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COMMUNITY AND ECOSYSTEM ECOLOGY Ground (Coleoptera: Carabidae) Assemblages in Organic, No-Till, and Chisel-Till Cropping Systems in Maryland

1 2 3 4 SEAN CLARK, KATALIN SZLAVECZ, MICHEL A. CAVIGELLI, AND FOSTER PURRINGTON

Environ. Entomol. 35(5): 1304Ð1312 (2006) ABSTRACT assemblages were compared in organic, no-till, and chisel-till cropping systems of the USDA Farming Systems Project in Maryland. The cropping systems consisted of 3-yr rotations of corn (Zea mays L.), soybean (Glycine max L. Merr.), and wheat (Triticum aestivum L.) that were planted to corn and soybean during the 2 yr of Þeld sampling (2001Ð2002). Each year, ground were sampled using pitfall traps during three 9- to 14-d periods corresponding to spring, summer, and fall. A total of 2,313 specimens, representing 31 , were collected over the 2 yr of sampling. The eight most common species represented 87% of the total specimens collected and included quadriceps Chaudoir, anceps (LeConte), rapidum (LeConte), pensylvanicus (DeGeer), chalcites (Say), impressefrons LeConte, punctiforme (Say), and aenea (DeGeer). Canonical variates analysis based on the 10 most abundant species showed that the carabid assemblages in the three cropping systems were distin- guishable from each other. The organic system was found to be more different from the no-till and chisel-till systems than these two systems were from each other. In 2002, ground beetle relative abundance, measured species richness, and species diversity were greater in the organic than in the chisel-till system. Similar trends were found in 2001, but no signiÞcant differences were found in these measurements. Relatively few differences were found between the no-till and chisel-till systems. The estimated species richness of ground beetles based on several common estimators did not show differences among the three cropping systems. The potential use of ground beetles as ecological indicators is discussed.

KEY WORDS Carabidae, organic, no-till, chisel-till, cropping systems

Ground beetles are among the most common epigeic tally sustainable farming practices where ecological found in temperate ecosystems, including understanding and management can substitute for annual cropping systems (Thiele 1977, Lo¨vei and Sun- pesticide inputs. derland 1996). Their ecological role, as part of a com- Another common interest in ground beetles stems plex of generalist predators of crop pests, has been from a desire to use them as ecological indicators shown by numerous studies in and (Rainio and Niemela 2003). Because of their ubiquity, Europe (Brust et al. 1986, Hance 1987, Clark et al. 1994, the relative ease in sampling them with pitfall traps, Menalled et al. 1999, Symondson et al. 2002). Other and the availability of good taxonomic keys, ground research has shown that some ground beetle species beetles have been studied as potential indicators of the may be important in inßuencing weed abundance and effects of a wide variety of management practices, species composition through on seeds including general land use (Larsen et al. 2003), pre- (Brust and House 1988, Zhang et al. 1997, Menalled et scribed Þre (Niwa and Peck 2002), managed ßooding al. 2001). Consequently, there is interest in the ability (Cartron et al. 2003), introduction of invasive plants to predict the effects of management practices on (Da´valos and Blossey 2004), introduction of trans- ground beetle abundance and diversity in agroeco- genic crops (French et al. 2004, Lopez et al. 2005), systems. Such information has potential use in guiding pesticide use (Ellsbury et al. 1998), and soil tillage research on the development of more environmen- (Belaoussoff et al. 2003). An implicit, although rea- sonable, assumption common in this area of research is that ground beetle abundance, species richness, 1 Corresponding author: Department of Agriculture and Natural and/or species diversity would decline with increas- Resources, Berea College, Berea, KY 40404 (e-mail: sean_clark@ berea.edu). ing magnitude or severity of human disturbance. How- 2 Department of Earth and Planetary Sciences, The Johns Hopkins ever, studies have shown that the response of ground University, Baltimore, MD 21218. beetles to management disturbance is often more 3 Sustainable Agricultural Systems Laboratory, USDAÐARS, BARC, complicated than this. Beltsville, MD 20075. 4 Department of , Ecology, and Organismal Biology, The Some studies of ground beetles in annual cropping Ohio State University, Columbus, OH 43210. systems indicate that there is greater ground beetle

0046-225X/06/1304Ð1312$04.00/0 ᭧ 2006 Entomological Society of America October 2006 CLARK ET AL.: CARABIDS IN MARYLAND CROPPING SYSTEMS 1305

Table 1. Summary of management practices in the NT, CT, and ORG cropping systems of the USDA FSP, Beltsville, MD, 2001–2002

Cropping system NT CT ORG Crop in 2001 Corn Corn Corn Crop in 2002 Soybean Soybean Soybean Winter cover crop 2000Ð2001 None None Vetch (killed by rolling; later tilled into soil) Winter cover crop 2001Ð2002 Rye (killed with herbicide) Rye (killed with disk) Rye (mowed) Fertilizer Corn: starter 10Ð20-10; Corn: starter 10Ð20-10; None sidedress urea, ammonium sidedress urea, ammonium nitrate Soybean: 0Ð0-60 nitrate Soybean: 0Ð0-60 Tillage and cultivation None Chisel plow, disk, Þeld cultivator Disk, Þeld cultivator, rotary hoe, row cultivator Pesticides Paraquat, atrazine, S-metolachlor, Atrazine, S-metolachlor, None glyphosate glyphosate

