Sublethal and sex-specific cypermethrin effects in toxicity testing with the midge *Chironomus riparius* Meigen

Goedkoop W, Spann N, Åkerblom N. Sublethal and sex-specific cypermethrin effects in toxicity testing with the midge *Chironomus riparius* Meigen. Ecotoxicology. 2010;19(7):1201-1208.We quantified sublethal and sex-specific cypermethrin effects in experiments (29 days) with the midge Chironomus riparius at different levels of sediment organic matter content (0, 5, and 20%). We found highly significant effects of cypermethrin concentrations and sediment type on emergence, mean development rate, and adult size. For example, emergence/survival rates were 70–100% below 0.8 μg/l and unaffected by organic matter content. At 3.2 μg/l, however, no larvae survived in sediment without organic matter, but survival successively increased to 26 ± 11% in sediment with 20% organic matter. Mean development rates were always higher for males than for females, and significant differences between sexes occurred consistently in controls and in treatments with our lowest concentration of 0.05 μg/l. Sex-specific differences in mean development rate decreased across the cypermethrin gradient, suggesting that male development was affected more than that of females at similar concentrations. We also found an increase in adult size across the concentration gradient in sediments lacking organic matter and suggest an increased feeding activity due to sublethal toxic stress as a probable causal mechanism. We speculate that the observed sex-specific effects on development rates and adult size can have strong repercussions on emergence timing and fecundity, respectively

Polymer–Magnesium Aluminum Silicate Composite Dispersions for Improved Physical Stability of Acetaminophen Suspensions

The aims of this study were to characterize the morphology and size of flocculates and the zeta potential and rheological properties of polymer–magnesium aluminum silicate (MAS) composite dispersions and to investigate the physical properties of acetaminophen (ACT) suspensions prepared using the composite dispersions as a flocculating/suspending agent. The polymers used were sodium alginate (SA), sodium carboxymethylcellulose (SCMC), and methylcellulose (MC). The results showed that SA, SCMC, and MC could induce flocculation of MAS by a polymer-bridging mechanism, leading to the changes in the zeta potential of MAS and the flow properties of the polymer dispersions. The microscopic morphology and size of the flocculates was dependent on the molecular structure of the polymer, especially ether groups on the polymer side chain. The residual MAS from the flocculation could create a three-dimensional structure in the SA–MAS and SCMC–MAS dispersions, which brought about not only an enhancement of viscosity and thixotropic properties but also an improvement in the ACT flocculating efficiency of polymers. The use of polymer–MAS dispersions provided a higher degree of flocculation and a lower redispersibility value of ACT suspensions compared with the pure polymer dispersions. This led to a low tendency for caking of the suspensions. The SCMC–MAS dispersions provided the highest ACT flocculating efficiency, whereas the lowest ACT flocculating efficiency was found in the MC–MAS dispersions. Moreover, the added MAS did not affect ACT dissolution from the suspensions in an acidic medium. These findings suggest that the polymer–MAS dispersions show good potential for use as a flocculating/suspending agent for improving the rheological properties and physical stability of the suspensions

Aedes albopictus and Aedes japonicus - two invasive mosquito species with different temperature niches in Europe

Abstract Background Aedes albopictus and Ae. japonicus are two of the most widespread invasive mosquito species that have recently become established in western Europe. Both species are associated with the transmission of a number of serious diseases and are projected to continue their spread in Europe. Methods In the present study, we modelled the habitat suitability for both species under current and future climatic conditions by means of an Ensemble forecasting approach. We additionally compared the modelled MAXENT niches of Ae. albopictus and Ae. japonicus regarding temperature and precipitation requirements. Results Both species were modelled to find suitable habitat conditions in distinct areas within Europe: Ae. albopictus within the Mediterranean regions in southern Europe, Ae. japonicus within the more temperate regions of central Europe. Only in few regions, suitable habitat conditions were projected to overlap for both species. Whereas Ae. albopictus is projected to be generally promoted by climate change in Europe, the area modelled to be climatically suitable for Ae. japonicus is projected to decrease under climate change. This projection of range reduction under climate change relies on the assumption that Ae. japonicus is not able to adapt to warmer climatic conditions. The modelled MAXENT temperature niches of Ae. japonicus were found to be narrower with an optimum at lower temperatures compared to the niches of Ae. albopictus. Conclusions Species distribution models identifying areas with high habitat suitability can help improving monitoring programmes for invasive species currently in place. However, as mosquito species are known to be able to adapt to new environmental conditions within the invasion range quickly, niche evolution of invasive mosquito species should be closely followed upon in future studies