Determination of cesium transfer factors by instrumental neutron activation analysis.

Food-chain models are used to predict radionuclide ingestion after fallout deposition. These models include those transfer processes (soil-to-plant transfer factor(s) [TF], plant-to-animal transfer coefficient(s) [TC] and concentration ratio [CR]) that are likely to be important for radiological assessment. The range of variability for transfer factors for the same plant groups is great, about 4-5 orders of magnitude, which limits their applicability. A better way to determine the best estimate the factors for radiocaesium and other important radionuclides is if the site-specific data are available. Soil, plant and animal samples were collected from a pasture area in Hungary during the vegetation period in 2016. Stable 133Cs concentration was analysed by comparative method with neutron activation analysis (NAA). The comparator and the samples were irradiated in thermal neutron flux 2.55 × 1012 ncm-2s-1 for 2 h (soil) and 6 h (vegetation, animal samples) in the TRIGA Mark II research reactor at the Nuclear Engineering Teaching Laboratory. After an appropriate decay time (12 days) the samples were measured by gamma-spectrometry and analysed. The observed stable caesium TCpm (0.48-0.53) and CRpm (0.41-0.45) were very close to 137Cs factors in the IAEA 2009 Report of 0.49 and 0.54, respectively. This methodology is particularly suitable for the simultaneous study of natural caesium in ecosystem compartments. Consequently, the transfer of stable caesium in a pasture field may be regarded as a useful analogy in predicting the long-term changes of 137Cs affected by site-specific environmental factors.

Comparative analysis of sex-pheromone-response antagonists in three races of European corn borer.

Behavioral responses of males from three New York races of European corn borer,Ostrinia nubilalis (Hübner), to various suspected sexpheromone-response antagonists were investigated with a flight tunnel protocol. Males from a bivoltine (Z) race and from a univoltine (Z) race utilizing a natural pheromone blend of 98∶2 (Z)-∶(E)-11-tetradecenyl acetates and males from a bivoltine (E) race utilizing a 1∶99 (Z)-∶(E)-11-tetradecenyl acetate ratio were flown to their natural blends and to blends containing 1 % of one of the following additional compounds: Z9-12∶OAc,E9-12∶OAc,Z9-14∶OAc, andE9-14∶OAc. In each race, the added components lowered significantly the number of individuals completing the behavioral sequence. The only exception was bivoltineE males flown to a blend withE9-12∶OAc added. The number completing the sequence in this case was statistically not significantly lower than the number that completed the sequence to the standard blend. In all three races, theZ9-14∶OAc produced the most dramatic reduction in completed flights, and in the univoltineZ race, this added component was significantly more effective in reducing completed flights than any other added component. The response to the Z9-14∶OAc is understandable given recently published findings of an electrophysiological study of single sensilla in the European corn borer.

Sex pheromone blend discrimination by male moths fromE andZ strains of European corn borer.

Sex pheromone behavioral responses were analyzed in a flight tunnel with European corn borer,Ostrinia nubilalis (Hübner), males from three distinct populations. Males from a bivoltine and a univoltine biotype using a 97.8∶2.2 blend (Z strains) of (Z)- and (E)-11-tetradecenyl acetate were assayed with treatments containing 0, 0.5, 1, and 3% of theE isomer. Males from neither population oriented in the plume to the 100%Z treatment, but bivoltine males oriented and flew to the source to the other three treatments, whereas univoltine males oriented and flew to the source only to the 1 % and 3 %E treatments. Males from a bivoltine biotype using a 1∶99 blend ofZ/E isomers (E strain) were assayed with sources containing 0, 0.5, 1, and 3% of theZ isomer. Males did not orient to the 0%Z source, but oriented and flew to the source to the other three treatments. In addition to using opposite geometric isomers for the main pheromone component, the bivoltineE strain differed from the bivoltineZ strain by producing and responding better to 1 % of the minor component and by storing 3 times more pheromone in the female glands. Contrary to previous reports, the blend of two pheromone components is significantly better than the main component alone in eliciting oriented flight and close-range behavior with males from all three populations of European corn borer.