Diapause Termination, Developmental Threshold and Thermal Requirements of Eggs of the Maple Aphid, Periphyllus californiensis Shinji

Abstract

The lower developmental threshold and thermal requirements for egg hatch of the maple aphid (Periphyllus californiensis) were estimated to be 4.58°C and 94.48 degree-days. Eggs of the maple aphid appear to have obligatory diapause and chilling seems essential for diapause development. No matter whether eggs in diapause were treated with 2°C chilling or placed in the field, at least 35 to 41 days were required for the first egg to terminate diapause. The time of egg hatch lasted for about a month or even longer. This long period of time in egg hatch may be related to the restricted period that food is available in early spring and the long period of budburst of host plants.

Key words:

• developmental threshold
• diapause
• egg hatch
• Periphyllus californiensis
• thermal requirements