Study of biology and natural controlling approaches of brown tail moth in Arasbaran forests

Brown-tail moth, Euproctis chrysorrhoea (L.) is a po/lyphagous defoliator, attacking forest trees and fruit trees,and has become a public health hazard owing to the minut irritant hairs carried by the larvae, pupa and female moths. the lymantriid is a pest in vast area of eorope and asia and a minor pest in america and canada. The moth is reported from Hamadan, Zandjan, MarkJ and Northern provinces in Iran, also is the most important defoliator of oak trees in all over the Arasharan torests (Azarbaidjan). it makes serious injury to oaks and IS other species in some years. With due atlention to it was previously recorded that Arasharan's Euproctis is Euproctis (=porthesia) mekmnia Stgr. , therefor in proposal of this plan we considered the same species. But exact studies on morphohiologic diffrence and genitalia organs showed that in the contrary the previouse reports, prevalent species in Arasbaran forests is Euproctis chrysurrhoea (L.). Acording to three years biological studies in leild and laboratory, the adult moth emerged from the mid-june to the end ofjuly and began to lay eggs frr 9 mid-july to the mid-August after mating. Elongate egg masses of 150-250 laid on lower surface of leaves and covered with the Brown hairs from abdominal tuft "tail' of female, the eggs after incubation period (15 20 doys) hatch from early Auguit and first instar larve feed on uper paranchyma of hosts leaves. During 35-40 days the larvae moult twice as they feed gregariously and gradually construct their winter nest in the same hosts which from feed. There are about 150 to 350 3-instar larvae in each uverwintering nest. In the following spring they recommence feeding and sometimes spin new shelters as they move fresh feeding sites. In the later stages of the development, after two moultings the larvae move away from the nests and often become solitary, the most serious defoliation (in spring) caused by these leaf-chewing larvae continue nearly for two months and finish from mid-june. They them spin silken cocoons between the leaves, either singly or groups and popate. About 20 days affer pupation adults emerge from the end ofjune. so there is only one generation per year. By studying on natural controlling methods ten species ot hiotic agents including two predator spider. five parasitoid wasps. a dipterous parasitoid, one kind of parasitoid nematoda also an unknown entomopathogenic agent (probably tungous) are founded that they have important act in decrease of the pest population. Key words: Brown-tail moth , Biology , Natural enemies, Arasharan forests.