Stingless Bee Larvae Require Fungal Steroid to Pupate

Area of Science:

• * Microbiology
• * Entomology
• * Symbiotic Relationships

Background:

• * The larval development of the stingless bee Scaptotrigona depilis is dependent on consuming a specific fungus within its brood cell.
• * Insect metamorphosis, including pupation, relies on ecdysteroid hormones, which insects cannot synthesize de novo and must obtain from their diet.

Purpose of the Study:

• * To identify the specific fungus involved in the S. depilis larval development.
• * To elucidate the nutritional contribution of the fungus to the bee.
• * To understand the molecular basis of this bee-fungus mutualistic symbiosis.

Main Methods:

• * Identification of the symbiotic fungus using phylogenetic analyses.
• * In vitro culturing assays with S. depilis larvae.
• * Dietary supplementation experiments with ergosterol.

Main Results:

• * The symbiotic fungus was identified as belonging to the genus Zygosaccharomyces.
• * Zygosaccharomyces provides essential steroid precursors necessary for S. depilis larval development.
• * Dietary ergosterol successfully replicated the developmental benefits of consuming the fungus.

Conclusions:

• * This study reveals an unprecedented bee-fungus symbiosis driven by the bee's requirement for dietary steroids.
• * The findings provide molecular insight into the mutualistic interaction between S. depilis and Zygosaccharomyces.
• * This research offers new perspectives on pollinator-microbiota interactions and their ecological significance.