Effects of reduced-risk insecticides on three orchid pests and two predacious natural enemies

Haleigh A. Ray, Marjorie A. Hoy


The toxicity of 2 reduced-risk pesticides, 2% horticultural oil with 0.05% Silwet L-77 and Grandevo (Chromobacterium subtsugae Strain PRAA4-1T), to 2 predators: Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae) and Hemicheyletia wellsina DeLeon (Acari: Cheyletidae), and 3 orchid pests: the two-spotted spider mite Tetranychus urticae Koch (Prostigmata: Tetranychidae), the phalaenopsis mite, Tenuipalpus pacificus Baker (Acari: Tenuipalpidae), and the longtailed mealybug Pseudococcus longispinus (Targioni-Tozzetti) (Hemiptera: Pseudococcidae) were tested. Grandevo did not kill either predator, and it failed to suppress populations of T. urticae and P. longispinus, but it reduced T. pacificus by 84%. The Silwet and horticultural oil mixture caused mortality of at least 82% in all 5 species tested.


Se probó la toxicidad de 2 plaguicidas de menor riesgo, 2% de aceite hortícola con 0.05% Silwet L-77 y Grandevo (Chromobacterium subtsugae Cepa PRAA4-1T), a 2 depredadores: Metaseiulus occidentalis (Nesbitt) (Acari: Phytoseiidae) y Hemicheyletia wellsina De Leon (Acari: Cheyletidae), y 3 plagas de orquídeas: la araña roja de dos manchas Tetranychus urticae Koch (Prostigmata: Tetranychidae), el ácaro de falenopsis Tenuipalpus pacificus Baker (Acari: Tenuipalidae), y la cochinilla harinosa con cola larga, Pseudococcus longispinus (Targioni-Tozzetti) (Hemiptera: Pseudococcidae). El Grandevo no mató los depredadores, y no pudo reprimir las poblaciones de T. urticae y P. longispinus, pero redujo el 84% de T. pacificus. La mezcla de Silwet con aceite hortícola causó una mortalidad de al menos 82% en todas las 5 especies probadas.


View this article in BioOne


Grandevo; Silwet L-77; pesticide selectivity; horticultural oil; Orchidaceae

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