Observations on biology of the filbert aphid (Myzocallis coryli, Homoptera : Aphididae) in hazelnut orchards

Abstract

Filbert aphid is a minor pest of hazelnut in hazelnut growing area of Turkey. However, in some years it builds up large populations during early summer and causes substantial damage. This is the first record on the biology of filbert aphid from Turkey. This study was carried out in two different hazelnut orchards. The overwintering eggs of this aphid found on filbert branches hatch from late January to mid-March. The hatching ratio of eggs collected from field were 77.5% at 14 degrees C, 80% at 18 degrees C, 87.5% at 22 degrees C and 47.5% at 26 degrees C. In early spring, aphids feed on buds and, after foliation, move to young leaves. Their population rapidly increases until the end of June. In early November, the population increases again. Sexual forms occur from mid-October to late November and first eggs are seen in these days. Most of overwintering eggs are found on the branches 1 cm in diameter. Seven 7 Coccinellid species were found as predators. These are Adalia bipunctata, Adalia decempunctata, Chilocorus bipustulatus, Coccinella septempunctata, Propylaea quatuordecimpunctata, Psyllobora vigintiduopunctata and Subcoccinella vigintiquatuorpunctata. There was no effective parasitoid suppressing aphid population. One unidentified parasitoid was also seen in very low number.