Host plant recognition by the root feeding clover weevil, 'Sitona lepidus' (Coleoptera: Curculionidae)

Abstract

This study investigated the ability of neonatal larvae of the root-feeding weevil, 'Sitona lepidus' Gyllenhal, to locate white clover 'Trifolium repens' L. (Fabaceae) roots growing in soil and to distinguish them from the roots of other species of clover and a co-occurring grass species. Choice experiments used a combination of invasive techniques and the novel technique of high resolution X-ray microtomography to non-invasively track larval movement in the soil towards plant roots. Burrowing distances towards roots of different plant species were also examined. Newly hatched 'S. lepidus' recognized 'T. repens' roots and moved preferentially towards them when given a choice of roots of subterranean clover, 'Trifolium subterraneum' L. (Fabaceae), strawberry clover 'Trifolium fragiferum' L. (Fabaceae), or perennial ryegrass 'Lolium perenne' L. (Poaceae). Larvae recognized 'T. repens' roots, whether released in groups of five or singly, when released 25 mm (meso-scale recognition) or 60 mm (macro-scale recognition) away from plant roots. There was no statistically significant difference in movement rates of larvae.