Insects tend gardens and wild plants

Predatory mites devour spider mites, bees take care of grey mould. Biological control agents beat chemical pesticides both in terms of effectiveness and the duration of their effect.

Insects tend gardens and wild plants In a recent column, Heikki Hokkanen, Professor of Agricultural Zoology at the University of Helsinki, pondered the secrets of our green planet and the part that insects play in maintaining the greenery.

“On Earth, there are over 100 animal species to every plant species, and more than three quarters of these animal species are insects. How on Earth is the planet so green?” Hokkanen asks.

Nature’s own defence mechanisms keep 95 percent of plant diseases and weeds under control. Hokkanen points out that even if there are thousands of pests, even as far north as Finland, it is only a handful of these that cause problems.

“Farmers have already learnt about biological pest control, and it is now the fastest-growing sector in plant protection.”

Biological pest control has long traditions in Finnish greenhouses.

“The spider mites that are a pest on cucumbers have been controlled, since the 1970s in Finland, using predatory mites. This method was adopted from the UK and has proved cheaper, easier and more effective than spraying plants with chemical pesticides several times a day.”

Hokkanen estimates that close to 100 per cent of greenhouse pest control in Finland is now dealt with using biological control agents. In his opinion, worldwide dissemination of this method is mainly limited by the efficiency demands of mass production. Biological pest control requires time and expertise.

However, Hokkanen also points out that many organisms are not difficult at all to manage and control, giving a cooperation project in Suonenjoki run by his department as an example. This is the third summer running that bees are being used to carry a natural pesticide against grey mould to the extensive strawberry fields in Suonenjoki. The results are promising, and about one per cent of Finnish strawberry growers already use the method even if research is still underway.

Read Hokkanen’s column “Why is our planet green?"

Text: Sanna Agullana
Photo: Wikipedia
14.7.2008
www.helsinki.fi/digitalcommunications
Translation: AAC Noodi Oy


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