abundance and/or species richness when tillage is Materials and Methods reduced or eliminated (House and Stinner 1983, Brust Study Site. The 16-ha study site is at the western et al. 1985, House and Parmelee 1985, Stinner and edge of the Atlantic coastal plain in Beltsville, MD. House 1990, Thorbek and Bilde 2003). Other studies The dominant soil types are Christiana (Þne, kaoli- have found no favorable effects from reduced tillage nitic, mesic Typic Paleudults), Matapeake (Þne-silty, on total ground beetle abundance or species richness mixed, semiactive, mesic Typic Hapludults), Keyport (Tyler and Ellis 1979, Ca´rcamo 1995, Belaoussoff et al. (Þne, mixed, semiactive, mesic, Aquic Hapludults), 2003). Because individual species respond differently and Matapex (Þne-silty, mixed, active, mesic Aquic to tillage due to preferences, timing of man- Hapludults). The 30-yr average annual precipitation at agement disturbances relative to life cycle, and/or the site is 1,110 mm, distributed evenly through the effects on food resources (Clark et al. 1993, 1997), total year. carabid abundance and species richness may not be Cropping Systems. In 1996, the FSP was established altered substantially even when changes in commu- at the site, which had previously been managed with- nity composition have occurred. Moreover, the effects out tillage since at least 1985. There were Þve cropping of tillage on ground beetles may be relatively short in systems represented, arranged in four randomized duration and not detected in longer-term sampling complete blocks (Cavigelli 2005). The plots are laid intervals. out side by side within each block with no borders in Most studies comparing carabid fauna in organic between them. The dimensions of each plot are 9.1 by and conventional cropping systems have reported 111 m. We report on data collected from three of the greater ground beetle abundance and species richness cropping systems: (1) a chisel-till and (2) a no-till under organic management (Dritschilo and Wanner based 3-yr corn (Zea mays L.)Ðsoybean (Glycine max 1980, Dritschilo and Erwin 1982, Kromp 1989, 1990, L. Merr.)Ðwheat (Triticum aestivum L.)/soybean ro- Ca´rcamo et al. 1995, PÞffner and Niggli 1996, Clark tation, and (3) a 3-yr organic cornÐsoybeanÐwheat/ 1999, Shah et al. 2003). Interestingly, organic farming hairy vetch (Vicia villosa Roth.) rotation. These sys- systems are often characterized by more frequent tems were selected for the study because they had physical disturbance of the soil because cultivations, similar crop rotations but differed in management rather than herbicides, are used for weed manage- inputs and practices. Sampling was conducted in the ment. However, organic systems donÕt have synthetic same plots during the 2001 and 2002 cropping seasons. pesticide inputs and tend to use cover crops and or- In 2001, the plots were in the corn phase of the rota- ganic amendments that may favor ground beetles di- tions; in 2002, they were in the soybean phase of each rectly by providing favorable habitat conditions or rotation. Corn in all systems and soybean in the or- indirectly by supporting prey populations. ganic (ORG) plots were planted in 76-cm rows; soy- The USDA Farming Systems Project (FSP), located bean in the no-till (NT) and chisel-till (CT) plots were in Beltsville, MD, was established in 1996 to evaluate planted in 19 cm rows. A rye cover crop was planted the sustainability of chisel-till, no-till, and organic using a no-till drill after corn harvest in all three cropping systems for the mid-Atlantic region of the systems. United States (Cavigelli 2005). One of the objectives A summary of management practices is presented in of the FSP is to understand the processes that inßu- Table 1. The NT plots were never tilled but did receive ence ecological community structure, including that herbicides before planting corn and after planting of soil macroinvertebrates. Here we report the Þnd- corn and soybean. The CT plots were tilled four ings from a comparison of ground beetle assemblages timesÑonce with a chisel plow, once with a disk, and in organic, no-till, and chisel-till cropping systems in twice with a Þeld cultivatorÑbefore planting corn the FSP. and twice with a disk before planting soybean. Weeds 1306 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 5 were controlled using herbicides after both crops Table 2. Carabid species collected from the USDA FSP site, were planted. The ORG plots were tilled two times, Beltsville, MD, 2001–2002 once with a disk and once with a Þeld cultivator, Species Number Percent before planting corn and cultivated four times after the corn was planted, twice using a rotary hoe and Scarites quadriceps Chaudoir 655 28 (LeConte) 409 18 twice using a row cultivator. The ORG plots received (LeConte) 318 14 no tillage before planting soybeans (soybeans were (DeGeer) 185 8 planted directly into a standing rye cover crop as in the (Say) 136 6 NT plots; in ORG plots, rye was killed after planting Clivina impressefrons LeConte 111 5 (Say) 86 4 soybeans using a ßail mower), but they were culti- (DeGeer) 83 4 vated four times after planting. The CT and NT plots (Duftschmid) ϩ A. 52 2 were fertilized with mineral fertilizers in accordance littoralis Mannerheim with University of Maryland soil testing recommen- rupestris (Say) 45 2 tricolor Dejean 38 2 dations for both crops. Corn in ORG plots was sup- Clivina bipustulata (Fabricius) 24 1 plied with N from the vetch cover crop. Chemical Anisodactulus rusticus (Say) 24 1 herbicides were applied to NT and CT plots according Harpalus affinis (Schrank) 24 1 to University of Maryland weed management recom- ochropezus (Say) 20 1 partiarius (Say) 18 1 mendations. No insecticides were used in any of the Harpalus herbivagus Say 15 1 cropping systems during the 2 yr of the study. sanctaecrucis (Fabricius) 14 1 Field Sampling and Data Analysis. Ground beetles Anisodactulus ovularis (Casey) 8 Ͻ1 were sampled in the 12 plots during the 2001 and 2002 Dyschiriodes globulosus (Say) 8 Ͻ1 Agonum octopunctatum (Fabricius) 8 Ͻ1 cropping seasons using unbaited pitfall traps. Six pitfall Harpalus erythropus Dejean 7 Ͻ1 traps (depth 95 mm by height 120 mm) were installed fulgens (Csiki) 7 Ͻ1 in a transect running down the center of each plot with pensylvanica (Linne´)6Ͻ1 10 m between each trap. Locating the traps the max- punctulata Olivier 4 Ͻ1 sericea (T.W. Harris) 3 Ͻ1 imum distance possible from the plot edges was in- Anisodactylus caenus (Say) 3 Ͻ1 tended to minimize edge effects. The traps contained longicornis (Say) 1 Ͻ1 propylene glycol and were maintained for 9Ð14 d (Fabricius) 1 Ͻ1 during each of three sampling periods: May (spring); Hayward 1 Ͻ1 July (summer); and October (fall). The contents of Total 2,313 100 the traps were preserved in 80% ethanol, sorted, and identiÞed using keys in Lindroth (1961Ð1969) and Ciegler (2000). The specimens were also compared ␭ test statistic from a multivariate ANOVA with reference specimens maintained at The Ohio (MANOVA) (SAS Institute 2004). State University and the National Museum of Natural History. Nomenclature follows Bousquet and Laro- chelle (1993) and Ball and Bousquet (2001). Results The relative abundances (also referred to as activity densities when using pitfall traps) of common species A total of 2,313 specimens, representing 31 species, and total ground beetles collected from each cropping were collected over the 2 yr of sampling (Table 2). All system each year, the measured species richness (ac- of the species except three, Harpalus affinis tual number of species collected) and estimated spe- (Schrank), Amara aenea (DeGeer), and Amara famil- cies richness of the carabid assemblages, and two in- iaris (Duftschmid), are native to North America. dices of species diversity were compared statistically Three of the species collected had not been recorded among the cropping systems using analysis of variance previously in Maryland according to Bousquet and (ANOVA) followed by the StudentÐNewmanÐKeuls Larochelle (1993): Scarites quadriceps Chaudoir, Ani- test when signiÞcant treatment effects were found sodactylus caenus (Say), and Harpalus affinis. The (P Յ 0.05). Analyses were run on ranked data when eight most common species represented 87% of the violations in normality were found. Estimated species total specimens collected and included S. quadriceps, richness was calculated with EstimateS 7.5 (Colwell Elaphropus anceps (LeConte), Bembidion rapidum 2005) using several common methods: bootstrap, Þrst- (LeConte), Harpalus pensylvanicus (DeGeer), Poeci- jackknife, and Chao2 (Walther and Morand lus chalcites (Say), Clivina impressefrons LeConte, 1998, Toti et al. 2000). Species diversity was calculated Agonum punctiforme (Say), and Amara aenea. All of using the Shannon and Simpson diversity indices as these species have been reported to be common in described in Brower et al. (1998). agricultural of central and eastern North Canonical variates analysis (CVA) was conducted America (Esau and Peters 1975, Dritschilo and Erwin on the 10 most common carabid taxa. To provide a 1982, Ferguson and McPherson 1985, Barney and Pass sufÞcient number of samples for this analysis (number 1986, Larochelle and Lariviere 2003, Larsen et al. of samples must be sufÞciently greater than number of 2003). Two species with relatively similar morpholog- variables for multivariate analyses), treatment was de- ical characteristics, Amara familiaris and A. littoralis Þned as cropping system plus year. Statistical com- Mannerheim, were considered a single taxon for this parisons among treatments were made using the Wilks analysis. October 2006 CLARK ET AL.: CARABIDS IN MARYLAND CROPPING SYSTEMS 1307

