Action de pesticides chez des insectes en fonction de leur etat physiologique: Etude de 2 insecticides et d'un melange d'herbicides chez les larves aquatiques de cloeon. (Ephemeropteres).

For the larvae of the ephemeron Cloeon, our studies of acute toxicity show that the degradation products of fenthion are more toxic than the insecticide itself.Doses of fenthion and lindane, responsible of a hight mortality, lead to a decrease in the moulting frequency of these larvae. A mixture of herbicides and degradation products of fenthion gave different results.

     

Les sensilles de l'antenne chez quelques blattes et en particulier chez Blaberus craniifer (Burm.)

Résumé Les organes sensoriels du scape et du pédicelle sont essentiellement propriocepteurs. Le fouet est très riche en chimiorécepteurs (plus de 100000) mais chez Periplaneta et Blatta, on observe un net dimorphisme sexuel qui n'existe pas chez Blaberus. La relation entre un tel dimorphisme et la perception des phéromones sexuelles est discutée. L'ultrastructure des trois principaux types de sensilles est décrite: Ce sont des grandes soies gustatives et mécanoréceptrices, des petites soies olfactives à paroi mince et percée de pores et de tubules qui sont innervées par un ou deux neurones, des petites soies olfactives à paroi épaisse et striée qui contiennent toujours quatre neurones. L'étude électrophysiologique préliminaire confirme les résultats ci dessus en ce qui concerne le rôle des sensilles: La phéromone grégaire peut être perçue au niveau de certaines petites soies olfactives striées.

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The antennal sensilla of some cockroaches with special reference to Blaberus craniifer (Burm.)

Summary The antennae of cockroaches were studied with both scanning and transmission electron microscope. The sense organs of the scape and pedicel are essentially proprioceptors. The chemoreceptors are very numerous on the flagellum (more than 100000) but in the case of Periplaneta and Blatta, a significant sexuel dimorphism is noticed. Such a dimorphism does not exist in Blaberus and its relation with the perception of the sexual attractants is discussed. Three principal sense organs of Blaberus are described: big thick walled hairs with gustatory and mechanoreceptive function; thin walled olfactory hairs with pore-tubules innervated by one or two neurons; thick walled grooved hairs with four neurons and olfactory function. Special attention was given to the secretory aspect of the accessory cells in the olfactory sensilla. A preliminary electrophysiological investigation confirms the above mentioned functional interpretations. The gregarious pheromone seems to be perceived by some little thick walled grooved hairs.

     

Etude des interactions sociales entre male et femelle chez la Genette (Genetta genetta L.): Relations entre marquage olfactif et agression

Study on Social Interactions between Male and Female Genets (Genetta genetta L.): Relations between Scent Marking and Aggression The aim of this work was to study the relations between marking behaviour and aggression in genets (Genetta genetta L.). Observations on social interactions were made on a socially stable pair and during encounters between unfamiliar pairs. In the first case, there appeared to be a relationship between marking activity in the male and aggression. During aggression periods, marking with the ano-urogenital region increased in the male and decreased in the female. Another striking variation concerned flank rubbing and hindleg rubbing. In both male and female these marking frequencies increased significantly during aggression periods and flank rubbing was modified by visual cues. Data recorded during encounters between unfamiliar pairs (one male being introduced in a female's cage) showed that agonistic behaviours were released through visual cues in females and olfactory cues in males. The same changes in marking frequencies were observed. These results also showed that ano-urogenital marking was inhibited in females during aggression periods. The adaptative significance of these phenomena is discussed.     

Caracterisation morphologique,chimique et serologique d'un mutant albinos de Neurospora crassa shear et dodge isole de semences de mache (Valerianella olitoria (L.) Poll.)

Résumé Un mutant albinos (sans carotènes) a deNeurospora crassa Shear &Dodge a été isolé de semences de mâche (Valerianella olitoria L.) sur le marché à Genève. Son appartenance à l'espècecrassa est démontrée sur les plans morphologique et sexuel, et il est désignéN. crassa al-Chg a. Il se distingue du type sauvage et d'un mutant albinos (al-2 15.300 a) étudié près du lieu de vente des semences, par la température optimum de croissance. Des tests sérologiques (immunoélectrophorèse) et des séparations de protéines sur gel d'acrylamide ont mis en évidence le degré beaucoup plus élevé de corrélation entre les mutants albinos (al-Chg et al-2) et le type sauvage deN. crassa qu'avec celui deN. sitophila. La valeur taxonomique de ces deux techniques est discutée, de même que l'origine éventuelle du mutant isolé.

