Beleid en debat

Little is really known about the total numbers of insect species our planet holds and it is estimated that only between 10 and 20 per cent of insect and invertebrate species have been classified and named. We may well ask ourselves as to why the world’s insect population is declining with some species facing extinction?

La Selva is a swath of intact Costa Rican jungle protected from development specifically for use by science researchers and educators. Hints of research projects can be seen along the over 30 miles of pathways that weave through the jungle – a tree tagged with orange tape, a 3-square-foot plot of jungle marked off with string.

Scientists have uncovered alarming declines in caterpillar diversity and their parasites across 22 years of monitoring in a protected forest in Costa Rica. Scientists studied the Lepidoptera order of moths and butterflies by collecting all externally feeding caterpillars — those found on leaves and not the inner tissue of a plant. They also collected the parasites that live off their caterpillar hosts, known as parasitoids, including wasps (order Hymenoptera) and flies (order Diptera).

Daran, dass unsere Insekten und damit auch unsere Vögel weniger werden, sollen hauptsächlich Pflanzenschutzmittel schuld sein. Jetzt haben Forscher aus Tokio bestätigt, dass sich Neonicotinoide auch im Wasser und damit auf Fische auswirken. Ein Team um Masumi Yamamuro von der Universität Tokio hat den japanischen Shinji-See über Jahrzehnte beobachtet. Der siebtgrößte See Japans liegt in der Präfektur Shimane, an seinen Ufern befinden sich Reisfelder.

Leonard et al. (1) presented an interesting approach to limit the impact of pathogens on honeybees by stimulating immunity via engineered symbionts. The urgency to safeguard pollinator services is undoubted. Massive declines in bees, insects in general, pose major concerns for ecosystem stability and food production. However, we see potential pitfalls in such technology driven approaches. Leonard et al. attribute high honeybee colony mortality to the parasitic mite Varroa destructor via synergistic interactions with RNA viruses. However, Varroa is only a significant concern for honeybees.

Our mechanistic understanding of the toxicity of chemicals that target biochemical and/or physiological pathways, such as pesticides and medical drugs is that they do so by binding to specific molecules. The nature of the latter molecules (e.g., enzymes, receptors, DNA, proteins, etc.) and the strength of the binding to such chemicals elicit a toxic effect in organisms, which magnitude depends on the doses exposed in a given timeframe.

Based on the science available to date, there is evidence to support the claim that bats are being negatively affected by neonicotinoid insecticides in several different ways, indirectly through reduction in insect abundance and directly through impairment.

The “fates of humans and insects are intertwined”, scientists have said, with the huge declines reported in some places only the “tip of the iceberg”. The warning has been issued by 25 experts from around the world, who acknowledge that little is known about most of the estimated 5.5 million insect species. However, enough was understood to warrant immediate action, they said, because waiting for better data would risk irreversible damage.