Guttation

Guttation is the exudation of drops of xylem and phloem sap on the tips or edges of leaves of some vascular plants, such as grasses, and also a number of fungi.

Girolami et al. (2009) found that guttation drops from corn plants germinated from neonicotinoid-coated seeds could contain amounts of insecticide consistently higher than 10 mg/L, and up to 200 mg/L for the neonicotinoid imidacloprid.

Concentrations this high are near those of active ingredients applied in field sprays for pest control and sometimes even higher.

It was found that when bees consume guttation drops collected from plants grown from neonicotinoid-coated seeds, they die within a few minutes.

Guttation droplets are consumed by numerous insects of different orders, and is an important and highly reliable source of essential carbohydrates and proteins.