An attempt to reconstruct the natural and cultural history of the granary weevil, Sitophilus granarius (Coleoptera: Curculionidae)

Abstract

It is generally accepted that stored grain insects are food opportunists and, when originally made the transition to man-made storage facilities, came from natural reservoirs like bird or rodent nests. This may not be true for Sitophilus granarius. Among all stored-product insects, the granary weevil S. granarius is the only species never recorded outside of storage facilities. Anatomical, physiological, and behavioural aspects of recent and hypothetical ancestral species in the genus Sitophilus are presented and discussed in terms of adaptation to the anthropogenic storage of grain. Full development inside the host kernel, endosymbioses with bacteria, and the reduction in flight activity to prevent water loss in a dry environment can be regarded as pre-adaptations for the evolution of a full synanthropic grain pest of cosmopolitan distribution. Faunistic, archaeological, and historical evidences of the pest's origin and spread in conjunction with early agriculture are reviewed to support a hypothesis of a co-evolutionary event with the dawn of Neolithic agriculture.