Genes of Bacillus thuringiensis var. kurstaki (Berliner) that encode
lepidopteran-specific toxins were engineered into maize for protection against the
European Corn Borer, Ostrinia nubilalis (Hbn.). Recent data suggest that
Lepidoptera may be negatively affected, if maize pollen contains high amounts of
Bt toxin and is diposited on host plants near maize fields. Monitoring
the environmental effects of commercial Bt maize fields requires effective use
of limited financial and logistical resources. The aim of this study was to develop
and apply tools for selecting relevant herbivore species for the field monitoring
of environmental Bt toxin effects via pollen deposition. We first present
a theoretical selection tree based on “risk index of Bt pollen for herbivores”
(IBtp). Our index consists of five classes from zero (not relevant) to four
(highly relevant) derived from data on potential temporal and spatial coincidence of pollen
exposure (A), feeding mode (B), susceptibility to lepidopteran-specific Bt toxins
(C) and hazard to rare and/or endangered species (“Red List”) (D). We then screened
the Macrolepidoptera database LEPIDAT to identify relevant species in Germany. Finally,
we also applied the index to species found in a local biocoenotic field study (Bonn,
Western Rhineland, Germany). Approximately 7% of the German Macrolepidoptera species
mainly occur in farmland areas and were selected as being potentially affected by Bt
pollen exposure. Of these species, 14% (= 1% of total) were found to be potentially
exposed on a regional scale. The combination of IBtp and database screening
enables us to pre-select species for monitoring purposes.