Embryonic Diapause in Aulocara elliotti and Ageneotettix deorum (Orthoptera: Acrididae): Low-Temperature Relationships

Abstract

Controlled environmental chambers were used to determine the effect of constant low temperatures (0–18°C) on diapause termination of the eggs of Aulocara elliotti (Thomas) and Ageneotettix deorum (Scudder), species that require low temperatures for diapause termination. When eggs of A. elliotti and A. deorum were incubated at 30°C without low-temperature treatments, 6.1% of A. elliotti hatched after ≍36 d of incubation and 1.5% of A. deorum hatched after ≍46 d of incubation. Exposure times (days) to selected constant low temperatures ranged from 15 to 100 d. For both species, the greatest hatch at all low temperatures was induced with exposures of >60 d. Optimum conditions for diapause termination of A. elliotti were calculated to be between 75 and 98 d exposure to 6.6–8°C. Optimum conditions for diapause termination of A. deorum were calculated to be between 75 and 77 d exposure to 7–8.6°C. These studies provide insight about the univoltinism of these insects and offer evidence that with these species, embryonic diapause terminates before the prolonged subfreezing temperatures of winter.