Consumption of fresh and buried seed by ground beetles (Coleoptera: Carabidae)

Zdenka Martinková,Alois Honěk,Pavel Saska

doi:10.14411/eje.2006.048

Abstract

Ground beetles (Carabidae: Coleoptera) are predators of the seed of herbaceous plants scattered on the ground, but prefer that of certain species. Foraging beetles encounter both freshly dispersed and seed exhumed from the soil bank. The predation on seed from the soil bank has never been studied and the effect of burial on seed acceptability is unknown. The preferences of two gen- eralist granivorous carabids, Harpalus affinis and Pseudoophonus rufipes, were investigated by offering them fresh (stored frozen after dispersal) and buried (for 6 months in the soil under field conditions) seed of six common weed species. Significantly more of the buried seed of Tripleurospermum inodorum and significantly less of that of Taraxacum officinale was eaten than fresh seed. For four other weed species the consumption of both kinds of seed did not differ. The preferences were similar in both species of carabid. The change in preference probably occurred because the seed of T. officinale was partially decayed and the repellent surface of T. inodorum seed abraded. Provided the seed in the soil bank does not decay it may have a similar or better food value for carabids than fresh seed.

Highlights

In Central and Western Europe, ground beetles (Carabidae) are the most important invertebrate consumers of the seed of herbaceous plant scattered on the ground (HonČk et al, 2003; Westerman et al, 2003)
The differences were highly significant in both H. affinis (T. officinale: p = 1.51 10–3; T. inodorum: p = 7.53 10–8) and P. rufipes (T. officinale: p = 3.31 10–4; T. inodorum: p = 4.85 10–7)
The smaller H. affinis accepted small seed of species like C. bursapastoris and M. album, which were rejected by the larger P. pubescens

Summary

Introduction

In Central and Western Europe, ground beetles (Carabidae) are the most important invertebrate consumers of the seed of herbaceous plant scattered on the ground (HonČk et al, 2003; Westerman et al, 2003). The seed eating (granivorous) species typical of arable land belong mainly to the tribes Harpalini (represented by several genera, e.g. Anisodactylus, Harpalus, Ophonus, Pseudoophonus, Stenolophus) and Zabrini (Amara, Zabrus) (Lindroth, 1949; Thiele, 1977; HĤrka, 1996). Typical of adults (Goldschmidt & Toft, 1997; Jorgensen & Toft, 1997a; HĤrka & Jarošík, 2003), is essential for successful larval development in some species (Jorgensen & Toft, 1997b; Saska & Jarošík, 2001). Seed predators aggregate in weedy agricultural fields (Kokta, 1988). Their role in decreasing the seed output of weeds on farmland is generally recognized (Luff, 1987; Lövei & Sunderland, 1996; Kromp, 1999; Tooley & Brust, 2002; HonČk et al, 2005). The choice differs between carabid tribes and at the species level is determined by the relative size of the seed to that of the carabid and other still incompletely understood qualities of the seed (HonČk et al, in prep)

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Conclusion