Table 1. description of the eight sampling sites where decaying leaf litter were collected.

Site	Type	Occurrence of treatmenta	Dominant species	Year of sampling	Toxicity in vitrob
Tal (1)	Forest	treated	Alnus glutinosa, Fraxinus excelsior	2002, 2003, 2005	+
Lav (2)	Forest	treated	Alnus glutinosa, Fraxinus excelsior	2002, 2003, 2005	+
Bre (3)	Forest	treated	Alnus glutinosa, Quercus robur	2002, 2003	+
Mon (4)	Forest	treated	Alnus glutinosa, Alnus incana	2002	+
StQ (5)	Forest	treated	Alnus glutinosa	2002	+
StB (6)	Forest	untreated	Alnus glutinosa, Fraxinus excelsior	2006	+
Cha (7)	Swamp	treated	Carex sp.	2002	+
StM (8)	Artificial	untreated	Populus nigra	2005, 2006	+

^aThe sites referred to as “treated” correspond to mosquito breeding sites where annual spreading of the insecticide Bti occurred for more than ten years. No Bti treatment was ever applied in “untreated” areas.

^bThe leaf litter samples were submitted to the 3-step process for in vitro synthesis of the toxicity: when more than 80% mortality was obtained in the bioassays for at least two leaf litter samples from the same site, the columns were referred to as “+”.