NOVELTY – The detection of mutant c.h. individuals for insecticide resistant gene comprises DNA extraction adn amplification by PCR sequence analysis and e.g. diagnosis based on PCR-RFLP. Also claimed is apparatus implementing the process. CLAIMED APPARATUS – The apparatus studies the esterase gene related to resistance to organophosphorated insecticides, and can alternatively employ diagnosis based on PCR allel-specific. USE – In biochemistry.