Development of Varroa jacobsoni in colonies of Apis mellifera iberica in a Mediterranean climate

Studies on Varroa jacobsoni population dynamics were conducted on 32 full-sized honeybee colonies of the Iberian bee race. The V. jacobsoni population growth followed an exponential model until it reached a collapse phase, in the experimental conditions this happened about 8 months to 1 year after chemical treatment. On average, the weekly intrinsic mite growth rates were very high, the yearly increases in mite population were 209 232-, 5 436-, 942- (with drone baiting) and 3 036-fold. A modelling approach was developed to describe the mite intrinsic growth rate regarding a) an overall range, b) only growth phenomena or c) only decay phenomena. The probability of each mite finding a free larva on which to reproduce, the occurrence of mite immigration, and the mite death rate were the most significant variables to explain the mite intrinsic growth rate during the growth phase. The model had a good fit, R-2 = 0.905, and good predictive performances, R-Prediction(2) = 0.896. (C) Inra/DIB/AGIB/Elsevier, Paris.