Butterflies: save our invisible biodiversity

Updated: Dec 1, 2021

Butterflies have always had a variety of meanings in man’s history. The belief that the human soul takes the shape of a butterfly is still widespread in Greece today, and their beauty and lightness are often compared to angels and fairies (1). While these insects continue to be at the centre of many ethical beliefs, they now also hold significant scientific importance and are vital contributors to the biodiversity of many ecosystems. Although generally, our attention is captured mainly by large animals, marginalising the small world that remains invisible, the microcosm to which these insects and other arthropods belong play a fundamental role in maintaining ecological balance. In the last twenty years, we have witnessed a considerable decline in butterflies and moths due to anthropogenic actions and, for this reason, it has become necessary to resort to conservation efforts. Friend of The Earth is taking part in the recovery of butterflies and moths with a global census relying on citizen science, which will help experts gain greater statistical insight on them. The basis of this project considers the importance of their ecological role, but also of their value as living beings on the planet.

There are more than one hundred and eighty thousand species of butterflies, among the one and a half million insects present on Earth. They belong to the order of Lepidoptera, a group that evolved 145 million years ago in various shapes and sizes. Almost immediately, they established an interdependence with flowering plants, that became fundamental nourishment hubs for adults and larval food on which caterpillars depend. Forests only take up 10% of the Earth's surface but host at least 50% of existing species of butterflies and moths. The country with the most species in the world – 3,642 species and 2,085 subspecies (20% of those found on the entire planet for context) is Colombia. This is due to its significant floral diversity and its unique territorial diversity, which ranges from the Andean Mountains to the Amazonian rainforest and the grasslands of the llanos (2).

Figure 2 - Aglais urticae, France

As many as 28% of all species assessed by the International Union for Conservation of Nature (IUCN) are at risk of extinction (3). Butterflies and moths have suffered disproportionately, and 53% of the world’s butterflies have suffered drastic declines in recent decades (4). The beginning of the loss in their their biodiversity, according to experts, corresponds to historical events linked to man’s presence. Although it is not agreed upon when it began, there is now general acceptance that we are at a point where human influence is significantly affecting the natural world. This has been labelled as the “Anthropocene”. A remarkable example demonstrated by a moth was reported in the 1950s by English naturalist Bernard Kettlewell. The White Moth Biston betularia, used to camouflage itself among clear lichens of birches’ trunks, in the 21st century it adapted its morphology and became black to blend in with the soot created by the pollution from the Industrial Revolution (5).

Climate Change is one of the most impacting human-mediated threats for butterfly and moth species. With the increase in average annual temperatures, butterflies, for example (even non-migratory ones) from Central and Northern Europe, are forced to migrate in search of milder temperatures. These movements, and the sudden temperature changes, put butterflies under biological stress as ectothermic insects. Being ectothermic, they rely on temperature to dictate several physiological processes such as reproductive cycles and normal vital functions. April 2021 was one of the coolest recorded in Britain’s history, it was followed by extremely heavy rains in May. Several UK species of butterflies were seriously damaged by the cold, low temperatures delayed the transformation of caterpillars into butterflies, and rain interfered with their flight (6).

Figure 3 - Catocala nupta, UK

Where Climate Change might be considered the most serious threat to butterflies and moths generally, habitat loss and habitat deterioration are likely the most significant threat to specialist species. Deforestation, particularly throughout tropical countries such as South America, Indonesia and Australia is a very serious threatening factor. Anthropogenic land-use change through the intensification of agriculture, changing forest management, and uncontrolled use of pesticides and herbicides leads to declines also. Since 1990 throughout Europe, for example, populations of farmland butterflies have decreased by 30% due to a combination of these reasons (7).

In the UK, the rarest species is Melitaea athalia, a small Palearctic nymphalid. Despite declines in recent years, it has had its population status restored back to better numbers thanks to conservation interventions over the last 20 years. Among these is the Wilder Blean Project, which is introducing the European bison, an ecosystem engineer, near Canterbury. Its actions have allowed for the regrowth of grass in which fritillary flowers grow, important floral resources on which many butterflies depend (8).

Butterflies and moths play a fundamental ecological role, partly as they are pollinating insects and are directly responsible for the reproduction of new floral generations. They are an integral part of the trophic chain and are food for many birds, reptiles, amphibians, and other arthropods. In addition to this, they are important environmental bioindicators. The presence of Lepidoptera in abundance and diversity indicates good habitat health.

A handful of studies have occurred demonstrating possible resolutions to Lepidoptera declines, these should be referred to when looking to preserve them. Good agricultural management, performed on a large scale through natural pesticide use, is one of the strategies that proved effective in conserving these insects in situ. One famous success story in the UK was the English-based MACMAN project, which was able to bring back the threatened lycaenid Maculinea arion, more commonly known as the ‘Large Blue’ from extinction (10). In 1979, following its disappearance in the UK, it was successfully reintroduced and had its populations nursed back to health following the provision of good ecological data and light ecosystem engineering (11).

Scientific research through genetic mapping, transects and expeditions are among a host of statistical methods helping preserve both rare and common butterflies and moths. One way of gaining important statistical insight which is proving particularly effective is Citizen Science, which relies on the public to obtain real-time images, geo-referenced points, and environmental/ meteorological information to enrich collection databases.

Figure 4 - Acherontia atropops moth, Italy

Friend of the Earth (of the World Sustainability Organisation) launched the Global Butterflies Census in January 2021 to raise public awareness for butterflies and moths, as well as their disappearance. They aim to spread knowledge regarding their biodiversity and collect essential information to evaluate their populations and better understand their behaviour (12). Anyone can participate in the global census and everyone's involvement is essential. It only takes two simple steps. Whenever you come across a butterfly or moth, you need to take a close-up photo without disturbing the specimen and send it via WhatsApp message to +39 351 2522520, together with your name and the coordinates of your position. Friend of the Earth will identify the species and store the information on its interactive map and census database. So far, we have catalogued more than 1,030 photos including almost 350 species of butterflies and more than 150 species of moths from 20 different countries (13). This information will help produce statistics to design and implement conservation measures. Everyone can join Friend of the Earth in this global effort to save butterflies and moths and make these tiny, beautiful, and important animals stand out.

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