WINTER HOST COMPONENT REDUCES COLONIZATION BY BIRD-CHERRY OAT APHID, RHOPALOSIPHUM-PADI (L) (HOMOPTERA, APHIDIDAE), AND OTHER APHIDS IN CEREAL FIELDS

Methyl salicylate, a volatile component of Prunus padus, the winter ho st of Rhopalosiphum padi, was found to reduce colonization of the summ er host by this aphid. The compound was identified by gas chromatograp hic analysis coupled with recordings from cells in the primary rhinari um on the sixth antennal segment of the aphid. Methyl salicylate elimi nated the attractancy of oat leaves to spring migrants in olfactometer tests. In Sweden, this compound significantly decreased colonization of field grown cereals by R. padi and in the U.K., populations of Sito bion avenae and Metopolophium dirhodum were significantly lower on tre ated plots.