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The aphid Chaitophorus leucomelas (Koch, 1854) is one of the most im-portant pests of poplar (Populus spp.) in Algeria. In the present study, water content in leaves and phytochemical analysis of two poplar species (P. nigra and P. deltoids) were carried out to assess their trophic impact on life-history traits of C. leucomelas. The study was conducted in two areas located north of Algeria during the period printano-summer. The results showed that each metabolite fluctuated at the expense of physiological variations in the plant depending on its reaction to the study area. Soluble carbohydrates gradually decreased over the two study seasons. The concentration of proline was higher for P. deltoids in Zeralda comparing to Soumâa. However, the flavo-noids showed close values. Interestingly, Relative water content and soluble carbohydrates had a positive effect on both aphid weight and lipidic ener-getic reserves on P. nigra, but on P. deltoids only carbohydrate content was marginally related to soluble carbohydrates.

In the last few years an increasing interest on species and hybrids of the genus Populus has occurred in Chile. However, such plantations are strongly affected by pest and diseases. With the aim to identify potentially resistant (or less susceptible) hybrids of the genus Populus, the susceptibility of some poplar hybrids growing in experimental nurseries in Southern-Center Chile to the aphid Chaitophorus leucomelas Koch and to the rust Melampsora spp. was assessed. Results showed that aphid abundance was higher in the month of March, particularly in Coinco (O’Higgins Region) and lower in Pillanlelbún (Los Ríos Regions) and Yumbel (Biobío Region). In Pillanlelbún the most susceptible hybrid to aphids was TD×TD [(P. trichocarpa x P. deltoides) x (P. trichocarpa x P. deltoides)], and the less susceptible ones were TD×D [(P. trichocarpa x P. deltoides) x P. deltoides], T×N (P. trichocarpa x P. nigra), TMxTM [(P. trichocarpa x P. maximowitzii) x (P. trichocarpa x P. maximowitzii)] and TDxT [(P. trichocarpa x P. deltoides) x P. trichocarpa]. Hybrid TxN (P. trichocarpa x P. nigra) was the most susceptible to rust in all testing sites, while the less susceptible hybrids were TDxT [(P. trichocarpa x P. deltoides) x P. trichocarpa], TDxD [(P. trichocarpa x P. deltoides) x P. trichocarpa] and TDxT [(P. trichocarpa x P. deltoides) x P. trichocarpa]. These susceptibilities varied among localities, particularly on aphids. Genetic and environmental factors accounting for by these results are discussed., En los últimos años se ha generado un creciente interés en el potencial forestal de las especies e híbridos del género Populus (álamos) en Chile. Sin embargo, algunas plagas y patógenos atacan severamente a estas plantaciones. Con el fin de identificar algunos híbridos resistentes (o menos susceptibles) a estas plagas, se evaluó la susceptibilidad de algunos taxones de Populus spp. al ataque del áfido Chaitophorus leucomelas y al hongo Melampsora spp. El estudio se realizó en tres localidades del centro-sur de Chile. Los resultados revelan que la densidad de áfidos fue mayor en marzo, particularmente en Coinco (región de O’Higgins) y menor en Pillanlelbún (región de Los Ríos) y Yumbel (región del Biobío). En Pillanlelbún el taxón más susceptibles a áfidos correspondió a TD×TD [(P. trichocarpa x P. deltoides) x (P. trichocarpa x P. deltoides)] y los menos susceptibles fueron TD×D [(P. trichocarpa x P. deltoides) x P. deltoides], T×N (P. trichocarpa x P. nigra), TMxTM [(P. trichocarpa x P. maximowitzii) x (P. trichocarpa x P. maximowitzii)] y TD×T [(P. trichocarpa x P. deltoides) x P. trichocarpa]. Las infecciones con Melampsora spp. se presentaron en orden decreciente en Coinco, Yumbel y Pillanlelbún. El taxón T×N fue el más susceptible a roya en las tres regiones, mientras que los menos susceptibles fueron TD×T, TD×D y TD×T. Estas susceptibilidades variaron entre localidades, principalmente para áfidos. No hubo correlación entre la abundancia de C. leucomelas y de Melampsora spp. Se discuten los factores genéticos y ambientales que podrían explicar estos resultados.

Phytosanitary interventions present harmful effects on environment and favour development of noxious insects resisting to active materials. Copious works took an interest to research of alternative methods to pesticides. Our study aim is to increase extracts toxicity of plant with insecticide activity and to evaluate global efficiency of bio-active molecules. Results have shown important effect of aqueous extracts from Dittrichia viscosa on the availability of Chaitophorus leucomelas (Hom., Aphididae) with a moderate resumption under the effect of extracts compared to the action of active substance. Analyses showed that aqueous extract ratio of Dittrichia viscosa / Silene fuscata had an effect more toxic on C. leucomelas compared to aqueous extract of the whole D. viscosa plant and extracts of different organs. Results pointed out the great discrepancy related to the structuring and arrival order of functional groups under different stress. Biocenotic resumption of functional groups was important under biologic stress effect compared to chemical stress.

