Effects of reducing recommended doses of insecticides and fungicides on the non-target insect Episyrphus balteatus [Diptera: Syrphidae]

The aim of this work was to assess both lethal and sub-lethal effects of four pesticides commonly used in field vegetables in south Belgium (Wallonia) on Episyrphus balteatus [Diptera: Syrphidae]. Acute toxicity and long term effects of the pesticides at the recommended and reduced doses were assessed in laboratory conditions by exposing the insects on plant leaves previously treated with the considered pesticide. Both tested insecticides, namely Karate(R) and Pirimor(R), were found to be very harmful for the beneficial hoverfly even at reduced doses. A kind of selectivity only appeared from 2.5% of the recommended dose. The two fungicides, namely Ronilan(R) and Quintalic(R), which showed a moderate acute toxicity had induced negative effects on long-term parameters, on both development and reproduction.