EN
Biological and operational factors contribute to the rate of resistance development in insect pests. Conventional resistance management relies on manipulation and exploitation of these factors to prevent, delay and reduce resistance development. Manipulation of biological factors of the storage system to control the phosphine resistant strains may be obtained by: (a) limiting the immigration of strains that are resistant to phosphine, and (b) reducing the number of pest generations per year. Operational factors are generally easier for manipulation than biological factors. Manipulation of operational factors may include: (a) use of rotations (use of methyl bromide to control phosphine-resistant strains), (b) use of phosphine in well-sealed enclosures only, (c) use of the SIROFLO system, (d) inclusion of integrated pest management (IPM) economic thresholds, (e) use of contact insecticides, (f) use of non-chemical methods control (natural enemies, hygiene, physical factors, etc.). The under-dosing and inadequate exposure periods over many years are the likely reason for the resistance to phosphine observed in some strains of stored product pests. Techniques of application and sealing must become more stringent to avoid severe resistance problems.