Sensitivity of European corn borer larvae (second instar) on pollen of B.t.-176 maize was tested during the research project 'Impact of pollen from transgenic B.t.-maize on non-target-lepidopterans' that was financially supported by the Federal Ministry of Education and Research (BMBF) and the Federal Environment Agency (UBA).  Bioassays were set up as no choice tests and caterpillars were fed with defined amounts of pollen from the transgenic cultivar B.t.-176 (PACTOL CB), which expresses the Cry1Ab ä endotoxin, as well as the conventional isogenic cultivar PACTOL.  After one week larval weight gain and mortality were recorded.  Mortality of the tested European corn borer larvae increased with increasing pollen numbers indicating a clear dose-response relationship.  Application of even 10 pollen grains B.t.-176 maize per larva led to an increased mortality rate of 28 ± 10,2 % as compared to the untreated control (10,31 ± 2,41 %).  Mortality between B.t.-176 variants and untreated control differed significantly if 20 (mortality rate = 59,56 ± 12,07 %) or more pollen grains per larva were applied.  The highest pollen dose tested (160 pollen grains per individual) caused a mortality rate of 80 ± 8,37 %.  Weight gain of larvae fed with pollen from B.t.-176 maize was lower as compared to the untreated control, but differences were not significant.  Ingestion of conventional maize pollen did not have positive nor negative effects on survival or development of the larvae.  The LC50-value was calculated with 32,43 B.t.-176 maize pollen applied per larva.  95 % confidence limit ranged between 19,38 and 48,8 pollen grains.  So susceptibility of 2nd instar larvae of the European corn borer to B.t.-176 maize pollen is comparable to susceptibility of larvae of some other European or North American butterfly species which are common in agricultural used habitats.  It is not possible to establish a laboratory rearing for most non-target-butterflies, which might possibly be affected by cultivation of B.t. plants.  Therefore we suggest that the European corn borer, which is easy to rear under laboratory conditions, can be used as a test organism in a GMO environmental risk assessment to investigate potential side effects of pollen from newly developed B.t. plants, expressing the Cry1Ab ä endotoxin, on larvae of non-target-lepidopterans from different groups (without Noctuidae).  (Please note, article text is in German.)