Effects of Internal Space Increase on Catalase and Defensin Gene Expression and Honey Production in Africanized Apis mellifera Honeybees

The aim of this study were evaluate the effect of beehive  internal space increase (adding supers) and its effect on honey production, catalase and defensin gene expression (related to stress). The experiment was conducted at UNESP, Botucatu, Brazil. Twenty Africanized beehives were used, divided into four treatments: T1: control, adding supers along the blossom period as needed, T2, T3 and T4, two, three and four supers, respectively, added simultaneously at the blossom beginning. Honey production was evaluated at the end of the blossom period. For defensin and catalase gene expression analyses foraging and internal bees were collected on days 0, 7, 14, 29, 56 and 98 and frozen at  -80 ° C. Results were compared by ANOVA followed by Tukey test (P <0.05). It was observed that the production of honey in T1 was significantly higher (24.33 ± 2.14 kg) compared with T2, T3 and T4 (17.50 ± 1.76, 14.76 ± 2.32 and 9.81 ± 1 87 kg, respectively). In relative quantification of gene catalase and defensin, T4 showed significantly higher expression when compared with the other treatments in the foraging bees. Internal bees did not differ among treatments throughout the experimental period. No difference was observed between the foraging and internal bees for catalase, for defensin T4 showed significantly higher expression in relation to internal.  It can be concluded that the supers managements can influence the honey production, catalase and defensin genes can be used as an indicator of the stress level in Africanized honeybees.

Keywords: Real Time PCR / welfare / gene expression