Post-introduction evolution in the biological control agent Longitarsus jacobaeae (Coleoptera: Chrysomelidae)

Area of Science:

• Ecology
• Evolutionary Biology
• Biological Control

Background:

• Biological invasions are models for studying rapid evolution.
• Biological control systems offer similar opportunities for evolutionary assessment.
• Longitarsus jacobaeae, a biocontrol agent for Jacobaea vulgaris, was introduced to Mt. Hood, Oregon.

Purpose of the Study:

• To assess post-introduction climatic adaptation in a biological control agent.
• To compare life-history traits of Longitarsus jacobaeae populations from different elevations.
• To evaluate the performance of adapted and non-adapted populations in reciprocal environments.

Main Methods:

• Common garden experiments comparing beetle populations from Italy, USA (Mt. Hood), and Switzerland.
• Reciprocal transplant experiments evaluating population performance across low and high elevations.
• Analysis of life-history characteristics, including aestival diapause and phenology.

Main Results:

• The Mt. Hood population exhibited significant changes in aestival diapause and phenology compared to low-elevation populations.
• The Mt. Hood population showed enhanced performance in its native high-elevation environment.
• Life-history shifts in the Mt. Hood population align with predictions for adaptation to cooler climates.

Conclusions:

• Longitarsus jacobaeae has undergone rapid, post-introduction climatic adaptation at Mt. Hood.
• Life-history evolution in this biological control agent demonstrates adaptation to cooler, high-elevation conditions.
• The study supports theoretical predictions of adaptation in response to environmental change.