Polar vortex and EAB
The unusually cold temperatures over the past several weeks generated many inquiries from the public about the cold tolerance of the Emerald Ash Borer and Oak Leaf Itch Mite.
Many have also asked if a significant amount of mortality of these arthropods will be experienced throughout Kansas as a result of these cold temperatures.
The answer to these inquiries depends upon the length of time lethal temperatures are experienced during a particular life stage of the arthropod. Like many insects, EAB can accumulate the anti-freezing agent, glycerol, that helps it survive freezing temperatures (Crosthwaite et al., 2011). EAB will overwinter as larvae and pre-pupae, both of which can easily survive temperatures under 0OF (Venette and Abrahamson, 2010) and the unusually cold temperatures recently experienced.
The majority of EAB overwinter as pre-pupae, which will freeze around -22OF (Crosthwaite et al., 2011) and according to Venette and Abrahamson (2010) EAB larval mortality steadily increases as the temperatures decrease until approximately 98% can be expected to die when temperatures reach -30OF.
The temperatures experienced across Kansas over the past several weeks were not nearly low enough or of a long enough duration to significantly impact the populations of either arthropod. Some EAB mortality might be experienced in the states north of Kansas where temperatures will drop much lower than those experienced in Kansas; however, EAB will simply refill those vacancies and recolonize those areas in subsequent years.
What it really boils (or freezes) down to is that the cold temperatures from the polar vortex are not a significant source of mortality for EAB or OLIM in Kansas.
Crosthwaite, J.C., Sobek, S., Lyons, D.B., Bernards, M.A. and Sinclair, B.J., 2011. The overwintering physiology of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). Journal of Insect Physiology, 57(1), pp.166-173.
Venette, R.C. and Abrahamson, M., 2010, May. Cold hardiness of emerald ash borer, Agrilus planipennis: a new perspective. In Black ash symposium: proceedings of the meeting (pp. 25-27).