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An albino mutant (without carotenes) ofNeurospora crassa Shear &Dodge has been isolated from seeds ofValerianella olitoria L. on sale in Geneva, Switzerland. Its taxonomic position was demonstrated morphologically and sexually. It is described asN. crassa al-Chg a. By its optimal growth temperature it differs from the wild type and from an albino mutant (al-2 15.300 a) studied near the selling place of the seeds. Serological tests (immunoelectrophoresis) and separation of proteins on acrylamide gel have made conspicuous the considerably higher degree of relationship existing between thealbino mutants (al-Chg and al-2) and the wild type ofN. crassa than between these mutants and the wild type ofN. sitophila. The taxonomic value of these methods and the possible origin of the isolated mutant are discussed.

     

Deux cas de Rhinosporidiose nasale chez une oie et un canard sauvages a Astrida (Ruanda-Urundi)

Conclusions Les auteurs relatent la découverte à Astrida de deux cas de rhinosporidiose nasale chez des anatidés très répandus en Afrique centrale: l'oie d' Egypte et le petit canard siffleur africain.Les lésions observées consistent en polypes des fosses nasales. Histologiquement ces polypes correspondent à des granulomes et leur structure est dans les grandes lignes identique à celle qu'on observe dans les lésions de rhinosporidiose nasale chez l'homme.Le parasite observé dans les lésions est morphologiquement identique àRhinosporidium seeberi, l'agent causal de la rhinosporidose chez l'homme.Les auteurs envisagent les conséquences de cette découverte au point de vue de l'épidémiologie de la rhinosporidiose humaine.     

Une inversion péricentrique à l'origine d'un polymorphisme chromosomique non-robertsonien dans une population de mastomys. (Rodentia-Murinae)

A sample of eight Mastomys natalensis from Fort-Lamy (Tchad) shows a non-robertsonian chromosomial polymorphism related to a pericentric inversion. All these Rats, have the same diploid number, i.e. 32. Four specimens have 8 small acrocentrics, the other chromosomes being meta- or submeta-centric; two possess only 6 small acrocentrics and two are provided with 7 of these elements (heterozygotes for the pericentric inversion). — The author discusses the possible part plaid by such mechanism in the chromosomal evolution and its bearing on speciation.

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A mon cher et vénéré collègue, le professeur J. Seiler.     

Nosema muris n. sp., a New Microsporidian Parasite of the White Mouse (Mus musculus L.)

SYNOPSIS. A microsporidian, Nosema muris n. sp., is described from laboratory white mice in Czechoslovakia. I t differs from Nosema cuniculi (Levaditi, Nicolau and Schoen, 1923) and other Microsporidia in mice in that it develops in the omentum and heart muscle, iorming large masses of schizonts and spores. The parasite is distributed to other tissues (liver, spleen, fat, peritoneal muscles, connective tissue and brain) by infected mononudear cells, and then forms localized cysts in them. Kidney, lungs, adrenal glands, pancreas and salivary glands are not infected. The parasite can be transmitted via the placenta, by feeding on infected tissues, or by experimental injection of ascitic fluid.     

Metabolisme lipidique chez l'Aspergillus versicolor (Vuill.) tiraboschi. Relations avec la biogenese de la sterig matocystine

Résumé L' Aspergillus versicolor est cultivé sur un milieu synthétique pendant 22 jours. Les productions de lipides et de stérigmatocystine sont comparées. Les acides gras des fractions neutres et polaires sont essentiellement: C 160, C 180, C 181 C 182, et C 183. Les quantités maximales de mycélium sec, de lipides neutres et de stérigmatocystine apparaissent respectivement au 4e, 7e et 20e jours. Une diminution de la teneur en lipides précède la phase de concentration maximale en métabolites secondaires du type polycéto-acide. Il semble que les lipides, et tout particulièrement l'acide palmitique, participent à la biogenèse de ces dérivés.

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Summary Aspergillus versicolor is cultivated in a synthetic medium for 22 days. Bioproduction of lipids and sterigmatocystin are compared. The fatty acids of the neutral lipid and polar lipids fractions are mainly: C 160, C 180, C 181, C 182, C 183. Maximal yields of dry weight, neutral lipids and sterigmatocystin occur, respectively, on the 4th, the 7th and the 20th days. These results and their comparison with other works emphasize that a fall of concentration in lipids precedes the phase of highest concentration in secondary metabolites of polyketide type; it appears that fats and particularly palmitic acid are present in biogenesis of these derivatives.

     

Mise en évidence d'un polymorphisme chromosomique de translocation dans une population naturelle d'Acanthoscelides obtectus (Coleoptère,Bruchidae) du Burundi

A translocation polymorphism in a naturally occurring population of Acanthoscelides obtectus (Coleoptera, Bruchidae) from Burundi.-A cytogenetic study of anAcanthoscelides obtectus population from Burundi was carried out using banding techniques and biometric analysis of chromosomes. This study revealed a very high frequency of translocation polymorphism in this naturally occurring population. The population structure was analysed in terms of this polymorphism. Possible evolutionary consequences of this phenomenon are suggested.