Thermo-hygrometric dynamics reveal divergent adaptive strategies in africanized and buckfast honey bees

The present study investigated the adaptive strategies of Africanized and Buckfast honey bee colonies in a dry tropical environment, considering the thermohygrometric dynamics of the colonies. The internal temperature (IT) and internal relative humidity (IRH) were continuously recorded 24 h a day for seven months, yielding 36,360 observations in ten Africanized colonies and 22,680 observations in eight Buckfast colonies for each variable. Canonical discriminant analysis captured 100% of the data variance (P < 0.05) and revealed two significant functions (p < 0.001). Function 1 (81.8%) differentiated colonies along the IRH gradient, whereas Function 2 (18.2%) distinguished genotypes based on IT. For Africanized colonies, principal component analysis retained two components (75.37% of the variance, P < 0.05), with the first associated with the thermal-environmental axis and the second with IRH. Africanized bees exhibited greater thermo-hygrometric stability throughout the day, whereas Buckfast colonies showed more pronounced afternoon increases in IT and higher hygrometric fluctuations. This study compared the thermo-hygrometric dynamics of Africanized and Buckfast bees and revealed their distinct adaptive strategies. Buckfast bees relied more intensely on evaporative thermolysis, displaying lower thermal stability and higher humidity, whereas Africanized bees maintained thermal stability with reduced humidity variation, primarily using ventilation and secondarily, evaporative cooling associated with fanning. These findings demonstrate that physiological plasticity under continuous heat stress is critical for colony survival in dry tropical regions. Future studies should integrate these variables with productivity metrics and investigate the dynamics of colonies exposed to direct solar radiation.