Du laurier dans les greniers de Grande Canarie. Insecticide naturel et conservation longue des récoltes à l’époque préhispanique

Insect pests are one of the main problems in the long-term storage of food, especially for grains. It has been estimated that before chemical insecticides were used systematically, insects damaged around 10-20 % of the stored grain, and in certain conditions they could spoil the whole harvest. There are historical documents recording the use of organic and inorganic products to kill or dispel the insect, but there is little archaeological data about this important aspect in food storage. This is partially due to the lack of in situ finds of conserved ancient foods. What methods and techniques were used to store food and avoid insect pests in the past ? In order to answer this question, this paper aims to provide new data on the methods and techniques employed in the past for the long-term storage of food plants by presenting the preliminary results of an analysis carried out in the framework of a multidisciplinary project of a group of granaries on the Island of Gran Canaria (Canary Islands, Spain) from the Pre-Hispanic period (ca. 500-1 500 AD). The indigenous populations of Gran Canaria were farmers that procured most of their food from cultivated plants and they built many granaries for their storage. The silos analyzed in the current work still contained archaeological remains of cereals, pulses, and both cultivated and wild fruits that were radiocarbon dated between 700-1 440 AD. To assure a better conservation, the grains were originally stored in the form of ears and pods inside silos carved in the rock. The stores were accompanied by Canarian bay leaves placed inside the silos to repel insects. Nevertheless, there is clear evidence that the stores were damaged by weevils indicating the serious problem these insects represented for long-term storage.