In-Field Monitoring of Beneficial Insect Populations in Transgenic Corn Expressing a Bacillus thuringiensis Toxin

Abstract

In 1998 and 1999, field studies were conducted near Rosemount, MN to assess the potential impact of transgenic sweet corn, transformed to express the Cry1Ab toxin from Bacillus thuringiensis Berliner var kurstaki (i.e., Bt corn), on several beneficial insects, including predatory coccinellids, chrysopids and anthocorids. Beneficial insects in both Bt and in non-Bt sweet corn were also monitored in field cages in 1999. Plants were visually sampled for beneficial insects by arbitrarily selecting 3 consecutive plants from each plot or 6 plants/cage. Rank transformed data were analyzed using the Kruskal-Wallis test, which indicated no significant within-year differences in the overall density of beneficial insect populations between Bt and non-Bt sweet corn. Coleomegilla maculata (DeGeer) was the dominant predator species detected in 1998 and 1999. A significant trend (P < 0.05) was found for C. maculata larvae in open plots, with non-Bt treatments having higher C. maculata levels than Bt. Also, C. maculata larval and adult densities, for caged plots, showed a significant trend for higher counts in the in non-Bt corn. No additional differences in species diversity of beneficial insects were detected using Hills N1. Neither Hippodamia convergens Guérin-Ménville, Adalia bipunctata (L.), nor Coccinella septempunctata L. were observed during 1999. Although our test detected significant trends for higher densities of C. maculata in non-Bt corn, the results also suggest that longer-term in-field studies with higher sample sizes are needed to further characterize what may be relatively subtle population effects in the field.

Effect of Bt-maize on epigeic spiders (Araneae) and harvestmen (Opiliones)

“…Evidence came both from laboratory and field observations. Densities of Chrysoperla larvae that fed on caterpillars on Bt maize were reduced in comparison with those on non-Bt maize (WOLD et al 2001). A study of JIANG et al (2004) found that Pirata subpiraticus (Boesenberg et Strand) spiders fed with preys (planthopper or aphid) that had ingested Bt rice, had this toxin in their body.…”

Applications (EFSA‐GMO‐RX‐MON810) for renewal of authorisation for the continued marketing of (1) existing food and food ingredients produced from genetically modified insect resistant maize MON810; (2) feed consisting of and/or containing maize MON810, including the use of seed for cultivation; and of (3) food and feed additives, and feed materials produced from maize MON810, all under Regulation (EC) No 1829/2003 from Monsanto

“…The EFSA GMO Panel is of the opinion that these data are not sufficient to identify a hazard or indicate a new mode of action of Cry proteins on the coccinellid species tested. Wold et al (2001) did not find adverse effects on Adalia bipunctata in laboratory and field studies (but reported some adverse effects on another coccinellid species in the laboratory test). Dhillon and Sharma (2009) ).…”

Impact environnemental des cultures transgéniques

“…Si la migration d'organismes prédateurs en réponse à une faible densité de proies herbivores nourries de plantes Bt a été observée dans certains cas , la plupart des études suggèrent plutôt des effets très limités sur les populations non visées (Al-Deeb et al 2001;Jasinski et al 2003;Liu et al 2002;Ning et al 2001;Sun et al 2002;Wold et al 2001). Dans un contexte agricole, l'effet des cultures Bt serait en fait négligeable comparativement aux effets négatifs généralement observés sur les mêmes populations avec les insecticides de synthèse, qui montrent souvent un effet toxique plus étendu (Musser et Shelton 2003;Reed et al 2001).…”