Spatial population structure of the predatory ground beetle Carabus yaconinus (Coleoptera: Carabidae) in the mixed farmland-woodland satoyama landscape of Japan

Yoshitake Kagawa,Kaoru Maeto

doi:10.14411/eje.2009.049

Abstract

To conserve the predators and parasitoids of agricultural pests it is necessary to understand their population structure in a mixed landscape, and to consider the spatial and temporal changes in their distribution and movement of adults and larvae. We studied the distribution and movement of the ground beetle Carabus yaconinus (Coleoptera: Carabidae), which inhabits farmland- woodland landscapes. We placed a large number of pitfall traps along the border between a wood and an orchard and counted the number of C. yaconinus adults and larvae caught in the traps from 13 April to 28 June 2005. Some of the adults were marked before they were released. Adults were most abundant at the edge of the wood and the number caught gradually decreased when entering into the wood. In contrast, larvae were only found in the interior of the wood, although they moved closer to the edge of the wood as they matured. Adult females were collected within the wood and neighbouring orchards more frequently than adult males. It is likely that females enter woodlands in search of oviposition sites and leave woodlands in search of high-protein food sources to support reproduction. For sustaining populations of C. yaconinus it is necessary to have woodlands of at least 60 m in width adjacent to farmland. It is possible to design an appropriate landscape if the habitat requirements of the predatory arthropods are well understood.

Highlights

INTRODUCTIONAgricultural landscapes generally include farmland, such as fields or orchards and semi-natural habitats (noncrop vegetation), such as woodland, hedgerows, or grassland
Agricultural landscapes generally include farmland, such as fields or orchards and semi-natural habitats, such as woodland, hedgerows, or grassland
Differences in the movements of the adults of both sexes of predatory arthropods, especially those related to female oviposition, are rarely studied, the importance of such studies is often stressed (Collins et al, 1996; Thomas et al, 2000; Altieri & Nicholls, 2004; Samways, 2005)

Summary

INTRODUCTION

Agricultural landscapes generally include farmland, such as fields or orchards and semi-natural habitats (noncrop vegetation), such as woodland, hedgerows, or grassland. Ground beetles (Coleoptera: Carabidae) are considered to be beneficial arthropods as they are generalist natural enemies of various agricultural insect pests and have been studied intensively in Europe and North America (Thiele, 1977; Luff, 1987; Luff et al, 1992) They are ubiquitous in agricultural landscapes and prey on a great variety of pest insects (Sunderland, 2002). Most studies have focused on the distribution and movement of adult beetles (Landis et al, 2000; Lee et al, 2002; Altieri & Nicholls, 2004; Tscharntke et al, 2007) with little attention to habitat use by larvae. This is true for ground beetles, and for many other predatory invertebrates (Altieri & Nicholls, 2004; Samways, 2005).

MATERIAL AND METHODS

RESULTS

DISCUSSION