Temperature effects on development in Aphelinus albipodus (Hymenoptera : Aphelinidae) from two geographic regions

Aphelinus albipodus Hayat & Fatima was imported to the United States for cl assical biological control of the Russian wheat aphid, Diuraphis noxia (Mor dvilko). Temperature effects on development of A. albipodus from two geogra phic regions (hereafter referred to as strains) were measured using the Rus sian wheat aphid as host. Temperature thresholds for egg to mummy, mummy to adult, and egg to adult development were 8.9, 10.9, and 9.7 degrees C for A. albipodus collected near Pingluo, China, and were and 8.5, 10.3, and 9.6 degrees C for A. albipodus collected near Urumqi, China. The time required to develop from egg to adult did not differ among strains. However, when t otal immature development was partitioned into egg to mummy and mummy to ad ult, the time required for development through these two periods differed a mong strains. The Urumqi strain developed faster than the Pingluo strain fr om egg to mummy, while the Pingluo strain developed faster from mummy to ad ult. Degree-day requirements for egg to mummy development were 135 and 104 for the Pingluo and Urumqi strains, respectively. Corresponding requirement s for mummy to adult development were 70 and 101 degree-days. The ability t o vary immature development rate in response to climate or other factors co uld have adaptive significance because it would permit the parasitoid to ex ploit environments over a broad geographic range.