Records on parasitoids of smaller poplar borer, Saperda populnea [Coleoptera, Cerambycidae] along the Danube in Bulgaria

Abstract

During the period 1986-1988 the parasitoids of smaller poplar borer, Saperda populnea L. (Coleoptera, Cerambycidae) along the Danube in Bulgaria were studied. A total of 898 smaller poplar borer galls were investigated-289 in 1986, 404 in 1987, and 205 in 1988. In the particular years the parasitoids of smaller poplar borer namely Billaea irrorata Meig. (Diptera, Tachinidae), Dolichomitus populneus Ratz. (Hym.: Ichneumonidae), and Iphiaulax impostor Scop. (Hym.: Braconidae) destroyed from 13.1 up to 28.0% of the pest larvae, thus decreasing their frequency together with the other limiting factors by 56.1% up to 81.2%. The tachinid fly B. irrorata decreased the smaller poplar borer larvae frequency by 9.3% up to 18.9%, while the ichneumonoid D. populneus, and the braconoid I. impostor destroyed insignificant percentages of these larvae-0.5% up to 1.7% and 0.5% up to 2.5% resp. The flight period of the pest preceded or almost coincided with the ones of D. populneus, and I. impostor. The fly B. irrorata always appeared last and its flight period was expanded. © 1991 Lavoisier Abonnements.