INFLUENCE OF PULP AND PAPER-MILL WASTE-WATER ON CHRYSOMELA-SCRIPTA (COLEOPTERA, CHRYSOMELIDAE) PERFORMANCE AND POPULUS PLANT TRAITS

The effect of wastewater irrigation on resistance of poplar trees to t he cottonwood leaf beetle, Chrysomela scripta F., was investigated. Fi ve Populus clones were tested in a greenhouse for their effects on the survival, fresh pupal weight, and development time (from egg to adult ) of the cottonwood leaf beetle when they were irrigated with either w astewater or freshwater. Foliar concentrations of nitrogen, mineral el ements (P, Mn, Mg, Ca, Na, K), phenolic glycosides, and leaf toughness also were measured to understand the potential mechanisms of resistan ce to the cottonwood leaf beetle: C. scripta performance was negativel y affected by irrigation with wastewater; both survival and pupal weig ht were reduced. Performance also varied among clones and was the wors t on Populus fremontii Watson variety wislenzensii, a native species. Leaf toughness and foliar N level were not affected by the irrigation treatment and were not correlated with larval growth and survival. Amo ng minerals, foliar concentrations of sodium increased with wastewater irrigation, and were related negatively to pupal weights. Foliar magn esium also was influenced by the irrigation treatment but it was not c orrelated with C. scripta performance. Manganese varied with clone, bu t not with the type of water used for irrigation, and was correlated n egatively with survival and related positively to development time. Di fferences in phenolic glycosides were observed between treatments and among clones, but there were no detectable relationships between pheno lic glycosides and C. scripta performance.