Standard methods for estimating strength parameters of Apis mellifera colonies
Keith S Delaplane, Jozef van der Steen and Ernesto Guzman-Novoa
This paper covers measures of field colony strength, by which we mean population measures of adult bees and brood. There are generally two contexts in which an investigator wishes to measure colony strength: 1. at the beginning of a study as part of manipulations to produce uniform colonies and reduce experimental error and; 2. as response variables during or at the end of an experiment. Moreover, there are two general modes for measuring colony strength: 1. an objective mode which uses empirical measures and; 2. a subjective mode that relies on visual estimates by one or more observers. There is a third emerging mode for measuring colony strength; 3. computer-assisted digital image analysis. A final section deals with parameters that do not directly measure colony strength yet give important indicators of colony state: flight activity at the entrance; comb construction; and two proxy measures of colony fitness: production of queen cells and drone brood. How to conduct different types of experiments are described, including infectious dose, dose effects, course of infection and longevity tests.