Insecticides

The Slovenian government has issued a temporary ban on seeds treated with neonicotinoid pesticides following reports about massive bee deaths in northeast Slovenia. More than 10% of the bee population in Pomurje has been killed, and the scope of the incident is spreading fast. Slovenian farmers called on the government to reverse its ban on corn seeds treated with neonicotinoid pesticides due to a lack of a conclusive link between recent bee deaths and the seeds.

Local food supplies are under increasing threat because the area’s bee population is experiencing ongoing decline, claims a lifelong Australian apiarist. The local industry expert, who asked not to be named, said the area between Tamworth and Toowoomba had lost more than 35% of its bee population in the past five years. And he believed that a common chemical used by domestic and commercial gardeners – a neonicotinoid insecticide – was partly to blame. The local industry expert is urging farmers and apiarists to come forward and report bee losses to the Australian Pesticides and Veterinary Medicines Authority (APVMA). “We need bees to pollinate berries, fruit, nuts, most of the foods we like to eat,” he said. “Without them we’re stuffed, so I hope people like eating gruel.”

Wie die Agentur für Gesundheit und Ernährungssicherheit (AGES) am Freitag (29.04.2011) in einer Aussendung mitteilte, könnten regionale Fälle von Bienensterben im Zusammenhang mit dem Maisanbau stehen. Auffallend sei, dass die eintreffenden Schadensmeldungen aus denselben Regionen stammen, die bereits in den Vorjahren betroffen waren. Wie die bisher verfügbaren Daten im Zuge der Erhebungen zeigten, könne "zumindest teilweise ein Zusammenhang zwischen Bienenschäden und insektizidgebeiztem Saatgut nicht ausgeschlossen werden", so die AGES. Bis 26. April wurden wurden Bienenschäden aus drei Bundesländern - Oberösterreich, Niederösterreich und Steiermark - gemeldet.

77 Millionen Mandelbäume warten in Kalifornien darauf bestäubt zu werden. Dazu brauchen die Farmer gut 1,5 Millionen Bienenvölker. "Das sind drei Viertel aller Bienen in den USA", rechnet Imker John Miller vor. "Praktisch jeder Bienenstock, der sich transportieren lässt, wird im Frühjahr hierher gebracht." Es herrscht ein dramatischer Mangel an Majas fleißigen Schwestern. Ganze Völker verschwinden. Im Verdacht stehen neuartige Pflanzenschutzmittel - so genannte "Neonikotinoide" - ebenso wie Krankheiten und die aus Asien eingeschleppte Varroa-Milbe, ein winziges Spinnentier, das die Bienen und ihre Brut regelrecht aussaugt.

A rapid analytical technique could facilitate more extensive studies of the reasons for the worldwide decline in bee populations. Studies using the method suggest insecticides used to coat crop seeds may be partly to blame. Neonicotinoid insecticides are used to coat crops such as corn and oilseed rape, and are one of several groups of chemicals identified as suspects in the disappearance of honey bees - a phenomenon referred to as colony collapse disorder. One theory is that the insecticides are passed to the bees in pollen. Using ultra-high performance liquid chromatography, Andrea Tapparo at the University of Padua in Italy and colleagues now show that it is possible for bees to pick up a lethal dose of insecticide by grazing on sap produced by crop plants and present on leaf tops. Building on earlier work in 2009, the researchers show that concentrations of neonicotinoids present in drops collected from the leaves of corn plants are high enough to kill bees within a few minutes.

Thiamethoxam is a neonicotinoid insecticide, a group of pesticides that acts selectively on insect nicotinic acetylcholine receptors (nAChRs), with only a little action on mammalian nAChRs. Nevertheless, the selectivity of neonicotinoids for the insect nAChRs may change when these substances are metabolized. Therefore, we aimed to determine the potential effects of thiamethoxam on mammalian brain, testing the performance in the open field and elevated plus-maze of rats exposed to this insecticide and, in order to establish the neurochemical endpoints, we measured the acetylcholinesterase activity in different brain regions (hippocampus, striatum and cortex) and the high-affinity choline uptake (HACU) in synaptosomes from rat hippocampus.

Treated animals received thiamethoxam (25, 50 or 100 mg/kg) for 7 consecutive days. The results showed that treatment with thiamethoxam induced an increase in the anxiety behavior at two doses (50 or 100 mg/kg). Moreover, there was a significant decrease in both HACU and acetylcholinesterase activity. Our hypothesis is that thiamethoxam (or its metabolites) could be acting on the central rats nAChRs. This would produce an alteration on the cholinergic transmission, modulating the anxiety behavior, acetylcholinesterase levels and HACU.