LOW-TEMPERATURE EFFECTS ON HATCH OF NORTHERN CORN-ROOTWORM EGGS (COLEOPTERA, CHRYSOMELIDAE)

This study determined the survival of northern corn rootworm eggs expo sed to different experimental low temperatures for up to 16 weeks. Egg s were obtained from adults collected in maize fields that had been in continuous maize for greater-than-or-equal-to 2 years. Eggs were plac ed in the field in September to simulate soil temperatures experienced by feral eggs. In November they were brought into the laboratory and subjected to temperatures of 0, -2.5, -5, -7.5, or -10-degrees-C for 2 to 16 weeks. Percent egg hatch following treatment declined as temper ature decreased and as duration of exposure at reduced temperature inc reased. This relationship was described by the equation HATCH = 42.70 - 5.51.TP + 5.67TM -0.54*(TP)2 - 0.26*(TM)2 + 0.42*TP*TM (r2 = 0.70), where TP and TM denote exposure temperature (C) and temperature durat ion (weeks), respectively.