SUMMARYWeed control failures due to herbicide resistance are an increasing and worldwide problem that significantly affect crop yields. Metabolism-based herbicide resistance (referred to as metabolic resistance) in weeds is not well characterized at the genetic level. An RNA-Seq transcriptome analysis was used to find candidate genes that conferred metabolic resistance to the herbicide diclofop in a diclofop-resistant population (R) of the major global weed Lolium rigidum. A reference cDNA transcriptome (19 623 contigs) was assembled and assigned putative annotations. Global gene expression was measured using Illumina reads from untreated control, adjuvant-only control, and diclofop treatment of R and susceptible (S). Contigs that showed constitutive expression differences between untreated R and untreated S were selected for further validation analysis, including 11 contigs putatively annotated as cytochrome P450 (CytP450), glutathione transferase (GST), or glucosyltransferase (GT), and 17 additional contigs with annotations related to metabolism or signal transduction. In a forward genetics validation experiment, nine contigs had constitutive up-regulation in R individuals from a segregating F 2 population, including three CytP450, one nitronate monooxygenase (NMO), three GST, and one GT. Principal component analysis using these nine contigs differentiated F 2 -R from F 2 -S individuals. In a physiological validation experiment in which 2,4-D pre-treatment induced diclofop protection in S individuals due to increased metabolism, seven of the nine genetically validated contigs were induced significantly. Four contigs (two CytP450, NMO, and GT) were consistently highly expressed in nine field-evolved metabolic resistant L. rigidum populations. These four contigs were strongly associated with the resistance phenotype and are major candidates for contributing to metabolic diclofop resistance.

The population dynamics of the grape leafhopper (Empoasca vitis) and its egg parasitoids (Mymaridae) were studied at five representative sites in the Franconian wine-growing region from 1998 to 2001. In contrast to other German wine-growing areas, only one generation of grape leafhoppers per season was observed. In general, irrespective of the application of insecticides, the peak density of the first generation was much lower than that of immigrating grape leafhoppers. As the observed mymarid:leafhopper ratios (1:0.8-1:4.8) of the first generation were extremely high, egg parasitoids might be effectively controlling the grape leafhopper in Franconian vineyards. Slightly elevated leafhopper densities at the end of the growing season were caused by migrating sister species. Intervention thresholds were rarely reached; however, stress symptoms as discoloured intercostal leaf areas or rolled leaf edges were widespread. Over the whole study period three mymarid species occurred at all monitoring sites: Anagrus atomus, Stethynium triclavatum and a species, not previously reported in the German wine-growing region, Anagrus avalae. The dominance relationships of these species were site-specific, differing more strongly between than within sites; however, differences could not be related to the kind of management or natural surrounding of the vineyards. A hatching experiment confirmed the biological significance of A. avalae as an effective antagonist.

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