Effects on monarch butterfly, Danaus plexippus L., after continuous exposure of larvae to natural deposits of Bacillus thuringiensis (Bt) and non-Bt pollen on milkweed, were measured in five studies. First instars were exposed at 3-4 and 6-7 d after initial anthesis, either directly on milkweed plants in commercial cornfields or in the laboratory on leaves collected from milkweeds in corn plots. Pollen exposure levels ranging from 122 to 188 grains/cm 2 /d were similar to within-field levels that monarch butterfly populations might experience in the general population of cornfields. Results indicate that 23.7% fewer larvae exposed to these levels of Bt pollen during anthesis reached the adult stage. A risk assessment procedure used previously was updated with a simulation model estimating the proportion of second-generation monarch butterflies affected. When considered over the entire range of the Corn Belt, which represents only 50% of the breeding population, the risk to monarch butterfly larvae associated with long-term exposure to Bt corn pollen is 0.6% additional mortality. Exposure also prolonged the developmental time of larvae by 1.8 d and reduced the weights of both pupae and adults by 5.5%. The sex ratio and wing length of adults were unaffected. The ecological significance of these sublethal effects is discussed relative to generation mortality and adult performance. BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses.Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne's Terms of Use, available at www.bioone.org/page/terms_of_use.Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. ABSTRACT Effects on monarch butterßy, Danaus plexippus L., after continuous exposure of larvae to natural deposits of Bacillus thuringiensis (Bt) and non-Bt pollen on milkweed, were measured in Þve studies. First instars were exposed at 3Ð 4 and 6 Ð7 d after initial anthesis, either directly on milkweed plants in commercial cornÞelds or in the laboratory on leaves collected from milkweeds in corn plots. Pollen exposure levels ranging from 122 to 188 grains/cm 2

In this paper, the native and nonnative floras of Boston, New York, Philadelphia, Washington, D.C., Detroit, Chicago, Minneapolis, and St. Louis urban areas are compared, and overall native diversity and nonnative diversity are correlated with a variety of factors. A total of 4,159 species has been reported in the eight urban areas. Of these, 2,708 (65.1%) are native to one or more of the urban areas and 1,451 (34.9%) are nonnative. Only 316 (11.6%) of the native species and only 109 (7.5%) of the nonnative species are common to all of the urban areas. When the similarity of native species is compared, Boston, New York, Philadelphia, and Washington, D.C., form a cluster, as do Detroit, Chicago, and Minneapolis; St. Louis is least similar to the other seven urban areas. Correlating climatic variables (growing season, temperature) and geographical variables (area, latitude, longitude) with species richness showed that nonnative species richness was most strongly correlated with longitude (probably as a function of age of settlement). This is in contrast * Published Online June 24, 2003 with past research on native species showing a strong correlation of native species richness with latitude and elevations due to climatic differences present at different latitudes and elevations. Further studies that incorporate data from additional urban areas are needed to determine if nonnative species richness continues to be strongly correlated with time of a city's settlement.

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unpublished data, 1990) indicate that annual ECB infestations average 0.37 larvae plant Ϫ1 for first generation The European corn borer [Ostrinia nubilalis (Hü bner)] is an impopulations and 1.56 larvae plant Ϫ1 for second generaportant pest of field corn (Zea mays L.) in the northeastern USA. One option for reducing yield loss from European corn borer (ECB) tion populations. Provided that similar infestations ocis the use of transgenic corn hybrids containing a modified Bacillus cur in the Northeast, this would have resulted in an thuringensis (Bt) gene. This study evaluated Bt hybrids, their near estimated annual loss of $35 million due to ECB for isolines, and leading non-Bt hybrids for grain yield, moisture, and Northeast corn producers in 2001. test weight under natural infestations of ECB in 2000, 2001, and 2002 Transgenic Bt corn hybrids were introduced in 1996 at four to six locations across Pennsylvania and Maryland each year. and effectively control ECB and eliminate yield losses Averaged over all locations and years, Bt, isoline, and lead hybrids when subjected to economic ECB infestations. The cost yielded 9.1, 8.6, and 8.5 Mg ha Ϫ1 , respectively. Grain moisture content effectiveness of these hybrids in the Northeast is uncerat harvest was 224, 216, and 214 g kg Ϫ1 and test weight was 705, 713, tain, however. The added cost of Bt hybrid corn seed and 713 kg m Ϫ3 for Bt, isoline, and lead hybrids, respectively. Overall, may be justified in areas with a high probability forBt hybrids produced higher yields, but also had higher grain moisture content at harvest and lower test weight than isoline and lead hybrids. Hyde et al., 1999aHyde et al., , 2003 and higher Yield and moisture content differences were correlated with ECB levels of damage per larva. Better information on ECB infestations, but test weight was not. Isoline and lead hybrid yields infestations and yield and quality of Bt corn grown in the were reduced by 2.37 and 2.60% respectively, for each ECB tunnel. ECB infestation (Northeast would help producers make more informed Precipitation had no consistent effect on Bt and non-Bt hybrid differdecisions when selecting hybrids for corn production. ences for yield, moisture, or test weight. Delayed planting dates were Singer et al. (2000) conducted a 4-yr study in New associated with higher ECB infestations. This may be beneficial in Jersey comparing ECB damage associated with manure predicting sites that could benefit from Bt hybrids. In some environor N fertilizer applications and found Bt corn hybrids ments in Pennsylvania and Maryland, Bt hybrids can result in signifiyielded 8 to 18% greater than non-Bt hybrids in the cant yield advantages.manure treatments, however only 2 to 6% greater in the fertilizer treatments (Singer et al., 2000). Cox and Cherney (2001) concluded that Bt hybrids did not yield to be similar for Bt and isoline hybrids under relatively