Persistent threat to Poland’s forests averted

The use of a biological pesticide has been very successful in controlling the Nun moth (Lymantria monacha), a serious insect pest of Poland’s forests.

    In early 1994 over 600,000 hectares (ha) of Polish forests were seriously infested by this major pest which consumes the trees’ needles. Unless treated quickly, massive tree loss would have occurred. An international emergency project costing US$22 million was in place by May with a plan of action preventing widespread defoliation of the valuable forests. The project involved nine organisations from Poland, Denmark and the UK. Although some conventional chemical pesticide, diflubenzuron, was used against the pest, more effective control was achieved using the biological pesticide Foray 48B, produced by Novo Nordisk.

    Polish forests cover more than 8.7 million ha, of which only 20% was healthy prior to the project. A combination of acid rain and pest damage has taken its toll over the years. In the past, chemical pesticides, including synthetic pyrethroids, have been used and have provided limited success. In 1984, 6.5 million ha were treated, but the pesticides used were broad spectrum and their toxicity to insects meant that predators and parasites of the Nun moth were also killed. This was a major cause of the subsequent pest increase.

Environmental and efficacy benefits of Foray

Foray only kills Lepidopteran pests such as the Nun moth. This biological pesticide is a strain of the Bacillus thuringienisis bacteria. In the Polish forests, the only practical way of applying it was by air using helicopters or light aircraft. At a volume of 4.0 litres per ha Micronair atomisers were used, as these provide more uniformly sized droplets in the spray, instead of hydraulic nozzles which produce more smaller droplets, causing the greatest drift, making them less environmentally acceptable.

    The Polish State Forests Department has a goal to reduce chemical pesticide use over the next few years and will rely increasingly on biologicals such as Foray, and use improved application technology. Initially Foray was applied to those areas of high environmental sensitivity to preserve biological diversity. After more widespread use, the Polish results were carefully monitored for their economic and biological impact. So far Foray has been very successful, so much so that in the short term near complete control has been achieved. The results from Poland have implications for other eastern and western European countries where similar problems exist especially Germany, Belarus, Ukraine, the Baltic Republics and the Czech republics. Currently pest control projects using biological pesticides are being developed in forests in Albania and Belarus.  

For more information: Micronair, Sandown, Isle of Wight, PO36 8QS, UK, Tel: +44 (0)1983 406111, Fax: +44 (0)1983 404 461.

[This article first appeared in Pesticides News No.27, March 1995, page 19]