Population suppression in the Queensland fruit fly, Dacus (Strumeta) Tryoni. I. The effects of male depletion in a semi-isolated population

Abstract

An experiment designed to assess the usefulness of a male attractant, 4-(p-acetoxypheny1)butan-2-one, for the control of relatively isolated populations of the Queensland fruit fly, is described. Traps baited with the lure and an insecticide were distributed at fairly high density throughout a small town and its immediate surroundings, while a similar town nearby was left untreated for purposes of comparison. The numbers of males killed each week in the treated town were estimated, and in both towns regular measurements were made of: (i) ratios of males to females; (ii) rates of insemination of mature females; and (iii) rates of infestation of fruit. The results show that there was a clear effect of the treatment in the early part of the season, but that this diminished as the season progressed until finally there was little difference between the populations. We conclude that this male attractant, used alone, is unlikely to provide effective control of the Queensland fruit fly, except perhaps when used against thoroughly isolated populations. It may, however, be more useful if used in combination with other methods which provide some protection against inseminated females.