Combined larvicidal and adulticidal treatments to control Culicoides biting midges (Diptera: Ceratopogonidae): Results of a pilot study

Abstract

Culicoides biting midges can transmit viruses such as bluetongue virus and Schmallenberg virus to ruminants and African horse sickness virus to equines. The control of Culicoides population can be based on physical and/or chemical methods. This study aims to evaluate the efficacy of larvicides and adulticides combined treatments to control the vector Culicoides populations. Field trials have been conducted during 2014 on seven farms in northern Sardinia (Italy). Three insecticide treatments (larvicides and adulticides) have been carried out on three farms, whereas four farms remained unsprayed as untreated controls. For the larval control two commercial formulations, based on diflubenzuron and Bacillus thuringiensis var. israelensis (H-14), have been used. Against adults a deltamethrin based product has been sprayed on the walls and roofs of animal shelters. Adult Culicoides have been collected on each farm twice a week with an Onderstepoort blacklight suction trap. After each treatment a significant reduction in the abundance of total Culicoides, C. imicola and C. newsteadi s.l., has been observed. The Obsoletus complex density has been affected by the first two treatments. Our results suggest the possibility to control the Culicoides populations with a combination of adulticide and larvicide treatments.

Keywords: Bluetongue; Culicoides; Insecticide treatments; Italy; Vectors.