對于螞蟻的幼蟻和蛹而言，患病就等于接到死亡判決,。當(dāng)成年螞蟻從它們一塵不染的巢穴中辨認出一只生病的衰弱螞蟻后,，它們僅僅會將病蟻搬出巢穴，讓其自生自滅,。
就像專業(yè)術(shù)語說的那樣，這種極端的“衛(wèi)生行為”是在擁擠的昆蟲巢穴中,，抑制疾病暴發(fā)的一種有效方式,。但是，研究人員在《BMC進化生物學(xué)》上報道說,，一些螞蟻蛹找到了一種方法,，使得它們能避免被巢穴驅(qū)逐——通過在防止細菌的繭蛹中生長，并以此躲避疾病,。
一直以來,，科學(xué)家希望能夠知道，為何在一些螞蟻物種中,，蛹會吐絲結(jié)繭,，包裹起自己的身體，然而在其他螞蟻種群中,，蛹卻是裸露的,。在一些奇怪的案例中，螞蟻甚至還能左右逢源：在相同的螞蟻種群里,，一些蛹會建造繭,，但是其他一些卻沒有。
當(dāng)研究人員利用致命真菌感染了不同的螞蟻物種后（有繭的,、裸露的或“猶豫不決”的蛹）,，成年螞蟻很快將生病的卵搬出巢穴。
但是,，結(jié)果顯示,，有繭的蛹通常被留了下來，并且即使它們?nèi)匀槐┞对谡婢?，這些螞蟻蛹也不會生病,。
研究人員推測,，這些繭就像是盾牌，幫助蛹抵御真菌的入侵,。對于螞蟻而言,，這真是一個雙贏的局面：蛹不會犧牲，而螞蟻群體也能免于流行病的威脅,。(生物谷Bioon.com)
生物谷推薦的英文摘要
BMC Evolutionary Biology doi:10.1186/1471-2148-13-225
Pupal cocoons affect sanitary brood care and limit fungal infections in ant colonies
Simon Tragust, Line V Ugelvig, Michel Chapuisat, Jürgen Heinze and Sylvia Cremer
Background
The brood of ants and other social insects is highly susceptible to pathogens, particularly those that penetrate the soft larval and pupal cuticle. We here test whether the presence of a pupal cocoon, which occurs in some ant species but not in others, affects the sanitary brood care and fungal infection patterns after exposure to the entomopathogenic fungus Metarhizium brunneum. We use a) a comparative approach analysing four species with either naked or cocooned pupae and b) a within-species analysis of a single ant species, in which both pupal types co-exist in the same colony.
Results
We found that the presence of a cocoon did not compromise fungal pathogen detection by the ants and that species with cocooned pupae increased brood grooming after pathogen exposure. All tested ant species further removed brood from their nests, which was predominantly expressed towards larvae and naked pupae treated with the live fungal pathogen. In contrast, cocooned pupae exposed to live fungus were not removed at higher rates than cocooned pupae exposed to dead fungus or a sham control. Consistent with this, exposure to the live fungus caused high numbers of infections and fungal outgrowth in larvae and naked pupae, but not in cocooned pupae. Moreover, the ants consistently removed the brood prior to fungal outgrowth, ensuring a clean brood chamber.
Conclusion
Our study suggests that the pupal cocoon has a protective effect against fungal infection, causing an adaptive change in sanitary behaviours by the ants. It further demonstrates that brood removal?originally described for honeybees as ?hygienic behaviour??is a widespread sanitary behaviour in ants, which likely has important implications on disease dynamics in social insect colonies.
