Ground Beetles (Coleoptera: Carabidae) and Other Insect Predators Overwintering in Arable and Fallow fields in Central Japan
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Appl. Entomol. Zool. 38 (4): 449–459 (2003) Ground beetles (Coleoptera: Carabidae) and other insect predators overwintering in arable and fallow fields in central Japan Kazuo YAMAZAKI,1,* Shinji SUGIURA2 and Koji KAWAMURA2 1 Osaka City Institute of Public Health and Environmental Sciences; Tennoji, Osaka 543–0026, Japan 2 Laboratory of Forest Ecology, Graduate School of Agriculture, Kyoto University; Kyoto 606–8502, Japan (Received 5 February 2003; Accepted 26 May 2003) Abstract To clarify assemblage patterns of overwintering ground beetles (Coleoptera: Carabidae) and other insect predators in farmland habitats for the purpose of proper land management to enhance beneficial predators, we collected carabid and other insect predators at eight plots including arable and fallow rice and vegetable fields and a bank of an adjacent irrigation pond in central Japan. In total, 159 adults and 268 larvae of 33 carabid species, and 178 individuals of at least 17 species of other insect predators were collected by the quadrat sampling method. In rice fields, both the num- ber of species and no. of individuals of overwintering carabid beetles increased as the soil became dry and vegeta- tional succession proceeded, whereas in fallow vegetable fields carabids decreased according to succession. Similar trends were confirmed in other insect predators. Variations of carabid species richness and abundances among the plots might be attributed to soil water content, vegetation and prey availability. In early-successional fallow vegetable fields, the larvae of the carabid genus Harpalus overwintered with high density; this appeared to be because the fin- gergrass Digitaria ciliaris (Poaceae), whose seeds were a potential food for Harpalus, were densely vegetated there. In a dry fallow rice field and early-successional vegetable fields, beneficial predators such as Dolichus halensis (Coleoptera: Carabidae), Agrypnus binodulus (Coleoptera: Elateridae), and soldier beetle (Coleoptera: Cantharidae) larvae hibernated with high densities. For proper farmland management to augment insect predators, it is desirable to maintain fallow rice and vegetable fields as relatively dry habitats and at early successional stages. Ploughing fallow fields in winter may reduce overwintering predacious insect larvae. Key words: Carabidae; hibernation; beneficial predators; pest control; habitat preference and Marshall, 1999; Pfiffner and Luka, 2000). INTRODUCTION Some studies have shown that predatory epigaeic In agroecosystems, polyphagous beneficial ar- insects which had overwintered in field margins thropod predators such as carabid and staphylinid emigrated into adjacent farmland in spring beetles and spiders can efficiently reduce the popu- (Coombes and Sotherton, 1986; Thomas et al., lations of some pest insects and slugs (Best and 1991, 2002). However, these studies were restricted Beegle, 1977; Edwards et al., 1979; Chiverton, to cereal and forage crop fields in Europe and 1986; Clarke et al., 1994; Kromp, 1999). Thus, North America (Kromp, 1999). emphasis has recently been placed on studies to In Japan and other temperate Asian regions, rice, create and manage farmland habitats for augmenta- vegetables and fruits are intensively cultivated on tion of such beneficial predators (Thomas et al., narrow plains and foothill areas of mountains. 1991; Lys and Nentwig, 1992; Lys et al., 1994; Farmland management practices in Japan are dif- Kromp, 1999). These studies indicate that field ferent from those in Europe and North America. margins and semi-natural habitats with dense vege- Assemblages of carabids and other predators in tation harbor high abundance and species richness Japan thus may be distinct from those in other of beneficial predators. These habitats not only world areas, although Luff (2002) compared the support feeding and reproductive activity but also carabid assemblages of various world farmlands in- function as overwintering refuges for the predators cluding Japan mainly at the genus level and dis- (Desender, 1982; Sotherton, 1984, 1985; Thomas cussed how dominant genera were common among * To whom correspondence should be addressed at: E-mail: [email protected] 449 450 K. YAMAZAKI et al. temperate world farmlands. Therefore, in order to gation ponds in central Japan. Firstly, assemblages use carabid beetles and other beneficial predators of carabids and other predators in each habitat are as biological control agents in Japan, the assem- described, and the habitats with high abundance blage patterns in each habitat and habitat prefer- and species richness of the predators are explored. ences of component species should be clarified. Similarities between assemblages