Vector Control

The control of the vector of Bluetongue, Culicoides midges, can partly be achieved by management measures such as modification of the habitat (storage of manure away from animals, drainage of ponds). Insecticides remain a simple and effective method of reducing midge populations.

Insecticides

Targeted application of insecticides with known low mammalian toxicity (e.g. the synthetic pyrethroids) in and around animal housing and directly to the target animals themselves are favored over broad scale aerial application.

Treatment of housing with insecticides is important as ruminants are bitten by female Culicoides midges in housing as well as at pasture. Application of larvicides to Culicoides breeding sites is also suggested.

Ectoparasiticides and Culicoides

In Northern Europe the control of Culicoides in ruminants has previously been neglected as they were not significant vectors of disease before the arrival of BTV-8. Most research in insecticides have instead focused on flies which usually attack the head and upper body of ruminants. Culicoides, however, prefer biting along the sides of the belly and lower legs. It is thus vital that insecticides which are poured along the backline of animals reach these target areas in sufficient concentrations to kill Culicoides, and any infected midges are killed quickly before they can transmit disease.

Butox® SWISH is a pour-on containing the knock-down synthetic pyrethroid, deltamethrin.  It is the only pour-on insecticide which has shown to be effective against the Culicoides midge in trials.  A study (1) undertaken in  2007 by Intervet found Butox® SWISH to rapidly kill midges at the body areas prone to midge bites.  Results from this trial support a recommendation of applying Butox® SWISH monthly to cattle as an aid in the control of midges.

Advantages of using Butox^® SWISH to control Culicoides midges

• The risk of disease transmission throughout the herd is reduced if an infected midge is killed quickly after coming into contact with a treated animal
• By killing female Culicoides midges, the amount of possible progeny in the surroundings are reduced.
• Treatment early in the season helps to minimise midge populations on the farm

¹ Mehlhorn (2008) Parasitology Research 102(3), 515-518

Butox^® SWISH applied along the top-line of a cow