Table 3. Mean no. of the most common carabid species and total carabids collected per pitfall trap and measured species richness per plot from three farming systems of the USDA FSP, 2001

Mean Ϯ SEM Carabids P NT CT ORG Scarites quadriceps 1.36 Ϯ 0.44 1.60 Ϯ 0.41 0.85 Ϯ 0.20 0.46 Elaphropus anceps 0.30 Ϯ 0.15 1.11 Ϯ 0.56 0.89 Ϯ 0.31 0.26 Bembidion rapidum 0.06 Ϯ 0.04 0.06 Ϯ 0.06 0.62 Ϯ 0.40 0.16 Harpalus pensylvanicus 0.23 Ϯ 0.08 0.08 Ϯ 0.06 0.09 Ϯ 0.06 0.40 Poecilus chalcites 0.02 Ϯ 0.02 0.09 Ϯ 0.04 1.42 Ϯ 0.83 0.14 Clivina impressefrons 0.06 Ϯ 0.04 0.14 Ϯ 0.07 0.16 Ϯ 0.03 0.43 Agonum punctiforme 0.09 Ϯ 0.04 0.11 Ϯ 0.03 0.62 Ϯ 0.28 0.11 Amara aenea 0.09 Ϯ 0.04b 0.11 Ϯ 0.04b 0.64 Ϯ 0.19a 0.01 Total carabid abundance 2.61 Ϯ 0.63 3.93 Ϯ 0.33 6.39 Ϯ 1.81 0.10 Measured species richness 10.00 Ϯ 1.47 11.00 Ϯ 1.35 12.75 Ϯ 0.65 0.08

Means with different letters within a row indicate signiÞcant differences, ANOVA, SNK, P Յ 0.05.

