of the Emerald ©2008 International Society of Arboriculture
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