Evaluation of the quality and impact of research at SLU (KoN2018)
Impact case study presented in the self-assessment by the Department of Ecology, Faculty of Forestry:
Stem coatings on conifer plants replace insecticides
Summary of the impact
In Swedish forestry, the use of insecticides is practically restricted to protection of conifer plants against the pine weevil, Hylobius abietis. Until recently, this meant prophylactic insecticide treatment of about 150 million plants annually. Since 2010, however, the insecticides are gradually being replaced by protective stem coatings, used in combination with various silvicultural countermeasures. These new methods and management strategies largely emanate from research at the Department of Ecology, SLU. Stem coatings are now used for half of the protected seedlings, and within a few years insecticides are judged to be almost completely phased out in Swedish forestry.
Research that underpins the impact case study
For several years the Swedish forestry sector funded research conducted within the Swedish Hylobius Research Program, led by Prof. Göran Nordlander. This research contributed significantly to the development of new, non-chemical protection methods, and also to adjustments in forest management reducing the risk of insect damage.
Studies of pine weevil feeding behavior led to the finding that sand with a grain size less than 0.2 mm stops weevil feeding as the grains enter in between the mandibles. This led to the innovation of a flexible coating covered with a layer of sand (“Conniflex”) applied to the plant stem in the nursery. Field tests showed that Conniflex effectively reduces damage caused by pine weevils. For the first time a real alternative to insecticide treatment of conifer plants had appeared. The innovation was patented and developed for commercial use by a small company in cooperation with the researchers, and later Conniflex was acquired by the largest producer of forest plants in Sweden.
Pest management of the pine weevil relies not only on direct protection of the plants but also on a number of other damage-reducing measures and considerations, such as site preparation followed by optimal choice of planting spot, timing of planting (year after harvest and time of the season), plant type and plant size, etc. How to optimize these silvicultural countermeasures for different situations has been a main focus for the research within the Swedish Hylobius Research Program, and results have been successfully implemented thanks to effective interactions with stakeholders.
Another important research focus has been methods to estimate damage risk, which varies considerably geographically and depending on forest management methods. Information on damage risk allows the foresters to make well adapted choices of countermeasures.
Details of the impact
Forest regeneration in northern Europe typically involves clear-felling followed by soil preparation and planting of conifer seedlings within three years after harvest. About 350 million seedlings are planted annually in Sweden, of which 150 million are provided some type of protective treatment. The unprotected plants are predominantly used in northern Sweden (approximately N of latitude 60oN). The annual cost for the damage by pine weevil has been estimated to several hundred million SEK. Since the early 1990s, the Swedish Chemicals Agency has repeatedly announced its intention to prohibit the use of insecticides for forest plants, because of the insecticides’ high toxicity to aquatic organisms and due to concerns regarding effects on the health of forestry workers. A ban was, however, never implemented because no satisfactory alternatives were available.
When the Conniflex coating proved to be an effective alternative and large-scale production had started the process of replacing the insecticides came naturally (with help from Swedish FSC, pushing the issue). Other protective coatings also appeared on the market after the breakthrough for Conniflex. The large scale production of Conniflex started in 2010, in 2016 about half of the insecticide use had been replaced, and in 2020 insecticides are judged to be almost completely phased out in Swedish forestry.
The awareness is steadily increasing in Swedish forestry of how to make use also of other measures that reduce damage by the pine weevil. Appropriate site preparation, timing of planting and choice of suitable plants may be combined in various ways together with either protected or unprotected plants, depending on geographic location and other conditions. The implementation of these pest management strategies has probably contributed to the increasing survival in forest regenerations recently documented by the Swedish Forest Agency (Skogsstyrelsen 2017b).
References to the research
Nordlander, G., Nordenhem, H. & Hellqvist, C. 2009. A flexible sand coating (Conniflex) for the protection of conifer seedlings against damage by the pine weevil, Hylobius abietis. Agricultural and Forest Entomology 11:91-100. http://dx.doi.org/10.1111/j.1461-9563.2008.00413.x
Nordlander, G., Hellqvist, C., Johansson, K. & Nordenhem H. 2011. Regeneration of European boreal forests: Effectiveness of measures against seedling mortality caused by the pine weevil Hylobius abietis. Forest Ecology and Management 262: 2354-2363. 10.1016/j.foreco.2011.08.033
Nordlander, G., Hellqvist, C. & Hjelm, K. 2017. Replanting conifer seedlings after pine weevil emigration in spring decreases feeding damage and seedling mortality. Scandinavian Journal of Forest Research 32: 60-67. http://dx.doi.org/10.1080/02827581.2016.1186220
Nordlander, G., Mason, E. G., Hjelm, K., Nordenhem H. & Hellqvist, C. 2017. Influence of climate and forest management on damage risk by the pine weevil Hylobius abietis in northern Sweden. Silva Fennica 51(5): article id 7751 (20 pp.). https://doi.org/10.14214/sf.7751
The pine weevil website with research news and information for successful pest management (in Swedish): “Snytbaggen – biologi och aktuell forskning” http://snytbagge.slu.se/
Sources to corroborate the impact
Giurca, A. & von Stedingk, H. 2014. FSC pesticides policy in Sweden (2014). Forest Stewardship Council, FSC Sweden, 16 pp. http://se.fsc.org/rapporter.289.htm (added 6 October 2014).
SLU News 2017. SLU awards for important and innovative research. https://internt.slu.se/en/news-originals/2017/10/SLU-awards-for-important-and-innovative-research/
Skogsstyrelsen 2017a. Produktion av skogsplantor 2016 (Summary: Production of seedlings 2016). Statistiska Meddelanden JO0313 SM 1701. Stockholm: Statistiska centralbyrån. https://www.skogsstyrelsen.se/globalassets/statistik/statistiska-meddelanden/produktion-av-skogsplantor-jo0313/2016-statistiska-meddelanden-produktion-av-skogsplantor.pdf
Skogsstyrelsen 2017b. Återväxternas kvalitet 2016/2017 (Summary: Quality of regrowth 2016/2017). Statistiska Meddelanden JO0311 SM 1701. Stockholm: Statistiska centralbyrån. https://www.skogsstyrelsen.se/globalassets/statistik/statistiska-meddelanden/atervaxternas-kvalitet-jo0311/2016-statistiska-meddelanden-atervaxtuppfoljning2.pdf