In 2001, only one of the eight most common species, 2 yr shows the effect that sample size has on the direct A. aenea, showed a signiÞcant cropping system re- measurement of species richness (Fig. 1). As the num- sponse. It was more abundant in the ORG system than ber of specimens collected increases, the number of in the other two systems. There were no signiÞcant species encountered also increases until an asymptote differences in total carabid abundance or measured is eventually reached (Gotelli and Colwell 2001). In species richness (Table 3). In 2002, however, there this study, the asymptote was not reached in any of the were signiÞcant differences among cropping systems three systems, but because the ORG system had the for four of the eight most common species, total cara- greatest number of total carabids and the highest mea- bids, and total species (Table 4). Three species, B. sured species richness in both years (Tables 3 and 4), rapidum, H. pensylvanicus, and A. aenea, were signif- it was apparently closest to this theoretical asymptote icantly more abundant in the ORG system than in the (Fig. 1). The bootstrap, Þrst-order jackknife, and other two systems, whereas S. quadriceps was more Chao2 methods allow for the estimation of the asymp- abundant in the NT system than in the ORG system. totes and show very similar values for the three sys- Two of those three species, H. pensylvanicus, and A. tems, ranging from Ϸ21 to 28 species (Table 5). These aenea, have been reported to feed on seeds (Laro- estimators showed no signiÞcant differences among chelle and Lariviere 2003, Lundgren 2005) and may the three cropping systems. have been inßuenced by the greater food supply in the The Shannon and Simpson diversity indices showed ORG system (Teasdale et al. 2004). The greater level the same general pattern among the three cropping of ground cover due to cover crops and weeds in the systems during the 2 yr, but only in 2002 were there ORG system (J. R. Teasdale, personal communica- signiÞcant differences (Table 6). In 2002, the ORG tion) also may have had a positive inßuence on carabid system had a signiÞcantly higher Shannon index value abundance. The total number of ground beetles col- compared with the other two cropping systems (F ϭ lected was greater in the ORG system compared with 5.7, df ϭ 2,6, P ϭ 0.02) and a signiÞcantly higher the other two systems, and the measured species rich- Simpson index value compared with the NT system ness was greater in the ORG compared with the CT (F ϭ 4.3, df ϭ 2,6, P ϭ 0.05). There were no signiÞcant system (Table 4). differences between the NT and CT systems for either A graph of the relationship between the mean cu- diversity index. mulative number of species and the mean cumulative CVA showed a signiÞcant treatment effect (WilksÕ number of ground beetle specimens collected over the ␭, P Ͻ 0.0001), with canonical variates 1 and 2 ex-

Table 4. Mean no. of the most common carabid species and total carabids collected per pitfall trap and measured species richness per plot from three farming systems of the USDA FSP, 2002

Mean Ϯ SEM Carabids P NT CT ORG Scarites quadriceps 3.25 Ϯ 0.69a 1.97 Ϯ 0.20ab 1.03 Ϯ 0.06b 0.02 Elaphropus anceps 1.14 Ϯ 0.10 1.39 Ϯ 0.59 1.30 Ϯ 0.22 0.91 Bembidion rapidum 0.63 Ϯ 0.33b 0.72 Ϯ 0.19b 2.61 Ϯ 0.64a 0.007 Harpalus pensylvanicus 0.52 Ϯ 0.34b 0.36 Ϯ 0.10b 1.48 Ϯ 0.57a 0.04 Poecilus chalcites 0.11 Ϯ 0.07 0.09 Ϯ 0.03 0.26 Ϯ 0.12 0.11 Clivina impressefrons 0.16 Ϯ 0.06 0.44 Ϯ 0.12 0.70 Ϯ 0.17 0.09 Agonum punctiforme 0.11 Ϯ 0.05 0.11 Ϯ 0.07 0.20 Ϯ 0.08 0.63 Amara aenea 0.05 Ϯ 0.03b 0.02 Ϯ 0.02b 0.30 Ϯ 0.11a 0.05 Total carabid abundance 6.76 Ϯ 0.57b 5.60 Ϯ 0.43b 9.31 Ϯ 1.08a 0.01 Measured species richness 13.25 Ϯ 1.03ab 12.00 Ϯ 0.82b 16.00 Ϯ 0.71a 0.05

Means with different letters within a row indicate signiÞcant differences, ANOVA, SNK, P Յ 0.05. 1308 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 5

Table 6. Shannon and Simpson diversity indices calculated for the ground beetle assemblages in NT, CT, and ORG cropping systems of the USDA FSP, 2001–2002

Cropping system Index and year P NT CT ORG Shannon 2001 0.72 0.68 0.91 0.10 Shannon 2002 0.73b 0.76b 0.93a 0.02 Simpson 2001 0.69 0.66 0.85 0.06 Simpson 2002 0.70b 0.75ab 0.83a 0.05

Means with different letters within a row indicate signiÞcant dif- ferences, ANOVA, SNK, P Յ 0.05.

