The dynamics of interacting populations

Assessing the impact of the many variables — both abiotic and biotic — that influence population dynamics is no easy task. In the 22 February Nature, Ottar Bjørnstad of the National Center for Ecological Analysis and Synthesis in Santa Barbara, California, and co-workers show how plastic boxes stocked with meal moths and their natural enemies can be used to test theories of population dynamics.

The Indian meal moth — a pest that feeds on stored products such as flour, nuts and dried fruit — was cultured alone or either with a parasitoid wasp or a baculovirus, both natural enemies of the meal moth. Bjørnstad et al., in a study supported by mathematical modelling, demonstrate that the lag between the introduction of a parasite and its effect on the density of the host population depends on the strength of the interaction between the two populations (Nature 2001, 409...