Dunng the past 5 yr nematodes of the genus A n g~c o l a , that parasitize the swim bladder of eels, have spread throughout Europe. They are especially common in young eels among which infestanon rates as high as 70 O/o have been recorded. These parasites were previously known only from East Asia and Austraha.
Water-soluble extractives from western red cedar heartwood, bark, and foliage were investigated for their toxicity to aquatic organisms. The heartwood lignans and bark extractives were found to be moderately toxic, but the foliage terpenes and heartwood tropolones were more toxic, causing 50% mortality to coho salmon (Oncorhynchus kisutch) fry at 0.33 and 2.7 mg/liter, respectively. Tropolones were significantly less toxic to invertebrates than to free-swimming stages of the fish tested. Fry were found to be the stage of development of coho salmon (O. kisutch) most sensitive to the tropolones, and eyed eggs the least sensitive. Sensitivity of the coho fry to tropolones was moderated by previous sublethal exposure or the presence of a chelatable cation. Results from field studies and a leaching study indicate that directly releasing cedar leachate from landfills or allowing logging debris to enter streams should be avoided.
The Dragonfly Fauna of the Western and Northern Parts of Mongolia and Some Phenomena of Their Intracontinental Isolation Based on 2100 specimens, mostly collected during the II. Mongol‐German Biological Expedition of 1964, a brief survey of the dragonfly fauna of Mongolia is given, including special remarks on those species the author met with in the western and northern districts of the country. 12 species are mentioned for the first time as components of the Mongolian fauna. Comparisons of several morphometrical characters (body length, relative length of the abdomen, absolute and relative body weight) between anisopteran species and between the population groups from north, west and south‐west Mongolia as well as from central Europe have led to some remarkable results: (1) According to the proportions of the body and the differences between males and females in relative length of the abdomen the species can be grouped into separate constitutional types (Aeshna type, Libellula type, Sympetrum type and others). These types seem to represent special evolutionary strategies to perfect the dragonfly body as a “flying machine”. (2) In the different parts of western Mongolia (northern mountain steppes and woodlands, western desert plains, Dzungarian deserts), the majority of the species is represented by populations differing from each other in measurements and/or body proportions. These differences may be as large as or even larger than the distinction rate between each of the Mongolian and the Central European populations. (3) The differences in body length and proportions between the population groups are expressions of different genotypes; it seems impossible to interprete them as results of diverse conditions for larval growth. (4) Some species of dragonflies in western Mongolia occur as geographically isolated populations; the Altai and other mountain ridges lying to the north and southwest separate them from populations in eastern Kazakhstan (Lestes macrostigma, Libellula quadrimaculata and, may be, some more).
The effect of temperature on developmental time of the palaearctic biotype of the solitary larval parasitoid, Apanteles rubecula Marsh., its longevity, parasitization rate and preference for larval instars of the host, Pieris rapae (L.) were studied in the laboratory. The duration of the internal development of A. rubecula from egg to cocoon lasted longer than the external pupal stage at all temperatures (15°, 20°, 25 °C). The development from egg to adult emergence required 46.8 days at 15°C and 17 days at 25°C. The cocoon weight was highest at 20°C (5.8 mg) and only at 25°C differed between females and males. Female A. rubecula lived significantly longer (16.5 days) than males (6.1 days). There was no distinct preoviposition period and the oviposition period lasted about 17 days. In general parasitization was rather low, since at maximum 2.5 host larvae were parasitized per day. Only the first three larval instars of P. rapae were parasitized with the highest parasitization rate of 57% in the first and the lowest of 10% in the third larval instar. Zusammenfassung Laboruntersuchungen zu Biologie und Parasitierungserfolg von Apanteles rubecula Marsh. (Hym., Braconidae) als solitärer Larvenparasitoid von Pieris rapae (L.) (Lep., Pieridae) Im Labor wurde die Entwicklungs‐ und Lebensdauer des paläarktischen Stammes von Apanteles rubecula Marsh. bei 3 unterschiedlichen Temperaturen, die bevorzugt parasitierten Larvenstadien von Pieris rapae (L.) sowie der Parasitierungserfolg der Parasitoidenweibchen untersucht. Die Entwicklung im Wirt von der Eiablage bis zur Kokonbildung dauerte bei allen untersuchten Temperaturen (15°, 20°, 25 °C) länger als die außerhalb des Wirtes von der Kokonbildung bis zum Schlupf der Imagines von A. rubecula. Die Entwicklung von der Eiablage bis zum Schlupf der Imagines verkürzte sich von 46,8 Tagen bei 15 °C auf 17 Tage bei 25 °C. Das Kokongewicht war am größten bei 20 °C (5,8 mg) und unterschied sich nur bei 25 °C zwischen Weibchen und Männchen. Die Weibchen lebten signifikant länger (16,5 Tage) als die Männchen (6,1 Tage). Der insgesamt relativ geringe Parasitierungserfolg der A. rubecula‐Weibchen erreichte ohne ausgeprägte Präovipositionsperiode bereits am Schlupftag den höchsten Wert (2,5 Larven), und die Ovipositionsperiode dauerte ca. 17 Tage. Nur die ersten drei Larvenstadien von P. rapae wurden erfolgreich parasitiert, mit der höchsten Parasitierungsrate von 57% im ersten und der niedrigsten von 10% im dritten Larvenstadium.
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