Allelochemical activity in Ardisia species (Myrsinaceae) against selected arthropods

Significant differences were found among 4 species of Ardisia (Myrsinaceae) when evaluated as host plants in separate tests for oviposition and longevity by the twospotted spider mite, Tetranychus urticae Koch, and for nymphal development by the whiteflies Bemisia argentifolii Bellows and Perring and the greenhouse whitefly Trialeurodes vaporariorum (Westwood). After being confined for 48 h on leaf disks, the number of T. urticae alive did not differ among the different Ardisia species but the number of eggs laid on A. crenata Sims and on A. japonica (Hornstead) Blume was significantly lower than on the other species. T. urticae females remained alive an average of 2.8 d on A. crenata leaf disks, 5.0 d on A. japonica and A. escallonioides Schechtendal and Chamisso, and 9.4 d on A. crispa (Thunberg) Aphonse De Candolle. T. urticae laid significantly fewer eggs on A. crenata, A. japonica, and A. escallonioides than on A. crispa. Nymphal mortality of B. argentifolii and T. vaporariorum was significantly higher on leaves attached to plants of A. crenata and A. japonica than A. escallonioides. Development rate of 1st and 2nd instars of the fall armyworm, Spodoptera frugiperda (Smith), was not significantly influenced when fed a meridic diet treated with pulverized dry leaf residue of either A. crenata or A. japonica. Development rate, larval weight, and cumulative mortality of the latter instars were significantly affected by high-concentrations of A. japonica. A purified major leaf component from A. crenata was isolated using high-pressure liquid chromatography with ultraviolet detection and found to be highly soluble in water. Oviposition by T. urticae females placed on disks cut from excised eggplant, Solanum melongena L., leaves that had imbibed an aqueous concentration of the purified leaf component was significantly reduced with increasing concentrations of the leaf component