Modelling mortality risks for treated insects relative to controls

SUMMARY A model is described for facilitating studies of insect mortality. The main feature of the model is that it includes a readily interpretable parameter which measures the mortality risk in each treatment group relative to a control group. Procedures for fitting the model are illustrated by reference to an experiment where leafhoppers were injected with spiroplasma strains; one such strain was shown to be pathogenic. Good fits have been found for data from other experiments.