Cannibalism and Coprophagy Are Modes of Transmission of Blastocrithidia triatomae (Trypanosomatidae) between Triatomines

Transovarial transmission was not detectable among Blastocrithidia triatomae- infected Triatoma infestans . Rather, B. triatomae was transmitted directiy between triatomines by cannibalism and coprophagy. Cannibalism conditions that excluded coprophagy always resulted in an infection of Dipetalogaster maxima . The efficiency of transmission was not influenced by the blood source—mice or chickens—fed to the infected donor bugs although chicken blood lyses the epimastigotes of the stomach population. Triatoma infestans was infected by coprophagy only if fed, not if unfed. Blastocrithidia triatomae in dry feces was taken up only if the feces were redissolved in fresh feces. Infections also appeared in groups of bugs fed on chickens previously used for feeding infected bugs.     

Seasonal shifts in genotype frequencies in the invasive cladoceran Daphnia lumholtzi in Lake Texoma,U.S.A.

1. We examined the ecological genetics of the invasive cladoceran Daphnia lumholtzi in a reservoir (Lake Texoma) in the southern USA. This species originates from the Old World subtropics and has spread across North America since the late 1980s after its inadvertent introduction to a reservoir in northeastern Texas. 2. The population genetic structure of D. lumholtzi was examined seasonally on 22 dates over a 3‐year period along a natural temperature and salinity gradient. 3. A two‐allele polymorphism at the phosphoglucose isomerase (PGI) locus was detected, while other loci tested showed no variation. Significant temporal heterogeneity existed in genotype frequencies with a major shift between summer and autumn. 4. Results of a multiple linear regression analysis revealed that a significant amount of variation was explained by day length, temperature and conductivity. Additionally, significant spatial heterogeneity of genotype frequencies between lake stations was observed, but was restricted to the summer. 5. Clonal isolates were used in controlled laboratory temperature and salinity tolerance experiments. Results suggest that salinity and temperature tolerance differed between PGI genotypes. 6. Genotype × environment interactions may play a significant role in the micro‐evolutionary dynamics of this invasive species and may have facilitated its rapid expansion across the North American continent.     

Flood-mediated dispersal versus hatching: early recolonisation strategies of copepods in floodplain ponds

1. We explored the quantitative contribution of two alternative recolonisation strategies by a combination of experimental and field data from the Little Tallahatchie floodplain (Mississippi, U.S.A.). In this area, several floods of short duration occur in winter and spring. During floods, lentic and lotic waterbodies of different size are connected for a limited period. 2. Shortly before the onset of the flood season we collected sediment samples from six temporary ponds. The emergence of seven cyclopoid species was recorded from the experimentally flooded sediments and was quantified over a 4‐week period. Water samples were taken in the same ponds after flooding, from which eight further species were recorded and quantified. 3. The contribution of flood‐dispersed individuals was variable among flooded ponds (between 38 and 94%), but numbers of flood‐dispersed colonists did not differ significantly from those of hatching individuals in flooded ponds. Our results demonstrate the equal importance of both hydrological connections and hatching from dormant stages as pathways for recolonisation by copepods if ponds are hydrologically connected. 4. The significance of recolonisation by hatching individuals in disconnected waterbodies was apparent in an isolated temporary pond that was exclusively recolonised by cyclopoid copepods emerging from the sediment.     

Voltinism flexibility of a riverine dragonfly along thermal gradients

Potential effects of future warming should be reflected in life history patterns of aquatic organisms observed in warmer climates or in habitats that are different in ambient temperature. In the special case of the dragonfly Gomphus vulgatissimus (L.) (Odonata: Gomphidae) previous research suggests that voltinism decreases from south to north. We analysed data on voltinism from 11 sample sites along a latitudinal gradient from about 44°N to 53°N, comprising small streams to medium-sized rivers. Furthermore, to simulate different conditions and to allow projections for future climate change scenarios, we developed a population dynamic model based on a projection matrix approach. The parameters of the model are dependent on temperature and day length. Our field results indicate a decrease in voltinism along the latitudinal gradient from southern to northern Europe and a corresponding increase of voltinism with higher temperatures. An increase in voltinism with width of the running water implies an effect of varying habitat temperature. Under the impact of global warming, our model predicts an increased development speed, particularly in the northern part of the latitudinal gradient, an extension of the northern range limit and changes in phenology of G. vulgatissimus , leading to an extension of the flight season in certain regions along the gradient.     

