Seasonal abundance and reproductive output of the dung flies Neomyia cornicina and N. viridescens (Diptera: Muscidae)

Ecology of zoophilic flies in livestock biocenoses of Ukraine

In modern animal husbandry of Ukraine, there are still some unresolved issues related to the high number of zoophilic flies in the territories of facilities and the spread of animal infectious and parasitic diseases. A detailed study of bioecological peculiarities of the dominant zoophilic fly species contributes to improving the effectiveness of measures to control ectoparasites. 27 zoophilic fly species have been found in animal breeding complexes. The maximum number of parasitic Diptera species was recorded on cattle-keeping premises. The biological properties of Neomyia cornicina (Fabricius, 1781) (size, shape, colour, duration of preimaginal phase development) were studied. Also, we studied the dynamics of the number and daily activity of dominant fly species (Musca domestica Linnaeus, 1758, M. autumnalis De Geer, 1776, Stomoxys calcitrans (Linnaeus, 1758)). When studying the intraspecies competition, a high-degree survival of M. domestica and M. autumnalis was determined in the conditions of critical nutritional deficiency (0.5 g of nutrient medium per larva) and increased density of individuals (the imago emergence was 38.6% and 34.0%, respectively). In similar maintenance conditions, the emergence of N. cornicina imago was low (14.6%). With a two-fold increase in the insectarium volume and in the amount of nutrient medium (1 g per larva), the imago emergence of M. domestica, M. autumnalis and N. cornicina increased to 64.0%, 39.2%, and 24.0%, respectively. With an even greater increase in the amount of nutrient medium (2 g per larva), the maximum emergence of imagoes of all the studied fly species was observed (M. domestica, M. autumnalis, and N. cornicina: 96.6%, 91.2% and 72.6%, respectively). In the conditions of interspecific competition, M. autumnalis suppressed N. cornicina even in conditions of a sufficient amount of nutrient substrate. In the competition between M. domestica and M. autumnalis, house fly dominated. Increasing the nutrient medium volume narrowed the gap between the competing species.

Aggregation in insect communities colonizing cattle-dung

Ruminant dung is a highly ephemeral, patchily distributed resource, which is used by a diverse community of invertebrate species. In such environments, high levels of insect aggregation may be important in facilitating stability and coexistence across patchily distributed populations. The aim of the present work was to quantify the aggregation of the insects colonising cow-dung in cattle pasture in southwest England and to test the hypothesis that the dung-pat community assemblage observed was the result of stochastic colonization. This was examined using batches of ten standardised, 1.5 kg, artificial cow pats placed out in cattle pastures in each of 24 weeks between May and October in 2001. Pats were left exposed in the field for seven days before being brought back to the laboratory, where any insect colonizers were collected and identified. Individual pats contained, on average, only half the number of insect taxa present in an entire batch put out at any one time. All larval coleopteran taxa, 20 of the 22 adult coleopteran taxa and 22 of the 23 dipteran taxa, showed significant aggregation, with the abundance of most taxa within pats approximating a negative binomial distribution. A simulation analysis was used to show that the observed relative frequency of taxa within pats did not differ from that expected by chance if colonisation is a random binomial event in which each species colonises a pat independently of all other species. Aggregated populations, of even highly abundant insects, may be more susceptible to the deleterious effects of insecticidal contaminants in dung than if they were evenly distributed, if by chance they colonize a pat containing insecticidal residues from a recently treated animal.