Individual Preferences and Social Interactions Determine the Aggregation of Woodlice

n°e17389.info:eu-repo/semantics/publishe

Solid-phase syntheses of Loloatins A-C

The cyclic decapeptides Loloatin A (cyclic L-valyl-L-ornithyl-L-leucyl-D-tyrosyl-L-prolyl-L-phenylalanyl-D-phenylal anyl-L- asparaginyl-L-aspartyl-L-tyrosyl), loloatin B (cyclic L-valyl-Lornithyl-L-leucyl-D-tyrosyl-L-prolyl-L-phenylalanyl-D- phenylalanyl-L-asparaginyl-L-aspartyl-L-trytophanyl) and loloatin C (cyclic L-valyl-L-ornithyl-L-leucyl-D-tyrosyl-L-prolylL-tryptophanyl-D-phenylala nyl-L- asp araginyl-L-aspartyl-L-tryptophanyl) have been synthesized by Fmoc-based solid-phase peptide synthesis, commencing with Asp linked to polystyrene RAM resin through its side chain, and by on resin cyclization of the linear decapeptide through Asp and Asn, followed by cleavage of Asp from the resin. Through the use of a unique combination of DMF/dichloroethane solvent mixture in the coupling steps, and careful monitoring of both coupling and Fmoc deprotection steps, the final cyclic peptides were obtained in overall yields of 31-37\%. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002

Factors affecting the field performance of an attracticide against the codling moth Cydia pomonella

Factors affecting the efficacy of an attracticide strategy for the control of the codling moth Cydia pomonella L (Lepidoptera: Tortricidae) were investigated using laboratory and field experiments. The sex-pheromone-based insect-control strategy utilises 100-?l droplets of a sticky, paste-like formulation containing 1 mg g-1 (E,E)-8,10-dodecadien-1-ol (codlemone) as an attractant for male moths and 40 mg g-1 cyfluthrin, a contact insecticide, applied to branches in the upper parts of the tree crown. The longevity of the treatment under field conditions was assessed in the laboratory by biological testing of variously aged samples of the attracticide formulation which had been applied to the bark of apple trees growing in commercial orchards. Electroantennogram responses of male moth antennae were used to compare codlemone release from the attracticide after different lengths of environmental exposure. Changes in insecticidal efficacy of the same samples were assessed with reference to the speed of knockdown (KT50) and the mortalities after 48 h among populations of male moths confined in cages containing samples of fresh and field-aged formulations. Gradual declines in both the amount of pheromone released and insecticidal activity were observed over the 10-week period of the experiments. Various factors associated with the behaviour of codling moths in the field which might influence the attracticide strategy were also investigated. Although the vertical position of attracticide sources within apple trees had a strong influence on their attractiveness, their horizontal position had none. Results of field trials showed that efficacy of the attracticide depends on the population density of the pest. Under the conditions of the current study a density of three or more sources per tree (= 4500 sources per ha) was required to attain satisfactory levels of codling moth control

Elucidation of the Solution Conformations of Loloatin C by NMR Spectroscopy and Molecular Simulation

NMR experiments combined with molecular simulation with X-PLOR have been employed to determine the solution conformation of the cyclic decapeptide loloatin C in three different solutions. In DMSO, the molecule possesses a hydrophobic aromatic "wall" consisting of Trp 6 and Phe 7, and a type I β-turn structure involving Val 1, Trp 10, Asp 9 and Asn 8 with a hydrophobic head at Val 1/Trp 10 and a hydrophilic tail at Asp 9 and Asn 8; another type II' β-turn was also located between Leu 3, Tyr 4, Pro 5, and Trp 6. In 70/ 30 [D 3]TFE/H 2O, however, loloatin C possesses a dumbbell structure with all the hydrophobic side chains projecting upward on one side, forming a hydrophobic surface, and the hydrophilic side chains projecting to the other side, together with most of carbonyl oxygen atoms, thereby forming a hydrophilic surface. However, in 30:70 [D 3]TFE/H 2O, loloatin C possesses an inverse γ-turn incorporating Tyr 4, Pro 5, and Trp 6, a hydrophobic zone involving the side chains of Leu 3, Trp 6, Trp 10, and Phe 7 and a hydrophilic tail involving the hydrophilic side chains of Orn 2, Asn 8, and Asp 9. The amphiphilicity of the dumbbell structure in 70/30 [D 3]TFE/H 2O is of interest in relation to the antibiotic activity of loloatin C. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.link_to_subscribed_fulltex

Laboratory and field experiments towards the development of an attract and kill strategy for the control of the codling moth, Cydia pomonella

A viscous formulation based on castor oil containing the pyrethroid insecticide cyfluthrin and E8, E10-dodecadienol, the main component of the codling moth sex pheromone, (Cydia pomonella L.: Tortricidae, Olethreutinae) was developed. The insecticidal performance of the formulation was evaluated in the laboratory using a tarsal-contact bioassay. The pheromone dosage required to attract male moths to the formulation was determined in behavioural tests performed in a wind tunnel. The efficacy of formulations applied to seedlings of the host plant was further investigated in glasshouse experiments conducted with male moths in small wire-gauze cages. The laboratory tests resulted in a formulation for preliminary field trials containing 4% cyfluthrin and 0.1% pheromone. During the 1995 growing season, experiments were conducted in apple orchards at three locations in Germany. The formulation was first applied to the bark of apple trees (Malus domestica) in mid May and then again in late July. A good level of control, comparable with a spray treatment using the insect growth regulator Alsystin was achieved. The potential of the attract and kill strategy, combining selective attraction of a pest species with the efficacy associated with a pyrethroid insecticide treatment, as a means of controlling the codling moth in commercial apple growing, is discussed

The potential of semiochemicals for control of Phorodon humuli (Homoptera: Aphididae)

Field experiments employing yellow water-traps with vials releasing methyl salicylate, butyl isothiocyanate, 4-pentenyl isothiocyanate and diethyltoluamide were conducted during the spring migration of Phorodon humuli (Schrank), with the aim of identifying substances which might be used in the field to deter landing on hop plants. Methyl salicylate and the two isothiocyanates reduced trap catches of P. humuli. During the spring of 1994 a slow-release formulation of methyl salicylate and a beta-acid-rich hop resin sprayed on to hop plants did not reduce aphid infestations significantly. In autumn cis,cis-nepetalactol the main component of P. humuli's sex pheromone, prepared by various synthetic routes, increased trap catches of males and gynoparae equally. Catches of males in pheromone traps situated in a hop garden decreased with increasing trap height. Catches of males in traps charged with increasing doses of the cis,cis-nepetalactol peaked at 1 mg and then plateaued, whereas catches of gynoparae peaked similarly at 1 mg and then decreased. The effects of kairomones from an extract of the primary host, sex pheromone and a visual cue from yellow compared with clear water-traps were additive. The prospects for developing a semiochemicals-based control strategy against P. humuli, using some or all of the above elements, are discussed