Electronic Thesis and Dissertation Repository


Master of Science




Dr. Brent J. Sinclair


Many insects are able to survive internal ice formation. However, the mechanisms underlying freeze tolerance are not well-understood, perhaps because of a lack of suitable model organisms. I found that the spring field cricket, Gryllus veletis, seasonally acquires freeze tolerance in the fall when kept outside in London, Ontario. Moreover, individuals acquired freeze tolerance in the laboratory in response to a simulated fall thermophotoperiod. Lab-acclimated G. veletis freeze at -6.1 ± 0.7 ºC and the acquisition of freeze tolerance is accompanied by the accumulation of proline and trehalose. Crickets survived temperatures as low as -12 ºC (1.5 h), and for one week at -8 °C. Lab-acclimated crickets were more cold-hardy than field-acclimatized crickets, with higher survival at both -12 ºC and after one week at -8 °C. Gryllus veletis is a suitable candidate for further investigating freeze tolerance because it is easily reared and manipulated in a controlled laboratory environment.