Determination of egg parasitization rate in the biological control of European cornborer in the Sakarya province

The study was carried out in the districts of Sakarya; Adapazari, Akyazi, Erenler, Sogutlu, Serdivan, Ferizli, Hendek, Karasu and Kocaali (Lepidoptera: Crambidae) to determine the rate of natural parasitism with egg parasitoid in 2018 and 2019. Samples were collected weekly between June and September. In the samples, 100 plants from each field were checked and whole leaf and especially under leaf were examined carefully. The parasitized and non-parasitized egg masses of corn borer were brought to the laboratory with plant parts. In the laboratory, egg masses were examined under stereoscopic microscope and eggs in each package was recorded separately. Counted egg packs were cultured in glass tubes in a temperature of 25 ± 1 °C, humidity adjusted to 65 ± 10% and 16 hours in light 8 hours dark climate room. The parasitized and non- parasitized O. nubilalis eggs were counted and recorded daily. The obtained parasitoid species were identified as Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae). The natural parasitism rate of T. brassicae in Sakarya in 2018 and 2019 was determined as 94.82% and 40.58%. The highest natural interference occurred in 2018. When districts were compared in 2018 and 2019, the highest parasitization rate occurred in Ferizli district (100%) in 2018, while the lowest parasitism were found in Kocaali district (21.43%).