Frontiers.org – Threatening the food chain: “In many cities, the streetlights run all night — but what does this mean for the plants and animals that live there? Scientists tested Japanese pagoda trees and green ash trees in Beijing to see what effect round-the-clock light has on them. They found that the leaves were tougher and that their levels of nutrients and defense substances had been altered. Insects were feeding on these tougher leaves less, with potentially significant implications for urban food chains. Light pollution disrupts circadian rhythms and ecosystems worldwide – but for plants, dependent on light for photosynthesis, its effects could be profound. Now scientists writing in Frontiers in Plant Science have found that exposure to high levels of artificial light at night makes tree leaves grow tougher and harder for insects to eat, threatening urban food chains. “We noticed that, compared to natural ecosystems, tree leaves in most urban ecosystems generally show little sign of insect damage. We were curious as to why,” said corresponding author Dr Shuang Zhang of the Chinese Academy of Sciences. “Here we show that in two of the most common tree species in Beijing, artificial light at night led to increased leaf toughness and decreased levels of leaf herbivory.”

See also Knowable – Air pollution makes it harder for bees to smell flowers – “…A growing body of research suggests that pollution can disrupt insect attraction to plants — at a time when many insect populations are already suffering deep declines due to agricultural chemicals, habitat loss and climate change. Around 75 percent of wild flowering plants and around 35 percent of food crops rely on animals to move pollen around, so that plants can fertilize one another and form seeds. Even the black mustard plants used in the experiment, which can self-fertilize, exhibited a drop of 14 percent to 31 percent in successful pollination as measured by the number of seedpods, seeds per pod and seedpod weight from plants engulfed by dirty air. Scientists are still working out how strong and widespread these effects of pollution are, and how they operate. They’re learning that pollution may have a surprising diversity of effects, from changing the scents that draw insects to flowers to warping the creatures’ ability to smell, learn and remember. This research is still young, says Jeff Riffell, a neuroscientist at the University of Washington. “We’re only touching the tip of the iceberg, if you will, in terms of how these effects are influencing these pollinators.”