Further Considerations regarding the repellency of spray components

Abstract

The apparatus previously used to demonstrate the repellent properties of DDT, fuel oil and methylated naphthalene auxiliary solvents towards certain Diptera was used in further studies of olfactory repellency in an attempt to narrow down the ingredients responsible for this effect, and consideration was given to the possibility of finding substitutes for them with less repellent or even attractive properties.Light, medium and heavy fractions were obtained by fractional distillation of fuel oil and each of two methylated naphthalene auxiliary solvents. In all these spray components the repellent properties are inversely related to the boiling point, and appear to be non-specific both chemically and by insects. Tests with materials of low volatility, however, showed that the effect is not a simple broad relationship between volatility and repellency.Butoxy-polypropylene glycol, widely used as a ‘repellent’ ingredient of livestock sprays, shows olfactory attractiveness to Musca domestica L. and Aëdes aegypti (L.). The odour of Drosophila melanogaster Mg. was shown to be attractive to the insect, regardless of sex.It is concluded that there seems little hope of an economic non-repellent material.It is suggested that the repellency of spray components might be counteracted by the addition of specific attractants, sex or other, to spray formulae. Alternatively, a useful space repellent spray, containing no toxicant, might be formulated from the lighter fractions of the solvent materials.