Stingless bees are distributed widely in the tropics, where they are major pollinators of several plant species. In this study, the karyotype of Meliponaquinquefasciata Lepeletier, 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 that M.quinquefasciata has the same chromosomal number as other Melipona Illiger, 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 of M.quinquefasciata could 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.

中文翻译：

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无刺蜜蜂 Meliponaquinquefasciata Lepeletier, 1836（膜翅目，Meliponini）的核型描述，重点强调 B 染色体的存在。

无刺蜂广泛分布在热带地区，是多种植物物种的主要传粉者。在这项研究中，对 Meliponaquinquefasciata Lepeletier, 1836 的核型进行了分析，重点是 B 染色体的存在。使用吉姆萨染色、C 显带技术、荧光染料连续染色和 FISH 分析排便后的幼虫。由于存在 0-4 条 B 染色体，染色体数目范围为 2n = 18 至 22（女性）和 n = 9 至 13（男性）。这一结果表明，M.quinquefasciata 与其他 Melipona Illiger, 1806 种具有相同的染色体数目。考虑到 A 互补，异染色质仅位于第 1 对的着丝粒周围区域。用染色霉素 A3 (CMA3) 染色并用 rDNA 探针标记，表明该区域对应于核仁组织区域。M.quinquefasciata的B染色体可以在不同地区的个体中找到，它们是完全异色的（C带）并且被4',6-二脒基-2-苯基吲哚（DAPI）均匀染色。在同一个体的细胞之间、同一群体的个体之间以及不同地点的群体之间检测到 B 染色体数量的差异。