Ecological and biological studies of parasitoids associated with olive bark beetle, Phloeotribus scarabaeoides bern.,coleoptera:scolytidae

This study was conductcd to survey and ecological studies of olive bark beetle, Phloeotribus scarabaeoides Bern. and its associated parasitoids in Fayoum Governorate during two successive years 2008 .2009. and to discrip the different staga and biological studies of the parasitoid, Cheiropachus quadrum(Fab.) (Hymenoptera: Pteromalidae) which may provide some basic knowledge of using these natural enemies an effective - control. Six hymenopterans species were recorded related with P. scarabaeoldes, in Fayoum Governorate; Cheiropachus quadrum (Fab.), Rhaphitelus maculates (Walk.), Cerocephala cornigera Westw. (Fam.: Pteromalidae). Eurytom morio Bohme. (Fam.:Eurytomidae), Cephalonomia sp. (Fam.: Bethylidae) and the parasitoid Dendrosoter protuberans Ness. (Fam.: Braconidae), which recorded for the first time in Egypt on this host. Population fluctuation of P. scarabaeoides beetles show that four generation were observed during 2008 and 2009, while the parasitoids population fluctuation showed one generation during 2008 and three generation were observed during 2009. Monthly abundance of the different recorded parasitoids species revealed that the parasitoid C. quadrum was the dominant specie; the relative annual percentage of this parasitoid was 75.8 and 39.8 during 2008 and 2009, respectively. The highest percentages of parasitism (10.43 and 17.9) were recorded through winter during 2008 and 2009, respectively. The results indicated that parasitoids had a considerable effect of the population of P. scarabaeoides beetles and so it is advisable not to interfere with pesticides and choose the most suitable timing for control this pest while avoiding damage parasitoids. The biological studies on the parasitoid C. quadrum indicated that the pest degree for rearing the parasitoid is 25ºC where the percentage of pupation and emergence were 100% and the percentage of female increased to 84.9 % when the parasitoid reared at this temperature. The laboratory rearing of the parasitoid showed the parasitoid prefer the pupal stage of the host and also that the parasitoid has two generation for each generation of the host.