Scientist are racing against time to better understand bees as many species of the vital pollinators face decline and colony collapse.

A new paper explores one of those little-understood areas: the relationship between leafcutter bees, leaves and microbes.

If you’ve ever seen leaves that look like someone went after them with a hole punch, you’ve likely seen the handiwork of leafcutter bees, which use leaf cuttings in their nests.

When a team led by University of Arizona graduate student Victoria Luizzi noticed that the bees chomped away at certain leaves while snubbing others – even on the same plant – they compared their microbial communities to learn why.

The likely reason: a more generous helping of the common mold aspergillus.

Further experiments suggested that aspergillus inhibits the growth of the fungal pathogen ascosphaera, which can kill larvae if it reaches the nest.

The findings, presented Thursday at the Ecology Society of America's annual meeting in Portland, Oregon, add a new aspect to plant-insect relationships.

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