Respiratory rhythms in stingless bee workers: circadian and ultradian components throughout adult development

Abstract

The workers of the stingless bee, Melipona quadrifasciata, assume different tasks during their adult life. Newly emerged individuals remain inside the nest, without contact with the external environment. Maturing workers go to more peripheral regions and only the oldest, the foragers, leave the nest. As this diversity of activities implies different metabolic patterns, oxygen consumption has been measured in workers of three different ages: 24-48 h (nurses), 10-15 days (builders), and older than 25 days (foragers). Oxygen consumption of individually isolated workers was determined by intermittent respirometry, under constant darkness and temperature of 25±1 °C. Sets of 24-h measurements were obtained from individuals belonging to each of the three worker groups. Rhythmicity has been assessed in the daily (24 h) and ultradian (5-14 h) domains. This experimental design allowed detection of endogenous rhythms without the influence of the social group and without inflicting stress on the individuals, as would be caused by their longer isolation from the colony. Significant 24-h rhythms in oxygen consumption were present in nurses, builders and foragers; therefore, workers are rhythmic from the age of 24-48 h. However, the amplitude of the circadian rhythm changed according to age: nurses showed the lowest values, while foragers consistently presented the largest ones, about ten times larger than the amplitude of nurses' respiratory rhythm. Ultradian frequencies were detected for all worker groups, the power and frequencies of which varied little with age. This means that the ultradian strength was relatively larger in nurses and apparently maintains some relationship with the queen's oviposition episodes.

Age-mediated and environmentally mediated brain and behavior plasticity in the stingless bee Melipona quadrifasciata anthidioides

“…In contrast, the increase in mushroom body volume of honeybee workers occurs mainly at the transition from nursing to foraging activities (Withers et al 1993;Farris et al 2001;Fahrbach 2006;Ismail et al 2006). However, honeybees remain within the hive for only between 1 and 3 weeks, performing various tasks before beginning to forage (Winston 1987); M. quadrifasciata anthidioides workers represent a distinct contrast, as they remain longer within the hive during their adult life (∼30 days) before gradually shifting their activities outside the hive (Waldschmidt and Campos 1997;Teixeira et al 2011).…”

“…The social environment is considered to be crucial for the increase of mushroom bodies in honeybees, affecting the behavior and circadian rhythms of locomotory activity in young bees (Maleszka et al 2009;Smith et al 2010;Teixeira et al 2011;Eban-Rothschild et al 2012). Therefore, the greater walking activity and the increase in mushroom bodies observed in field-reared M. quadrifasciata anthidioides are likely consequences of their more social complex environment under natural conditions than in the laboratory (Maleszka et al 2009).…”

“…Conspecific interactions also contribute to modulating circadian rhythms in the nurse honeybees (Shemesh et al 2010;Eban-Rothschild et al 2012). In M. quadrifasciata anthidioides, the contact of nurse bees with foraging bees and the presence of the queen are important for circadian rhythm synchronization and also influence gene expression in young nurse bees to initiate colony activities (Hartfelder et al 2006;Teixeira et al 2011). Although we did not explore a broad behavior repertoire in field-reared bees compared with laboratory-reared bees, our results regarding the walking behavior of M. quadrifasciata anthidioides suggest that the environmental (social) complexity of the colony may affect the behavioral plasticity of the colony individuals.…”

Métodos lineares e não-lineares de análise de dados cronobiológicos de Melipona quadrifasciata (Hymenoptera, Meliponini)

“…Conforme se modificam as funções exercidas, a localização das operárias na colônia se altera: as abelhas mais jovens, recém-emergidas, ficam na região central da colmeia, sendo que, à medida que envelhecem, ocupam áreas mais periféricas, até deixarem a colônia para coletar alimento (Teixeira et al, 2011). Isso faz com que as operárias passem a ter contato, paulatinamente, com as variações do ambiente externo, haja vista a região mais interna da colmeia apresentar condições reguladas (Loli, 2008).…”

“…Em M. quadrifasciata, foi verificada a existência de ritmos circadianos e ultradianos de consumo de O 2 em operárias de diferentes faixas etárias (nutrizes, construtoras e forrageiras), sendo que a amplitude dos ritmos aumentava com a idade do indivíduo (Teixeira et al, 2011) .…”