Butterflies

Britain's native butterflies are dying out – with numbers almost halving since 1976

Populations have fallen by 48 per cent overall with the worst affected species – the white-letter hairstreak – down by 96 per cent. Conservationists say the decline is down to intensive farming practices and fewer wild flowers in the countryside. The survey, carried out for the Department for Environment, Food and Rural Affairs (Defra), examined two classes of butterfly – those that are specific to a particular terrain and those that dwell in the wider countryside, farmland or gardens. Habitat specialists were down 61 per cent, while the latter group fell 41 per cent – an overall drop of almost 50 per cent. The figures do not include migrant species. The survey also found that since 1990, numbers of woodland species have fallen by 51 per cent, reaching a historical low in 2012. Species in severe decline include the brown argus, common blue, gatekeeper, holly blue, and the marbled white.

Dakota skipper and Poweshiek skipperling are in deep trouble

With most of their prairie habitat sliced and diced by agricultural development, the Dakota skipper (Hesperia dacotae) and Poweshiek skipperling (Oarisma poweshiek) have long been in trouble. The butterflies were put on the Endangered Species List in 2014, and this week, the U.S. Fish and Wildlife Service designated about 46,000 acres of critical habitat for the two species. “That these butterflies have survived at all is because of the good stewardship of some of the region’s landowners,” said USFWS Midwest regional director Tom Melius. “We will continue to work with these and other landowners to ensure the conservation of remnant prairie habitat and these prairie butterflies.” Specifically, the USFWS has designated about 19,900 acres of critical habitat in Minnesota, North Dakota and South Dakota for the threatened Dakota skipper, and about 25,900 acres in 56 units in Iowa, Michigan, Minnesota, North Dakota, South Dakota and Wisconsin for the endangered Poweshiek skipperling. Of the total 33,742 acres of critical habitat, about 12,050 acres is common to both species.

Comparative Losses of British Butterflies, Birds, and Plants and the Global Extinction Crisis

There is growing concern about increased population, regional, and global extinctions of species. A key question is whether extinction rates for one group of organisms are representative of other taxa. We present a comparison at the national scale of population and regional extinctions of birds, butterflies, and vascular plants from Britain in recent decades. Butterflies experienced the greatest net losses, disappearing on average from 13% of their previously occupied 10-kilometer squares. If insects elsewhere in the world are similarly sensitive, the known global extinction rates of vertebrate and plant species have an unrecorded parallel among the invertebrates, strengthening the hypothesis that the natural world is experiencing the sixth major extinction event in its history.

European grassland butterfly abundance has declined by 30% since 1990

Due to their high numbers of species and their wide range of ecological requirements, butterflies, like birds and vascular plants, are good expressions of the level of biodiversity (that is, the variety of life forms) in our landscapes. Their generally low dispersal capacity, their short life cycle and a high sensitivity and responsiveness to climate conditions also make butterflies good bioindicators of environmental change. In addition, butterflies are emblematic, well known and easy to identify in the field. The European Grassland Butterfly Indicator represents one of the EU biodiversity indicators of the European Environment Agency (EEA). Data for seventeen grassland butterfly species have been used to assess abundance trends between 1990 and 2013. Of those seventeen species, "ten have declined in the EU, three have remained stable and three increased. For one species the trend is uncertain". At the European scale, grassland butterfly abundance has declined by 30% since 1990.

Natuurbehoud vereist een radicale ommekeer naar niet-chemische plaagbeheersing en duurzame gifvrije landbouw

Bijen en andere bestuivende insecten - essentiële schakels in onze voedselproductie - lopen ernstig gevaar door bestrijdingsmiddelen. Dat blijkt uit een studie van de European Food Safety Authority (EFSA)[1]. Ongeveer een derde van de voedselgewassen is direct afhankelijk van bestuiving door onder andere bijen[2]. Het gaat slecht met honingbijen, wilde bijen en hommels in Nederland en Europa. De drie zogenaamde neonicotinoiden worden al jaren door wetenschappers aangewezen als voorname oorzaak. Dit zijn bestrijdingsmiddelen waarmee boeren plaaginsecten zoals bladluizen van hun gewassen weren. Bijen en hommels zijn daarbij onbedoeld slachtoffer. Een in 2013 ingesteld gedeeltelijk verbod heeft te weinig effect gehad op de toepassing van de pesticiden. In Nederland mag 85 procent van het gebruik van de stoffen gewoon blijven doorgaan, zo bleek uit eerder onderzoek door het Centrum voor Landbouw en Milieu[3]. Zo is het toegestaan fruitboomgaarden na de bloei te sproeien, het middel in kassen of bij de aardappelteelt te gebruiken, ondanks dat wetenschappelijk vaststaat dat deze praktijk de natuur om zeep helpt. Daarnaast bedingen sommige EU landen uitzonderingen op het deelverbod – zoals recentelijk Groot Brittannië voor behandeling van koolzaad[4].

