Global Warming Could Magnify Insect-Driven Apparent Competition Between Native and Introduced Host Plants in...

Area of Science:

• Ecology
• Invasive Species Biology
• Climate Change Impacts

Background:

• Sub-Antarctic islands face significant threats to endemic species from invasive plants.
• Generalist pest invasions may exacerbate native plant suppression via apparent competition.
• Understanding these interactions is crucial for conservation in vulnerable ecosystems.

Purpose of the Study:

• To investigate the role of invasive aphids in apparent competition between native and invasive plants.
• To assess the impact of warming temperatures on aphid population dynamics on different host plants.
• To predict how climate change might influence plant community structure in sub-Antarctic islands.

Main Methods:

• Compared biological parameters (survival, fecundity, development time) of the invasive aphid Myzus ascalonicus on native Acaena magellanica and invasive Senecio vulgaris.
• Assessed the effect of a simulated 3°C temperature increase on aphid population dynamics on both plant species.
• Utilized population modeling to project changes in pest population doubling times under different temperature scenarios.

Main Results:

• Myzus ascalonicus exhibited higher survival, fecundity, and faster development on the native Acaena magellanica compared to the invasive Senecio vulgaris.
• Warming temperatures disproportionately increased the population growth rate of M. ascalonicus on the native plant species.
• Under a 3°C increase, pest population doubling time was 40% higher on the invasive plant versus 28% on the native plant under current temperatures.

Conclusions:

• Invasive aphids can facilitate the competitive exclusion of native plants through apparent competition.
• Global warming amplifies this effect, favoring aphid populations on native plants and potentially accelerating native species decline.
• Conservation strategies must consider indirect effects of climate change and pest-plant interactions in sub-Antarctic ecosystems.