A metallic green-black beetle is making its way in a yellow sea of rape flowers. A pollen beetle! Quite pretty to look at, but damaging for the rape plant. The farmer would prefer not to see more of its kind in his field of yellow, but what to do? Should he immediately start spraying with an insecticide or should he wait and see how things develop?

A new database being developed in the EU can help the farmer make the best decision so that both the environment and the crop benefit. The database will contain information about crop pests and effective measures against them, among other things. The database is being developed in a comprehensive collaboration between scientists from several EU countries in a project called ENDURE.

Several researchers from the Faculty of Agricultural Sciences, University of Aarhus, are participating in ENDURE with their knowledge and research. When it comes to harmful insects, senior scientist Lars Monrad Hansen from the Department of Integrated Pest Management is the expert.

- We contribute to the database with knowledge of, among other things, the pollen beetle in rapeseed. We are making a survey of available knowledge about rapeseed plants in EU with regard to pests – including pollen beetles – fungal diseases and other diseases and weeds, he explains. Pollen beetles are Lars Monrad Hansen’s specialty. He has been involved in developing a model that can indicate how serious an insect attack is based on a simple field count.

It is not necessary to use an insecticide if you just spot a few pollen beetles. On the other hand, you should not wait until the attack is serious. So where is the limit?

- The threshold for when to spray against pollen beetles is climate dependent. If a rape plant has had favourable climatic conditions, it can, to a certain degree, resist pests. As a survival mechanism it produces more pods that it can cast off. A light pollen beetle attack in the rape can actually benefit the farmer because it initiates the plant’s whole defence system, leading to a higher rape yield, explains Lars Monrad Hansen.

Good conditions lead to robust rape plants that can withstand relatively serious attacks before spraying becomes necessary. However, if there is a prolonged dry spell, then it is more difficult for the rape to withstand an attack of beetles using this mechanism, and chemical plant protection becomes more necessary.

In order to use the model, you count the number of affected plants in a certain area in the field. On the basis of this count, the model then calculates how serious the attack is in the whole field. With knowledge of local climate conditions and thereby the threshold for the number of pollen beetles it takes before you start spraying, the farmer has a helpful decision-making tool.

- This tool can also be used in other countries. That is why we are sharing our knowledge via the database. Our contributions are based on research results that by and large originate from the Faculty of Agricultural Sciences, says Lars Monrad Hansen.

The database will also contain information about which measures can be taken against the various pests as well as information about pest resistance against the various agents. The information can be used to advise farmers about alternating between relevant agents in order to avoid building up resistance.

- Pollen beetles in most of Europe are resistant to the most commonly used pyrethroids. The second generation pyrethroid tau-fluvalinate is even more effective but in Denmark we have found a slight resistance against this, too. The neonicotinoides are still 100 percent effective, says Lars Monrad Hansen.

In the ENDURE project the scientists are collaborating on charting the extent of resistant insects so that a future strategy can be prepared.

For more information please contact: Senior scientist Lars Monrad Hansen, Department of Integrated Pest Management, Faculty of Agricultural Sciences, University of Aarhus, telephone: +45 8999 3638, mobile: 2228 3334, e-mail: LarsM.Hansen@agrsci.dk

ENDURE, European Network for the Durable Exploitation of Crop Protection Strategies, is a so-called “network of excellence (NoE)” which is financed by EU’s 6th Framework Programme.

The aim of ENDURE is to create a European research network that will also exist after the funding of ENDURE ceases at the end of 2010. The research activities aim to achieve a better understanding of pest biology and the interaction between plants and their pests and, based on this knowledge, to develop new, innovative control strategies in which dependence on effective pesticides is reduced compared to the present. This can be achieved by combining analytical and system-based approaches and by promoting collaboration between biologists, agronomists, economists and sociologists. Another important goal of ENDURE is to ensure that new knowledge is communicated to all relevant parties: farmers, advisers, the industry, politicians and, not least, consumers.

Read more about ENDURE at www.endure-network.eu .