Ulf Nilsson

Swedish University of Agricultural Sciences | SLU · Department of Ecology

The carrot psyllid (Trioza apicalis, Förster (Homoptera: Psylloidea: Triozidae)) is a serious phloem-feeding pest of carrots in Scandinavian countries. Carrot fields attacked at a sensitive growth stage can be completely destroyed. A damaged plant typically develops curled leaves and shows stunted growth. In an ongoing scientific project, a pest ma...

This 3-year field study investigated the combined effect of floral resources and perennial shelter habitats (i.e. conservation strips), and crop rotation in supporting natural enemies of the cabbages root fly, Delia radicum. Habitat manipulation with conservation strips increased the overall catches of hymenopteran parasitoids. However, conservatio...

En nyckel till att skapa bättre livsmiljö för de naturliga fienderna är att öka mångfalden av olika växter i och omkring fälten1. Genom att samodla rätt växter med grödan eller i fältets kanter erbjuds tillgång till växtbaserad föda och/eller alternativa bytesdjur under perioder då det vanliga bytesdjuret inte finns tillgängligt. Ökad växtdiversite...

Biological control of pest insects can be improved by providing natural enemies with additional food resources such as floral nectar within the production field. However, herbivores may also benefit from this practice. The aim of this 3‐year field study was to investigate if dill and buckwheat, aimed as food resources for natural enemies, could inc...

Many parasitoids use volatiles produced by plants as important cues during their food and host search process. We investigated the attraction of the parasitic wasp Trybliographa rapae Westwood (Hymenoptera: Figitidae) to volatiles emitted from plants infested by the cabbage root fly Delia radicum L. (Diptera: Anthomyiidae), as well as to volatiles...

This study investigated differences in flower preferences between the parasitoid Trybliographa rapae Westwood (Hymenoptera: Figitidae) and its host, the economically important pest of cruciferous crops, the cabbage root fly, Delia radicum L. (Diptera: Anthomyiidae). The data obtained were used to suggest selective food plants in conservation biolog...

A survey of the parasitoid complex of lily leaf beetle (Lilioceris lilii) was conducted in Sweden from 2006 to 2007. Total parasitism varied between 21 and 57%. The most abundant parasitoids were the ichneumonids Lemophagus errabundus and L. pulcher and the eulophid Tetrastichus setifer. The potential for biological control is discussed.

Strawberries (Fragaria × ananassa) are the most important soft fruit crop in Sweden and most commonly grown as a perennial crop. Colletotrichum acutatum J.H. Simmond was detected on strawberries in Sweden for the first time in the autumn of 2003. Anthracnose caused by C. acutatum has previously been found on rhododendron in Sweden (2). The infected...

Under 2008 och våren 2009 genomfördes försök i laboratorium för att undersöka hur den allvarliga skadegöraren på kål, lilla kålflugan, Delia radicum, kan överleva och tillgodogöra sig nektar från olika nektarkällor (blommande växter), samt för en av dess viktigaste naturliga fiender, parasitstekeln Trybliographa rapae. Syftet med studien är att fin...