Are there fewer insects than before in Quebec? The question seems absurd when asked in the middle of the forest, in mid-July, in the Jacques-Cartier National Park, while a cloud of mosquitoes and flies buzz around the two entomologists visiting the field.
They are there to examine an insect trap. The trap, suspended at head height, has two funnels which collect the small birds that strike one of the transparent panels of the device. Nicolas Bédard, one of the entomologists, unscrews the jar to observe the harvest: he finds cantharides, beetles, wireworms and other beasts with strange names.
Two steps from the trap, he sees a Zopheridae on the trunk of a dead tree. This brown, dented beetle, about one centimeter, looks like two drops of water on a piece of bark. When the entomologist touches it, it drops and retracts its legs: the camouflage is perfect.
Insects are everywhere around us, but without us paying too much attention to them. In recent years, however, studies have shown that insect populations have balding in several ecosystems on the planet.
The very severe declines measured in certain regions raise fears of an “insect Armageddon”. However, no inventory made it possible to gauge the situation in Canada.
But for thirty years now, Christian Hébert, the other entomologist present in the cloud of diptera, has been placing traps in the forests of Quebec. And with the observations of this researcher, unique in their longevity, certain “disturbing” findings are beginning to emerge. The insects here would also be in decline.
“We felt things, but we did not have enough data to be formal in our conclusions,” said Mr. Hébert in the red pickup truck of his employer, the Laurentian Forestry Center, which reports to the federal government. on the road to the park.
Comparisons
Through the window of the van, we see a gray spot on a mountain of green fir trees. It was the hemlock looper, an insect native to North America, that killed off these conifers in July 2012 with a sudden epidemic. The cyclic epidemics of this moth disrupt the fauna, flora and industry forest.
Mr. Hébert, a calm 63-year-old man, studies the evolution of insect communities after disturbances such as forest fires, the passage of insect pests or the spreading of insecticide. For each of its projects, control plots, outside the sectors affected, allow comparisons to be made.
However, when the issue of insect decline made headlines in 2017, he realized that his test plots were worth gold. If there was an overall trend, he should be able to observe it by placing the same traps, in the same places, years later. He therefore set out to return to certain sites visited in the past.
Jacques-Cartier Park, 50 km north of Quebec City, was thus targeted this year for a new round of trapping, because the spanworm epidemic is blowing its ten candles there. A comparison will be possible at the end of the summer.
However, traps deployed in the Parc des Grands-Jardins – where a forest fire wreaked havoc in 1999 – already reveal a strong decline on the control plots. While there were an average of 231 flying beetles per trap in 2000, they were only 88 in 2019. Among the beetles trapped on the ground, the count fell from 81 to 42.
Before jumping to conclusions, however, other data were needed. And that’s where Mr. Bédard comes in.
This twenty-something, a passionate amateur entomologist, spends his weekends hunting bugs. He has a sharp eye. On the ground north of Quebec with The duty, he sees two black beetles frolicking. “The male is all black, the female is spotted,” he remarks, taking the two glowing insects in his hands.
Since last year, Mr. Bédard has been leading a research project in forest entomology on the North Shore with a view to obtaining a master’s degree from Université Laval. He spent the summer of 2021 criss-crossing this region to place dozens of traps in the boreal forest. Every two weeks, he took the harvest from the traps.
The objective of his project, carried out under the leadership of Mr. Hébert, is to evaluate the effect of the spreading of Btk — a biological insecticide sometimes used to control the spruce budworm — on the rest of the insects in the forest. At the same time, traps placed in control plots can provide information on the issue of decline.
Because, over the decades, Mr. Hébert’s team has visited more than 200 sampling sites on the North Shore. “These are not necessarily always the same sites, but they are in the same geographical universe, so we can compare them,” argues the researcher. Result: insects are 30% less numerous than before in this region.
Abundance and biodiversity
Long-term monitoring of insect populations requires monastic rigor and patience, both in the field and in the laboratory.
The René-Martineau Insectarium at the Laurentian Forestry Center (CFL) in Quebec City has, according to the latest estimate, about 200,000 specimens. Caroline Bourdon, the (aptly named) technician in charge of the collection, turns a crank to slide the shelves on rails and open a passage between two rows of cabinets.
“I found Anticosti 1998! she exclaims. In a cabinet, labeled Coleoptera, is a drawer with specimens taken from this island in the Gulf of St. Lawrence 24 years ago. Hundreds of tiny insects, each attached to the end of a needle, are stored there for posterity.
Mr. Hébert’s team has traveled to Anticosti Island several times. Its first harvest dates back to 1993, a year after the Earth Summit in Rio, which brought the issue of biodiversity to the fore. He found insects galore there, including 253 specimens of a rare long-horned beetle that hadn’t been seen in Canada for decades.
The entomologist now hopes to have the funds to send his team back to Anticosti next year and do a follow-up thirty years later, which would make it his longest period of comparison. Two students or technicians are expected to spend the whole summer there, so considerable costs are involved.
Identifying the swarms of insects collected during these expeditions then requires a lot of work. Leaning over his microscope, Alain Labrecque, an entomologist on the team, strives to shoot dozens of dried moths. This veteran taxonomist keeps a book handy with hundreds, if not thousands, of butterflies that look identical to the amateur eye.
“There are a lot of little browns and little grays,” he admits as he prepares samples for genetic analysis. These methods, newly implemented in the research center, allow identification complementary to that based on morphology. Sometimes two identical specimens are, in fact, two separate species.
It is therefore imperative to collect insect specimens now to find out if “cryptic” species, unknown to specialists, are silently disappearing. “At the federal level, we are the only ones with the kidneys strong enough to return to the same site twenty years later”, supports Sandrine Picq, a geneticist from the CFL.
Nebulous causes
It’s hard to explain why insect populations are declining. The existence of a generalized collapse is not supported by all entomologists. Certainly, in highly populated regions of the world, such as Europe, habitat destruction and the use of pesticides are a major reason for the problem, with global warming as an aggravating factor.
And in the boreal forest of Canada and Quebec? Despite his decades of experience, Mr. Hébert does not know what is going on. The forests he studied on the North Shore and in Charlevoix seem in any case far enough away from cultivated land for us to be able to rule out the agricultural hypothesis.
The intricacies of ecosystems are extremely complex, so much so that astonishing phenomena may be involved. A study published this year, carried out in Alberta, indicates for example that the presence of earthworms – a species which, in North America, is slowly extending its territory towards the north – is associated with a sharp decrease in insect populations in floor.
To fully understand the causes of the decline in Canada, it will first have to be more precisely documented, believes Mr. Hébert. This researcher-civil servant dreams of seeing permanent monitoring stations in Canada’s national parks. Park biologists could themselves check the insect traps every two weeks.
“We don’t have a research program on the decline of biodiversity, and even less on the decline of insects,” laments Mr. Hébert. While we talk more than ever about the impoverishment of fauna and flora, why does a surveillance network not yet exist? “That’s a good question for our decision-makers in Ottawa,” he replies.