Mitotic activity of the brain ganglia in different subphases of the last larval instar of Melipona quadrifasciata lepeletier (Hymenoptera, apidae, meliponini)

Resumo

In recent years, the number of cytogenetic studies on Melipona species has increased considerably. However, most cytogenetic techniques used for these studies require preparations with a great number of metaphase cells for reliable analysis of the karyotypes. The present study seeks to evaluate which subphase of the last larval instar of Melipona quadrifasciata Lepeletier provides the greatest number of metaphases, which is here considered a direct measure of mitotic activity. A total of 25 defecating larvae were selected based on the quantity of feces in their intestines, so as to maintain five larvae in each of the five different developmental subphases. The brain ganglia of each larva were extracted and used for cytogenetic preparation. The number of metaphase mitotic cells per preparation was counted. An analysis of variance (ANOVA) model, with Tukey's post hoc tests, was conducted. It was observed that larvae in the second subphase, defined here as the subphase in which feces were visible below the segment VII, provided the greatest number of metaphases. Therefore, it is the most appropriate developmental subphase for cytogenetic preparations of brain glanglia in M. quadrifasciata and possibly in other Melipona species.