In Vitro Production of Metacyclic Forms of Trypanosoma musculi and Their Infectivity in CBA Mice1

ABSTRACT. Bloodstream forms of Trypanosoma musculi, cultured in Schneider's drosophila medium at room temperature, multiply and differentiate through a series of developmental stages into infective metacyclic trypomastigotes in 10 days. Oral inoculation with these culture forms into CBA mice produced a parasitemia similar to that produced by intraperitoneal infection with bloodstream forms except for a three-day longer prepatent period. Attempts to induce parasitemia with bloodstream forms given orally were unsuccessful.     

Comparison of Atrazine-Resistant and -Susceptible Biotypes of Senecio vulgaris L.: Effects of High and Low Temperatures on the in vivo Photosynthetic Electron Transfer in Intact Leaves

The effects of temperature on the yield of in vivo modulatedchlorophyll fluorescence were measured in intact leaves of atrazineresistantand -susceptible biotypes of the weed Senecio vulgaris L. At25 ?C, the photochemical quenching (q_Q of steady-state chlorophyllfluorescence was reduced by around 30% in the atrazine-resistantmutant as compared to the susceptible wild type, indicatinga higher reduction state of the primary electron acceptor Q_Aof photosystem II in the former biotype. Moderately elevatedtemperatures (above 30 ?C) further increased the steady-stateconcentration of reduced in the mutant. Analysis of the temperature dependence of both the photochemicalquenching q_Q and the initial fluorescence level F_o clearly indicateda drastically enhanced heat-sensitivity of the photochemicalapparatus in the atrazine-resistant Senecio leaves. The heat-inducedchanges in F₀ and q_Q were closely correlated, suggesting thatthe phenomenon responsible for the rise in F₀ was also involvedin the inhibition of the photosynthetic electron flux. Low temperaturesalso affected reoxidation but, in contrast to heating, no apparent differences were observed in the behaviourof the two biotypes exposed to chilling stress. Key words: Atrazine-resistance, chlorophyll fluorescence, heat stress, Senecio vulgaris     

The Effect of Vanadate on Phosphate Transport in Aged Potato Tuber Tissue 2Solarium tuberosum)

The effect of orthovanadate on the uptake of phosphate by agedpotato tuber tissue was investigated to study the relationshipwith plasma membrane ATPase activity. Vanadate inhibited therate of phosphate uptake by aged discs with a maximum effectat 500 µM (58% inhibition). When vanadate was added tothe ageing medium for 24 h, the subsequent rate of phosphateuptake was also markedly decreased (68% inhibition). The resultsshow that the inhibition by vanadate was not due to enhancedleakage of phosphate nor to a non-specific toxic effect. Furthermore,complementary experiments with erythrosin B and molybdate wereconsistent with the hypothesis that vanadate acts specificallyon the plasma membrane ATPase and that this enzyme is involvedin maintaining the driving force for active uptake of phosphate(via co-transport with protons) by storage cells of potato tubers. Key words: Proton-phosphate co-transport, vanadate, plasma membrane ATPase, unloading     

An Isoenzyme Analysis of the Genus Phytomonas: Genetic, Taxonomic and Epidemiologic Significance

ABSTRACT We studied 31 Phytomonas stocks isolated from various hosts and a broad geographical range by isoenzyme electrophoresis (14 loci) and population genetics analysis. The total variability is considerable since many stocks share no allele. Population genetic analysis strongly suggests that Phytomonas zymodemes behave as natural clones, as already proposed by us for several other protozoan species. These clones should be considered as actual taxa in all applied studies. Latex plants and phloemic plants (coconut and palm trees) harbor distinct sets of clones; hence, latex plants studied in this article are probably not a reservoir for parasites of the coconut and palm tree.     

Role of terpenes from aphid-infested potato on searching and oviposition behavior of Episyrphus balteatus

To cope with pathogen and insect attacks, plants develop different mechanisms of defence, in both direct （physical and chemical） and indirect ways （attractive volatiles to entomophagous beneficials）. Plants are then able to express traits that facilitate ＂top-down＂ control of pests by attracting herbivore predators. Here we investigate the indirect defence mechanism of potato plants by analyzing the volatile patterns of both healthy and aphid- infested plants. Important changes in the emitted terpene pattern by the Myzus persicae infested host plant were observed. Using Solid Phase MicroExtraction （SPME） and GC-MS, the （E）-fl-farnesene （EBF） appeared to be emitted by aphid-infested potato and not by healthy plants. To assess the infochemical role of these volatile releases after aphid damage on the aphidophagous predators Episyrphus balteams, the hoverfly foraging behavior was assessed using the Observer 5.0 software （Noldus, Wageningen, The Netherlands）. Aphidfree potato plants were also used as a control volatile source in the predator behavioral study. While aphid-infested plants induced efficient searching and acceptation behaviors leading to egg-laying, no kairomonal effect of healthy potato plants was observed, leading to longer immobility durations and shorter searching periods in the net cage. High oviposition rate of E. balteatus was observed when aphid-infested potato was used （mean of 48.9 eggs per laying and per female）. On the other hand, no egg was produced by the hoverfly on healthy aphid-free plants. The E. balteatus foraging and reproductive behaviors according to the volatile emission from aphid-infested plants are discussed in relation to the potential use of active infochemical molecules in integrated aphid pest management.     

Adult movements between populations in the specialist butterfly Proclossiana eunomia (Lepidoptera, Nymphalidae)

Abstract.

• 1 The structure of local populations of a monophagous butterfly, the bog fritillary Proclossiana eunomia, was studied in a complex of suitable habitat patches separated by spruce plantations or fertilized pasture.
• 2 An unexpected high level of adult movements between habitat patches was detected by a mark—release—recapture technique. Local populations were connected by adult movements across unsuitable habitats, leading to a meta-population structure.
• 3 This evidence of the metapopulation structure of a specialist butterfly challenges the supposed relationship between habitat specialization and closed, isolated populations.
• 4 Males and females of P.eunomia exhibited different spatial behaviours; females were more likely to emigrate and dispersed further than males. These differences in spatial behaviour are related to the mating system.