Cooperation and competition in a colony of the polygynous stingless bee Melipona bicolor, illustrated by two kinds of worker eggs and the behaviours of workers laying them - Velthuis, Hayo Hans Willen; Pereboom, Zjeffrie; Koedam, Dirk; Imperatriz-Fonseca, Vera Lucia (Proceedings of the Section Experimental and Applied Entomology of the Netherlands Entomological Society (N.E.V., 2003)