Fecundity and trapping of Varroa destructor (Mesostigmata: Varroidae) in Greek drone brood of Apis melifera (Hymenoptera: Apididae)

This study estimates the parasitization levels and fecundity of the ectoparasitic mite Varroa destructor Oudemans in drone brood of bee colonies located in Northern Greece. Based on successive observations in spring and early summer, the study also examines whether early entrapment of mites into the drone brood cell decreases the mite population levels in the succeeding generation. Varroa populations in drone brood were extremely high (approx. 40%) in early spring, although numbers dropped significantly (approx. 20%) after the entrapment and removal of mites into the drone brood (t=4.14518, P=0.0136, Mann-Whitney: P=0.005). In most cases, more than half of the inspected cells were occupied with two or more parental mites. No significant differences were found in the reproductive performance of the Varroa mites between the two successive generations in spring and early summer (t=-0.607, P=0.554, Mann-Whitney: P=0.128). The reproductive performance of V. destructor ranged from 1.5-3 progeny per female individual (m1:1.673, SE=0.09 and m2:2.02, SE: 0.44 for the first and second generations, respectively). A positive and significant correlation was observed between the drone and the mite populations (y=0.830+1.153x, F=8.851, P=0.41, R²:0.689 and y=0.319+0.968x, F=45.276, R²: 0,938, P=0.07 for the first and second mite generations, respectively). There were no significant differences in the number of infested and non-infested cells during the first observations (m1: 105.2, SE: 25.0, m2: 170.0 SE: 40.0, t=-1.38, P=0.203, Mann-Whitney: n1:81.0, n2:142.5, P=0.0656). On the contrary, during the second observations the number of infested cells was significantly lower (m1: 27.6, SE:8.1, m2:262.8, SE:69.0, t=-3.39, P=0.027, Mann-Whitney: P=0.012, n1:20, n2:340).