ISO 6639-1:2025

Cereals and pulses - Determination of hidden insect infestation - Part 1: General principles

This document establishes general principles for the methods of the determination of hidden insect infestation in cereals and pulses.

Céréales et légumineuses — Détermination de l'infestation cachée par les insectes — Partie 1: Principes généraux

Žito in stročnice - Določanje prikritega napada insektov - 1. del: Splošna načela (ISO 6639-1:2025)

Ta dokument določa splošna načela za metode določanja prikritega napada insektov v žitu in stročnicah.

General Information

• Status: Published
• Publication Date: 11-Jun-2025
• ICS: 67.060 - Cereals, pulses and derived products
• Technical Committee: ISO/TC 34/SC 4 - Cereals and pulses
• Drafting Committee: ISO/TC 34/SC 4 - Cereals and pulses
• Current Stage: 6060 - International Standard published
• Start Date: 12-Jun-2025
• Due Date: 24-Oct-2026
• Completion Date: 12-Jun-2025
• Ref Project: SIST ISO 6639-1:2025 - Cereals and pulses - Determination of hidden insect infestation - Part 1: General principles (ISO 6639-1:2025)

Relations

• Revises: ISO 6639-1:1986 - Cereals and pulses - Determination of hidden insect infestation - Part 1: General principles
• Effective Date: 15-Oct-2022

Overview

ISO 6639-1:2025 - "Cereals and pulses - Determination of hidden insect infestation - Part 1: General principles" defines the general principles for detecting insect pests that develop inside individual cereal grains and pulse seeds. The standard clarifies terminology (for example, hidden infestation vs initial observed infestation), explains why standard grain sampling (ISO 24333) is not always appropriate for insect detection, and describes the two main categories of detection methods: reference and rapid methods.

Keywords: ISO 6639-1:2025, hidden insect infestation, cereals and pulses, grain sampling, detection methods

Key topics and technical requirements

• Scope and definitions: Clear definitions of hidden infestation, grain, increment and initial observed infestation (eggs, larvae, pupae stages are addressed).
• Sampling principles: Sampling for hidden infestation departs from representative sampling because insect distribution is often non‑random (concentrated in warmer or surface layers, bag edges, etc.). Increments may be treated separately when distribution data are required, or combined to form bulk samples then reduced to laboratory samples.
• Methods overview:
  • Reference method: Incubation of samples at standard temperature and relative humidity with periodic examination - highly accurate but slow (weeks). Best for insects that complete larval/pupal stages inside kernels.
  • Rapid methods: Shorter alternatives (minutes to hours) that include flotation, carbon dioxide (CO2) production measurement, and acoustic approaches (see ISO 6639-4 for specifications). Rapid methods trade speed for some limits in detecting eggs and very young larvae.
• Emerging and potential techniques: Non‑destructive and instrumental approaches summarized in the standard include near‑infrared (NIR) spectroscopy, hyperspectral imaging, thermal imaging, electronic noses (E‑Nose), solid phase microextraction–GC‑MS, and molecular assays. Each is described with advantages and limitations (cost, training, sensitivity, calibration needs).
• Practical limitations: Sample handling (sieving, etc.) can kill insects; some life stages (eggs, early larvae) are difficult to detect reliably with most rapid methods.

Applications and users

ISO 6639-1:2025 is intended for:

• Grain storage/warehouse managers and quality control teams monitoring stored-product pests
• Grain inspection bodies and laboratories performing infestation assays
• Food safety and supply‑chain auditors assessing lot condition
• Manufacturers of detection equipment (acoustic, NIR, hyperspectral, E‑nose)
• Researchers developing or validating new rapid detection techniques

The standard helps users choose suitable methods based on required speed, cost, and whether results should indicate insect counts or mass of damaged grain.

Related standards

• ISO 6639-3 - Reference method (incubation)
• ISO 6639-4 - Rapid methods (flotation, CO2, acoustic)
• ISO 24333 - Cereals - Sampling (contrasted in this standard)
• ISO 5527 - Cereals - Vocabulary

Use ISO 6639-1:2025 to align pest-detection practice with internationally accepted principles for reliable, comparable measurement of hidden infestation in cereals and pulses.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2025
Nadomešča:
SIST ISO 6639-1:1997
Žito in stročnice - Določanje prikritega napada insektov - 1. del: Splošna načela
(ISO 6639-1:2025)
Cereals and pulses — Determination of hidden insect infestation — Part 1: General
principles (ISO 6639-1:2025)
Céréales et légumineuses — Détermination de l'infestation cachée par les insectes —
Partie 1: Principes généraux (ISO 6639-1:2025)
Ta slovenski standard je istoveten z: ISO 6639-1:2025
ICS:
67.060 Žita, stročnice in proizvodi iz Cereals, pulses and derived
njih products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

International
Standard
ISO 6639-1
Second edition
Cereals and pulses —
2025-06
Determination of hidden insect
infestation —
Part 1:
General principles
Céréales et légumineuses — Détermination de l'infestation
cachée par les insectes —
Partie 1: Principes généraux
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling . 2
5 Methods of determining hidden infestation. 2
Bibliography . 5

