Worker Longevity in an Amazonian Melipona

Worker longevity in an Amazonian Melipona (Apidae, Meliponini) species: effects of season and age at foraging onset Rafael Leandro Corrêa Gomes, Cristiano Menezes, Felipe Andrés León Contrera To cite this version: Rafael Leandro Corrêa Gomes, Cristiano Menezes, Felipe Andrés León Contrera. Worker longevity in an Amazonian Melipona (Apidae, Meliponini) species: effects of season and age at foraging onset. Apidologie, Springer Verlag, 2015, 46 (2), pp.133-143. 10.1007/s13592-014-0309-y. hal-01284431 HAL Id: hal-01284431 https://hal.archives-ouvertes.fr/hal-01284431 Submitted on 7 Mar 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Apidologie (2015) 46:133–143 Original article * INRA, DIB and Springer-Verlag France, 2014 DOI: 10.1007/s13592-014-0309-y Worker longevity in an Amazonian Melipona (Apidae, Meliponini) species: effects of season and age at foraging onset 1 2 Rafael Leandro Corrêa GOMES , Cristiano MENEZES , 1 Felipe Andrés León CONTRERA 1Laboratório de Biologia e Ecologia de Abelhas, Instituto de Ciências Biológicas, Universidade Federal do Pará, Campus Universitário do Guamá, Rua Augusto Corrêa, n°1, Belém, Pará, Brazil CEP: 66075-110 2Laboratório de Botânica, Embrapa Amazônia Oriental, Trav. Dr. Enéas Pinheiro s/n°, Caixa Postal, 48, Belém, Pará, Brazil CEP 66095-100 Received 7 April 2014 – Revised 1 July 2014 – Accepted 17 July 2014 Abstract – We studied the relationship between worker longevity and the age of foraging onset in the bee Melipona fasciculata, as well as the longevity oscillation in the rainy and dry seasons. Workers that emerged in the rainy season started to forage later and lived at least 50 % longer than foragers from the dry season. In both periods, a higher longevity was observed in workers that started to forage earlier in life but did not forage all days of their careers. We also showed, by using a Weibull model, that workers experienced higher mortalities at older ages in the rainy season, but the same model did not fit with the data from the dry season. This lack of fit in the dry season can be explained by the high mortality of workers that did not start to forage in this season and to other intrinsic factors of the colonies. Thus, the age of foraging onset and internal colonial factors must be considered in studies examining worker longevity in free-foraging colonies in this diverse group of eusocial bees. Melipona fasciculata / stingless bees / mortality / survival curves / weibull model 1. INTRODUCTION differences in longevity between queens and workers are behavioral costs, as well as genetic, Longevity is a key evolutionary force affect- morphological, and physiological issues (e.g. ing adaptations in the different life histories of Biesmeijer and Tóth 1998; Amdam and Omholt insects, and solitary and social species contrast 2002). in several aspects, such as in their life expec- Regarding the honeybee, studies on their life tancy (Keller and Genoud 1997) and in the expectancy in temperate regions have shown different longevity patterns among castes (Carey differences in the longevity of summer and 2001). In bees, the main factors used to infer winter bees. Apis mellifera Linnaeus, 1758 workers may live about 1 month in summer, whereas they may survive up to 8 months in Electronic supplementary material The online version of this article (doi:10.1007/s13592-014-0309-y) contains winter (Amdam and Omholt 2002). However, in supplementary material, which is available to authorized tropical and subtropical environments honeybee users. longevity does not present these strong seasonal differences. Rather, they present differences Corresponding author: F.A.L. Contrera, [email protected] related to the age structure of the colonies, with Manuscript editor: James Nieh higher mortality associated with high mean 134 R.L.C. Gomes et al. worker age and low proportion of young different longevity patterns in the main clima- workers and a slight increase in longevity is tological periods of the region (rainy and dry), seen in the tropical rainy season (Terada et al. and (b) whether there is a relationship between 1975; Winston 1979, 1980). longevity and the age of foraging onset. We The energetic effort that workers expend hypothesized that foragers would have an during their life also plays a role in survival extended life expectancy in the rainy season, patterns, when we take into account the effort to since they would spend more time inside the search for resources and predation risks met nest, and that mortality rate would substantially outside the nest (Page and Peng 2001). This was increase after workers shifted from internal observed in A. mellifera by Wolf and Schmid- work to external activities. Hempel (1989), who showed that workers to which extra work effort