each other than either was to the organic system in either year. In addition, differences among treatments were not caused by differences in the number of S. Fig. 1. Species accumulation curves showing the rela- quadriceps, the most common species at the site. tionship between the mean cumulative number of ground beetle species collected and the mean cumulative number of specimens collected per cropping system over 2 yr of sam- pling at the USDA FSP, 2001Ð2002. Discussion The quest to understand the effects of human-in- plaining 77 and 19% of total variability, respectively duced ecological disturbances is fundamental to de- (Fig. 2). Canonical variates 1 and 2 were both signif- Ͻ veloping practical, science-based approaches to man- icant (MANOVA, P 0.0001). The mean value of aging ecosystems. This includes cropland, which canonical variate 1 was signiÞcantly different among covers Ϸ20% of the land area in the United States all six system-by-year treatments except that the CT (Vesterby and Krupa 2001). No-till and organic pro- system in 2001 and NT system in 2002 were not dif- duction systems have emerged in recent decades as ferent from each other (Table 7). Canonical variate 1 more environmentally sustainable alternatives to con- separated samples most strongly according to the ventional, tillage-based production systems that are numbers of Bradycellus rupestris (Say) and P. chalcites highly dependent on synthetic fertilizer and pesticide found in each sample and secondarily according to the inputs and fossil fuels and are vulnerable to acceler- numbers of A. punctiforme, B. rapidum, C. impresse- ϩ ated soil erosion. These alternative systems have been frons, and A. familiaris A. littoralis found in each promoted because of shown beneÞts, including re- sample (data not shown). Samples with high values of duced pesticide use, fuel use, and soil erosion, and canonical variate 1 tended to have high numbers of B. reduced potential for offsite environmental pollution. rupestris, A. punctiforme, B. rapidum, and C. impresse- However, the environmental pros and cons of no-till frons and low numbers of P. chalcites and A. familiaris ϩ and organic production systems differ. A. littoralis. Mean values for canonical variate 2 According to The National Organic Program of the were not different between the two conventional sys- USDA, organic production systems “emphasize the tems within a given year but all other treatment com- use of renewable resources and the conservation of parisons were signiÞcant (Table 7). Differences soil and water to enhance environmental quality” among treatments in canonical variate 2 were caused (The National Organic Program 2005). The primary primarily by differences in the numbers of A. aenea, H. distinction between organic and conventional crop pensylvanicus, and B. rapidum found in samples. Sam- production systems is that organic systems donÕt use ples with high values of canonical variate 2 had rela- synthetic fertilizers and pesticides. However, tillage is tively high numbers of H. pensylvanicus and B. rapi- typically used for managing weeds and preparing soil dum and relatively low numbers of A. aenea. Taken as a seedbed. In contrast, the advantages of no-till together, these CVA results show that, while almost all management are derived from the lack of soil distur- treatments differed from each other to some extent, bance. These include increased soil organic matter the two conventional systems were more similar to and water inÞltration and a reduction in soil erosion and fuel use (Hargrove 1990, Uri et al. 1999). Con- Table 5. Estimated species richness of ground beetles in the ventional synthetic herbicides are still a component of NT, CT, and ORG cropping systems of the USDA FSP using three no-till systems, but the crop residues found on the common estimation methods, 2001–2002 surface may provide habitat and food for epigeic or- Cropping system ganisms, such as ground beetles, that play an ecolog- Method P NT CT ORG ical role in suppressing crop pests. The objective of this study was to examine how Bootstrap 21.0 20.8 21.7 0.80 ground beetles are inßuenced by different systems of Jackknife 25.2 25.4 23.8 0.73 Chao-2 24.2 27.7 22.0 0.46 annual crop production. Several common measure- ments and standard ecological indices and estimators No signiÞcant differences among cropping systems, ANOVA. were used, allowing the results to be compared with October 2006 CLARK ET AL.: CARABIDS IN MARYLAND CROPPING SYSTEMS 1309

