The treatments carried out in each section are carried out at the beginning of each one of them, so that the product causes a toxic plume for the simulid larvae downstream from the treatment point. The time during which the product is being applied (10 minutes) guarantees that a high percentage of the larvae found in the river can get to ingest the applied product.
For the development of the treatments, a basic protocol is followed that consists of:
- conducting a survey prior to treatment (called day -1) to determine the density of black fly larvae and estimate the need to apply a treatment,
- application of the Bti product and,
- carrying out a second survey (called day +1), after the treatment, in order to determine the effectiveness of the product.
Treatments are performed by helicopter. Of the different methods evaluated, this is the one that gave the most guarantees of effectiveness due to its speed in moving along the sections, its easy accessibility to the points determined on the cartography and its ability to stay in geostationary flight and power apply the product for the established time.
These treatments are carried out first thing in the day, when the weather conditions are favorable (absence of wind, lower temperatures, etc.), which reinforces the use of this application system.
For the correct development of the treatments, the support of different land teams that are in charge of transporting the product, loading the helicopter, supervising the treatment conditions and enabling the three loading points that are used correlatively in each treatment is necessary. .
The treatment carried out in the Flix area is a specific treatment whose characteristics allow it to be done manually. Its range is that of a good part of the meander of Flix, where there is a presence of macrophytes and a stream of water conducive to the existence of simulid larvae.