POSTDIAPAUSE DEVELOPMENT AND SPRING EMERGENCE OF THE EUROPEAN CORN-BORER, OSTRINIA-NUBILALIS, IN ISRAEL

The European corn borer (ECB), Ostrinia nubilalis (Hubner) (Lepidoptera: Pyralidae), is the major pest of corn (Zea mays L.) in Israel. We investigated the temporal patterns of pupation and emergence of various overwintering ECB populations in Israel during 1992-94. The association between Julian dale (JD) or cumulative degree-days (DD) and the rates of either pupation or emergence was studied using simple linear regression models. Differences between populations in JDs required to reach 50% pupation amounted to 5%, whereas for DD differences amounted to 26%. Similarly, at 50% emergence, differences between populations were up to 3% for JD and to 12% for DD. Two different forecasting models are proposed for either pupation or emergence. Based on these models, both pupation and emergence develop over a period of 4 to 5 weeks, and they are expected to occur between the following JDs: onset of pupation, 66-70 (March 7-11); 50% pupation, 96-102 (April 6-12); onset of emergence, 85-94 (March 26-April 4); and 50% emergence, 115-121 (April 25-May 1). Pupal development required 160 DD (confidence interval [C.I.] 141-179 DD) and it is expected to take ca 16 days (C.I. 14-18 days). The simple linear regression models obtained in this study are suggested as preliminary phenological models for the temporal prediction of postdiapause pupation and emergence of ECB.