Fig. 2. Cropping system plots graphed on the Þrst two canonical variates generated from the 10 most common species of the USDA FSP. Canonical variates 1 and 2 account for 77 and 19% of total variability, respectively. All system-by-year combinations are signiÞcantly different from each other according to canonical variate 1 except for chisel-till system in 2001 and no-till system in 2002. According to canonical variate 2, the organic system was signiÞcantly different from the chisel-till and no-till systems in both years (P Ͻ 0.0001). other similar studies. In general, the differences ob- bers of carabids in organic systems (Dritschilo and served between the ORG and CT systems are consis- Wanner 1980, Kromp 1989, 1990, Ca´rcamo et al. 1995, tent with other studies comparing carabid assem- PÞffner and Niggli 1996, Clark 1999, Shah et al. 2003), blages in organic and conventional cropping systems but this sampling method precludes the separation of (Clark 1999 and references therein). In 2002, the rel- absolute density from activity. Further research could ative abundance, measured species richness, and spe- be aimed at addressing the question but methods for cies diversity were greater in the ORG than in the CT measuring carabid absolute densities are labor inten- system. Similar patterns were observed in 2001, but no sive (e.g., Frank 1971, Best et al. 1981, Brust et al. 1985, statistically signiÞcant differences were observed. In- Clark et al. 1995). terestingly, the estimated total species richness did not The Þnding of greater species diversity in the ORG differ between these two systems. The apparent in- system according to the Shannon and Simpson indices consistency between the measured and estimated spe- does differ from most other studies comparing cara- cies richness values resulted from the greater number bids in organic and conventional cropping systems of ground beetles collected in the ORG system. This (Dritschilo and Wanner 1980, Ca´rcamo et al. 1995, difference in relative abundance suggests a question Clark 1999, Shah et al. 2003). While the expectation for future study: do organic cropping systems have may be that carabid assemblages would have higher higher carabid absolute densities than conventional diversity in organic farming systems because of the systems? Published comparisons of ground beetles in reduction in pesticide use and addition of organic organic and conventional systems using pitfall traps amendments and cover crops, research has not shown and equal sampling effort usually report greater num- this. Some researchers have debated the usefulness of these and other diversity indices for comparing Table 7. Mean canonical variates for the 10 most common ground beetles assemblages as well as the meaning of carabid species for six cropping system-by-year treatments of the such numbers (Dritschilo and Erwin 1982, Jarosˇõ´k USDA FSP 1991). Nevertheless, these tools provide a means of Treatment Canonical variate 1 Canonical variate 2 simplifying large, complex data sets on ecological com- munities for ease in comparison. NT 2001 3.3e 0.6c CT 2001 7.2d 0.8c The relative similarity in the carabid assemblages of ORG 2001 21.4a Ϫ2.8d the NT and CT systems is somewhat surprising be- NT 2002 6.9d 4.2b cause some research has indicated that a reduction in CT 2002 11.7c 5.2b soil disturbance by tillage and consequent accumula- ORG 2002 19.4b 7.1a tion of detritus in no-till and reduced tillage systems Means with different letters within a column indicate signiÞcant beneÞts ground beetles and other epigeic inverte- differences, ANOVA, SNK, P Յ 0.05. brates (Stinner and House 1990). However, other 1310 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 5 studies using pitfall traps have shown that carabid References Cited abundance, species richness, and diversity are not Ball, G. E., and Y. Bousquet. 2001. Carabidae Latreille, 1810, inßuenced signiÞcantly by tillage (Ferguson and pp. 32Ð132. In R. H. Arnett, Jr. and M. C. Thomas (eds.), McPherson 1985, Belaoussoff et al. 2003), although the American beetles, vol. 1. CRC, Boca Raton, FL. relative abundances of individual species may be Barney, R. J., and B. C. Pass. 1986. Ground beetle (Co- (Clark et al. 1997). leoptera: Carabidae) populations in Kentucky alfalfa and The CVA based on the 10 most abundant species inßuence of tillage. J. Econ. Entomol. 79: 511Ð517. showed that the carabid assemblages in the three Belaoussoff, S., P. G. Kevan, S. Murphy, and C. Swanton. 2003. Assessing tillage disturbance on assemblages of cropping systems were distinguishable from each ground beetles (Coleoptera: Carabidae) by using a other even in the relatively narrow plots of this Þeld range of ecological indices. Biodivers. Conserv. 12: study where at least some carabid movement between 851Ð882. plots would be expected. The differences observed Best, R. L., C. C. Beegle, J. C. Owens, and M. Ortiz. 