SEASONAL ABUNDANCE OFRHOPALOSIPHUM PADI(L.) (HOMOPTERA: APHIDIDAE) IN WHEAT AND ITS ROLE AS BARLEY YELLOW DWARF VIRUS VECTORS

Wheat is a most important crop without which human nutrition is unimaginable. Along with fertiliser, variety and other cultivation elements an important role in the amount of the yield is played by pests, above all by aphids, which reduce the quality of the grain and also transmit BYDV. The most dangerous barley yellow dwarf virus (BYDV) vector in Croatia is the speciesRhopalosiphum padi(L.). Research was carried out from 1996 to 2003 with the use of a Rothamsted suction trap (RST) located in Zagreb. The results obtained show that the speciesR. padiis the dominant species during the aphid remigration (autumnal) flight when its share in the total aphid population comes sometimes to more than 18%. Then it is at its most dangerous for the transmission of the virus to the just-sprouted winter wheat crop. Since the species flies at maximum daily temperatures of below 10 ºC, or mean daily temperatures of 5 ºC, it is necessary to shift the dates of the sowing, to monitor flight activities and abundance and carry out chemical control of the vector in autumn if theR. padipopulation is large.