Foraging ecology of Reticulitermes grassei (clément) with re feren ce to its management as a pest of timber

Abstract

Subterranean termites from the genus Reticulitermes are an important pest of wood in service throughout southern Europe and elsewhere. For effective termite control with long term protection but minimal environmental damage, new integrated approaches to termite management are needed. Baiting-based systems seem to be promising non-traditional methods for termite control, targeting the colony as a whole. However, control through baiting is only feasible when it is known that the toxicant can be transferred to all the colonies foraging on the infested area and also throughout each individual colony. Accordingly, the work described is specifically designed to achieve a better understanding of the distribution and delimitation of colonies within a population of Reticulitermes, with parallel insights into foraging behaviour and colony organization. Initially, the species/subspecies spectrum present within the notional Reticulitermes group in Portugal was reassessed. It was shown that Reticulitermes grassei is the only species encountered. Foraging activity was then assessed in an experimental woodland site over two successive annual cycles, both by the sampling of natural lying dead wood and by a standard baiting grid. R. grassei seem to select wood with larger diameter, with an apparent preference for material already decayed by fungi. Both termite and fungal attack on wood seems to be promoted by higher moisture levels, such as prevail in larger litter items and during seasonal rains. Termites were unable to detect and direct their foraging towards sound wood in laboratory conditions, suggesting that the network of infochemical signals is more complex than just volatiles emanating from sound wood. Mark-release-recapture (MRR) was used to delineate foraging groups, which were then allocated to their parent colonies by the use of microsatellite markers. The results suggest that resource sharing is a facultative behaviour, specifically when food is not a limiting factor for colony development. The implications of all these findings for bait technology and protocols are discussed, with reference to the local population ecology of Reticulitermes.