1981. between the treatments in this study probably reßect Population density, dispersion, and dispersal estimates for habitat preferences of individual carabid species or Scarites substriatus, chalcites, and Harpalus pennsylvanicus (Carabidae) in an Iowa cornÞeld. Envi- differences in food availability rather than direct pos- ron. Entomol. 10: 847Ð856. itive or negative effects on isolated or semi-isolated Bousquet, Y., and A. Larochelle. 1993. Catalogue of the Ge- carabid populations caused by management activities. (Coleoptera: , , The ORG system was found to be more different from Carabidae including ) of America north of the two conventional systems than the NT and CT Mexico. Mem. Entomol. Soc. Can. 167: 1Ð397. were from each other. The regular use of cover crops Brower, J. E., J. H. Zar, and C. N. von Ende. 1998. Field and laboratory methods for general ecology. McGraw-Hill, in the ORG system, and its effect on the soil food web, New York. may account for this difference. The assemblages Brust, G. E., and G. J. House. 1988. Weed seed destruction within individual cropping systems over the 2 yr of the by arthropods and rodents in low-input soybean agro- study also differed signiÞcantly according to the CVA, ecosystems. Am. J. Alternative Agric. 3: 19Ð25. possibly caused at least in part by the different crops Brust, G. E., B. R. Stinner, and D. A. McCartney. 1985. grown each year. Tillage and soil insecticide effects on predator-black cut- worm (Lepidoptera: Noctuidae) interactions in corn If a goal is to use ground beetles as indicators of agroecosystems. J. Econ. Entomol. 78: 1389Ð1392. ecological conditions or the effects of past distur- Brust, G.E., B.R. Stinner, and D.A. McCartney. 1986. Pred- bances, researchers need to consider whether com- ator activity and predation in corn agroecosystems. En- munity level attributes or indices, such as species rich- viron. Entomol. 15: 1017Ð1021. ness, diversity, or some other multimetric index, are Ca´rcamo, H. A. 1995. Effect of tillage on ground beetles really useful or if instead focus should be given to (Coleoptera: Carabidae): a farm-scale study in central Alberta. Can. Entomol. 127: 631Ð639. individual species or groups of species based on Ca´rcamo, H. A., J. K. Niemela, and J. R. Spence. 1995. Farm- knowledge of their biology and environmental sensi- ing and ground beetles: effects of agronomic practice on tivities or preferences. In addition, the dependence on populations and community structure. Can. Entomol. 127: pitfall traps for sampling, although cost effective, has 123Ð140. real limitations when comparing data from different Cartron, J.-E.E., M. C. Molles, Jr., J. F. Schuetz, C. S. Craw- treatments within a study or one study to another. ford, and C. N. Dahm. 2003. Ground arthropods as po- tential indicators of ßooding regime in the riparian forest Because no information on absolute densities can be of the middle Rio Grande, New Mexico. Environ. Ento- gained from pitfall trap data, we know very little about mol. 32: 1075Ð1084. the effects of human disturbances on the actual den- Cavigelli, M. (ed.). 2005. In-depth review brieÞng book of sities of ground beetle species, something that may be long-term Þeld experiment to evaluate sustainability of of profound importance when considering integrated organic and conventional cropping systems (http://ars. pest management and biological control. usda.gov/SP2UserFiles/Place/12650400/2.FSP10-Year ReviewSummaryBook110705.pdf). Ciegler, J.C. 2000. Ground beetles and wrinkled bark bee- tles of South Carolina (Coleoptera: Geadephaga: Cara- Acknowledgments bidae and Rysodidae). Biota of South Carolina, vol. 1. We thank A. Conklin, P. Krawczel, M. Davis, S. Placella, C. Clemson University, Clemson, SC. Endris, M. Hurwitz, N. Traylor-Knowles, M. Drusano, E. Clark, M. S. 1999. Ground beetle abundance and commu- nity composition in conventional and organic tomato Reed, G. Darlington, C. Rasmann, E. Kmitch, S. Denise, and systems of CaliforniaÕs Central Valley. Appl. Soil Ecol. 11: L. Jawson for help in the Þeld and laboratory. M. White, L. 199Ð206. Vallely, and J. Meyer assisted in sorting, counting, and pin- Clark, M. S., S. H. Gage, and J. R. Spence. 1997. Habitats and ning specimens. T. Erwin and W. Steiner provided access to management associated with common ground beetles a carabid reference collection at the National Museum of (Coleoptera: Carabidae) in a Michigan agricultural land- Natural History for use in identiÞcation. This study was scape. Environ. Entomol. 26: 519Ð527. supported by a grant from the Center for Livable Future, Clark, M. S., J. M. Luna, N. D. Stone, and R. R. Youngman. Johns Hopkins School of Public Health, and by the JHU 1993. Habitat preferences of generalist predators in re- DeanÕs Research Grant to K.S. S. Placella was supported by duced-tillage corn. J. Entomol. Sci. 28: 404Ð416. the National Science Foundation, REU supplement to DEB Clark, M. S., J. M. Luna, N. D. Stone, and R. R. Youngman. 9714835. 1994. Generalist predator consumption of armyworm October 2006 CLARK ET AL.: CARABIDS IN MARYLAND CROPPING SYSTEMS 1311

