Voltinism of the European corn borer, Ostrinia nubilalis, in Slovakia
1998
Cagan, L. (Slovenska Polnohospodarska Univ., Nitra (Slovak Republic). Katedra Ochrany Rastlin)
From 1987 to 1995 the occurrence of the second generation of the European corn borer was investigated in Slovakia. In 1994, for the first time in Slovakia, pupal cases were observed in stalks, indicating the development of the second generation adults of the pest. Pupal cases were not found in other years of study. The difference between the year 1994 and the other years was found when degree-days accumulation at base 10 degrees C was calculated for the periods from the date when the first eggs were observed up to July 14 (daylight 15 hours 40 minutes) or July 19 (daylight 15 hours 30 minutes). These numbers were the highest in 1994 and reached 297.0 degrees C and 365.4 degrees C, respectively. Degree-days accumulation during the whole year was also the highest in 1994 (1,545.3 degrees C). The results indicate that even extremely high temperatures in some years have almost no influence on diapause of the European corn borer developing on maize plants in Slovakia, and the population is completely univoltine.
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