An investigation of possible changes in behaviour patterns of the red flour beetle, Tribolium castaneum (Herbst) after nineteen generations of selection

Abstract

This thesis compares the adults behaviour of two strains of the Red Flour Beetle, Tribolium castaneum. The study was initiated by carrying out a selection experiment, using phenotypic assortative and phenotypic random mating, for high pupa weight: pupa weight being positively correlated with adult weight. The result was that after twenty generations two populations were established; a selected line with an average weight of 3.36 ±.10 mg and a control line with an average weight of 2.13 ±.16 mg. Using individuals from these two populations five comparative behavioural studies were then carried out. In four of the studies, namely:- (1) Spontaneous movement against time. (2) Movement within the flour. (3) Movement between the surface and the flour. (4) Emigration away from the surface of the flour. The individuals of high pupa weight showed a significant difference from the randomly selected control population. The fifth pattern that of light sensitivity showed the selected individuals to be more sensitive than the control individuals. However this difference was not significant. The hypothesis put forward to explain this behavioural difference, is that the increase in body size modified the sense organs and therefore caused the insects to react differently to environmental stimulus, as seen in the response to ethylquinone.