外来種アリがマルハナバチの採餌を妨害する生態系干渉を発見(When ants battle bumble bees, nobody wins)

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2025-11-12 カリフォルニア大学リバーサイド校 (UCR)

カリフォルニア大学リバーサイド(UCR)の研究によると、ミツバチ(特にマルハナバチ)とアリが餌資源をめぐって競合すると、どちらの種も利益を得られず、生態系全体に悪影響が及ぶ可能性が示された。実験では、花蜜の主要訪花者であるマルハナバチの採餌活動にアリを加えると、アリは蜜源を占拠する一方で、マルハナバチは摂食量を減らし、花粉媒介効率が著しく低下した。しかし、アリ側も蜜の入手効率は十分に向上せず、両方の集団が資源確保に失敗する「lose–lose」の状況となった。研究者は、アリの侵入(特に外来アリ)が野生のポリネーターに与える影響は従来考えられていた以上に深刻で、作物の受粉サービスにも連鎖的な損失をもたらし得ると警告している。本研究は、送粉者保全のためにはアリとミツバチの相互作用の管理が不可欠であることを示すものである。

外来種アリがマルハナバチの採餌を妨害する生態系干渉を発見(When ants battle bumble bees, nobody wins)
Bumble bees on a feeder in the lab surrounded by Argentine ants. (Michelle Miner/UCR)

<関連情報>

ミツバチはアリの直接的な攻撃に応じて蜜採集行動を調整する(膜翅目:ミツバチ科とアリ科) Bees modulate behavior during nectar foraging in response to direct ant aggression (Hymenoptera: Apidae and Formicidae)

Michelle Constanza Miner, Erin E Wilson Rankin
Journal of Insect Science  Published:07 November 2025
DOI:https://doi.org/10.1093/jisesa/ieaf076

Abstract

Nectar thieves may seriously impact pollinator foraging behavior and, ultimately, pollination services in natural and agricultural contexts. Despite strong interest in pollinators and their services, there remain gaps in our knowledge as to how ants influence bee foraging decisions. Here, we characterized ant–bee interactions at shared resources and the subsequent behavioral sequences exhibited by bees. We found that two-thirds of bumble bee (Bombus impatiens Cresson) behaviors at nectar resources involved direct interactions with Argentine ants (Linepithema humile Mayr). Consistent with predictions of interference competition, the number of ants at a shared resource decreased the probability of a bee feeding and increased the likelihood of a bee being bitten. Similarly, getting bitten by an ant decreased the probability that a bee would subsequently feed and increased the likelihood that a bee engaged in aggressive responses, such as gaping mandibles and attacking the ant. Behavioral sequences fell into two clusters: Cluster 1 was characterized by feeding and nonaggressive behaviors, and Cluster 2 was exemplified by strings of aggressive behaviors. Behavioral sequences that included aggression were longer and more diverse than those involving predominately nonaggressive behaviors, demonstrating that aggression (either on the part of the bee or the ant) extended behavioral exchanges and disrupted bumblebee foraging and resource collection. Our study identified that ant abundance and aggressive biting behaviors were strong predictors of subsequent bee actions. Such experiences may contribute to learned avoidance of ants in future encounters, consistent with interference competition theory, and have broader implications for disrupted foraging in social animals.

生物環境工学
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