ladybugs

Every spring, urban parks across half of Europe deal with the same problem: pests. The most common and traditional response continues to be chemical pesticides: they are effective and cheap to keep insects such as aphids at bay, but they have a well-documented ecological cost on other auxiliary fauna and the soil. However, some European cities have been exploring an even older alternative for years: returning the natural predators that always kept them at bay to the ecosystem. Logroño has just taken that step: This spring it will release ladybugs and other insects in several of its green spaces. Ladybugs and Anthocoris as a natural pesticide. The City Council of Logroño, through the UTE Espacios Verdes Logroño, is carrying out these days biological control actions in parks and gardens in the maple trees and rose bushes on Paseo del Espolón, in the lime trees in Plaza Primero de Mayo, Parque Gallarza and Parque del Carmen and in the Cercis specimens on San Antón Street. As? Introducing their natural predators. Ladybugs are the friendly and well-known face of this operation, but beneath that mottled red mantle hides a voracious predator capable of devouring several hundred aphids during its lifetime. He Anthocoris nemoralis (a predatory bug) is much less known to the general public, but equally essential on a biological level: it is a predatory bug that attacks psyllids, mites and other phytophages that especially affect urban trees. Why is it important. Because it is a natural measure to decimate pests without the need for conventional phytosanitary treatments that also favors biodiversity in the urban environment. Conventional pesticides eliminate the target species, but they also kill pollinators such as bees and butterflies, contaminating the soil and aquifers. In the long term, they end up having a kind of rebound effect in the form of resistance, which forces the use of increasingly higher doses or more aggressive compounds. Hence Europe has been warning for some time about its use and the need to look for alternatives. On the other hand, this measure also has its relevance in public health: these urban green spaces are places of daily traffic where applying phytosanitary products in those environments implies human exposure that biological control completely eliminates. The WHO has documented the effects of chronic exposure to organophosphate and pyrethroid pesticides on health, especially in children. Context. It’s no secret that we are running out of insects: this specific study in Germany shows a disappearance of 75% of flying insects in 27 years (the study is from 2017), a trend that is expanding throughout Europe. The reasons are several: pesticides, loss of habitat, pollution and climate change are just a few. Cities play a role in that they bring together many species of insects in a small space. What is a biodiversity sink can become a refuge: cities like Barcelona, ​​Huesca, Zaragoza, Pamplona, ​​Madrid and Logroño itself They have been implementing for years comprehensive pest management strategies that include biological control as a central element. Vitoria-Gasteiz deserves special mention: one of the green capitals in Europe carries out environmental policies sustainable management of urban green areas. How it works. The biological balance is simple: predator – prey. In an ecosystem in its unaltered state, aphids would be naturally regulated by their predators and would only be triggered when the balance is broken, something that in fact happens in cities, where the diversity of auxiliary fauna is low. The solution is not to eliminate the pest with a chemical product, but restore lost predatory pressure. What makes this approach so valuable is that it is a selective measure: an insecticide destroys what is in front of it, while ladybugs and Anthocoris nemoralis concentrate their activity on prey that is part of their natural diet, leaving intact populations of bees or butterflies that visit the same flora. Yes, but. The initiative from Logroño has an important blind spot: the origin of the released insects. We do not know if these ladybugs and Anthocoris nemoralis come from local populations or from foreign commercial breeding. Introducing non-native specimens can alter the genetics of wild populations in the region and even end up displacing native ones. On the other hand, we do not know the number of insects released and whether there will be subsequent monitoring: to know if the biological control has worked it is necessary to measure the density of the pest before and after, record the survival and dispersal of the released individuals and compare with control areas where there has been no release of insects. In Xataka | The European Union believes it has a solution for the decline of wine in Spain: plucking the “green” grapes in La Rioja In Xataka | The terraces of hoteliers have been taking over city streets for years. Logroño has a plan for them Cover | Afaaq Afzal and Tom Winkler