was imposed had a 2. MATERIAL AND METHODS reduced life span and diminished foraging activity compared to workers subjected to 2.1. Study site normal foraging efforts. In stingless bees (Tribe Meliponini; Michener This study was conducted in the meliponary of the 2013), most studies on longevity (revision in Botany Laboratory of Embrapa Amazônia Oriental Halcroft et al. 2013) have been conducted on (1°26′11.52″ S, 48°26′35.50″ W), located in Belém, subtropical species (e.g. Terada et al. 1975; Pará State, Brazil, from February-April and August- Simões and Bego 1991; Halcroft et al. 2013). In November 2012, which corresponded to the rainy and the French Guyana, Roubik (1982), studying dry seasons in the region, respectively (Moraes et al. Melipona fulva Lepeletier, 1836 and M. favosa 2005). For the categorization of rainy and dry seasons (Fabricius, 1798), found that workers had a we used the rainfall data generated in the São Brás longer life-span in the rainy season compared to weather station (Climurb Project (IG/UFPA/CNPq). the dry season, probably due to the greater resource availability and higher foraging effort 2.2. Colonies by workers. Since most stingless bees feed from pollen Three colonies of M. fasciculata of similar and nectar harvested by workers, the foraging population sizes and food stores (all strong colonies effort may be a relevant factor in longevity with large populations and large food stores reserves) regulation. The time spent searching and were used in this study. They were kept in hives collecting these resources may be considered designed for their breeding (model in Cortopassi- an equivalent of foraging effort, because the Laurino et al. 2006) and a glass plate was placed greater the time spent, the greater the energy between the lid and the upper-nest, to allow the expenditure in flight and handling the resource. observation of internal structures and of bee behavior. Thus, time and effort spent on foraging proba- A 15-cm plastic tube was placed in the entrance (3- bly influences bee longevity, as well as the age cm diameter), to ease the visualization of forager at which foragers start their career, as shown in departure and entrance. The glass plate and tube were the honeybee (Wolf and Schmid-Hempel 1989; placed in the nests at least a month before the Becerra-Guzmán et al. 2005). experiments, to allow the bees to habituate to them In this study, we looked at the longevity and thus not alter their normal behavior. patterns of workers from a meliponine species from the Amazonian Region, M. fasciculata 2.3. Bee marking Smith, 1854. Melipona fasciculata is a medium to large-sized species, whose colonies are In each colony, the older brood combs from which relatively small (about 300–400 bees; Kerr et bees were ready to emerge were removed and placed al. 2001). We focused on two main questions: in an incubator box to allow the capture of newly (a) whether workers from this species present emerged individuals. After their emergence, the Longevity of Melipona fasciculata workers 135 workers used in the experiment (rainy season, n=91; time interval (in days) when the bee was observed dry season, n=109) were weighed with a digital foraging for the first time until its death. precision balance (d=0.001 g) and received an individual tag with unique colors and numbering to 2.5. Data analysis differentiate workers and colonies (tag weight, 0.01 g; Queen Marking Kit, E.H. Thorne beehives To verify possible seasonal differences on the Ltd.). The tags were placed with non-toxic and survival curves of M. fasciculata colonies, we used unscented glue on the thorax, so as to not hinder Kaplan-Meier curves and later comparisons through bee movement and flight, and workers were returned the log-rank test (StatSoft, Inc 2013). To test the to their hives a few minutes after marking. relation between worker longevity and weight, and between longevity and foraging onset age in the two 2.4. Data collection periods, we employed a Spearman correlation test. We performed a Kruskal-Wallis variance analysis After the marked workers were returned to the nest, (data were not normal nor had variance homogeneity) they were observed daily at least four times a day, in the to compare longevity and the foraging onset age afternoon, to verify their survival. The interval between among the resource specialists and mixed foragers, each observation was at least 60 min. Observations lasted during the rainy season. We used the Mann–Whitney up to 10 days after the last registry of a living worker, and test to compare the days of potential foraging to determine the life-span of each worker, we counted between seasons and the time of pollen and nectar both external and internal (in-nest) observations.

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