Effect of host plant nitrogen fertilization on the biology of the two-spotted spider mite, Tetranychus urticae
1985
Wermelinger, B. | Oertli, J.J. | Delucchi, V.
Females of Tetranychus urticae Koch were reared on leaf discs of apple trees and bush beans grown at different N concentrations (0.6-75 mM NO⁻ ₃. N-deficiency increased pre-imaginal development time, pre- oviposition period, and decreased female weight, fecundity and oviposition rate of the mites. N, water, amino acid, and sugar content of the apple leaves were positively correlated with weight and egg production and negatively correlated with development time and pre-oviposition period. The reverse correlations were found with total phenol content of the leaves and above mite parameters. A reduction of leaf N by 50% was related with a tenfold decline in fecundity on apple leaves. The stress mainly affected the oviposition rate and to a lesser extent the oviposition period. On apple leaves the net reproductive rate (av. no. ♀ offspring per ♀, Ro), mean length of a generation (T), and innate capacity for increase (rm) were Ro = 40.3, T = 17.1, and rm = 0.22 for the standard N concentration, and 4.7, 25.0, and 0.06 for strong N-deficiency, respectively.
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