This study investigated oyster infection dynamics by different strains of Vibrio aestuarianus isolated before and after the apparent re-emergence of this pathogen observed in France in 2011. We conducted experiments to compare minimal infective dose, lethal dose 50 and bacterial shedding for six V. aestuarianus strains. Whatever the strain used, mortality was induced in juvenile oysters by intr...

Effect concentrations in fish LC50 tests with directly acting electrophiles are lower than those of unreactive chemicals that act by narcosis. LC50 values of more hydrophobic reactive chemicals tend to approach those of unreactive chemicals. Quantitative studies to correlate fish LC50 data to physical-chemical properties indicate that LC50 values of reactive chemicals depend on hydrophobicity a...

Secondary production of the burrowing mayfly, Hexagenia limbata, was quantified from four sites differing in seasonal salinity within the Lower Mobile River, Alabama, from October 1995 to September 1996. This population was univoltine, with emergence occurring from late May through early August. Comparisons with other populations of this species showed latitudinal trends suggesting that summer ...

Mortality of pear psylla to amitraz was studied by means of bioassays. Variation between samples, temporal variation within the season in one orchard and spatial variation between Swiss regions were considered. Variation between samples was large enough to produce different Probit functions and LC50 values. Temporal and spatial variations were too small to indicate resistance. Prediction interv...

The erythrocyte abnormality test was analyzed in kidney cells of freshwater fish, Labeo rohita exposed to tannery industry effluent. The 96h LC50 value of tannery effluent against fish was calculated by Finney method and it comes out to be 7.07%. Three sublethal concentrations on basis of 96h LC50 value (3.53%, 1.76% and 0.88%) were selected. Fishes were exposed to these concentrations for 24h,...

A chitin synthesis inhibitor, novaluron, was evaluated under laboratory conditions for its larvicidal activity against a field population of the housefly, Musca domestica L. (Diptera: Muscidae), by feeding and dipping methods. The concentrations used were 1, 2.5, 5, 10 and 20 mg a.i./kg in both methods. The product caused >80% larval mortality at 10 and 20 mg a.i./kg. Of the two methods, feedin...

Laboratory tests of fipronil and its degradation products have revealed acute lethal toxicity at very low concentrations (LC50) of <0.5 microg/L to selected aquatic macroinvertebrates. In streams draining basins with intensive rice cultivation in southwestern Louisiana, USA, concentrations of fipronil compounds were an order of magnitude larger than the LC50. The abundance (rho=-0.64; p=0.015) ...

The susceptibility of Culex quinquefasciatus to chemical insecticides in two field sites in Kuala Lumpur was evaluated using the WHO standard susceptibility test. Less then 7days old female mosquitos, reared from wild caught females were exposed to discriminating dosages of insecticides at recommended exposure periods. The larval bioassay were conducted using the multiple concentrations and the...

Marine algal community signifies a huge source of compound endowed with ingenious structure and potential biological activities. Cytotoxicity of plant or fungal material is considered as the presence of antitumor compounds. In this study, ethanol extracts of seaweeds Dictyota dichotoma var. velutricata, D. hauckiana, D. indica, Iyengaria stellata, Jolyna laminarioides, Melanothamnus afaqhusaini...

1Tropical Health Department, High Institute of Public Health, University of Alexandria, Alexandria, Egypt. ABSTRACT We conducted a study to determine the laboratory and field efficacy of neem oil towards anopheline larvae. No difference in LC50 was observed between laboratory and field strains for temephos, chlorpyriphos-methyl/fenitrothion and neem oil. No difference in susceptibility was foun...