Rapid intergenerational changes in morphology and behaviour in colonies ofAfricanized and European honey bees (Apis mellifera) from tropical Yucatan, Mexico

An evaluation of honey bee (Apis mellifera) defensive behaviour, worker mor phometrics and worker brood cell size was conducted in an apiary in an area undergoing Africanization with the aim of documenting the rate of change o f these traits across generations, and their reliability to accurately iden tify colonies. Ten European and 10 Africanized parental colonies (generatio n P; groups 1 and 2, respectively) were selected in accordance with their m orphometrics and subjective evaluation of their behaviour in the field. The se colonies were tested for three traits of defensiveness using a standard protocol. Colonies' worker morphometrics and worker cell dimensions were al so measured. After the P generation colonies were tested, queens were remov ed and colonies were allowed to requeen themselves. The virgin queens of th e following generation (F1) were allowed to mate freely and, six months lat er, colonies were again tested. This procedure of mother-daughter queen rep lacement and testing of colonies was performed two more times (F2 and F3 ge nerations). Wilcoxon-Mann-Whitney tests and Pearson's correlation analysis were used to test for differences between groups in defensive and morpholog ical traits and to determine the relationship between traits in each genera tion. The results of this study showed that individual colonies dramaticall y changed their worker morphometrics and defensive behaviour from one gener ation to the next. However, all colonies, whether originally Africanized or European, came to resemble more the Africanized type across subsequent gen erations. Correlations between morphometrics and defensive behaviour were n ot always consistent Although morphometrics might still be a reliable metho d for quick identification of colonies it seems that defensive behaviour al one may provide an inadequate trait by which to discriminate among neotropi cal honey bee types, especially Africanized-European hybrid colonies.