What happens to Mimic after it is sprayed?

First, Mimic (tebufenozide) is added to water and mixed. This mixture is then aerially applied at a rate of 1 to 2 litres per hectare. The Mimic portion of this mixture is fixed at 290 ml per hectare; this is less than the contents of a can of soda pop. Nozzles on the aircraft break the liquid mixture into small droplets (atomize) so that when the drops land on foliage they are small enough to be eaten by spruce budworm.  The research areas designated for Mimic require one spray treatment only, unlike Btk which usually require two.

The upper canopy of the forest is where the spruce budworm is most commonly found therefore, it is also the best location for droplets to be deposited. Because the forest canopy acts as a filter; few droplets reach the ground. Research conducted by the Canadian Forest Service has shown that 90 to 95% of the spray is deposited in the forest canopy (Kreutzweiser & Nicholson, 2007). The portion that reaches the ground stays in the upper 5 cm (2 inches) of the soil and leafy debris and does not leach away. It is broken down over time by soil microbes, sunlight, and moisture (Sundaram, 1997), (Thompson & Kreutzweiser, 2007). Research has also shown that any Mimic that reaches the ground is not harmful to soil invertebrates (Addison, 1996).

Mimic deposited on the shoots and needles of the spruce and fir trees is eaten by the budworm larvae. The larvae stop feeding almost immediately and die within a day or two. Mimic deposited in the canopy is relatively rainfast and is not easily washed off by rainfall (Sundaram, 1995).

Water bodies are identified on maps and are excluded from all treatment areas during the planning phase:  there is no targeting of visible water bodies. Based on research conducted by the Canadian Forest Service, Mimic that lands on water has no noticeable environmental impact. Research scientists have studied the effects of tebufenozide on aquatic invertebrates and found that there were no significant harmful effects on most organisms at concentrations expected after aerial spraying: even if a water body were to be unintentionally sprayed (Kreutzweiser & Nicholson, 2007. Kreutzweiser et. al. 1994; 1998).

The most recent review of tebufenozide states that ‘No adverse effects on birds, mammals or aquatic species are likely to occur from exposure to tebufenozide (US Department of Agriculture, 2012).

References:

Addison, J.A. 1996. Safety testing of tebufenozide, a new molt-inducing insecticide for effects on non-target forest soil invertebrates Ecotoxicological Environmental Safety 33, 55-61.

Kreutzweiser, D, and Nicholson, C. 2007. A Simple Empirical Model to Predict Forest Insecticide Ground-Level Deposition from a Compendium of Field Data. Natural Resources Canada, Sault Ste. Marie Ontario Canada P6A5M7. In Journal of Environmental Sciences & Health Part B, V 42, pg. 107-113. USA.

Kreutzweiser, D., Capell S., Wainio-Keizer K., and Eichenberg, D. 1994. Toxicity of new molt inducing insecticide (RH-5992) to aquatic macroinvertebrates. Ecotoxicological Environmental Safety 28, 14-24.

Kreutzweiser, D.P., Gunn, J.M., Thompson, D.G., Pollard, H.G., and Faber, M.J. 1998. Zooplankton community responses to a novel forest insecticide, tebufenozide (RH-5992), in littoral lake enclosures. Canadian Journal of Fisheries and Aquatic Sciences 55:639-648.

Sundaram, K.M.S. 1997. Persistence & Mobility of Tebufenozide in Forest Litter and Soil Ecosystems under Field and Laboratory Conditions, Natural Resources Canada, Sault Ste. Marie Ontario Canada P6A5M7 in Pesticide Science V 51, 115-130. UK.

Thompson, D., and Kreutzweiser, D. 2007. A Review of the Environmental Fate and Effects of Natural ‘Reduced Risk’ Pesticides in Canada. In K.D. Racke and A. Felsot (editors), Crop Protection Products for Organic Agriculture: Environmental, Health, and Efficacy Assessment, ACS Books, American Chemical Society, Washington. pp 245-274.

Sundaram, K.M.S. 1995. Photostability & Rainfastness of Tebufenozide Deposits of Fir Foliage.  Natural Resources Canada, Sault Ste. Marie Ontario Canada P6A5M7. In American Chemical Society, 0097-6156/95/0595-034. USA.

US Department of Agriculture - Forest Service. 2012. Gypsy Moth Management in the United States: A Cooperative Approach. Final Supplementary Environmental Impact Statement V 1, pg. 11. USA.

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