Lignin impedes access to cellulose during biofuel production and pulping but trees can be genetically modified to improve processing efficiency. Modification of lignin may have nontarget effects on mechanical and chemical resistance and subsequent arthropod community responses with respect to pest susceptibility and arthropod biodiversity. We quantified foliar mechanical and chemical resistance traits in lignin-modified and wild-type (WT) poplar (Populus alba × Populus tremula) grown in a plantation and censused arthropods present on these trees to determine total abundance, as well as species richness, diversity and community composition. Our results indicate that mechanical resistance was not affected by lignin modification and only one genetic construct resulted in a (modest) change in chemical resistance. Arthropod abundance and community composition were consistent across modified and WT trees, but transgenics produced using one construct exhibited higher species richness and diversity relative to the WT. Our findings indicate that modification of lignin in poplar does not negatively affect herbivore resistance traits or arthropod community response, and may even result in a source of increased genetic diversity in trees and arthropod communities.

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Summary The numbers of eggs of Wheat Bulb Fly (Phorbia coarctata Fall.), present in fields of swedes, oats, and potatoes were determined. The highest numbers were found under swedes, the lowest under potatoes; oats held an intermediate position. The first eggs were present at the beginning of July under all crop plants examined. It is assumed, that the oviposition of Wheat Bulb Fly is influenced by plant cover of the soil.

Zusammenfassung Zur Prüfung von Insektiziden gegen landwirtschaftliche Schädlinge in Freiland (Beispiel: Sattelmücke, Haplodiplosis equestris Wagn.) wurde erstmals eine Versuchsanlage erprobt, bei der ein 1 m breiter, unbehandelter Randstreifen entlang einer Feldseite vor 10 behandelten und einer unbehandelten Parzelle lag. Sechs Parzellen wurden mit Parathion, vier Parzellen mit Methoxychlor behandelt. Die Mittel wurden in verschiedener Dosierung (1 n, 3 n und 5 n) und auf je einer Parzelle zweimal in einfacher Dosierung (1 n) ausgebracht. Ergebnisse: 1) Der Randstreifen ist auf seiner gesamten Länge verschieden stark befallen. — 2) Der Befall nimmt auf der unbehandelten Parzelle vom Rand zur Mitte des Feldes ab (Kontrollstellen in 0,5 m, 3 m und 9 m Tiefe). Zur Ermittlung der Wirkung der Insektizide wurde der Wirkungsgrad nach Abbott diesem Bef allsunterschied entsprechend korrigiert. — 3) Zwei Behandlungen mit dem Insektizid normaler Dosierung hatten eine etwas bessere Wirkung als eine Behandlung mit demselben Insektizid in drei‐ oder fünffacher Dosierung. Summary An experimental design for testing insecticides against agricultural pests in the field (as tested with the saddle gall midge, Haplodiplosis equestris Wagn.) was investigated. This system included an untreated bordertract of 1 m width alongside a field with 10 treated and one untreated plot behind the bordertract. Six plots were treated with parathion and four with methoxychlorid. The insecticides were applied once and twice in the various concentrations (1 n, 3 n and 5 n). Results: 1. Plants on the bordertract have been infested differently on its whole length. 2. The infestation decreased in the untreated plot from the border towards the center of the field (controlled at 0,5, 3 and 9 m distance from the border). Investigating the effectiveness of the insecticides, the Abbott's formula was corrected according to the difference in infestation. 3. Two treatments with an insecticide at normal concentration were more effective than one treatment with the same insecticide at three and five times the concentration.