Brain amines, aggression, reproducion and the emergence of social behavior in the bee Megalopta

Biogenic amines in the brain modulate aggression and reproduction in insects, and coordinate social organization in highly derived social insects like honeybees and ants. Because the emergence of eusocial groups (those with a reproductive queen and sterile workers) involves competition for dominant status and reproductive division of labor, brain amines are almost certainly involved, but results are inconsistent across primitively social groups. We use the facultatively eusocial or solitary halictid bee Megalopta genalis to test the effects of Dopamine (DA) and Octopamine (OA) on ovary development and aggressive interactions in solitary and social Megalopta. We supplemented OA and DA at the pupal and newly eclosed adult stages to test for developmental effects. We staged aggressive encounters between solitary nesters and also nest-mate queens and workers to test the effect of OA on aggression. These are the first data comparing the effects of DA and OA on solitary and social individuals of the same species.