Overige insecten

"Eindeutig widersprechen wir der Fördergemeinschaft für nachhaltige Landwirtschaft (FNL), die allein der Bienenmilbe Varroa die Schuld an den Völkerverlusten gibt", unterstreicht NABU-Präsident Olaf Tschimpke. Das weltweite Bienensterben habe komplexe Ursachen, wie eine neue Studie der UN-Umweltorganisation UNEP belegt: Demnach schwächen der Verlust der Biodiversität, ausgeräumte Agrarlandschaften und der Einsatz von Pestiziden die Bestäuber ganz erheblich, und zwar sowohl Wildbienen und Hummeln als auch Honigbienen. "Statt auf seriöse Fakten zu bauen, missbraucht die industrienahe FNL das Deutsche Bienenmonitoring (DEBIMO) für ihre tendenziösen Botschaften", kritisiert Tschimpke.

Ecological changes caused by the insecticide imidacloprid were monitored in experimental paddies throughout a cultivation period. A total of 88 species were observed, with 54 of them aquatic. Plankton, nekton, benthic, and terrestrial communities from imidacloprid fields had significantly less abundance of organisms compared with control fields, either for the entire period or during early stages. The absence of Chironomus yoshimatsui and typical paddy ostracods from imidacloprid fields was most remarkable; as a consequence, green algae blooms (Spirogyra sp.) developed, which in turn hampered the establishment of weeds. Such changes occurred while residues of imidacloprid in water were present at levels greater than 1 μg/L. The overall diversity was similar in all fields and increased constantly until the end of the study. Phytophagous insects dominated in early communities, gradually giving way to predators and scavengers during late stages, but imidacloprid fields had a lower proportion of the latter trophic group. Multivariate analyses helped to describe and differentiate the communities between treatments and control. Hazard- and risk-assessment methods failed to predict imidacloprid impacts, probably because of deficiencies in the exposure and relevant toxicity data used.

The neonicotinoid insecticides imidacloprid, acetamiprid, dinotefuran, thiamethoxam and clothianidin are commonly used in greenhouses and/or interiorscapes (plant interiorscapes and conservatories) to manage a wide range of plant-feeding insects such as aphids, mealybugs and whiteflies. However, these systemic insecticides may also be harmful to natural enemies, including predators and parasitoids. Predatory insects and mites may be adversely affected by neonicotinoid systemic insecticides when they: (1) feed on pollen, nectar or plant tissue contaminated with the active ingredient; (2) consume the active ingredient of neonicotinoid insecticides while ingesting plant fluids; (3) feed on hosts (prey) that have consumed leaves contaminated with the active ingredient. Parasitoids may be affected negatively by neonicotinoid insecticides because foliar, drench or granular applications may decrease host population levels so that there are not enough hosts to attack and thus sustain parasitoid populations. Furthermore, host quality may be unacceptable for egg laying by parasitoid females. In addition, female parasitoids that host feed may inadvertently ingest a lethal concentration of the active ingredient or a sublethal dose that inhibits foraging or egg laying.

Dr. Henk Tennekes has been involved with cancer research for most of his career. His work regarding bees began after reading an official report to the Dutch Minister of Agriculture on the decline of bees. He was amazed at the lack of information on insecticides as a possible factor in the bee decline. Dr. Tennekes then began to research the impact of neonicotinoid insecticides such as imidacloprid and clothianidin, and discovered that their dose:response characteristics are similar to those of carcinogens.