Effect of Potassium and Sodium on Fecundity and Survivorship of Japanese Beetles

The effect of potassium and sodium on the fecundity and survivorship of a generalist insect herbivore, the Japanese beetle (Popillia japonica), was determined by topically treating leaves of a hostplant (Japanese knotweed, Polygonum cuspidatum) with salt solutions. The mean concentrations of sodium and potassium in unsprayed leaves (by dry weight) were 0.05% and 2.51%, respectively. Potassium concentrations of the leaves were enhanced up to 3.26%; sodium concentrations were enhanced up to 0.68%. Female beetles had higher survivorship on the control diets (unsprayed leaves and leaves sprayed with distilled water) than on the salt-treated diets. Males had higher survivorship on the control diets and leaves with mean sodium concentration of 0.12% than on the other diets