Structure of Arthropod Communities in Bt Maize and Conventional Maize – …

JOURNAL FÜR KULTURPFLANZEN, 63 (12). S. 401–410, 2011, ISSN 1867-0911 VERLAG EUGEN ULMER KG, STUTTGART Originalarbeit Bernd Freier1, Christel Richter2, Veronika Beuthner2, Giana Schmidt2, Christa Volkmar3 Structure of arthropod communities in Bt maize and conventional maize – results of redundancy analyses of long-term field data from the Oderbruch region in Germany Die Struktur von Arthropodengesellschaften in Bt-Mais und konventionellem Mais – Ergebnisse von Redundanzanalysen von mehrjährigen Felddaten aus dem Oderbruch 401 Abstract both communities (1.5% and 1.2%, respectively). The results correspond with those of other studies. They show The arthropod biodiversity was investigated in half-fields the enormous dynamics of arthropod communities on planted with Bt maize (BT) and non-insecticide treated maize plants and on the ground and the relatively low conventional maize (CV) and in one-third fields planted effect of maize variant. with BT and CV plus either isogenic (IS) or insecticide-treated conventional maize (IN) in the Oderbruch Key words: Arthropods, spiders, carabids, community region in the state of Brandenburg, Germany, an impor- composition, Bt maize, biodiversity, redundancy analysis tant outbreak area of the European corn borer, Ostrinia nubilalis (Hübner), from 2000 to 2008. Three different arthropod communities – plant dwelling arthropods Zusammenfassung (PDA), epigeic spiders (ES) and ground-dwelling carabids (GDC) – were enumerated by counting arthropods Im Oderbruch, ein wichtiges Befallsgebiet des Maiszüns- on maize plants during flowering (PDA, 2000 to 2007) or lers (Ostrinia nubilalis (HÜBNER)), wurde in den Jahren by pitfall trapping four weeks after the beginning of flow- 2000 bis 2008 die Biodiversität der Arthropoden in hal- ering (ES and GDC, 2000 to 2008). The counted arthro- ben Feldern jeweils mit Bt-Mais (BT) und nicht mit Insek- pods (PDA) were determined to different taxonomic tiziden behandelten konventionellen Mais (CV) und teil- levels, and the spiders and carabids captured in pitfall weise in dreigeteilten Feldern mit BT und CV plus einer traps were identified to species level. The data were isogenen (IS) oder insektizid-behandelten Sorte (IN) un- systematized and verified for choice of appropriate statis- tersucht. Drei unterschiedliche Arthropodengesellschaf- tical method. Redundancy analysis (RDA) proved to be a ten – Pflanzenbewohner (PB), epigäische Spinnen (ES) suitable method. The results showed that 83.2% of spe- und epigäische Laufkäfer (EL) – wurden mittels Bonitu- cies variation in PDA was explained by year-site-date ren der Pflanzen zu Beginn der Blüte (PB, 2000 bis 2007) combinations and maize variant. Bt maize contributed und durch wöchentliche Bodenfallenfänge über vier Wo- only 1.2% to species composition, but this low rate was chen nach Beginn der Blüte (ES und EL, 2000 bis 2008) significant. Regarding the spiders and carabids commu- erfasst. Die PB wurden je nach den Möglichkeiten auf nities, 66.3% and 82.7% of species variation was caused unterschiedlichem taxonomischen Niveau und die ES by year-site combinations and maize variant, respectively. und EL nach Arten bestimmt. Die Daten wurden syste- The contribution of Bt maize was low but significant in matisiert und für die Wahl der geeigneten statistischen Institute Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Strategies and Technology Assessment, Kleinmachnow, Germany1 Humboldt-Universität zu Berlin, Faculty of Agriculture and Horticulture, Berlin, Germany2 Martin-Luther-Universität Halle-Wittenberg, Institute for Agriculture and Nutritional Sciences, Halle/Saale, Germany3 Correspondence Prof. Dr. Bernd Freier, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Strategies and Techno- logy Assessment, 14532 Kleinmachnow, Germany, E-Mail: [email protected] Accepted 31 August 2011 BERND FREIER et al., Structure of arthropod communities in Bt maize and conventional maize – … Auswertungsmethode verifiziert. Die Redundanzanalyse 2007; AVIRON et al., 2009; HIGGINS et al., 2009). Previous Originalarbeit erwies sich als geeignete Methode. Die Ergebnisse zeig- studies have shown that there is a special need for ten, dass 83,2% der Artenvariation der PB aus den Jahr- long-term field studies to evaluate the risks of Bt maize Ort-Termin-Kombinationen und Maisvarianten zu erklä- on arthropod communities under typical field conditions. ren waren. Bt-Mais steuerte nur 1,2% zur Artenkomposi- The aims of the present investigation was to analyze tion bei, dennoch war dieser Anteil signifikant. Im Hin- the structure and dynamics of arthropod communities in blick auf die ES und EL verursachten die Jahr-Ort-Kombi- fields planted with Bt maize and conventional maize nationen und die Maisvarianten 66,3% und 82,7% der based on data collected by counting arthropods on maize Artenvariation. Der Beitrag von Bt-Mais war mit 1,5% plants and in pitfall traps (ground-dwelling spiders and und 1,2% in beiden Gesellschaften gering aber signifi- carabids) in the years 2000 to 2008. kant. Die Ergebnisse stimmen überein mit denen anderer Studien. Sie zeigen die enorme Dynamik der Arthropo- dengesellschaften in Maisbeständen und den geringen 2 Material and Methods Effekt von Bt-Mais auf die Biodiversität. 