Al Toufailia Hasan, Alves Denise A, Bento José M S, Marchini Luis C, Ratnieks Francis L W
Laboratory of Apiculture and Social Insects, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
Departamento de Entomologia e Acarologia, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Piracicaba, São Paulo 13418-900, Brazil.
Biol Open. 2016 Nov 15;5(11):1712-1718. doi: 10.1242/bio.018549.
Social insects have many defence mechanisms against pests and pathogens. One of these is hygienic behaviour, which has been studied in detail in the honey bee, Apis mellifera Hygienic honey bee workers remove dead and diseased larvae and pupae from sealed brood cells, thereby reducing disease transfer within the colony. Stingless bees, Meliponini, also rear broods in sealed cells. We investigated hygienic behaviour in three species of Brazilian stingless bees (Melipona scutellaris, Scaptotrigona depilis, Tetragonisca angustula) in response to freeze-killed brood. All three species had high mean levels of freeze-killed brood removal after 48 h ∼99% in M. scutellaris, 80% in S. depilis and 62% in T. angustula (N=8 colonies per species; three trials per colony). These levels are greater than in unselected honey bee populations, ∼46%. In S. depilis there was also considerable intercolony variation, ranging from 27% to 100% removal after 2 days. Interestingly, in the S. depilis colony with the slowest removal of freeze-killed brood, 15% of the adult bees emerging from their cells had shrivelled wings indicating a disease or disorder, which is as yet unidentified. Although the gross symptoms resembled the effects of deformed wing virus in the honey bee, this virus was not detected in the samples. When brood comb from the diseased colony was introduced to the other S. depilis colonies, there was a significant negative correlation between freeze-killed brood removal and the emergence of deformed worker bees (P=0.001), and a positive correlation with the cleaning out of brood cells (P=0.0008). This shows that the more hygienic colonies were detecting and removing unhealthy brood prior to adult emergence. Our results indicate that hygienic behaviour may play an important role in colony health in stingless bees. The low levels of disease normally seen in stingless bees may be because they have effective mechanisms of disease management, not because they lack diseases.
群居昆虫有许多抵御害虫和病原体的防御机制。其中之一是卫生行为，这在蜜蜂（西方蜜蜂）身上已有详细研究。有卫生行为的蜜蜂工蜂会从密封的蜂巢中移除死亡和患病的幼虫及蛹，从而减少蜂群内疾病的传播。无刺蜂（Meliponini）也在密封的蜂巢中培育幼虫。我们研究了三种巴西无刺蜂（盾无刺蜂、光盾无刺蜂、窄胸无刺蜂）对冷冻致死幼虫的卫生行为。48小时后，所有这三个物种移除冷冻致死幼虫的平均水平都很高，盾无刺蜂约为99%，光盾无刺蜂为80%，窄胸无刺蜂为62%（每个物种8个蜂群；每个蜂群进行三次试验）。这些水平高于未经过选择的蜜蜂群体，约为46%。在光盾无刺蜂中，蜂群间也存在相当大的差异，两天后移除率在27%至100%之间。有趣的是，在移除冷冻致死幼虫最慢的光盾无刺蜂蜂群中，从蜂巢中羽化出的成年蜜蜂中有15%翅膀萎缩，表明存在一种尚未明确的疾病或紊乱。尽管总体症状类似于蜜蜂中变形翅病毒的影响，但在样本中未检测到这种病毒。当将患病蜂群的巢脾引入其他光盾无刺蜂蜂群时，移除冷冻致死幼虫与畸形工蜂羽化之间存在显著的负相关（P = 0.001），与清理蜂巢之间存在正相关（P = 0.0008）。这表明卫生状况较好的蜂群在成年蜜蜂羽化前就能检测并移除不健康的幼虫。我们的结果表明，卫生行为可能在无刺蜂的蜂群健康中发挥重要作用。无刺蜂中通常疾病水平较低可能是因为它们有有效的疾病管理机制，而不是因为它们没有疾病。