(Lepidoptera: Noctuidae) and effect of predator re- Larsen, K. J., T. T. Work, and F. F. Purrington. 2003. Habitat moval on damage in no-till corn. Environ. Entomol. 23: use patterns by ground beetles (Coleoptera: Carabidae) 617Ð622. of northeastern Iowa. Pedobiologia 47: 288Ð299. Clark, M. S., J. M. Luna, and R. R. Youngman. 1995. Es- Lindroth, C. H. 1961–1969. The ground beetles (Carabidae, timation of adult carabid absolute densities in a no-till exc. Cicindelinae) of Canada and Alaska. Parts 1Ð6. Opus- corn Þeld by removal sampling. Appl. Soil Ecol. 2: cula Entomologica, Lund, Sweden. 185Ð193. Lopez, M. D., J. R. Prasifka, D. J. Bruck, and L. C. Lewis. Colwell, R.K. 2005. EstimateS: statistical estimation of spe- 2005. Utility of ground beetle species in Þeld tests of cies richness and shared species from samples, version 7.5 potential nontarget effects of Bt crops. Environ. Entomol. (http://purl.oclc.org/estimates). 1317Ð1324. Da´valos, A., and B. Blossey. 2004. Inßuence of invasive herb Lo¨vei, G. L., and K. D. Sunderland. 1996. Ecology and be- garlic mustard (Alliaria petiolata) on ground beetle (Co- havior of ground beetles (Coleoptera: Carabidae). Annu. leoptera: Carabidae) assemblages. Environ. Entomol. 33: Rev. Entomol. 41: 231Ð256. 564Ð576. Lundgren, J. G. 2005. Ground beetles as weed control Dritschilo, W., and D. Wanner. 1980. Ground beetle abun- agents: effect of farm management on granivory. Am. dance in organic and conventional corn Þeld. Environ. Entomol. 51: 224Ð226. Entomol. 9: 629Ð631. Menalled, F. D., J. C. Lee, and D. A. Landis. 1999. Manip- Dritschilo, W., and T. Erwin. 1982. Responses in abundance ulating carabid beetle abundance alters prey removal and diversity of cornÞeld carabid communities to differ- rates in corn Þelds. BioControl 43: 441Ð456. ences in farm practices. Ecology 63: 900Ð904. Menalled, F. D., J. C. Lee, and D. A. Landis. 2001. Herba- Ellsbury, M. M., J. E. Powell, F. Forcella, W. D. Woodson, ceous Þlter strips in agroecosystems: implications for S. A. Clay, and W. E. Riedell. 1998. Diversity and dom- ground beetle (Coleoptera: Carabidae) conservation and inant species of ground beetle assemblages (Coleoptera: weed seed predation. Great Lakes Entomol. Carabidae) in crop rotation and chemical input systems 34: 77Ð91. for the northern Great Plains. Ann. Entomol. Soc. Am. 91: Niwa, C. G., and R. W. Peck. 2002. Inßuence of prescribed 619Ð625. Þre on carabid beetle (Carabidae) and spider (Araneae) Esau, K. L., and D. C. Peters. 1975. Carabidae collected in assemblages in forest litter in southwestern Oregon. En- pitfall traps in Iowa cornÞelds, fencerows, and prairies. viron. Entomol. 31: 785Ð796. Environ. Entomol. 4: 509Ð513. Pfiffner, L., and U. Niggli. 1996. Effects of bio-dynamic, Ferguson, H. J., and R. M. McPherson. 1985. Abundance organic, and conventional farming on ground beetles and diversity of adult Carabidae in four soybean cropping (Coleoptera: Carabidae) and other epigaeic arthropods systems in Virginia. J. Entomol. Sci. 20: 163Ð171. in winter wheat. Biol. Agric. Hort. 12: 353Ð364. Frank, J. H. 1971. Carabidae (Coleoptera) of an arable Þeld Rainio, J., and J. Niemela. 2003. Ground beetles (Co- in central Alberta. Quaes. Entomol. 7: 237Ð252. leoptera: Carabidae) as bioindicators. Biodivers. Conserv. French, B. W., L. D. Chandler, M. M. Ellsbury, B. W. Fuller, 12: 487Ð506. and M. West. 2004. Ground beetle (Coleoptera: Cara- SAS Institute. 2004. SAS/STAT 9.1 userÕs guide. SAS Insti- bidae) assemblages in a transgenic corn-soybean crop- tute, Cary, NC. ping system. Environ. Entomol. 33: 554Ð563. Shah, P. A., D. R. Brooks, J. E. Ashby, J. N. Perry, and I. P. Gotelli, N., and R. K. Colwell. 2001. Quantifying biodiver- sity: procedures and pitfalls in the measurement and Woiwod. 2003. Diversity and abundance of coleopteran comparison of species richness. Ecol. Lett. 4: 379Ð391. fauna from organic and conventional management sys- Hance, T. 1987. Predation impact of carabids at different tems in southern England. Agric. Forest Entomol. 5: 51Ð population densities on Aphis fabae development in sugar 60. beet. Pedobiologia 30: 251Ð262. Stinner, B. R., and G. J. House. 1990. Arthropods and other Hargrove, W.L. 1990. Role of conservation tillage in sus- in conservation-tillage agriculture. Annu. tainable agriculture. Proceedings of the 13th Annual Rev. Entomol. 35: 299Ð318. Southern Conservation Tillage Conference for Sustain- Symondson, W.O.C., K. D. Sunderland, and M. H. Green- able Agriculture, 16Ð17 July, Raleigh, NC. stone. 2002. Can generalist predators be effective bio- House, G. J., and B. R. Stinner. 1983. Arthropods in no- control agents? Annu. Rev. Entomol. 47: 561Ð594. tillage soybean agroecosystems: community composition Teasdale, J. R., R. W. Mangum, J. Radhakrishnan, and M. A. and ecosystem interactions. Environ. Manag. 7: 23Ð28. Cavigelli. 2004. Weed seedbank dynamics in three House, G. J., and R. W. Parmelee. 1985. Comparison of soil organic farming crop rotations. Agronomy J. 96: 1429Ð arthropods and from conventional and no- 1435. tillage agroecosystems. Soil Tillage Res. 5: 351Ð360. The National Organic Program. 2005. Organic food stan- Jarosˇı´k, V. 1991. Are diversity indices of carabid beetle dards and labels: the facts (http://www.ams.usda.gov/ (Col., Carabidae) communities useful, redundant, or mis- nop/Consumers/brochure.html). leading? Acta Entomol. Bohemoslov 88: 273Ð279. Thiele, H.-U. 1977. Carabid beetles in their environments. Kromp, B. 1989. Carabid beetle communities (Carabidae: Springer, New York. Coleoptera) in biologically and conventionally farmed Thorbek, P., and T. Bilde. 2003. Reduced numbers of gen- agroecosystems. Agric. Ecosyst. Environ. 27: 241Ð251. eralist predators after crop management. Kromp, B. 1990. Carabid beetles (Coleoptera: Carabidae) J. Appl. Ecol. 41: 526Ð538. as bioindicators in biological and conventional farming in Toti, D. S., F. A. Coyle, and J. A. Miller. 2000. A structured Austrian potato Þelds. Biol. Fert. Soils 9: 182Ð187. inventory of Appalachian grass bald and heath bald spider Larochelle, A., and M.-C. Lariviere. 2003. A natural history assemblages and a test of species richness estimator per- of the ground-beetles (Coleoptera: Carabidae) of Amer- formance. J. Arachnol. 28: 329Ð345. ica north of Mexico. Pensoft Series Faunistica, SoÞa, Bul- Tyler, B. M., and C. R. Ellis. 1979. Ground beetles in three garia. tillage plots in Ontario and observations on their impor- 1312 ENVIRONMENTAL ENTOMOLOGY Vol. 35, no. 5

tance as predators of northern corn rootworm, Diabrotica Walther, B. A., and S. Morand. 1998. Comparative perfor- longicornis (Coleoptera: Chrysomelidae) Proc. Entomol. mance of species richness estimation methods. Parasitol- Soc. Ontario 110: 65Ð73. ogy 116: 395Ð405. Uri, N. D., J. D. Atwood, and J. Sanabria. 1999. The envi- Zhang, J., F. A. Drummond, M. Liebman, and A. Hartke. ronmental beneÞts and costs of conservation tillage. En- 1997. predation on seeds and plant population viron. Geol. 38: 111Ð125. dynamics. Maine Agricultural and Forest Experiment Sta- Vesterby, M., and K.S. Krupa. 2001. Major uses of land in tion, Orono, Maine. the United States, 1997. Resource Economics Division, Economic Research Service, US Department of Agri- Received for publication 10 February 2006; accepted 9 June culture, Washington, DC. 2006.