are also ana- In Japan, Habu and Sadanaga (1961, 1963, lyzed. Overwintering developmental stages and 1965, 1969, 1970a, b, 1971) described larval mor- breeding seasons of the sampled carabid beetles phology of carabid beetles and noted their biology are compared among habitats. Then, habitat prefer- in cultivated fields and paddy fields based on labo- ences for beneficial species are examined, and in ratory rearings. Carabid assemblages and faunae turn land management practices to enhance benefi- have been described from paddy fields, forage crop cial insect predators against pest insects in Japa- field, cabbage field, fig orchards and vineyards dur- nese agroecosystems are discussed. ing the warm season using pitfall-trapping (Torii, 1974; Yano et al., 1989, 1995; Yahiro et al., 1992; MATERIALS AND METHODS Ishitani et al., 1994; Ishitani and Yano, 1994; Ishi- tani, 1996; Suenaga and Hamamura, 2001; Yano, Study site. The study site was located in a rural 2002). Yahiro and Yano (1997) reported long-term area of Son-enji (34°489N, 135°439E, ca. 100 m data on a carabid assemblage caught by a light trap above sea level), Hirakata City, Osaka Prefecture, set at a farmland area which comprised rice, cereal central Japan (Fig. 1). The landscape of this area is and vegetable fields, orchards and irrigation ponds. well preserved, comprising mosaics of coppice However, in Asia including Japan, no quantitative woodlands, rice and vegetable fields, irrigation study on overwintering carabid assemblages in ponds and streams, and therefore relatively rare farmland and adjacent semi-natural habitats has plants and insects that prefer grassland and marsh- been reported. Quantitative assemblage data of hi- land habitats were still extant (Kankyô-kagaku Co., bernating carabids and other insect predators in 2001). There were many arable and fallow rice and each farmland habitat is useful to create and man- vegetable fields at the study site. Fallow fields were age overwintering refuges for the predators. at various successional stages. These farmlands Carabid life-cycle patterns (breeding season and were surrounded by secondary forests composed hibernating developmental stage) vary across cli- mainly of the Japanese red pine Pinus densiflora matic regions and habitats (Murdoch, 1967; Paar- and the oak Quercus serrata. mann, 1979; Andersen, 1984). However, the life Overwintering ground beetles and other insect cycles of most carabid species excluding the tribe predators were sampled at the following eight plots Carabina are not well known in Japan (for Cara- which were within a 1 km2 area. Table 1 shows the bina see Sota, 1985). Collecting ground beetles in environmental conditions of sampling plots. Age winter helps to elucidate their life cycles, espe- after cultivation in each plot was estimated by con- cially their hibernating stages. Information on life sulting with farmers and based on vegetational suc- cycles of beneficial carabid species may be essen- cession. Vegetational succession advanced from A tial for proper land-management practices to aug- to C in rice fields, and from D to G in vegetable ment those already in use; In Europe, deep plough- fields. ing during autumn or winter is known to reduce the Methods. We arbitrarily set three quadrats numbers of overwintering carabid beetles and other (1.6 m31.6 m) per plot on the ground except the predators (Kromp, 1999; Pfiffner and Luka, 2000). two plots (D: 2 quadrats and F: 1 quadrat), that This negative effect to carabids may be severe for were unfortunately ploughed while sampling. All hibernating larvae compared with overwintering the quadrats except the bank of an irrigation pond adults, since the larvae appear to be more vulnera- were set on relatively flat and horizontal ground. ble to physical disturbance than the adults. Ground inclination of three quadrats on the pond In the present study, we sampled overwintering bank was ca. 50°. We then dug up each quadrat to a carabid beetles and other insect predators in arable depth of 40 cm using hoes, and inspected the soil and fallow fields (rice and vegetables) with differ- thus obtained for ground beetles and other insect ent successional stages and a bank of adjacent irri- predators (see Yamazaki et al., 1999, 2002). The Overwintering Ground Beetles in Rice and Vegetable Fields 451 Fig. 1. Study site of the ground beetles and other insect predators overwintering in farmland habitats. A to H denote sampling plots. Table 1. The environmental conditions of sampling plots Years after Plots Land use Dominant plants abandonment A Arable rice field — Astragalus sinicus (Leguminosae), grasses B Wet fallow rice field 1 Oenanthe javanica (Umbelliferae), Stellata sp. (Caryophyllaceae) C Dry fallow rice field 1 Erigeron canadensis (Asteraceae), A. sinicus D Fallow vegetable field 1 0.5 Digitaria ciliaris (Poaceae), E. canadensis E Fallow