Decline in insects not to be taken lightly
Research shows that populations, including pollinator species, decreased in Germany over the past 30 years
A shock study has reported a 75% decline in Germany’s flying insect numbers over the past 30 years. Flying insects are a fundamental part of the world’s ecosystem and agriculture: butterflies, wasps and bees, among others, pollinate the plants that ultimately keep people fed and alive.
But SA’s insect prognosis is not as dire, say local experts — although there are no data to back that up.
In a paper published in journal PlosOne, German scientists reported that they set malaise traps, which look like camping tents made of netting, in 96 protected areas and found that insect biomass declined across all ecosystems and habitats.
In a journal interview following the publication, lead author Casper Hallmann said: "Our results imply that the entire flying insect community has been devastated, including common species that are usually found in high numbers. Ironically, this decline was seen in protected areas, which are supposed to help preserve biodiversity and ecosystem stability."
In their paper, the authors say the significant and widespread decline in insect biomass — irrespective of habitat or landscape configuration — points to large-scale factors affecting insect populations. While there has been a great deal of research on the health of specific insects, such as bees, this study shows that there has been a decline across the board.
Asked why insects were important, Hallmann said: "Insects are highly significant, being responsible for plant pollination and nutrient recycling as well as acting as a food source for animals such as birds, bats and small mammals. Lack of insects is very likely to be detrimental to the entire ecosystem, in terms of its diversity as well as its stability and function."
Hallmann said he hoped that this research would galvanise policy makers to take action. "These results demand action at the national and international level to instigate measures that will preserve insects and the ecosystems that rely on them."
Jonathan Colville, an entomologist at the South African National Biodiversity Institute (Sanbi), says that the German study is "alarming" because it had been conducted over such a long period. "If it was five years, we’d be more sceptical, but this is three decades of sampling — long enough to get a handle on a trend," he says.
IF ONE WANTS TO REALLY TACKLE INSECTS SERIOUSLY, WE’LL NEED MORE TAXONOMISTS AND RESEARCHERS….
SA, which has a smaller commercial agriculture industry operating for a shorter period of time, should be in a better position compared with its European brethren.
"Western Europe has been hugely influenced by humans for centuries. They’ve had really intense agriculture and have changed their landscapes quite drastically. If one flies into Germany, you can see the agricultural landscapes," Colville says.
"SA is not as heavily impacted in terms of commercial-scale agriculture. We have it in SA, but we also have large tracts of natural vegetation left."
The Kruger National Park is about 5% of Germany’s total surface and — although the largest — it is one of many national parks in SA.
"I’m sure we’ve lost some insect species," says Colville, "but whether we’re having such drastic declines as Germany, we can’t say. Unfortunately, we don’t have the data or the long-term studies."
He thinks it is unlikely the decline is so large in SA.
The German study focuses on biomass, the total weight
of insects collected, not on species diversity.
"[The study] focused on the biomass, which is just the weight of the insects. Is it also a decline in species numbers?" Colville asks.
Biodiversity is often a buzzword in conservation circles, as it is vital for the health and functioning of an ecosystem. It also makes the system more resilient and able to adapt to changing temperatures and weather patterns — while some species may die out from these changes, others will be able to fill the gap created by their disappearance.
SA is a global biodiversity hotspot. The Cape region, for example, is home to the smallest of the world’s six floristic kingdoms with more than 9,000 vascular plants, about 70% of which are endemic. It has taken more than a century to create that census of plants, and it is still not complete.
"In terms of insects, we’ve probably got tens of thousands of species [in that region alone]," Colville says.
It took a century for botanists to catalogue plant species and it would take even longer to do the same for insects. — especially since they are less popular
than other creatures in SA.
Global conservation efforts — and SA is no exception — tend to focus on "plants and furries", says Colville. "It’s difficult to work on insects, the sheer scale of diversity and numbers is overwhelming. If one wants to really tackle insects seriously, we’ll need more taxonomists, researchers and scientists working on insects in SA."
Colville’s research at Sanbi, part of a five-year research fellowship, focuses on insect diversity hot spots.
"We don’t know for SA where the hotspots of insect diversity are, the numbers of species and endemics [in these areas] and how our insect diversity is distributed across SA," he says. "What I’m trying to do is get foundational information in order to work out where our insect species in SA are concentrated, and their diversity."
This also involves going through natural history collections to determine the historic spread of species and to gauge how that distribution and diversity changed. There are many projects under way to digitise information about and catalogue SA’s flora and fauna.
In October, the government launched the Natural Sciences Collections Facility, which will be a virtual facility collating the more than 30-million plant, animal and fossil specimens scattered between about 40 museums. Sanbi will act as a hub, co-ordinating activity.
There are many threats facing the country’s natural ecosystems, from land-use changes to the burgeoning of invasive species. But a major threat, often under-recognised, is a lack of knowledge.
"If you don’t have the knowledge, you can’t act, you can’t conserve, you can’t be proactive," says Colville. "The lack of knowledge is a threat in itself…. Many species might go extinct before we find them."