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  • Author or Editor: I. Sivcev x
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{\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\fnil\fprq2\fcharset0 Times-AH;}} \viewkind4\uc1\pard\lang1024\f0\fs24 In order to monitor the spread and population density of Diabrotica virgifera virgifera LeConte in the Serbian territory, Hungarian Csalomon pheromone traps were used as the primary monitoring tool in 1998. Out of 515 locations, adults were detected at 437 locations. Compared to 1997, the western corn rootworm population increased. In 1998, the area infested by D. virgifera virgifera was approximately 61,400 km2. The population increased at a slower rate than in previous years, probably due to extremely hot and dry weather. A population of economic importance was recorded on an area that measured 14,000 km2. Within this area, 455.13 km2 (45,513 ha) of damaged corn was reported. The estimated corn yield loss varied from 1% to 70%, but in most fields, the estimated yield loss was approximately 30%. Control recommendations, based on the number of captured WCR adults, are being considered for 1999 in monoculture corn as well as in continuous corn. \par }

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Authors: M. Tóth, I. Sivcev, I. Ujváry, I. Tomasek, Z. Imrei, P. Horváth and I. Szarukán

Trap designs baited with the synthetic sex pheromone have been optimized for trapping of the western corn rootworm Diabrotica v. virgifera LeConte (Coleoptera: Chrysomelidae) (WCR), which has recently been introduced into Europe. The best trap design proved to be the sticky “cloak” trap (code name “PAL”), which catches only males, and is being used in many countries of Europe for detection and monitoring the spread of the new pest. Preliminarily the range of attraction (as defined by Wall and Perry, 1987) of the pheromone traps was estimated to be <10 m. The performance of yellow sticky plates (used by others for monitoring of the pest) was insignificant as compared to the activity of the pheromone baited traps, and yellow colour had no discernible effect on catches in pheromone traps. The known floral lure of WCR containing 4-methoxy-cinnamaldehyde and indole proved to be active also towards the population in Europe, attracting both females and males. Yellow colour slightly increased catches by the floral lure, hence a yellow sticky “cloak” trap has been developed (code name PALs). Pheromone baited PAL traps caught a total of about 4 times more beetles than the floral baited PALs, which latter however appeared to be preferentially active for females. When placed into the same trap, the pheromonal and floral lures did not interfere with each other's activity.

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Pherocon AM (PhAM) trapping and visual counting are two commonly used methods for identifying maize fields in the USA that contain a sufficient number of adult western corn rootworms (WCR), Diabrotica virgifera virgifera LeConte to cause economic root damage by larvae the following year. Therefore, the estimation of adult WCR population plays an important role in management decisions (rotation or treatment). The goals of this study were (1) to compare adult WCR data obtained by PhAM trapping to “whole plant count” data in different maize developmental stages, (2) to determine the period in which the data obtained by both methods show the highest correlation, (3) to determine the regression curve between capture of WCR on PhAM as an independent variable and number of WCR observed by visual plant count, and (4) to determine if the “whole plant count” method can serve as a substitution for PhAM trapping under European conditions. Three samplings were conducted in 2006 in 38 fields in Croatia and one sampling was conducted in 22 fields in Serbia. Sampling in Croatia was conducted when maize plants were in the R 65-69, R 73-77 and R 79-85 developmental stages according to BBCH identification keys of maize. Sampling in Serbia was conducted when maize plants reached R 69-71 developmental stages. Three to six PhAM traps were placed in each 0.5 to 4 ha maize field seven days prior to sampling. Visual counts were conducted on the same day as trap inspections. Adult WCR densities in the PhAM traps were correlated to adult densities on whole plants. Statistical analyses comparing the results of PhAM trapping with the visual “whole plant count” method showed that there is a significant medium to strong correlation between them. Correlation coefficients varied depending on the data used in the analysis. When sampling was conducted in the first half of August (maize developmental stages R 69-77), the correlation coefficients were the highest (r(R 6971) = 0.8677 and r(R 73-77) = 0.706). Coefficients of determination were the highest as well [r2 (R 69-71) = 0.753; r2 (R 73-77) = 0.4984]. Therefore, the most appropriate period for sampling is during the first half of August. At that time, the majority of the maize plants were between the R 69 and R 77 developmental stages. According to the results, 0.5–1 visually determined adult/plant corresponds to 40 adults/trap/week. This shows that both methods are equally useful for estimating the population densities of WCR in the Central European region.

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Abstract

Reduction of several polynitroarenes with isopropanol in a flow-type reactor in the presence of Al2O3 catalyst was studied. Temperature-controlled highly selective reduction of one, two, or three nitro groups in all the studied polynitroarenes proved to be feasible. N-alkylation of the reaction products was the predominant side reaction at high temperatures, except for the reduction of 2,7-dinitronaphthalene: in this case, a considerable amount of alkoxylated product was obtained. Benzo[c]cinnoline was the main product of reduction of 2,2′-dinitrobiphenyl.

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