Invasive Ants Disrupt Bumble Bee Foraging

Bumble bees may defeat Argentine ants in one-on-one fights, but the battles come at a cost to the hive.

Published on Feb. 20, 2026

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A new study finds that when bumble bees encounter invasive Argentine ants at feeding sites, they may defeat the ants in direct clashes but still return to the colony with less nectar. The aggressive ant presence induces prolonged confrontations, causing bees to waste energy and time that could be spent foraging efficiently.

Why it matters

Bumble bees already face numerous pressures, and this research suggests invasive ants may be adding another layer of stress. As important pollinators, understanding these 'nectar wars' and their impact on bee colonies is crucial.

The details

In lab experiments, researchers observed over 4,300 individual bee behaviors from 415 bumble bees. When possible, bees avoided feeders with ants present, but conflicts still escalated. While bees usually prevailed in one-on-one fights, the prolonged aggressive exchanges meant they spent less time actually collecting nectar. This energy expenditure and time loss could negatively impact the entire bee colony, though researchers are still studying how colonies respond when foragers return with less food.

  • The study was published in the Journal of Insect Science in November 2025.

The players

Michelle Constanza Miner

A former UC Riverside entomology graduate student who conducted the research.

Erin E Wilson Rankin

A professor at UC Riverside who oversaw the lab experiments.

Argentine ants

An invasive ant species that relies on overwhelming numbers to control food sources, rather than stinging.

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What they’re saying

“With how important bumble bees are as pollinators, it made sense to try and understand more about what's going on in these tiny nectar wars, because they could have a big impact.”

— Michelle Constanza Miner, Former UC Riverside entomology graduate student (Journal of Insect Science)

“They can dominate a food resource just by showing up en masse.”

— Erin E Wilson Rankin, Professor, UC Riverside (Journal of Insect Science)

“We do see the aggression being bi-directional. Sometimes you'll see ant heads on the bee's legs because they were feeding, and in response to an attack, the bee bit the ant and decapitated it.”

— Erin E Wilson Rankin, Professor, UC Riverside (Journal of Insect Science)

“Mandibles are like teeth, but not only used to chew. They can flare open to handle flowers or crunch a foe.”

— Michelle Constanza Miner, Former UC Riverside entomology graduate student (Journal of Insect Science)

“The ant presence induced prolonged aggressive exchanges. Even though that one bee might benefit from being aggressive in the short term, it may not be beneficial for the colony overall.”

— Erin E Wilson Rankin, Professor, UC Riverside (Journal of Insect Science)

What’s next

Researchers still do not know how bee colonies respond when foragers return with less nectar, and plan to study whether the colony sends out additional foragers to compensate.

The takeaway

This research highlights how invasive species can disrupt critical pollinator populations, even when individual bees appear to 'win' their battles. Understanding these complex interactions is crucial to supporting bumble bee health and the broader ecosystem they sustain.