OVERWINTERING SURVIVAL OF 7 IMPORTED COCCINELLIDS IN THE TEXAS HIGH-PLAINS

In a four-year study (1990-1993), seven species of exotic coccinellids [Cycloneda ancoralis (Germar): Eriopis connexa Germar, Hippodamia tre decimpunctata Say,, H. variegata (Goeze), Oenopia conglobata (L.), Pro pylea 14-punctata (L.), and Sycmnus frontalis F.], imported for potent ial control oi the Russian wheal aphid. Diuraphis noxia (Kurdjumov), s uccessfully overwintered in the Texas High Plains when caged on native range grasses. Survival ranged from 58.6% for H. tredecimpunctata to a low of 2.4% for S. frontalis. Differences in percentage survival ove r years were due to climatic conditions. Higher percentage recoveries were made in colder years with snow cover. An absence of snow cover in conjunction with cold temperatures was more detrimental to overwinter ing survival than warmer temperatures.