The invasion of the carnivorous carabid beetle Trechisibus antarcticus on South Georgia (sub-Antarctic) and its effect on the endemic herbivorous beetle Hydromedion spasutum

Recently two species of carabid beetle were accidentally introduced onto the sub-Antarctic island of South Georgia. Both species are carnivorous and flightless. One of the species, Trechisibus antarcticus, is locally very abundant and in the process of invading the coastal lowland area, where the endemic herbivorous beetle Hydromedion sparsutum (Perimylopidae) is common. Field samples showed the abundance of the endemic species to be much lower, and its adult body size to be larger, in carabid-infested locations than in carabid-free locations. The sample data allowed us to estimate the growth rate of the H. sparsutum larvae and to reconstruct the most likely life-cycle of both species. A laboratory experiment showed a high mortality for the first three (out of six) larval instars of H. sparsutum in groups which had been subjected to predation by T. antarcticus. The duration of the period during which the larvae are vulnerable to predation was shown in a growth experiment to depend on food type. Quantitative and qualitative aspects of the interaction between the introduced predator and the endemic prey, and conditions which allowed the former to invade are discusse

Recent lepidopteran records from sub-Antarctic South Georgia

No Lepidoptera (butterflies and moths) are known to be residents of South Georgia. This paper presents new records of three lepidopterans on the island. Two, Agrotis ipsilon (Noctuidae) and Plutella xylostella (Yponomeutidae), are well-known migrants. The third, Plodia interpunctella (Pyralidae), is closely associated with human habitation. In the context of regional trends of climate warming P. xylostella may already possess the ecophysiological capacity to permit establishment on South Georgia

Electrochemical Performance of Anthocleista djalonensis on Steel-Reinforcement Corrosion in Concrete Immersed in Saline/Marine Simulating-Environment

In this paper, electrochemical techniques were employed to study performance of different concentrations of Anthocleista djalonensis leaf-extract admixtures on the corrosion of steel-reinforcement in concrete immersed in 3.5 % NaCl, for simulating saline/marine environment. Analysed test-results showed that the corrosion rate correlated directly with admixture concentration and inversely with cube of the ratio of standard deviations of corrosion potential and corrosion current. The 0.4167 % A. djalonensis (per weight of cement) exhibited optimal inhibition efficiency, g = 97.43 ± 1.20 %, from analysed experimental data, or 94.80 ± 3.39 %, from predicted correlation model, on steel-reinforcement corrosion in the medium. The other admixture concentrations also exhibited high efficiencies at inhibiting steel-reinforcement corrosion in the chloride contaminated environment. Isotherm fittings of he experimental and predicted performance suggest that they both obeyed the Langmuir adsorption model. Evaluated parameters from the isotherm model indicated favourable adsorption and predominant chemisorption mechanism by this environmentally-friendly inhibitor of steel-reinforcement corrosion in the saline/marine simulating- environment. © 2014, The Indian Institute of Metals - IIM