ARBEITSGEMEINSCHAFT DER INSTITUTE FÜR ... - HAL - INRIA

SUMMARY
Varroa jacobsoni and Tropilaelaps clarae in bee colonies of Apis mellifera
Varroa jacobsoni and Tropilaelaps clarae are new parasites of the honey bee,
Apis rnellifera, in Southeast Asia. A non-adaptable host-parasite relationship can
lead to considerable bee damage. Although both mites are present in Thailand,
colonies are usually infested with only 1 of the 2 parasites. The infestation of
adult bees and brood by Varroa jacobsoni was larger the more recent the last
treatment with an acaricide had been carried out, which occured 10 day
intervals. Varroa jacob.soni was almost totally repressed by Tropilaelaps clarae
in colonies left untreated for 2 years. Therefore, the repression of Tropilaelaps
I
clarae by Varroa jacobsoni is purely artificial. In contrast, the reverse process of
repression is the natural one.
A reason for the repression of the parasite may be due to different reproduction
rates. The reproduction curves for parasites in worker brood differ significantly.
The time of appearance and the number of develo>mental stages of Varroa
jacobsoni, correspond largely with those found by IFANTIDIS (1983) in Europe. In
contrast to Varroa jacobsoni, Tropilaelap.s clarae, only lays eggs shortly after
sealing of brood cells. Not only is the second egg laid male, but female and male
eggs are laid in approximately equal numbers. Varr-oa females and Tropilaelaps
females produced 68 % and 71 % surviving offspring, respectively. The reproduction
coefficient of all mites with respect to the brood was 1,27 for Varroa
jacobsoni and 1,02 for Tropilaelaps clarae. Therefore, Tropilaelaps clarae
produced significantly fewer offspring. A faster increase in the population of Tropilaelaps
clarae can be explained by the fact that they survive outside of
brood cells 1 or 2 days only (W OYKE , 1985). So they have to enter brood cells for
reproduction in this period. The female was more frequently infertile in cells
simultaneously infested with both parasites than in those only infested with 1
parasite. The chance for Varroa jacobsoni to reproduce becomes smaller with an
increase in the population of Tropilaelaps clame. This could be a reason for
the repression of this parasite.
RÉSUMÉ
Varroa jacobsoni et Tropilaelaps clarae
dans le.s colonies d’abeille.s Apis mellifica en Thaïlancfe
Varroa jacobsoni et Tropilaelaps clarae sont de nouveaux parasites de
l’abeille, Apis mellifica, dans le sud-est asiatique. Une relation hôte-parasite non
adaptée peut conduire à des dégâts considérables chez les abeilles. Bien que les