Abstract

Phytoseiid mites were released on young potted citrus trees to evaluate their effectiveness in controlling twospotted spider mite, Tetranychus urticae Koch, and citrus red mite, Panonychus citri (McGregor), in single and mixed-species infestations. In infestations averaging 10 T. urticae per leaf, Phytoseiulus longipes Evans, Galendromus occidentalis (Nesbitt), Neosieulus californicus (McGregor), and Euseius stipulatus Congdon released at a rate of 1 per leaf reduced spider mites by >85% 1wk after release. When the infestation consisted of an average of 22 P. citri per leaf, releases of E. stipulatus, N. californicus , and Galendromus helveolus (Chant) required 3 wk to exert 74–80% control of P. citri . Amblyseius limonicus Garman & McGregor was not effective in controlling P. citri at any time during the 6-wk sampling period. When the infestation was mixed, G. occidentalis was the most effective species in controlling both pest species. Predaceous mites more effectively eliminated T. urticae eggs than P. citri eggs, resulting in more rapid and complete control of T. urticae . Of the effective predators, densities of the more specialized Galendromus, Neoseiulus , and Phytoseiulus species of predators declined as the prey declined, whereas densities of the Eusieus and Amblyseius species remained at levels of 0.2–1.5 predaceous mites per leaf even in the absence of prey.

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