Environmental windows for foraging activity in stingless bees, Melipona subnitida Ducke and Melipona quadrifasciata Lepeletier (Hymenoptera: Apidae: Meliponini) - Maia-Silva, Camila; Imperatriz-Fonseca, Vera Lucia; Silva, Cláudia Inês; Hrncir, Michael (Sociobiology: an international journal on social insects, 2014)