Lydella thompsoni Herting (Dipt., Tachinidae), a parasitoid of the European corn borer, Ostrinia nubilalis Hbn. (Lep., Pyralidae) in Slovakia, Czech Republic and south-western Poland

This paper shows that, within Central Europe, parasitism of the European co rn borer (ECB) by the tachinid parasitoid, Lydella thompsoni (LT) increased from 0.47 to 1.49% in south-western Poland (51 degrees 03'N), to 4.31-21.9 5% in eastern Slovakia (48 degrees 20'N). The synchrony between the parasit oid LT and its primary host: the ECB, was studied in Central Europe under c onditions where the host is univoltine, but the parasitoid is bivoltine. A cumulated total of more than 400 LT was field-collected from overwintering ECB larvae. The parasitoid hibernated as larva inside the host. Pupation st arted in the second half of the following March and 50% of pupation was sur passed in the first half of April. The first parasitoid adults emerged at t he end of April and the majority at the beginning of May. Development thres hold temperatures for 50% pupation was determined to be 2.7 degrees C, and for 50% adult emergence 5.0 degrees C; the respective thermal constants wer e 178.8-179.8 and 237.7-251.8 Celsius degree-days. Emerged adults did not p arasitize overwintered ECB larvae in spring, hence there must be an alterna te host for the first generation of LT in areas of univoltine life cycle of the ECB. Parasitization of the ECB larvae by LT continued until the end of July. The first parasitoid adults from this second generation emerged in t he second half of August. By the end of the season, nearly one-third of LT adults had emerged. The rest of this generation apparently overwintered in the larval stage.