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

Abstract

-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 2 Prediction = 0.896. © Inra/DIB/AGIB/Elscvier, Paris

Varroa destructor infestation impact on Apis mellifera carnica capped worker brood production, bee population and honey storage in a Mediterranean climate

“…On the other hand, non-infested colonies were probably weakened by the negative effect of repeated fluvalinate applications (Barbattini et al, 1989;Slabezki et al, 1991;Liu, 1992), meaning that the magnitude of the differences between non-infested and infested colonies may have been underestimated. Considering the entire experimental period, the daily finite rates of mite population increase were slightly lower (1.0123) than the ones also obtained in Mediterranean conditions by Kraus and Page [(1995); 1.0137 to 1.0214], Verdú [(1993, 1995) immigration rates (Branco et al, 1999;Delaplane and Hood, 1999)] or genetic (bee strain) variations.…”

“…Some of the reasons that can partly explain this fact [also mentioned by Branco et al (1999)] include limitations imposed by host conditions upon mite reproduction and survival rates and, eventually, a considerable increase in desertion of highly miteinfested adult honey bees (that may occur much more frequently in the terminal phase of V. destructor infestation). This feed-back mechanism of host terminal condition in restricting mite population growth has been ignored by relevant models of mite population dynamics (Fries et al, 1994;Fries, 1996;Martin, 1998).…”

“…Furthermore, the observed pattern of V. destructor population dynamics is incongruent with the exponential growth / decay cycles hypothesised to occur in A. mellifera colonies in temperate climates (Fries et al, 1994;Fries, 1996). In Mediterranean climates, there are no such successive cycles and most acaricide-untreated mite-infested colonies can be expected to die within approximately one year after becoming infested (Calatayud and Verdú, 1992;Rinderer et al, 1993;Murilhas, 1994;Branco et al, 1999).…”

“…However, the uninterrupted presence of brood (except perhaps for a short period associated with swarming) in Mediterranean climates (Vieira et al, 1990;Puerta et al, 1993;Ferrer-Dufol et al, 1994;Calatayud and Verdu, 1995;Branco et al, 1999) is a major qualitative difference to that pattern. The milder winter conditions in Mediterranean climates and the availability of food during a considerable part of the winter account for this difference in the brood-rearing cycle, which, in turn, is relevant to the intrinsic growth rate of V. destructor.…”

Effects of Lactobacillus Johnsonii AJ5 Metabolites on Nutrition, Nosema Ceranae Development and Performance of Apis Mellifera L.

“…1) were: i) number of combs fully covered with bees (estimated as number of combs covered with adult bees), ii) open and sealed brood areas (according to Branco, Kid & Pickard, 1999) and iii) quantity of honey and pollen (estimated as number of combs covered with honey or pollen, respectively). 7.…”