Environmental influence on urban rodent bait consumption

Anticoagulant poisoning is a common rodent control method in urban areas, but rodents may exhibit versatile feeding behavioural habits in varying environmental conditions. This study has been conducted to determine those environmental factors that could directly influence bait consumption and which therefore may affect an urban rodent control plan carried out with chemical methods. In the city of Bologna (Italy), 2500 bait stations have been monitored in various urban biotopes and the bait consumption studied in relation to several environmental factors, using both bivariate and multivariate analysis. Results reveal that the rodent patch distribution triggers the avoidance of baits placed outside of their home-range, hence the importance on bait placement. The logistic regression model confirms that vegetation, harbourage and water supplies are important variables in determining bait consumption, probably because they may spatially and temporarily facilitate the agoraphobic rodent movement, ensuring undisturbed bait consumption. The role of predators (dogs and cats) and food competitors (synanthropic birds) remains insignificant. However, bait eating invertebrates may consume part of the bait. For a proper rodent control plan the first real need is to minimize the alternative food sources, which may compete with baits. Weather conditions in which rodents could possibly pass unnoticed (fog and rainfall) may encourage bait consumption, vice versa with a cold climate. The considered environmental factors have satisfactorily explained bait consumption, highlighting the importance of human influence. The study of environmental factors may be useful in categorizing several site-specific conditions where rodent control efforts should be targeted, enhancing any intervention by matching the correct and specific strategy.     

Clonal variation in growth, arsenic and heavy metal uptakes of hybrid Eucalyptus clones in a Mediterranean environment

Variation in growth, arsenic and heavy metal uptakes by aboveground tissues (leaves, stems and branches) of 13 hybrid Eucalyptus clones selected for biomass production in a Mediterranean environment (E. camaldulensis × E. viminalis; E. camaldulesis × E. grandis; E. camaldulensis × E. globulus subsp. bicostata) was investigated on agricultural soils field-contaminated with arsenic (As), cadmium (Cd), chrome (Cr), lead (Pb), copper (Cu) and zinc (Zn) in an ex situ nursery experiment in central Italy. Large variation in growth and contaminant uptake amongst the tested clones was observed. All plants survived and 12 clones grew better than the control (E. camaldulensis). All clones accumulated the contaminants to which they were exposed: As, Cu, Pb and Zn concentrations were significantly higher in leaves than in stems and branches, supporting the potential for phytoremediation of these contaminants by Eucalyptus short rotation woody crops (SRWC). Significant positive correlations between the average contents of Cd–Pb, Cd–Cu, Cd–Zn, Pb–Cu, Pb–Zn and Cu–Zn in the aboveground tissues were detected. Clones revealed better phytoextraction performance than that of the control. Four promising clones for biomass production and phytoremediation were identified for prospective use in SRWC on contaminated soils in Mediterranean environments.     

Seroprevalence of Neospora caninum antibodies and its consequences for reproductive parameters in dairy cows from Dakar–Senegal,West Africa

The aim of this study was to determine the seroprevalence of Neospora caninum antibodies and its effects on reproductive parameters in cows in intensive dairy herds in Dakar. Randomised blood samples were taken for serology from 196 cows in four herds with a history of sporadic abortion. All of the sera were assayed for antibodies against N. caninum, Candida guillermondii, Coxiella burnetii, and Chlamydophila sp. The associations between serostatus and reproductive parameters (abortion, number of inseminations to conception, and calving to conception interval) were assessed over a period of 5 years (2004–2008). The seroprevalence of N. caninum antibodies in dairy cattle was 17.9%. The local Gobra breed and crossbreeds had higher levels of N. caninum antibodies than exotic breeds (p < 0.05). For the most recent pregnancies, seropositive cows required more inseminations to establish conception than seronegative cows (p < 0.05). The results indicate that dairy cattle from Dakar are exposed to N. caninum. Neosporosis should, therefore, be systematically considered as a cause when the calving to conception interval is prolonged.     

Risk factors and spatial distribution of urban rat infestations

Urban rat infestations have multifactorial causes and may result in severe public health and environmental problems, as well as heavy economic losses. The identification of putative environmental determinants of urban rat infestations and the mapping of areas prone to experiencing such infestations (hot spots) are crucial for effectively addressing intervention efforts. We investigated the associations between a selection of environmental factors and the occurrence of rat infestations in the city of Madrid, Spain. This was done by modelling 10,956 citizen-reported rat sightings from 2002 to 2008 using generalized additive models, both at municipality (Madrid) and district (Latina) levels. Increased age and density of housing, and decreased distance to vegetated areas, markets and cat feeding stations were factors associated with an increased risk of rat infestations. Risk maps for rat infestations were also developed and recurrent hot spots of rat activity were identified. Although a better fit to the data was obtained in the model for the smaller scale and possibly more environmentally homogenous study area of Latina, modelling the spatial distribution of rat sightings was useful for identifying factors associated with an increased risk of urban rat infestations, as well as for identifying hot spots of rat activity, providing local authorities with a practical tool for effectively targeting intervention efforts to high-risk situations based on the local environmental contexts.