Insecticides

Insects are quietly but rapidly disappearing. Michael McCarthy explains why their loss is bad news for the planet.

We grow flowers in our gardens for our own enjoyment. But colour and perfume are really the plants’ way of advertising themselves to insects. Sweet nectar and protein-rich pollen are bait to encourage insects to visit. In return, pollen is carried from one flower to another on their bodies so the flowers are fertilised. Bees are among the most beneficial insects for a garden. The best way to attract them to your garden is to provide them with some of their favourite plants such as lavender, foxgloves, rosemary, sunflowers and bluebells. Flowers with long narrow petal tubes, such as evening primrose and honeysuckle, are visited by moths and butterflies. Only their long tongues can reach deep down to the hidden nectar. Short-tongued insects include many families of flies and some moths. They can only reach nectar in flowers with short florets. Hoverflies, wasps, ladybirds, lacewings, ground beetles and centipedes are the gardener’s friends and will help control garden pests such as aphids and caterpillars. Insects such as spiders, mites, millipedes, sow bugs, ants, springtails and beetles inhabit the soil food web in the uppermost 2 to 8 inches of soil. They participate in decomposing plant and animal residue, cycling nutrients, creating soil structure and controlling the populations of other soil organisms, including harmful crop pests. Decaying organic matter in soil is the source of energy and nutrients for garden vegetables and ornamental plants. By growing flowers attractive to a range of insects, our gardens can also become important feeding stations for bats, hedgehogs, birds and other wildlife. The most important factor when encouraging wildlife into your garden is not to use insecticides.

Under pressure from the US State of California, pesticide manufacturers have voluntarily withdrawn the pesticide imidacloprid from usage on almonds. Imidacloprid is widely blamed as contributing to the dieoff of honeybees around the world. Apparently, industry voluntarily removed almonds from the list of “approved uses” rather than undergo the public scrutiny and cost involved in re-evaluating a pesticide which industry now says is a "small-market” for them. Almonds are a major cash crop for politically influential and ecologically-aware California. The voluntary withdrawal of this pesticide was reportedly so unusual to the United States Environmental Protection Agency (USEPA) that they were, apparently, unsure how to process the application.

2010 veröffentlichte der holländische Toxikologe Henk Tennekes ein international beachtetes Fachbuch mit dem Titel »Disaster in the Making«. Er beschreibt das extreme Artensterben bei Insekten und Vögeln der Agrarlandschaft – in England genauso wie in Holland oder Deutschland. Rebhühner, Kiebitze, Haubenlerchen und Braunkehlchen und selbst die früher so häufige Feldlerche werden immer seltener. Tennekes belegt das Artensterben mit vielen wissenschaftlichen Publikationen, die er in seinem Buch vorstellt. Die Ursache sieht der Toxikologe in einer Gruppe neuer Pestizide, der Neonikotinoide. Diese fordert er sofort zu verbieten. Noch vor Weihnachten 2011 kam die limitierte deutsche Ausgabe mit dem Titel »Das Ende der Artenvielfalt – Neuartige Pestizide töten Insekten und Vögel« auf den Markt.

California regulations require the Department of Pesticide Regulation (DPR) to investigate reports of possible adverse effects to people or the environment resulting from the use of pesticides. If a significant adverse impact occurred or is likely to occur, the regulations require DPR to reevaluate the registration of the pesticide. In February of 2009, DPR placed certain pesticide products within the nitroguanidine insecticide class of neonicotinoids containing the active ingredients imidacloprid, clothianidin, dinotefuran, and thiamethoxam into reevaluation. This reevaluation is based on an adverse effects disclosure regarding the active ingredient imidacloprid. The disclosure included twelve ornamental plant residue studies and two combination residue, honey, and bumble bee studies of imidacloprid use on a number of ornamental plants. DPR’s evaluation of the data noted two critical findings: (1) high levels of imidacloprid in leaves and in blossoms of treated plants, and (2) increases in residue levels over time. Data indicate that use of imidacloprid on an annual basis may be additive, in that significant residues from the previous use season appear to be available to the treated plant.