Deltamethrin application on colonized olive logs: Effect on the emergence of the olive bark beetle Phloeotribus scarabaeoides Bernard 1788 (Coleoptera: Scolytidae) and its associated parasitoids

The olive bark beetle, Phloeotribus scarabaeoides, is a pest of olive trees causing severe injuries near inhabited foci. The pyrethroid insecticide, deltamethrin, has been tested at different doses during 3 years in olive logs already colonized by this scolytid, by monitoring the emergence of P. scarabaeoides adults and their parasitoids. In 2005 due to unusual low winter temperatures, the insect population was very low, precluding drawing any conclusion. The insecticide doses in 2004 and 2006 affected the emergence of the olive bark beetle, with a reduction ranging from 1% to 13%. The doses of 2006 also controlled the emergence of another olive pest, Leperisinus varius. The incidence on the hymenopteran parasitoids was, in general, high at all the tested deltamethrin doses, ranging from 0.0025% to 0.01% active ingredient. The lowest dose employed in 2006, corresponding to 0.00125%, reduced pest emergence without a significant effect on the hymenopteran parasitoids population, except for Cheiropachus quadrum.