In de Duitse deelstaat Noordrijn-Westfalen verdwijnen de insecten, in Nederland zal het niet anders zijn

Naar aanleiding van de Internationale Dag van de Biodiversiteit waarschuwt de natuurbeschermingsorganisatie NABU in de Duitse deelstaat Noordrijn-Westfalen tegen dramatische ontwikkelingen bij de insecten. Meer dan 60 procent van de hommel soorten zijn uitgestorven in de regio Krefeld. Een soortgelijke situatie bestaat in de hoofdstad Düsseldorf bij de vlinders, waarvan 58 procent van de soorten reeds zijn verdwenen. "Om aandacht te vestigen op het uitsterven van soorten, hoeven we niet langer te wijzen naar het regenwoud - het gebeurt voor onze deur", zegt NABU districtsvoorzitter Josef Tumbrinck. Volgens onderzoek van entomologen gaat niet alleen het aantal insectensoorten maar ook het totale bestand van alle op een plaats voorkomende vliegende insecten dramatisch achteruit. Op diverse locaties heeft de Entomologische Vereniging Krefeld in de afgelopen drie jaar gegevens over insecten verzameld via gestandaardiseerde methoden en vergeleken met de testresultaten van 15 tot 25 jaar geleden. Hieruit bleken dramatische verliezen van 70 tot 80 procent van de biomassa van vliegende insecten.

Birds and butterflies suffering severe decline on farmland in UK

Butterflies including gatekeepers, large skippers, small coppers and small tortoiseshells are in severe decline on agricultural land, while breeding farmland bird populations hit their lowest recorded level in England in 2013, having more than halved since 1970. Breeding farmland birds and butterflies are declining in both the long and short term, while woodland birds and butterflies have also seen numbers fall in past decades. In 2013, breeding woodland birds in England reached their lowest recorded level, more than a quarter (28%) below 1970 levels. Butterfly populations have tumbled by almost a half (48%) since 1990.

Sinds de invoering van neonicotinoiden verdwijnen de vlinders op het boerenland

De boerenlandlandvlinders zijn in Nederland vanaf 1992 sterk achteruit gegaan. Dit blijkt uit de graslandgraadmeter. De achteruitgang is in het agrarisch gebied nog sterker dan in natuurgebieden, maar ook dan in stedelijk gebied. Uit de prachtige plaatjes van het vroegere boerenland kun je bedenken welke vlinders daar hebben rondgevlogen. Uit de beperkte gegevens die van vroeger beschikbaar zijn, en uit verslagen en collecties van vlinderaars, komt een gevarieerd beeld naar voren. De zilveren maan op de graslanden, soms vergezeld van de moerasparelmoervlinder. Drie verschillende soorten vuurvlinders en hele massa’s zandoogjes. Niet alleen veel soorten, maar ook gewoon heel veel vlinders. Dat kom je nu op het boerenland niet meer tegen.

Insect population is down by 45% in just 35 years

The world’s population of creepy crawlies has fallen by nearly half – but that is bad news for us, experts warn. A study published in the journal Science, reveals that the number of slugs, spiders, worms and other invertebrates has fallen by 45 per cent over the past 35 years as the human population has doubled. Experts fear this will harm the planet as creepy crawlies play an important role in pollinating crops, pest control, decomposition and ensuring soil remains packed with nutrients, as well as water filtration. In the UK the number of beetles, butterflies, bees and wasps has fallen by up to 60 per cent. Experts warn that fewer insects would have a huge effect on crop production as up to 75 per are pollinated by insects, amounting to around 10 per cent of the world's food supply. And the cost of pest control without natural predators could be more than £2.6 billion pounds in the United States alone. Scientists fear a drop in the insect population could also spark a decline in birds, which prey on pests that damage crops, and amphibians, which help keep water supplies free from algae. Decreasing invertebrate numbers are also known to compromise food production due to reduced pollination, seed dispersal and insect predation.

Soil-Applied Imidacloprid Translocates to Ornamental Flowers and Reduces Survival of Adult Lady Beetles and Larval Butterflies

Integrated Pest Management (IPM) is a decision making process used to manage pests that relies on many tactics, including cultural and biological control, which are practices that conserve beneficial insects and mites, and when needed, the use of conventional insecticides. However, systemic, soil-applied neonicotinoid insecticides are translocated to pollen and nectar of flowers, often for months, and may reduce survival of flower-feeding beneficial insects. Imidacloprid seed-treated crops (0.05 mg AI (active ingredient) /canola seed and 1.2 mg AI/corn seed) translocate less than 10 ppb to pollen and nectar. However, higher rates of soil-applied imidacloprid are used in nurseries and urban landscapes, such as 300 mg AI/10 L (3 gallon) pot and 69 g AI applied to the soil under a 61 (24 in) cm diam. tree. Translocation of imidacloprid from soil (300 mg AI) to flowers of Asclepias curassavica resulted in 6,030 ppb in 1X and 10,400 ppb in 2X treatments, which are similar to imidacloprid residues found in another plant species we studied. A second imidacloprid soil application 7 months later resulted in 21,000 ppb in 1X and 45,000 ppb in 2X treatments. Consequently, greenhouse/nursery use of imidacloprid applied to flowering plants can result in 793 to 1,368 times higher concentration compared to an imidacloprid seed treatment (7.6 ppb pollen in seed- treated canola), where most research has focused. These higher imidacloprid levels caused significant mortality in both 1X and 2X treatments in 3 lady beetle species, Coleomegilla maculata, Harmonia axyridis, and Hippodamia convergens, but not a fourth species, Coccinella septempunctata. Adult survival were not reduced for monarch, Danaus plexippus and painted lady, Vanessa cardui, butterflies, but larval survival was significantly reduced. The use of the neonicotinoid imidacloprid at greenhouse/nursery rates reduced survival of beneficial insects feeding on pollen and nectar and is incompatible with the principles of IPM.