EFFECT OF DIFFERENT CONDENSED TANNINS ON TRICHOPLUSIA NI PERFORMANCE

To examine the assumption that condensed tannins exhibit uniform activ ity against herbivores, tannins extracted from four plant species with different in vitro protein binding abilities were fed to larvae of Tr ichoplusia ni in artificial diets. Larvae were measured for survivorsh ip, growth and food consumption at three tannin concentrations (0.001% , 0.01% and 0.05% w. wt.). Larval performance was negatively affected by the tannins tested in a dose-response fashion, giving the different plant-derived tannins different activity thresholds. We did not find any significant correlation between the biological effects of these ta nnins and their protein binding abilities. This study indicates that d ifferent species of tannins do not act uniformly against a tannin sens itive herbivore, and that these differences can not be attributed to t heir different in vitro protein binding abilities.