Infectivity of Steinernema feltiae in Fenamiphos-treated Sand.

T h e e n tomo p a t hogen i c n e m a t o d e Steinernema feltiae is compat ible with many chemical pesticides including insecticides, mi t i c ides , fung ic ides , and h e r b i c i d e s (1,3,4,7,9,10). Cer ta in o rganophospha t e and carbamate pesticides, however , adversely affect S. feltiae (5,6). Removal or dilution o f the pesticides with water usually results in ne ma t o d e recovery , infect ion o f the insect host, and normal deve lopmen t (5,6). Studies were conduc ted by placing the infective stage o f the n e m a t o d e in a pesticide solution or suspension. T h e purpose o f ou r study was to de t e rmine the infectivity of S. felliae in sand t rea ted with a granular fo rmula t ion o f the organophospha te pesticide, fenamiphos. T h e All strain o f S. feltiae, cul tured on Galleria mellonella as descr ibed by Dutky et al. (2), was s tored at 10 C and used within 6 weeks af ter harvest. Fenamiphos (ethyl3 -me thy l -4 [me thyhh io l ] -pheny l [ 1 -methylethyl] phosphoramida te ) (Mobay Chemical Corp. , Kansas City, MO) was ob ta ined as a 15% granular formula t ion . Sand (particle size f rom 0.21 to 0.85 ram) was mixed with granules containing fenamiphos (mixtu re he r e a f t e r r e f e r r e d to as fenamiphos) at the rates o f 30, 60, and 120 m g / k g dry sand in a twin shell b l ende r for 10 minutes. T he se fenamiphos rates equaled 4.5, 9.0, and 18.0 mg a . i . /kg dry sand, respectively. These rates approximate low, medium, and high field rates o f fenamiphos incorpora t -