2nd World Congress of Herpetology

Abstract Natterjack toads (Bufo calamita) form metapopulations consisting of interacting local and temporal breeding assemblages. The gene flow between simultaneously reproductive local populations is limited at the adult stage to about 2% roaming males and around 20% of females. The gene flow between temporal populations breeding successively at the same locality is based on about 0–15% of males and 0–29% of females reproducing in different temporal breeding assemblages. The annual mortality rate of males ranges between 50 and 60%, corresponding to a maximum life expectancy of about 7 years. The main cause of local extinction is always deterioration of the habitat, namely destruction of the breeding habitat or a dry climate.     

Effects of stream flooding on the distribution and diversity of groundwater‐dependent vegetation in riparian areas

1. Effects of the frequency and duration of flooding on the structural and functional characteristics of riparian vegetation were studied at four sites (n = 80, 50 × 50 cm, plots) along medium‐sized naturally meandering lowland streams. Special focus was on rich fens, which – due to their high species richness – are of high priority in nature conservation. 2. Reed beds, rich fens and meadows were all regularly flooded during the 20‐year study period, with a higher frequency in reed bed areas than in rich fen and meadow areas. In rich fens, species richness was higher in low frequency flooded areas (≤3 year^?1) than in areas with a high frequency of flooding (>3 year^?1) or no flooding, whereas species richness in reed beds and meadows was unaffected by flood frequency. 3. The percentage of stress‐tolerant species was higher in low intensity flooded rich fen areas than in high intensity and non‐flooded areas, indicating that the higher species richness in low frequency flooded rich fens was caused by competitive release. We found no indication that increased productivity was associated with high flooding frequencies. 4. We conclude that the restoration of morphological features in stream channels to increase the flooding regime can be beneficial for protected vegetation within riparian areas, but also that groundwater discharge thresholds and critical levels for protected vegetation should be identified and considered when introducing stream ecosystem restoration plans.     

African Buffalo Serum Contains Novel Trypanocidal Protein

ABSTRACT. The high ability of African buffalo, as compared to domestic cattle, to control infections with Trypanosoma brucei brucei IL Tat 1.4 organisms did not correlate with the timing or magnitude of parasite surface coat-specific antibody responses and may have resulted from the constitutive presence in buffalo blood of a novel trypanocidal factor. Buffalo plasma and serum contained material that killed bloodstream stage T. b. brucei, T. b. rhodesiense, T. b. gambiense, T. evansi, T. congolense , and T. vivax organisms during four h of incubation at 37° C in vitro. Serum from eland was also trypanocidal whereas serum from oryx, waterbuck, yellow-back duiker, cattle, horse, sheep, goat, mouse, rat, and rabbit was not trypanocidal. The buffalo serum trypanocidal material was not lipoprotein, or IgG, and had the following properties: 1) a density of < 1.24 g/ml determined by flotation ultracentrifugation; 2) insolubility in 50% saturated ammonium sulphate; 3) non-reactivity with anti-bovine IgM, and anti-bovine IgG; 4) non-reactivity with protein G, and protein A; 5) a relative molecular mass of 152 kDa determined by chromatography on Sephacryl S 300, and of 133 kDa determined by chromatography of the 50% SAS cut of IgG-depleted buffalo serum on Superose 12; 6) no associated cholesterol; and 7) inactivation by digestion with proteinase K that was immobilized on agarose.