What could the loss of insects mean for the ecosystems that feed us?


A few days ago I opened a jar of honey that I hadn’t touched in months. The thick golden syrup was covered in black spots – ants that had fallen dead after eating the nectar. I hadn’t seen that in years. It seems a long time ago when a forgotten chocolate bar, a piece of fruit, an uncovered cube of cheese or even a crumb of cake lured a troop of foraging insects out of nowhere. Their pheromone traces warned more colony members who would join the effort to break the food down into tiny particles that they carried home.

These seemingly pesky creatures are very diverse – there are more than 13,000 known species of ants and at least 10,000 species yet to be discovered. They outperform humans by about a million to one. There are highly organized ant communities almost everywhere – cities, villages, forests, farms. EO Wilson, arguably the greatest living – and sometimes controversial – naturalist in the world, writes in Tales from the Ant World (Liveright, 2020): “Ants invade every available nesting site, taking control of most of the available food sources, and creating one Arthropod hegemony that controls every level of the country, from the highest canopy to the lowest root mass. “

There are more than 13,000 known species of ants and at least 10,000 species that have yet to be discovered. They outperform humans by about a million to one. (Source: Getty Images)

Still, there could be fewer ants than there were about three decades ago. Last year, a study in Science reported that the population of insects like ants, grasshoppers, and butterflies has declined by nine percent every decade for the past 30 years.

Goodbye forever? Ant armies are known to use force to defend their homeland, after all. In Social Conquest of Earth (Liveright, 2012), Wilson writes that snipers in the Solomon Islands during World War II were “known to fear weaver ants as much as the Japanese”.

However, the reality is more sobering. The decline of ants, butterflies, bees, wasps, grasshoppers, fireflies, and dragonflies could go well beyond their own demise. Without insects we wouldn’t get much of our vegetable food and without beetles the world would be overrun with rotting material. Insects are the primary users: They digest decomposed bodies and dead wood, control the spread of weeds, agricultural pests, pathogens and other organisms that make life difficult for people. They are resources for medicines and indicators of habitat quality. Much like earthworms, ants are ecosystem engineers who, while tunneling through the earth to form their complex mounds, redistribute nutrients in the soil and improve air and water circulation.

Point of no return: Throughout history, humans have influenced insects and biodiversity networks. (Source: Getty Images)

Wilson calls insects “the little creatures that rule the world”. But aside from a few charismatic species – monarch butterflies, for example – most species of the insect class are rarely monitored or counted. Beyond the pioneering studies of entomologists Daniel Janzen and Winifred Hallwachs of Wilson and the University of Pennsylvania, our knowledge of the fate of most ant species is based on anecdotal accounts. In a landmark address 34 years ago at the opening of the National Zoological Park in Washington, DC, urging the world to pay more attention to the fate of invertebrates, Wilson said, “If invertebrates went away, I doubt human beings Species “could take more than a few months. Most fish, amphibians, birds, and mammals would go extinct around the same time. Next would be the bulk of flowering plants, and with them the physical structure of the majority of the world’s forests and other terrestrial habitats. The earth would rot. If dead vegetation accumulated and dried up, the channels of nutrient cycles narrowed and closed, other complex forms of vegetation and with them the last remains of vertebrates would perish. The remaining mushrooms would also perish after a population explosion of tremendous proportions. Within a few decades, the world would revert to a state it was in a billion years ago, made up mostly of bacteria, algae, and some other very simple multicellular plants. “

Wilson is among the scientists who believe that insect decay is one of the most catastrophic aspects of the “sixth extinction.” Janzen and Hallwachs have been warning of this for at least four decades. “I have observed the gradual and very visible decline in Mexican and Central American insect density and biodiversity since 1953 and Winnie since 1978. The loss is very real … and the reasons are very obvious: intensive forest and agricultural simplification of very large areas, massive use of pesticides , Habitat fragmentation and, at least since the 1980s, an ever increasing climate change in temperature … will lose a great deal of time. The house is burning. We don’t need a thermometer. We need a fire hose, ”Janzen wrote in 2019 in an article in the international journal for nature conservation science, Biological Conservation.

Butterflies, moths and bees are worst affected. The US has lost almost half of its bee colonies in the past 70 years. The creatures’ demise began immediately after DDT was introduced in the 1940s and even continued after America discontinued the insecticide in 1972.

David Wagner and his associate editors of this January’s seminal issue of the American multidisciplinary scientific journal PNAS on insect decline believe that “many of the butterfly declines in Europe are due to changes in agricultural practice after World War II … when modern tractors and mechanized” became Equipment used to accelerate the industrialization of agriculture, insecticides became widespread, and synthetic fertilizers could be produced and used in vast quantities ”. Deforestation, mainly for agricultural expansion, is proceeding at a pace that is having alarming effects on insects and other arthropods. We don’t even know the true extent of this crisis, fear Wagner and his colleagues.

bumblebee Butterflies, moths and bees are worst affected. (Source: Getty Images)

In their contribution to this collection, Janzen and Hallwachs write about the “heterogeneous blanket” of the effects of climate change. Humans have influenced insects and biodiversity networks throughout their history. But in most cases in the past, the effects of the attack have been reversed. Because of climate change, write Janzen and Hallwachs, much of this reversal does not take place: “A 200 year old tree with all its accompanying parts of thousands of ecosystem networks now and during its lifespan, now exposed to climate change, no longer has the climate or.” the interacting partners in order to reproduce as his parents did. The herbivores, pollinators, seed dispersers, mycorrhizas, decomposers, diseases, competitors, commensals, mutualists, parents, parasites, and predators are all different from what a seed, seedling, and sapling was. Only minimal recovery is likely, the original cassandras fear insect death.

In 2009, French entomologist Nicola Gallai estimated that India has lost nearly 40 percent of its honeybees since the 1980s. “Although there is no shortage of information about honey-producing bees in India, information about other indigenous bee species is scant and ambiguous from the start,” write Manjishtha Bhattacharya, Sankar Acharya and Susanta Chakraborty in a 2017 article in an open access – Journal, Tropical Conservation Science.

Last year, a study in a village in Andhra – reported in the International Journal of Tropical Insect Science – compared a 1996 firefly census in the same area and found that the population of these beetles had declined by 80-90 percent. Scientists attribute the decline to the unscientific use of pesticides in rice fields. Research in other parts of the world has attributed the decline of these creatures to light pollution – the energy-efficient LEDs, ironically inspired by these glowing insects, are particularly known for disrupting firefly courtship rituals, in which males and females play around with the play of light and color to attract the other’s attention. Lights from houses, buildings and cars distort these signals and fewer larvae are born every year. The International Union for Conservation of Nature’s Firefly Specialist Group believes that such studies, while invaluable, need long-term data to support them. In the past year, more than 20 scientists from different parts of the world came together to issue a “Warning to Mankind about Insect Dying”. In the Biological Conservation they said, “If we lose insects, we lose more than species. Such losses lead to a decline in important ecosystem services on which humankind depends. “

Source link


Leave A Reply