a study on the incidence of woolly poplar aphid, phloemyzus passerinii (hom.: aphididae) on poplar species and clones in hamedan province, iran

woolly poplar aphid, phloeomyzus passerinii (signoret), is considered as an important and serious pest of poplar in iran and many countries. during 2002-2003, resistance and susceptibility of 12 poplar clones to p. passerinii were evaluated in hamedan province of iran. number of formed aphid colonies found in a surface unit was counted three times during a growing season. the clones populus alba 58/57, p. deltoides 72/51, p. deltoides missoriensis, p. x. euramericana 214, p. nigra 62/72, p. nigra 62/140 and p. nigra 62/149 were immune to the insect pest, but the remaining of p. nigra clones were infested variously. analysis of variance conducted on obtained data, revealed a significant difference (î± = 1%) between the clones. mean infestation of p. nigra 56/72 was significantly higher than other studied clones in all sampling dates. mean infestation of branches (at four main geographical directions of tree) was significantly different in the first sampling date, but not in two other dates. natural enemies of the aphid collected in this region were exochomus nigromaculatus (goeze), chilocorus bipustulatus l., sympherobius pygmaeus (rambur), anthocoris sp., orius sp. and chiracanthium sp. the species, e. nigromaculatus and s. pygmaeus‎ are reported for the first time on p. passerinii. the two parasitoid species, thaumatomyia elongatula (becker) and pachyneuron sp., are reported for the first time on this pest from iran. mean density of t. elongatula and s. pygmaeus‎ were higher than other natural enemy species and placed in same lsd test class. mean density of the parasitoid wasp, pachyneuron sp., was less than other natural enemies.