The development and reproduction rates of the bristle louse, Chaitophorus leucomelas, from the area around Gottingen, were studied under laboratory conditions at 15 °C and 25 °C. All experimental series were carried out on the apterous virginoparous morph. The aphids were raised on single leaf discs in Petri dishes. Mortality rate, fecundity rate and ecdysis were registered daily and newly born nymphs from the second and third reproductive day were used to initiate each new generation. All further young were only counted and removed. The developmental rate almost doubled when the temperature was increased from 15 ° to 25 °C. The actual reproductive phase of the adults was reduced however so that the number of progeny at 25 °C is lower than at 15 °C. At 15 °C the rates of progeny deposition remains constant during almost the entire reproductive phase, but at 25 °C it decreases continuously. The death rate at the higher temperature was greater, especially during the first larval stages. Thus the lower life expectancy at 25 °C, as well as the lower fecundity is almost balanced by the more rapid development. Zusammenfassung Die Entwicklung der Pappellaus Chaitophorus leucomelas auf Blattscheiben in 15 °C und 25 °C Die Entwicklungsgeschwindigkeit und Reproduktionsrate von der Borstenlaus C. leucomelas, die in der Gottinger Umgebung vorkommt, wurde im Labor in 15 °C und 25 °C untersucht. Ausmas und Grenzen der Vermehrungsrate dieser Aphide sollten erfast werden. Alle Versuchsserien wurden an der Morphe aptere Virginopara durchgefuhrt. Sie wurden auf einzelnen Blattscheiben in Petrischalen gezogen, Todesrate, Fruchtbarkeitsrate und Hautungen taglich registriert und neugeborene Larven vom 2. und 3. Reproduktionstag fur neue Generationen angesetzt. Alle weiteren Jungen wurden nur gezahlt und danach entfernt. - Die Entwicklungsgeschwindigkeit verdoppelt sich bei der Temperaturerhohung, ebenso verkurzt sich die eigentliche reproductive Phase der Adulten. So ist die Gesamtnachkommenzahl in 25 °C niedriger als in 15 °C, ebenso die durchschnittliche Nachkommenzahl pro Blattlaus. In der Temperatur von 15 °C bleibt die tagliche Nachkommenzahl wahrend der gesamten Reproduktionsphase konstant, sie nimmt in 25 °C dagegen kontinuierlich ab. Umgekehrt ist die Todesrate in der hoheren Temperatur hoher als in der niedrigeren, besonders in den ersten beiden Larvenstadien. Damit gilt fur das Populationswachstum folgendes: Die niedrigere Lebenserwartung in 25 °C sowie die geringere Fruchtbarkeit werden fast ausgeglichen durch die schnellere Entwicklung. Die optimale Zuchttemperatur fur diese Aphide konnte zwischen 15 und 25 °C liegen.

Areopraon chaitophori n. sp. associated with Chaitophorus leucomelas Koch on Populus nigra is described and illustrated. The main diagnostic characters of Areopraon species are discussed, and a key for identification of European species is provided. The distal dorsal part of the second metasomal tergite of Areopraon species has a very prominent horizontal longitudinal protuberance which represents a new diagnostic character for Areopraon.

Poplars are frequently attacked by aphids. The differential susceptibility of poplar hybrids to the aphid Chaitophorus leucomelas Koch (Sternorrhyncha: Aphididae) has been described, but the mechanism underlying this pattern is unknown. This work tested the hypothesis that poplar resistance to this aphid is associated with the presence of volatiles and secondary plant compounds that affect host selection and feeding behavior. This hypothesis was tested by studying the host choice and feeding behavior of C. leucomelas on two poplar hybrids with contrasting susceptibilities to this aphid ([Populus trichocarpa TorreyGray x Populus deltoides Bartram ex Marshall] x P. deltoides [TD x D], and [P. trichocarpa x Populus maximowiczii Henry] x [P. trichocarpa x P. maximowiczii] [TM x TM]). The results showed that C. leucomelas rejected leaves of the TM x TM hybrid and did not prefer odors from either hybrid. Electronic monitoring of the probing behavior of C. leucomelas suggested the involvement of antifeedant factors in the TM x TM hybrid. In addition, the chemical characterization of volatiles, epicuticular waxes, and internal phenols of leaves from both poplar hybrids revealed that TM x TM had a higher abundance of monoterpenes, sesquiterpenes, n-alkanes, and phenols. These results are discussed in terms of their contribution to poplar breeding programs aimed at enhancing insect resistance.

En los últimos años se ha generado un creciente interés en el potencial forestal de las especies e híbridos del género Populus (álamos) en Chile. Sin embargo, algunas plagas y patógenos atacan severamente a estas plantaciones. Con el fin de identificar algunos híbridos resistentes (o menos susceptibles) a estas plagas, se evaluó la susceptibilidad de algunos taxones de Populus spp. al ataque del áfido Chaitophorus leucomelas y al hongo Melampsora spp. El estudio se realizó en tres localidades del centro-sur de Chile. Los resultados revelan que la densidad de áfidos fue mayor en marzo, particularmente en Coinco (región de O’Higgins) y menor en Pillanlelbún (región de Los Ríos) y Yumbel (región del Biobío). En Pillanlelbún el taxón más susceptibles a áfidos correspondió a TD×TD [ (P. trichocarpa x P. deltoides) x (P. trichocarpa x P. deltoides)] y los menos susceptibles fueron TD×D [ (P. trichocarpa x P. deltoides) x P. deltoides], T×N (P. trichocarpa x P. nigra), TMxTM [(P. trichocarpa x P. maximowitzii) x (P. trichocarpa x P. maximowitzii)] y TD×T [ (P. trichocarpa x P. deltoides) x P. trichocarpa]. Las infecciones con Melampsora spp. se presentaron en orden decreciente en Coinco, Yumbel y Pillanlelbún. El taxón T×N fue el más susceptible a roya en las tres regiones, mientras que los menos susceptibles fueron TD×T, TD×D y TD×T. Estas susceptibilidades variaron entre localidades, principalmente para áfidos. No hubo correlación entre la abundancia de C. leucomelas y de Melampsora spp. Se discuten los factores genéticos y ambientales que podrían explicar estos resultados.