Karyotypic description of the stingless bee Melipona quinquefasciata Lepeletier, 1836 (Hymenoptera, Meliponini) with emphasis on the presence of B chromosomes

Abstract

Stingless bees are distributed widely in the tropics, where they are major pollinators of several plant species. In this study, the karyotype ofMeliponaquinquefasciataLepeletier, 1836 was analysed, with emphasis on the presence of B chromosomes. Post-defecating larvae were analysed using Giemsa staining, the C-banding technique, sequential staining with fluorochromes, and FISH. The chromosome number ranged from 2n = 18 to 22 (females) and from n = 9 to 13 (males) due to the presence of 0–4 B chromosomes. This result demonstrates thatM.quinquefasciatahas the same chromosomal number as otherMeliponaIlliger, 1806 species. Considering the A complement, heterochromatin was located only in the pericentromeric region of pair 1. Staining with chromomycin A3(CMA3) and labelling with rDNA probe, indicated that this region corresponded to the nucleolus organising region. The B chromosomes ofM.quinquefasciatacould be found in individuals from different localities, they were completely heterochromatic (C-banding) and uniformly stained by 4’,6-diamidino-2-phenylindole (DAPI). Variations in the number of B chromosomes were detected between cells of the same individual, between individuals of the same colony, and between colonies from different localities.