BIOLOGY, IMPACT, AND MANAGEMENT OF TRIOXYS PALLIDUS IN HAZELNUT ORCHARDS OF OREGON, U.S.A.

An aphidiid parasitoid Trioxys pallidus introduced to Oregon from Europe during 1984 for controlling filbert aphid. The parasitoid was subsequently mass cultured and released in the state and recoveries were made during 1985 showing establishment. Further studies during a twelve year (1985–1986) period indicate that the parasitoid had adapted to Oregon climatic conditions and reduced the aphid populations throughout the region. The biology of the parasitoid is well synchronized with aphid biology, thus making it an excellent fit for biological control. The biological, and economic impacts and management of this successful classical biological control program are discussed in this paper.