Artificial light at night disrupts trophic and population dynamics of lady beetles and pea aphids in cool conditions

January 3 – Febuary 28, 2021

Meeting Abstract

S1-11  Mon Jan 4 18:00 – 18:30  Artificial light at night disrupts trophic and population dynamics of lady beetles and pea aphids in cool conditions Miller, CR*; Vitousek, MN; Thaler, JS; Cornell University; Cornell University; Cornell University

Natural variation in light has historically correlated with seasonal changes in temperature, providing an honest cue to organisms with seasonal life history cycles. However, with the onset of widespread artificial light at night (ALAN), light is no longer reliably associated with changes in temperature, leading to altered behavior under different environmental conditions. We experimentally investigated impacts of cool temperature and constant light on a lady beetle-aphid-fava plant system to ask 1) how do contrasting temperatures and light influence aphid population growth? and 2) what are the behaviors underlying impacts on this common assemblage’s dynamics? First, we investigated direct effects of treatments on predator (Coccinella septempunctata and Coleomegilla maculata) feeding behavior, aphid predator evasion tactics, aphid population dynamics and plant growth. We then assessed the net effects of ALAN on aphid (Acyrthosiphon pisum) population growth by manipulating temperature and light cycles of our tri-trophic interaction over a ten-day period. Overall, we found that ALAN had multidirectional effects which vary in prevalence under different temperature regimes. Aphids had high population growth rates in cooler treatments, a potential impact of negative density-dependent growth patterns we tracked with and without predators. Aphids and predators reacted differently to variation in light and temperature: we observed evidence of bottom-up food web impacts as aphids excelled in cool, light conditions, and we found top-down control of aphids was strengthened by heightened predatory success in warm conditions, particularly under non-constant light. This knowledge may impact how scientists manage common insect pests during different times of year under the brightening night sky.

the Society for
Integrative &