Evaluation of decreasing deltamethrin concentration in the treatment of olive logs: effects on the olive bark beetle and its associated parasitoids

Abstract

An assay was conducted over 2 years (2005 and 2006) to investigate the effects of reducing deltamethrin concentrations, from 0.01 to 0.00125% a.i., in olive logs prior to colonization by the olive bark beetle, Phloeotribus scarabaeoides Bern. (Curculionidae, Scolytinae) on the population densities of the pest and its associated parasitoids. Effects were measured in terms of numbers of penetration holes in logs, numbers of insects captured in containers placed under the logs, and numbers of insects emerging from logs. The results from 2005 showed no differences, there being low insect numbers that year as a consequence of an unusually cold winter. In 2006 beetles dug negligible numbers of reproduction galleries inside logs treated with deltamethrin at different concentrations, and emergence from the treated logs was significantly reduced. A repellent effect rather than a direct effect of the insecticide is hypothesised. Parasitoid wasps were captured in low numbers in containers under the logs, both in the control and the insecticide treatments. The emergence of parasitoids from control logs was significantly higher than from treated logs. A further reduction of deltamethrin concentration is recommended in olive beetle management.

Comparative efficacy of different pesticides against mango bark beetle Hypocryphalus mangiferae Stebbing (Coleoptera: Scolytidae)

“…The relative potency analyses also revealed that the chlorpyrifos, emamectin and imidacloprid took relatively shorter times to eradicate 50% of the population than deltamethrin or bifenthrin. The low potency of pyrethroids than chlorpyrifos, emamectin and imidacloprid in the field could be attributed to the repellent effect of pyrethroids against bark beetles (Ruano et al . 2009).…”