Entomologists: Brazilian Stingless Bee Must Cultivate Special Type of Fungus to Survive

Oct 23, 2015 by News Staff

A team of entomologists has discovered that a stingless bee species from Brazil feeds its larvae on a special type of fungus grown in the nest.

Brazilian stingless bees (Scaptotrigona depilis). Image credit: Cristiano Menezes.

Brazilian stingless bees (Scaptotrigona depilis). Image credit: Cristiano Menezes.

In a paper published in the journal Current Biology, the team reports the first case of an obligatory relationship between the Brazilian stingless bee (Scaptotrigona depilis) and a fungus of the genus Monascus.

The scientists made this discovery quite by accident. One of the team members, Dr Cristiano Menezes of the Brazilian Agricultural Research Corporation, was on a quest to produce queens of the Brazilian stingless bee in the lab.

When he kept the developing bees in a humid chamber, he saw a lot of white fungus begin to grow out of control, and then the larvae died. The scientist thought it was some kind of a disease plaguing the bees.

But then he noticed the fungus growing much less rampantly in natural brood combs. It seemed as though something in the bees’ more natural environment was keeping the fungus under control. He tried raising the bees under less-humid conditions and noticed a big change.

“I observed that the fungus grew intensively for a few days and then disappeared. After that, I obtained more than 90% survival rate in the trials,” Dr Menezes explained.

He suspected that the larvae were eating the fungus. When he recorded their behavior in a natural brood comb, he could see them gobbling it up.

Dr Menezes and his colleagues now report that larvae reared in dishes on sterilized larval food supplemented with fungal mycelia survive 76% of the time. Those raised without the fungus rarely make it – surviving just 8% of time.

According to the team, the fungus originates from the material the bees use to make brood cells.

“Since the bees recycle and transport this material between nests, fungus would be transferred to newly built cells, and also to newly founded nests,” they said.

The scientists suspect other bees will be found to depend on fungi too.

“Symbiosis between bees and microorganisms seems to be much more frequent than we thought before and is being explored recently by other researchers to improve colony health,” Dr Menezes said.

“The diversity of social, sub-social, and non-social bees is so big, especially in the tropics, that it is quite probable that other farming systems exist.”

Interestingly, a very similar fungus of the genus Monascus has been used in Asian cultures for centuries as a food preservative.

Related fungi are known to secrete chemicals with anti-microbial, anti-cancer, and other health benefits.

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Cristiano Menezes et al. 2015. A Brazilian Social Bee Must Cultivate Fungus to Survive. Current Biology 25; doi: 10.1016/j.cub.2015.09.028

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