ISO 6322-3:1989

Overview

ISO 6322-3:1989 provides practical guidance for the control of vertebrate and invertebrate pests affecting stored cereals and pulses. The part focuses on recognising onset of infestation, factors that influence insect and mite development, the phenomenon of grain heating caused by pests, and practical measures for prevention and control. An informative Annex A summarises limiting and optimum conditions for population increase for 23 insect and mite pests.

Key Topics

• Onset of infestation: Infestation may begin in the field or during harvest and handling; pulses are frequently already infested when put into store. Field infestation by storage insects is common in warm regions and can continue in storage if conditions permit.
• Factors affecting development: Temperature, grain moisture content, relative humidity of inter-granular air and the nature of the grain are primary determinants of insect and mite growth. Most serious insect pests require about 15 °C or higher for multiplication; mites generally tolerate temperatures about 5 °C lower. Grain with moisture under 9% (m/m) is generally secure from insect or mite attack, while some species (e.g., khapra beetle) can breed at very low moisture (reported around 2%).
• Heating of grain: Insect and mite activity can produce internal heating. Temperatures often rise until insects move outward or immatures die; insect-initiated "dry grain heating" can evolve into "damp grain heating" where moulds develop. Typical upper temperatures reported include insect-related peaks not usually above 42 °C, and damp heating seldom above 62 °C (commonly about 52 °C).
• Annex A: Provides limiting and optimum conditions (temperature, relative humidity, reproduction rates) for 23 common pests to support risk assessment and monitoring.

Applications

ISO 6322-3 guides operational decisions in grain storage and logistics:

• Design of prevention programs: hygiene, proofing of stores, and removal of harbourage for rodents and insects.
• Environmental control: drying, aeration, refrigerated or hermetic storage, and controlled atmospheres to keep conditions below pest multiplication thresholds.
• Direct control methods: trapping and baits for rodents, contact insecticides for surfaces, and fumigation for deep-seated infestations; fumigation must be performed by trained personnel and is usually non-residual.
• Integrated approaches: combining mechanical, biological (limited use, e.g., Bacillus thuringiensis for some moths), chemical and physical methods to minimise losses and residues.

Related Standards

• ISO 6322-1 and ISO 6322-2 (other parts of storage guidance)
• ISO standards on insect infestation determination (e.g., ISO 605 and ISO 6639 series)

Notes: chemical use and residue limits should follow national regulations and FAO/WHO Codex recommendations; maritime pesticide use should follow IMO guidance. ISO 6322-3:1989 emphasises integrated, safety-conscious pest management to protect mass, quality and marketability of stored cereals and pulses.