EXPERIMENTAL INVESTIGATIONS OF THE EFFECTS OF AIR-POLLUTANTS ON APHIDS ON CONIFEROUS TREES

The relative growth rates of two aphid species feeding on Sitka spruce (Picea sitchensis) and one species on Scots pine (Pinus sylvestris) w ere measured on two year old trees prefumigated with either ozone (O3) or nitrogen dioxide (NO2) and compared with the growth rates of aphid s grown on trees which were exposed to filtered air. All three species showed increased growth rates on trees which were prefumigated with 1 00ppb NO2 for periods in excess of 24 hours. However the effects of pr efumigation with O3 were more complex. Only on species, Cinara pilicor nis, responded to this treatment and there was a strong interaction be tween the fumigation treatment and the temperature experienced by the plants during fumigation.