This premix, formulated with the active ingredient lufenuron, belonging to the family of benzoylureas, inhibits the production of chitin and thereby interferes in the development of the louse's exoskeleton and hence the moulting, thus generating the death of the parasite and preventing it from reaching its adult stage.
As reported by Elanco, its presentation is oral powder at 10 per cent concentration, delivered as premix for use in commercial feed of salmonids. Meanwhile, the posology is 5mg of lufenuron/kg/day, to achieve a total therapeutic dose of 35mg/kg over a period of at least seven days. Treatments are administered in the diets of smolts prior to their transfer to sea.
Low metabolism efficiency
According to the regional manager of Aquaculture in Elanco Animal Health, Fernando Flores, Imvixa is a product that, at very low doses, achieves therapeutic levels in skin and subcutaneous tissue, and remains there for a very long time, controlling the parasite for a period of between six and eight months after treatment.
“The period of effectiveness is long, but does not cover the entire fattening cycle of salmon. The idea, first, is to use this product only once for each production cycle, rotating it with other products in order to extend the useful life of this drug in the industry and, therefore, once concluded the effectiveness period, the suggestion is to alternate with other delousing agents,” said the executive, adding that they expect to complete a whole portfolio of products to complement Imvixa in the remaining months of the fattening stage.
Reduced risk of resistance
Meanwhile, despite having similarities with other delousing agents, such as diflubenzuron and teflubenzuron, the active ingredient of Imvixa has its own characteristics that differentiate it from other drugs, whether of the same chemical family or not, Fernando Flores said: “Its level of efficiency is much higher compared to other tools on the market. In fact, this is the compound against external parasites in salmon with the longest lasting effect in the world; historically, it has a history of resistance or virtually nonexistent efficacy failure in all markets in which it has been used before,” he revealed.
As an example, he said that, at first, lufenuron was designed to control fleas on pets. In that market, after 20 years of use, there has been no report of resistance. In turn, in the case of its agricultural use, there have only been four reports of resistance within the same period, in species maintained in laboratory conditions in challenge models of efficiency.
Another advantage described by the executive, is that the product has Maximum Residue Levels (MRL) accepted in the most important markets for Chile. “It is possible to meet that MRL very early, even before the product stops working, as the withdrawal period of Imvixa is around four and a half to five months,” he said. In the coming days, the company will inform about the ‘import tolerance’ established in the US for this product.
Meanwhile, with respect to the risk that the use of this product may pose to other animals (eg molting stage in crustaceans), the executive said that Imvixa should only be used in land-based freshwater sites with a treatment system for effluent and treatment of solids. Therefore, it should not be released to the environment. “That's part of its condition of use. Thus, there is a guarantee that the product will not have contact with the environment or with species that are in the environment.”
The commercial launch of Imvixa, held last Thursday at the Teatro del Lago, in Frutillar, was attended by about 150 representatives of the Chilean salmon industry, including numerous executives, researchers, veterinarians and authorities related to the sector.
Other speakers at the event included the vice president for Emerging Business at Elanco Animal Health, Rob Aukerman; the director of the Latin American Center for Economic and Social Policies (Clapes UC) and Chile's former Finance Minister, Felipe Larraín; and the director of Economic Research at the National Federation of Coffee Growers of Colombia, José Leibovich.