Effects of different concentrations of glyphosate (Roundup 360 ® ) on earthworms ( Octodrilus complanatus , Lumbricus terrestris and Aporrectodea caliginosa ) in vineyards in the North-East of Italy

The study aims to analyse the effects of the herbicide glyphosate (Roundup 360 ® ) on three key earthworm species. The taxa collected from treated and untreated sites were subsequently bred in uncontaminated soil terraria with serial concentrations of the herbicide. The chosen taxa included two anecic ( Lumbricus terrestris and Octodrilus complanatus ) and one endogeic ( Aporrectodea caliginosa ) earthworms. Lumbricus terrestris collected from uncontaminated soil (Lt1) and in a conventionally managed vineyard (Lt2). Aporrectodea caliginosa and Octodrilus complanatus collected from the same uncontaminated site where L. terrestris (Lt1) were collected. Uncontaminated natural grassland soil filling the terraria was characterized for physical-chemical properties. The reproduction rate expressed in earthworms cocoon production was the measure for the effects on worms survival after 21 and 42 days of exposure to 0.59, 2.9, 5.79 g/m 2 of glyphosate, where the dose applied in vineyards in the North-East of Italy goes from 0.72 g/m 2 to 4.32 g/m 2. Earthworms in untreated terraria were found all alive, while specimens exposed to glyphosate (Roundup 360 ® ) showed a decreasing survival rate and a sharp decline in the number of cocoons. L. terrestris (Lt2) showed a survival rate between 64% and 92% after 21 days, and between 44% and 76% after 42 days. L. terrestris (Lt1) showed a lower resistance to herbicide (survival rate: 36%–84% after 21 days and 12%–76% after 42 days). A. caliginosa was also affected (survival rate: 32%–76% after 21 days and 12%–68% after 42 days). Glyphosate demonstrated severe effects on Oc. complanatus, collected on non-contaminated soils, with the lowest values of survival rate (33% after 21 days and 7% after 42 days of exposure). A significant reduction in the cocoons number (about 70%) was observed for L. terrestris (Lt1) and A. caliginosa after 21 days of exposure, whereas L. terrestris (Lt2) showed about 50% of cocoon production. Results indicate the occurrence of some resistance mechanisms on anecic earthworms in vineyards that have been exposed to glyphosate for at least three decades. However in spite of the long period of application of glyphosate the impact of this largely applied herbicide is still serious (up to 26% of mortality) especially on the deep-burrowing earthworms species ( Oc. complanatus and L. terrestris ).