Overige insecten

The Dutch toxicologist Henk Tennekes was invited to give a presentation on the risk profile of neonicotinoid insecticides for arthropods to committee members of the Dutch Board for the Authorisation of Plant Protection Products and Biocides (Ctgb). An English version of the presentation, which took place on 25 May 2011 at the Bee House in Wageningen, The Netherlands, is attached. Attached also is an article on the influence of Bayer Cropscience on Dutch policy makers (which appeared in the magazine "Vrij Nederland" on April 4, 2012).

During the past 120 years, a large number of natural enemies has been collected and evaluated for use in augmentative biological control programmes. Particularly during the last 30 years many efficient species have been identified and currently at least 230 species are commercially available globally. Today, the commercial biological control industry is well organized, has developed mass production, shipment and release methods as well as adequate guidance for farmers. The industry has intensively collaborated with the public research sector in design of quality control programmes, which are applied during natural enemy production and shipment. The industry also cooperated in preparing environmental risk assessment methods for biological control agents. In several areas of agriculture augmentative biological control has obtained considerable successes and is now a reliable and appreciated element of IPM programmes. Despite all this progress, augmentative biological control is applied on a frustratingly small acreage.

Many farmland bird species have declined markedly in Europe in recent decades because of changes in agricultural practice. The specific causes vary and are poorly known for many species. The Little Owl, which feeds extensively on large invertebrates and is strongly associated with the agricultural landscape, has declined over most of northwestern Europe, including Denmark. We investigated the likely reasons for the population decline in Denmark by identifying patterns of local extinction (scale, 5 × 5 km2) and estimating demographic parameters affecting local survival, focusing on changes over time and their relationship to habitat characteristics.

Nous avons cherché à savoir si les insecticides, lorsque utilisés sous forme granulaire et de façon intensive pour contrôler l'altise (Phyllotreta sp.) dans le colza (Brassica napus et B. napa), jouent un rôle dans le déclin des populations d'oiseaux des prairies canadiennes.

In the Netherlands, 766 species of larger moths are considered native. About one-third of the species are decreasing and all species together show a significant, declining, trend in abundance. It may well be that the severe decline in some bird species in Northwestern Europe, especially of those that inhabit agricultural landscapes like Corn Bunting (Miliaria calandra) and Eurasian Skylark (Alauda arvensis), is related to the decline in moth diversity. It can be hypothesized, that the most important trigger is the period in which these birds feed their young.

We studied arthropod occurrence in fallow land, extensively used pastures, extensively used meadows (cut twice or three times a year) and intensively used meadows (cut more than three times ayear) in Upper Bavaria.

Medium-sized arthropods (5-15mm) were encountered much less frequently on intensively used and fallow land than on pastures and extensively used meadows. Large individuals (>15mm) were observed most frequently on pastures but were hardly found on intensively used meadows. In autumn they occurred almost exclusively on pastures and fallow land. Species richness was the highest on pastures and the lowest on intensively used meadows. The study underscores the depletion of arthropod fauna and in particular the decline of large arthropods on intensively used meadows. It indicates that extensively used meadows and extensively used pastures in particular are the most favourable sources of nutrition for insectivores such as reptiles, amphibians, birds or bats.

Aerially-foraging insectivorous birds have experienced dramatic population declines in North America over the past several decades, but a dearth of data on their limiting factors makes hypotheses about these declines difficult to test. The common link among these declining species is their diet and it is therefore likely that avian population changes are linked to changes in insect prey. We determined that the onset of the population crash for chimney swifts was associated with 1) a major reduction in the amount of beetle and bug prey, and 2) an increased reliance on fly prey. The causes for these changes in prey base remain to be seen, but may be related to historical use of pesticides and contaminants. If chimney swifts serve as a model species for all aerially-foraging insectivores, then our study may have revealed the historical proximate mechanism for their guild-wide decline.

We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded vascular plants, pollinators, aphids and their predators. Further, five conventional fields which were treated with insecticides were compared with 10 non-treated conventional fields. Organic fields had five times higher plant species richness and about twenty times higher pollinator species richness compared to conventional fields. Abundance of pollinators was even more than one-hundred times higher on organic fields.