7th May 2024
Lesley Stubbings of the SCOPS Steering Group has supported advice from the Ruminant Health & Welfare Group (RHWG) about avoiding ineffective and sometimes inappropriate steps to reduce midge activity in the hope of reducing bluetongue transmission. She is quoted in a RHWG press release below, urging farmers not to use insecticides in an unsustainable way. Further information on this topic is also avialable via an AHDB technical bluetongue webinar.
Advice for farmers to ‘ACT’ on BTV-3
Farmers and the industry must remain Aware, apply Caution and use evidence-based Tactics to ACT and mitigate against the latest strain BTV-3.
Following a technical AHDB meeting with the support of Ruminant Health & Welfare, Lesley Stubbings, sheep consultant and SCOPS adviser (Sustainable Control of Parasites in Sheep) says: “The fact is, a single bite from a single infected midge will reliably transmit BTV-3. This means that trying to control midges is futile and is not going to impact on the risk of BTV-3 transmission. It is crucial that we ACT with this knowledge in mind.”
Speaking as a spokesperson for the working technical group, Ms Stubbings says: “We’re recommending that farmers are aware of the facts and avoid misinformation to prevent unnecessary actions and costs. As an emerging new strain of bluetongue, with no vaccine currently available, the industry is taking learnings from research, science and our EU counterparts, who experienced clinical cases during 2023, to provide the most up-to-date advice and guidance.
“Many have questioned the role of insecticides in controlling midges and in controlling BTV-3 transmission. They are not the same. There needs to be clear distinction between midge control and BTV-3 control,” she adds. “There is no evidence that insecticides can prevent infection as they do not kill Culicoides midges (the specific type of midge that transmits bluetongue) fast enough to prevent the first bite. Similarly, there is no evidence that insecticides prevent onward transmission of bluetongue and there is also no evidence that insect repellents (which deter insects), have any effect on the transmission of BTV-3.
“Therefore, the use of insecticides or repellents to try to prevent BTV-3 infection is not recommended. They may have detrimental effects on the environment as well as being an unnecessary cost. Farmers will not be able to significantly reduce the number of midges in a specific area, nor for long enough to prevent BTV-3 transmission.”
Ms Stubbings says: “When it comes to tactics for midge control, air movement is key. It’s also important to note that midges are most active during dusk and dawn. Farmers should act to maximise natural ventilation, particularly by taking advantage of hills, wind and rain. Farmers in the Netherlands favoured housing animals with powerful fans, providing air flow of more than 3m/s, for example.
“Midge control through increased wind speed may reduce midge biting rate but it won’t eliminate all biting and therefore won’t necessarily prevent bluetongue transmission. As we know, it only takes a single bite from a single infected midge to reliably transmit BTV-3,” she says. “This small practical insight from the Netherlands feels better than doing nothing and will be a tactic farmers can act on to potentially help midge control on-farm.”
Currently, there are no products licensed for Culicoides midge ‘control’. Any products sold for this purpose would be off licence and the industry cautions that excessive use could l cause negative environmental and ecological impacts as well as resistance in other parasites.
Ruminant Health & Welfare and AHDB has brought together experts right across the four nations, including scientists, research and veterinary professionals to ensure the right information is available for farmers. They are advising farmers to ‘act’ on BTV-3 by being aware of how bluetongue is transmitted as a vector-borne disease, while providing caution against misinformation, and promoting evidence-based tactics on-farm.
In the UK, bluetongue, including BTV-3, is a notifiable disease, so anyone suspecting the disease must take action and report it to the Animal and Plant Health Agency (APHA). Further information about how to ACT on BTV-3 and the latest updates please visit Bluetongue Virus - Ruminant Health & Welfare.
