Vision is Important for Plant Location by the Phytophagous Aquatic Specialist Euhrychiopsis lecontei Dietz (Coleoptera: Curculionidae)

The aquatic milfoil weevil Euhrychiopsis lecontei Dietz (Coleoptera: Curculionidae) is a specialist on Myriophyllum spp. and is used as a biological control agent for Eurasian watermilfoil (Myriophyllum spicatum L.), an invasive aquatic macrophyte. We show evidence that visual cues are important for plant detection by these weevils. Weevils had difficulty locating plants in dark conditions and were highly attracted to plant stems in the light, even when the plant sample was sealed in a vial. However, weevils were equally attracted to both M. spicatum and another aquatic macrophyte, coontail (Ceratophyllum demersum L.) in vials. Turbidity (0–100 NTU) did not significantly influence visual plant detection by the weevils. This work fills a void in the literature regarding visual plant location by aquatic specialists and may help lead to a better understanding of when and where these weevils will find, accept, and damage their target host-plants.