Published online by Cambridge University Press: 10 July 2009
Laboratory and field experiments were carried out to study the toxicity of 3:5 dinitro-ortho-cresol and its sodium salt to the honey bee.
The acid DNOC was shown to be a rapidly acting poison under a wide variety of conditions and its toxicity was not greatly affected by differences in temperature or humidity during or after treatment.
Although both the acid and salt were equally toxic as stomach poisons, considerable differences were observed between the two substances as aqueous sprays and dry films. The toxicity of the sodium salt as an aqueous spray was considerably influenced by the humidity of the environment after spraying; the higher the humidity the greater the kill.
The sodium salt was apparently non-toxic as a dry film and increasing the humidity of the environment had no effect until the saturation point was reached and the salt went into solution. At this point the salt was almost as rapid in action as the acid. The type of surface on which the film was deposited was also shown to affect the toxicity.
Experiments were carried out on the penetration of the two substances through beeswax and these confirmed that whilst the acid could penetrate the beeswax in all forms tested the salt would only penetrate in aqueous solution.