Abstract. The larvae of Lypephaeopa (Stephens, 1836) are found on dead wood substrates in streams and lakes. Gut content analy ses, scanning electron microscopy of larval mouthparts, and gallery structure revealed characteristics of this habitat preference. The guts of the larvae contained mainly wood fragments whereas other food items (detritus, algae, fungi, inorganic particles) were much rarer. The suitability of the mouthparts to scrape wood surfaces, and the adaptative elongation of the silk-secreting spinneret, which facilitates the construction of retreats consisting of a tunnel-like silken net incorporating mainly wood fragments, are discussed. Retreat-construction under laboratory conditions indicated that larvae exploit new feeding areas by steadily extending their galleries.Tips of the maxillary palps bear five sensilla styloconica and five sensilla basiconica, almost all bearing an apical pore. Three sen silla styloconica, two with an apical peg, and two small inconspicious sensilla basiconica are located on the galea. Possible function of these sensilla is discussed on the basis of studies on the closely related sister-group of Lepidoptera.
We found the alien amphipod, Echinogammarus berilloni (Catta, 1878) in a temporary karstic stream system (Westphalia, Germany). We investigated the effect of the seasonal low flow and desiccation on the distribution and the relative abundance of E. berilloni and on the native amphipods, Gammarus fossarum Koch, 1835 and G. pulex (Linnaeus, 1758). E. berilloni does not colonize the headwaters of the study area. Due to the seasonal low flow situation or even stream drying, this longitudinal limit of distribution can already occur in a further downstream section. After total drying the recolonization of E. berilloni in the temporary stream section mainly happens by drift from the permanent upstream sections, if a population has been established there. The relative abundance of E. berilloni and of the native amphipods, G. pulex and G. fossarum within the temporary stream sections is highly correlated with the temporary discharge regime. While in the permanent downstream sections E. berilloni successfully competes with the native gammarids and almost completely replaces them, Gammarus spp. dominate in the temporary reaches.
ZUSAMMENFASSUNGDer Neozoe Echinogammarus berilloni (Catta, 1878) konnte in einem verkarsteten temporären Fließgewässer-System (Westfalen, Deutschland) nachgewiesen werden. Wir untersuchten den Einfluss von Austrocknung und Niedrigwasser auf die Verbreitung und relative Abundanz von E. berilloni und der heimischen Amphipoden, Gammarus fossarum Koch, 1835 und G. pulex (Linnaeus, 1758). E. berilloni besiedelt nicht die Oberläufe des Untersuchungsgebietes. Diese längszonale Verbreitungsgrenze kann durch die saisonale Austrocknung oder Niedrigwassersituation bereits in einem unteren Gewässerabschnitt auftreten. Nach einer totalen Austrocknung erfolgt die Wiederbesiedlung der temporären Gewässerabschnitte durch E. berilloni hauptsächlich per Drift aus den permanenten Abschnitten im Oberlauf der Karstgewässer, wenn dort eine Population vorhanden ist. Die relative Abundanz von E. berilloni und der heimischen Amphipoden, G. pulex und G. fossarum korreliert stark mit dem temporären Abflussregime. Während in den permanenten Gewässerabschnitten 1 )
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An important aspect of the association of Lype phaeopa (Stephens) with submerged wood is the oviposition behavior of adult females, which preferably oviposit their eggs on moist emergent or submerged parts of woody debris with a structured surface. The eggs are commonly deposited in cracks and crevices using the elongated ovipositor. Ovipositor morphology and various sensilla on the tip and along the ovipositor were studied by scanning electron microscopy and their possible function discussed. Structure of these sensilla and pre-oviposition behavior of the females point to a preference for certain oviposition sites on woody debris. This may be a key factor for the distribution and development of the larvae.
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