The toxicity of phosphine to adults of Tribolium castaneum (Herbst): Phosphine-induced narcosis

The narcotic effect of phosphine on adults of Tribolium castaneum was examined over concentrations ranging from approx 0.2 to 50 mg/l. Times to narcosis decreased with higher concentrations as did the rate of decrease of these times consistent with a decreasing rate of uptake with increasing concentration. Correlations between narcosis times and mortality were examined but were only of limited value for rapidly estimating mortality response. Moreover, from these correlations it was not possible to resolve the question as to whether narcotised insects have a better chance of survival. Narcosis may have practical implications in terms of phosphine resistance.