Fluctuating asymmetry has sometimes been employed to indicate disruption of developmental homeostasis. Such disruption is thought to be a result of increased developmental stress. In this study we examine the relationship between fluctuating asymmetry and inbreeding level in two differing breeding systems: the marine harpacticoid copepod Tisbe holothuriae, a typically outbreeding diploid, and the common honeybee Apis melli/era, which is haplo-diploid. Inbreeding has previously been shown to constitute a developmental stress in populations of T. holothuriae, but the same is yet to be conclusively shown in A. melli/era.T. holothuriae showed an increase in the level of fluctuating asymmetry with increased levels of inbreeding. No difference in the level of asymmetry was observed for A. melli/era when outbred lines were compared with inbred lines. It is concluded that fluctuating asymmetry provides a useful technique for the measurement of developmental stress caused by inbreeding.

Eggs and larvae of L. cuprina were coIJected from natural fly strikes in a flock of Merino ewes in which sheep had been either treated with the insecticide dieldrin or left as controls. An analysis of gene and genotype frequencies of Rdl locus, which determines resistance to dieldrin, provides support for the existence of strong selection operating during larval development on sheep whose fleece contain insecticide residue. Resistance genotypes appear to be at a disadvantage both in the laboratory and in the insecticide-free environment of control sheep. There is no evidence that flies of different resistance status choose oviposition sites on the basis of the presence of dieldrin residues in the fleece.An explanation is provided for the observation that natural selection for insecticide resistance in the sheep blowfly utilizes major locus variation although the response to laboratory selection is polygenic in origin. The parameters determining the evolution of insecticide resistance in L. cuprina on sheep are discussed.

Populations of L. cuprina from the Baimsdale, Glenrowan, Hamilton and Torrita areas of Victoria were found to have similar high diazinon resistance status, following near fixation of a single allele at the Rl locus. Pure-breeding resistant strains were derived from each area and used as base populations for a selection program on adults. An approximate doubling of the level of resistance to diazinon was achieved in each strain after eight generations of selection. Relaxation of selection over seven generations showed the response had generated a stable plateau in all but the Torrita selected strain, which regressed towards the resistance level of the original base population.

Lucilin, the main storage protein of larval fat body and hemolymph in the sheep blowfly, Lucilia cuprina, has been isolated as a series of trimers composed of subunits of 83,000 +/- 5%, daltons. Extensive electrophoretically detectable polymorphism of lucilin subunit patterns occurs in wild and laboratory populations of Lucilia; from four to nine bands are seen in any one individual. Evidence from genetic, electrophoretic, immunological, and structural studies suggests the existence of a series of 12 or more closely related structural loci (designated Luc-1 to Luc-12) which may have arisen through gene duplication. Codominant allelic variation has been found at several of these loci. Luc-1 and Luc-3, and probably the other structural loci of the series, are located on chromosome 2.

Artificial strikes were initiated on sheep at different times after treatment with either diazinon (an organophosphorus compound) or lindane (an organochlorine compound).