Demographic traits of Eotetranychus pruni from Belgian and Tunisian orchards, in comparison with Tetranychus urticae

Eotetranychus pruni was recorded in Belgian and Tunisian apple orchards for the first time. The aim of this study was to compare a Belgian (Vieusart) and a Tunisian strain (Grombalia), with respect to their life history and demographic traits. Furthermore, a Tunisian strain of Tetranychus urticae (Sousse) was also added to the study, in order to evaluate the potential status of the Tunisian strain of E. pruni. Experiments were carried out in the laboratory (24 degreesC) on apple leaf discs. Significant differences were noticed between the two species, with respect to development time (males), fecundity and fertility (egg hatching), but no differences could be detected between the two strains of E. pruni. Life tables were set up to describe the population statistics. The calculated intrinsic rates of natural increase (r(m)) appear to be rather low per se and do not correspond to those of typical "r strategic pests". The Bootstrap procedure allows us to estimate the confidence interval for these r(m) values. By using this method, the two Tunisian strains (T. urticae and E. pruni) appear to be quite similar, and contrast with the Belgian strain (E. pruni). The potential pest status of the Tunisian strain of E. pruni is discussed