Effect of Endod, a natural molluscicide, on the attachment of zebra mussels

Endod, Phytolacca dodencandra which has been used in East Africa for many years as soap, has been shown to possess molluscicide properties. Previous studies have found Endod to be lethal for zebra mussels (Dreissena polymorpha) at concentrations higher than 20.0 mg/L, while lower concentrations weaken and inhibit their attachment and aggregation. To study the mode of action, we investigation the effect of Endod on the strength of attachment of zebra mussels to the substratum by treating the animals at 5.0 mg/L, 10.0 mg/L and 20.0 mg/L of Endod for 4.0 hours, 8.0 hours and 20.0 hours. The strength of attachment was measured by allowing a mussel to attach on to a microslide and lifting the animal with a fork connected to counter weights. Weights were added until the animals were detached. The force needed for detachment was converted into Newtons. The experiment suggest that the Endod target site is not in the chemical structure of the threads themselves or the adhesion of the threads to the substratum. The target site is the byssal gland which synthesize the byssal threads.