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  • Author or Editor: J. Fail x
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In 2000-2002 thrips species were collected from mature white cabbage head leaves in Hungary. The total number of the sampled specimens was 4226. Out of the 3374 identified adults Thrips tabaci was predominant (91.3%). Frankliniella tenuicornis was found in significant number (6.9%) with rather extraordinary appearance in 2000 (15.1%) but in the other years its frequency was lower (0.5%, 1.9% respectively). The rest of the adults (1.8%) were: Frankliniella intonsa, Aeolothrips intermedius, Thrips angusticeps, Thrips atratus, Haplothrips aculeatus, Limothrips denticornis, Anaphothrips obscurus, Chirothrips manicatus and Scolothrips longicornis. The 852 second instar larvae were also identified. 96.4% was Thrips tabaci, 2.7% Thrips angusticeps and 0.8% Anaphothrips obscurus. In spite of the fact that in 2000 15.1% of the adults on cabbage was Frankliniella tenuicornis, not a single larva was found. Therefore we concluded that in Hungary it is only the thelytokous populations of Thrips tabaci that are of high importance as thrips pest of white cabbage.

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The onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae) has been recognized as a severe worldwide pest of white cabbage ( Brassica oleracea L. convar. capitata provar. capitata Duch.) for almost three decades. Although the most effective control measure is the use of resistant varieties, little is known about the resistance mechanism(s) involved. In 2007, a study at Tordas, Hungary, was carried out with 6 varieties to confirm that antixenosis is at least partly responsible for the resistance against onion thrips. The number of adult thrips and their progeny was counted on the outer ten head leaves at one-third of the heading process. At the same time, the light reflectance of old and outer head leaves was measured. The onion thrips damage was also assessed at full maturity. Antixenosis was found to be responsible for the resistance of ‘Balashi’, ‘Bloktor’ and ‘Riana’ varieties, since the number of adults and offspring found on head leaves was significantly lower than that of ‘Green gem’, ‘Hurricane’ and ‘Quisto’. The resistant varieties (‘Balashi’, ‘Bloktor’ and ‘Riana’) similarly suffered significantly lower damage than the susceptible ones (‘Green gem’, ‘Hurricane’ and ‘Quisto’). The light reflectance spectra of all six varieties were almost identical in the case of the old leaves, but a difference was found between the susceptible and resistant varieties when the reflectance of the outer head-forming leaves was measured. Similarly, the colour of the old leaves was not greatly different, but that of the outer head-forming leaves was correlated to the number of thrips adults found in the cabbage heads.

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Several synthetic floral lures have been described for the cetoniin scarabs Cetonia aurata aurata L. and Potosia cuprea Fabr. (Coleoptera, Scarabaeidae), exploiting their olfaction-guided behavioural preference for a wide range of flower volatiles.

A ternary mixture of 3-methyl eugenol, 1-phenylethanol and (E)-anethol has previously been described as a powerful synthetic floral attractant for both C. a. aurata and P. cuprea. The first objective of the present research was to test whether isoeugenol and eugenol, with a very similar molecular structure to 3-methyl eugenol, can substitute 3-methyl eugenol in the ternary blend. All baited traps caught significantly more of both species than unbaited control traps, however, traps containing 3-methyl eugenol caught significantly more than those with either isoeugenol or eugenol. This indicates a fine tuning in behavioural response to 3-methyl eugenol.

The second objective was to devise simpler attractant combinations for C. a. aurata and P. cuprea, based on previous field studies with synthetic floral compounds. Both C. a. aurata and P. cuprea showed strong attraction to the combination of 2-phenylethanol and 4-methoxyphenethyl alcohol, while the combination of 2-phenylethanol and 1,2,4-trimethoxybenzene resulted in medium-size catches, however, mostly catching P. cuprea. This level of selectivity may lead to the development of more selective lures for P. cuprea, and provide a better understanding of the feeding-related olfactory ecology of the two important pest chafer species.

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Although Thrips tabaci is a well-known vector of Tomato spotted wilt virus (TSWV) it does not belong to the spreaders of this dangerous pathogen in North America. The possible explanation of the differences in its vector efficiency in Europe and in North America is rooted in the fact that out of the two subspecies of T. tabaci, i.e. T. tabaci tabaci and T. tabaci communis only the specimens of the latter were introduced from Europe into North America. To support our hypothesis we have used a molecular marker that detects intraspecific ribosomal DNA sequence variations between the two subspecies of T. tabaci.

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In autumn 2002 field screening tests were carried out at the National Institute for Agricultural Quality Control in order to assess the susceptibility of 52 white cabbage varieties to Thrips tabaci. The evaluation based on the degree of damage occurring on the head leaves. In case of each variety, all the damaged leaves of 10 mature cabbage heads were marked with the appropriate value of the six-degree damage rating scale created for the procedure. The ratings for each leaf expressed the size of the damaged surface proportional to the surface of the whole leaf. Varietal resistance was represented by the sum of these values (proportional to the surface of the first head leaf) expressing the damage observed on the whole head. The number of damaged leaves was also counted. All varieties suffered smaller or greater damage. However, 'Bariton', 'Bently', 'Desmond', 'Avalon', 'Masada' and 'Transam' were the least damaged and described as resistant varieties, therefore recommended for late autumn cabbage production. The damage decreased from month to month from September till December.

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Abstract  

Following the accident at the nuclear reactor at Chernobyl, in the Soviet Union on April 26, 1986, we performed a variety of measurements to determine the level of the radioactive fallout on the western United States. We used gamma-spectroscopy to analyze air filters from the areas around Lawrence Livermore National Laboratory (LLNL), California, and Barrow and Fairbanks, Alaska. Milk from California and imported vegetables were also analyzed. The levels of the various fission products detected were far below the maximum permissable concentration levels.

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Authors: K. Surano, G. Hudson, R. Failor, J. Sims, R. Holland, S. MacLean and J. Garrison

Abstract  

Helium-3 (3He) mass spectrometry for the analysis of low-level tritium (3H) concentrations (0.5 to 5 Bq·l–1) in environmental sample matrices was compared with conventional low-level -decay counting methods. The mass-spectrometry method compared favorably, equalling or surpassing conventional decay-counting methods with respect to most criteria. Additional research and method refinements may make3He mass spectrometry the method of choice for routine, low-level to very-low-level (L<0.5 Bq·l–1)3H measurements in a wide variety of environmental samples in the future.

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