Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 1998
Publication Date: N/A
Interpretive Summary: Temperature controls the development and activity of insects. Lysiphlebus testaceipes is a parasitoid of the greenbug, the most economically important insect pest of wheat and sorghum in the Southern Great Plains region. The parasitoid occasionally maintains greenbug infestations below the economic threshold in wheat and sorghum, but effective biological control is inconsistent. We found that the temperature threshold for immature development of L. testaceipes is higher than that of other aphidiid parasitiods of cereal aphids. However, the degree-day requirements for development of L. testaceipes are lower than those for other cereal aphid parasitoids. The high developmental threshold and low degree-day requirement is typical of a species that is most active in warm weather and may help explain why L. testaceipes provides inconsistent biological control, especially in late-winter and early-spring when greenbug infestations often build to damaging levels on winter wheat. Results lend support to the idea that classical biological control programs for the greenbug should be continued in an attempt to establish parasitoids that are effective at lower temperatures, to help control greenbugs in late- winter and early-spring.
Technical Abstract: Temperature effects on development of immature Lysiphlebus testaceipes(Cres were measured at five temperatures (10, 14, 18, 22, and 26 deg C) using greenbugs, Schizaphis graminum (Rondoni), as hosts. The temperature threshold for development from egg to the adult stage was estimated to be 6.01 deg C, while the corresponding degree-day requirement for development was 140 DD. The temperature threshold for immature development of L. testaceipes was higher than that of other aphidiid parasitoids of cereal aphids that have been studied. However, degree-day requirements for development of L. testaceipes were substantially lower than those for other aphidiid parasitoids of cereal aphids.