Reproductive Interference in an Introduced Bumblebee: Polyandry may Mitigate Negative Reproductive Impact

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Biology

Background:

• Reproductive interference (RI) is a significant threat to native species, particularly in cases of introduced species.
• Bumblebees (Bombus spp.) are important pollinators, and their population dynamics are crucial for ecosystem health.
• Hybridization and inviable egg production are key indicators of reproductive interference.

Purpose of the Study:

• To review hybrid production between introduced *Bombus terrestris* and native Japanese bumblebees (*B. ignitus*, *B. hypocrita sapporoensis*).
• To assess the impact of interspecific mating on native bumblebee reproduction and population dynamics.
• To evaluate proposed management strategies for controlling invasive bumblebee populations.

Main Methods:

• Comparative review of hybrid production data in Japan.
• Analysis of interspecific mating events between *B. terrestris* and native species.
• Evaluation of proposed control methods including native male releases and insecticide application.

Main Results:

• New data confirm hybrid production between introduced *B. terrestris* and native *B. ignitus* in Honshu.
• Interspecific mating results in inviable egg production, disrupting native *B. h. sapporoensis* and *B. ignitus* reproduction.
• Species replacement is facilitated by RI, with increased mating frequencies in *B. terrestris* queens suggesting potential polyandry evolution.

Conclusions:

• Introduced *B. terrestris* poses a significant threat to native Japanese bumblebees through reproductive interference.
• Management strategies, including biological control via native male releases and chemical control using insect growth regulators, are proposed.
• Understanding RI dynamics is critical for conserving native pollinator populations and managing invasive species.