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO’s adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4, Cereals
and pulses.
This second edition cancels and replaces the first edition (ISO 6639-1:1986), which has been technically
revised.
The main changes are as follows:
— according to the insect developmental stages causing damage, the definition and general of hidden
infestation has been modified;
— the sampling location, time and period have been modified;
— rapid methods in Table 1 have been modified based on ISO 6639-4;
— some potential techniques in Table 2 have been added.
A list of all parts in the ISO 6639 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Some species of adult insects are especially adapted to attack whole grains and normally spend a considerable
part of the life cycle, including the entire larval feeding period, inside grains. Other species in their larval
stage create an entrance hole within a grain, covering it after entry and an adult exit hole is created after the
process of pupation, from which it then emerges. These insects constitute a hidden infestation that cannot
readily be seen in consignments or samples (as opposed to an initial observed infestation).
Most insect pests of stored grains are very small, under 5 mm in length, cryptic in behaviour and dull in
colour. Those that fly do so mostly in dull light or at high temperatures. Thus, even when they are living
freely outside the grains, and do not constitute a hidden infestation as described above, they are not easy to
detect unless populations are large enough to induce noticeable activity.
Being mobile, at least in the free-living form, insects are capable of moving through a bulk of grain and
tend to concentrate in those parts of the bulk most favourable for feeding and breeding. Such centres of
insect activity are not necessarily static; they can expand, contract or move for many complex reasons. The
most important reasons are changes in the physical condition of the grain (e.g. temperature and moisture
content) and overcrowding of the insects due to rapid breeding. Thus, the distribution of insects in a bulk of
grain is rarely random, and their detection requires specialist knowledge and techniques.

v
International Standard ISO 6639-1:2025(en)
Cereals and pulses — Determination of hidden insect
infestation —
Part 1:
General principles
1 Scope
This document establishes general principles for the methods of the determination of hidden insect
infestation in cereals and pulses.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
initial observed infestation
free-living insects that are immediately apparent to the eye when the sample is first examined
3.2
hidden infestation
insects which are present within individual grains (3.3) either because they are at juvenile stages and have
developed from eggs laid inside the grains, or because they lay eggs outside of the grain kernel and the larva
emerging from egg gnaws a hole, no larger than a pin prick, through which it enters the kernel till adult
Note 1 to entry: Hidden infestation is not normally apparent upon first examination of the sample.
3.3
grain
cereal grains and/or seeds of pulses
3.4
increment
amount of material taken at one time at each individual sampling point throughout a lot
[SOURCE: ISO 5527:2015, 2.6.1.10]
...

International
Standard
ISO 6639-1
Second edition
Cereals and pulses —
2025-06
Determination of hidden insect
infestation —
Part 1:
General principles
Céréales et légumineuses — Détermination de l'infestation
cachée par les insectes —
Partie 1: Principes généraux
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling . 2
5 Methods of determining hidden infestation. 2
Bibliography . 5

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO’s adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4, Cereals
and pulses.
This second edition cancels and replaces the first edition (ISO 6639-1:1986), which has been technically
revised.
The main changes are as follows:
— according to the insect developmental stages causing damage, the definition and general of hidden
infestation has been modified;
— the sampling location, time and period have been modified;
— rapid methods in Table 1 have been modified based on ISO 6639-4;
— some potential techniques in Table 2 have been added.
A list of all parts in the ISO 6639 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Some species of adult insects are especially adapted to attack whole grains and normally spend a considerable
part of the life cycle, including the entire larval feeding period, inside grains. Other species in their larval
stage create an entrance hole within a grain, covering it after entry and an adult exit hole is created after the
process of pupation, from which it then emerges. These insects constitute a hidden infestation that cannot
readily be seen in consignments or samples (as opposed to an initial observed infestation).
Most insect pests of stored grains are very small, under 5 mm in length, cryptic in behaviour and dull in
colour. Those that fly do so mostly in dull light or at high temperatures. Thus, even when they are living
freely outside the grains, and do not constitute a hidden infestation as described above, they are not easy to
detect unless populations are large enough to induce noticeable activity.
Being mobile, at least in the free-living form, insects are capable of moving through a bulk of grain and
tend to concentrate in those parts of the bulk most favourable for feeding and breeding. Such centres of
insect activity are not necessarily static; they can expand, contract or move for many complex reasons. The
most important reasons are changes in the physical condition of the grain (e.g. temperature and moisture
content) and overcrowding of the insects due to rapid breeding. Thus, the distribution of insects in a bulk of
grain is rarely random, and their detection requires specialist knowledge and techniques.

v
International Standard ISO 6639-1:2025(en)
Cereals and pulses — Determination of hidden insect
infestation —
Part 1:
General principles
1 Scope
This document establishes general principles for the methods of the determination of hidden insect
infestation in cereals and pulses.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
initial observed infestation
free-living insects that are immediately apparent to the eye when the sample is first examined
3.2
hidden infestation
insects which are present within individual grains (3.3) either because they are at juvenile stages and have
developed from eggs laid inside the grains, or because they lay eggs outside of the grain kernel and the larva
emerging from egg gnaws a hole, no larger than a pin prick, through which it enters the kernel till adult
Note 1 to entry: Hidden infestation is not normally apparent upon first examination of the sample.
3.3
grain
cereal grains and/or seeds of pulses
3.4
increment
amount of material taken at one time at each individual sampling point throughout a lot
[SOURCE: ISO 5527:2015, 2.6.1.10]

4 Sampling
Sampling for insects is critical for management. The methods of sampling cereals and pulses specified in
ISO 24333 are not appropriate for sampling for hidden infestation in cereals and pulses, because of the non-
random distribution of insect populations, particularly after a period of prolonged storage or transportation.
Specialized techniques, not intended or suitable for determining grain quality, as specified by ISO 24333,
include selecting samples from the top and outer layer of bags or pac
...