Influence of subzero thermal shocks on survival of Leptinotarsa decemlineata
In Wisconsin, US, experiments were carried out to investigate the survival of Leptinotarsa decemlineata (EPPO A2 pest) after exposure to subzero shocks during diapause. Adult beetles were collected from fields and then subjected to controlled environmental conditions which simulated a diapause period. Groups of the Colorado beetles were then subjected to cold shocks of -4ø, -6ø, -8ø, -10ø and -12ø C lasting 4, 6, 8, 10 and 12 h, respectively. It was found that the survival of Colorado beetles decreased dramatically following cold shocks ; -4ø C. (a) Based on these results further experiments were conducted to investigate the possibility enhancing the overwintering mortality of Colorado beetles by manipulating the temperatures of its diapause habitat. Field plots received an artificially mulched trap crop to provide a late-season food source to arrest adult dispersal and a suitable, protected overwintering site to retain beetles in the trap crop area. During an extrem cold front the mulch was removed from the plot and subsequently the temperatures in the soil dropped drastically. Consequently, the survival of Colorado beetles significantly decreased in the disturbed habitats. (b)
(a) Kung, K-J.S.; Milner, M.; Wyman, J.A.; Feldman, J.; Nordheim, E. (1992) Survival of Colorado potato beetle (Coleoptera: Chrysomelidae) after exposure to subzero thermal shocks during diapause.
Journal of Economic Entomology ;85, ;1695-1700.
(b) Milner, M.; Kung, K-J.S.; Wyman, J.A.; Feldman, J.; Nordheim, E. (1992) Enhancing overwintering mortality of Colorado potato beetle (Coleoptera: Chrysomelidae) by manipulating the temperature of its diapause habitat.
Journal of Economic Entomology 85, 1701-1708.