Moth scales, preserved in the mud of a coniferous forest lake, have been used to identify outbreaks of these insects over the past 10,000 years. This groundbreaking new technique, reported in the open-access journal Frontiers in Ecology and Evolution, can tell us more about the frequency and intensity of past and future insect epidemics, their impact on the forest environment and how they are linked to climate change.
Moths are one of the most widespread and recognizable insects in the world. In the boreal forests of North America, which are mainly comprised of coniferous, evergreen trees, the larva of one moth species -- the Spruce Budworm -- can periodically cause severe and widespread damage. This leads to millions of dollars of lost revenue to the forest-based economy.
It was during a routine observation of one of these outbreaks that the researchers had a 'eureka' moment.
This hunch turned out to be true. Taking a 5-meter-long core of sediment from a forest lake near Québec, which represented 10,000 years' worth of sediment deposit, the researchers at the Québec University spent five years perfecting their method of extracting, examining and counting moth scales under the microscope from each sediment layer.
"Our analysis revealed peaks of moth scales that corresponded to known periods of insect outbreak. This means we can work out when these epidemics occurred before records began," says Dr. Lionel Navarro joint-lead author, based at the Québec University, who spent a lot of time in the laboratory processing these samples. "This new method will be of enormous help to future research in areas as wide as ecology and evolution, biodiversity conservation, climate change and forestry."
They continue, "Currently, climate change is one of the biggest challenges of our planet. Understanding our past ecosystems is essential to predicting the future. Based on climate-change predictions, insect outbreaks will be more frequent, with higher severity. Our new technique can help us understand how moths and butterflies react to different climatic scenarios and environmental changes, so we can predict their response to climate change, as well as their vulnerability and extinction risk."
Source: Frontiers [February 22, 2018]