2.1 Sampling Stichwörter: Arthropoden, Spinnen, Laufkäfer, The field studies were conducted at different farms in Zusammensetzung von Arthrodengesellschaften, the Oderbruch region in the state of Brandenburg, Bt-Mais, Biodiversität, Redundanzanalyse Germany, east of Berlin, near the Polish border from 402 2000 to 2008. An additional field study was carried out at site Spickendorf (near Halle, Germany, in the state of 1 Introduction Saxony-Anhalt) in the year 2000. Fields were divided into two parts (half-fields) planted with Bt maize (BT) Since the beginning of Bt maize growing around the and non-insecticide treated conventional maize (CV) or world, numerous laboratory experiments (HILBECK et al., into three parts (third-fields) planted with BT and CV 1998; MEIER and HILBECK, 2001; ROMEIS et al., 2004) and plus either isogenic conventional maize (IS, 2000 or in- field studies have been performed to study its effects on secticide-treated conventional maize (IN, 2004–2006). non-target arthropods and other organisms in the fields Baythroid 50 (2004) and Steward (2005, 2006) were (LUDY, 2005; RAUSCHEN et al., 2010; WENDT et al., 2010), used to control Ostrinia nubilalis in IN maize. Tab. 1 in the adjacent field boundaries (LOSEY et al., 1999; summarizes the fields investigated and samplings per- SAXENA et al., 1999; FELKE and LANGENBRUCH, 2001, 2003), formed in the study. All half-fields and third-fields were and in nearby aquatic systems (CHAMBERS et al., 2010). In subjected to the same agricultural management mea- 2003, an IOBS/WPRS working group was established to sures, and all fields had a similar previous cropping and better communicate research findings on the ecological management history. impact of genetically modified organisms, particularly Bt Arthropods were sampled in the maize fields by the maize. following methods: Field studies on Bt maize (Cry1Ab) have generally Arthropod counting on plants: At 5 or 10 (only in focused on possible direct side-effects of the associated 2001) sampling points in each half- or third-field, arthro- toxin on non-target lepidoptera species that are espe- pods on three or four maize plants each were counted cially sensitive to toxin (WAQUIL et al., 2002; SZENAZI et and determined by the naked eye. Counts were per- al., 2004) and other non-target organisms. Most of these formed at the time of flowering in all years, and also studies were designed as field plot experiments with during the late flowering and milk stages in 2001 to 2005 replicates or as field-field comparisons with replicates in (Tab. 1). different years and sites and aimed to assess and compare Pitfall trapping: Ten (2000 to 2002) or six (2003 to densities of species or higher taxonomic units in Bt maize 2008) 10-cm traps containing 2% formaldehyde solution and other maize-growing systems (HIGGINS et al., 2009; were installed in each half- or third-field for four or six WENDT et al., 2010). In general, no significant impact of (2000, 2001) weeks after the beginning of maize flower- Bt maize on non-target arthropods was found (SANDIVO ing. Traps were emptied at weekly intervals. All trapped et al., 2007; ROMEIS and SHELTON, 2009) except in lepi- spiders and carabids were determined to species level. In dopteran larvae feeding maize or maize pollen which each case, the distance between each of the sampling contents a toxic amount of toxin (EIZAGUIRRE et al., 2010). points was about 20 meters. Furthermore, sampling Apart from density analysis, the impact of maize-grow- points were arranged along the mid-line of each half- or ing systems including Bt maize (Cry1Ab, Cry3Bb, Cry 1F) third-field to ensure inclusion of arthropod communities on biodiversity parameters in arthropod communities within the fields and to exclude the influence of those has been investigated in field studies (LESLIE et al., 2010). from surrounding habitats and field borders. However, such investigations are costly and must be car- Taxonomic determination of carabids species was carried out on sufficiently large fields. Multivariate statisti- ried out by Joachim GRUEL, Andreas SCHOBER and Ismail cal methods such as correspondence analysis are gener- HUSSEIN based on the classification guides of

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