The control of insects in export grain by admixture chemicals


Cereals & Oilseeds
Project code:
01 May 1992 - 30 September 1992
AHDB Cereals & Oilseeds.
AHDB sector cost:
Project leader:
M P Kelly and K M Amos CSL-Slough



About this project


For many years cargoes of grain exported from the United Kingdom have been accompanied by either trade-sourced certificates of quality, or Ministry of Agriculture, Fisheries and Food, Phytosanitary Certificates. These are not interchangeable. The Phytosanitary certificates are only required when the government of the importing country insists on the cargo complying with its quarantine procedures under International Plant Health regulations.

To achieve "freedom from live (invertebrate) pests", required under both trade and government quality procedures, many cargoes are sprayed with admixture (contact) insecticides, a recognised method of disinfestation for inland stored grain. However, despite earlier HGCA-funded research, there are many gaps in our knowledge concerning the effects of these insecticides on several species in cold grain over extended exposure periods. This project addresses these questions.

Six species of beetles, representing common grain and food storage pests on various international quarantine lists, were placed on separately-sprayed batches of grain, using three UK-approved admixture insecticides, and looked at (as separate replicates) every two-days over 28 days. A total of 13,440 insects were used in over 4,000 replicates, and the test temperatures, attempting to simulate winter grain exports, were 10, 7.5, 5 and 3°C.

The insects showed varying abilities to withstand low temperatures: there was some survival in all species at 10 and 7.5°C, but only the grain weevil and rust-red grain beetle showed survival at both 5 and 3°C, by the end of the trial.

Exposure to each of the insecticides speeded up 100% kill at all temperatures, except at 3°C. Here, the effects of natural mortality and insecticidal action are not clearly defined but, again, in all cases, 100% kill was achieved by the end of the experiment.

There is considerable variation of reaction between the six species of insects, the three insecticides and the four temperatures. Traders or inspectors referring to these results for guidance in dockside situations must ensure that insect identifications are correct, and that average grain cargo temperatures are obtained from frequent monitoring, before estimating the effects during that particular voyage.