No abstract

Due to the length of egg-laying period (> 80 days), two applications of insecticides against cabbage stem weevil (Ceutorhynchus pallidactylus Marsh.) are currently needed. However, resistance of pollen beetle (Brassicogethes aeneus F.) to pyrethroids complicates the choice of suitable insecticide for the second application. The active ingredients cypermethrin, etofenprox, pymetrozine, indoxacarb and chlorpyrifos-ethyl applied as second spring applications to winter oilseed rape crops were assessed under field conditions from 2016 to 2018 to ascertain how they could reinforce the effects of the first spring application (beta-cyfluthrin) on cabbage stem weevil. Chlorpyrifos-ethyl and etofenprox strengthened the effects of the first spring spray on cabbage stem weevil markedly more than cypermethrin. Pymetrozine and indoxacarb, effective on resistant populations of pollen beetles, showed the lowest contribution to increase the effects. Indoxacarb showed a low effect on C. pallidactylus in laboratory tests too. The impacts of the bans on active ingredients chlorpyrifos-ethyl and pymetrozine are discussed.

Bruchus pisorum L., is an economically important pest of field pea (Pisum sativum L.) crops worldwide, however, no fully effective methods (conventional, alternative) of its control exist now. To fill this knowledge gap, possibilities of trap cropping were tested in the years 2015–2017. Two field pea varieties differing in the start of flowering, and one spring barley variety, were used to design four different types of crops, that were compared in large plot trials (2.82 ha). It was hypothesized the females would prefer zones planted with early flowering variety for oviposition. In all three seasons, females placed more eggs on pods in the parts of plots planted with the early flowering variety, and positive aggregation of the eggs and infested seeds were recorded there too. In cases where the egg-laying period is shorter than 14–21 days, the early flowering variety located at the margins should serve efficiently as a trap crop.

79 responses in shoot culture of the apple rootstock MM 106 treated with NaCl, KCl, mannitol or sorbitol. -Biol. Plant. 50: 61-68, 2006. Morard, P., Caumes, E., Silvestre, A.: Influence of nutritive solution concentration on the growth and mineral nutrition of tomatoes. -Can. J. Plant Sci. 84: 299-304, 2004. Morgan, J.M.: Osmoregulation and water stress in higher plants. Hare, R.: Avenues for increasing salt tolerance of crops, and the role of physiologically based selection traits. -Plant Soil 247: 93-105, 2002. Munns, R.: Genes and salt tolerance: bringing them together. -New Phytol. 167: 645-663, 2005. Navarro, J.M.; Botella, M.A., Cerdá, A., Martínez, V.: Phosphorous uptake and translocation in salt-stressed melon plants. -J. Plant Physiol. 158: 375-381, 2001. Navarro, J. M, Garrido, C., Martínez, V., Carvajal, M.: Water relations and xylem transport of nutrients in pepper plants grown under two different salts stress regimes. -J. Plant Growth Regul. 41: 237-245, 2003.

No abstract

AbstractŠAFÁŘ, J., ŠŤASTNÁ P., HULA, V.: Impact of type of pitfall traps and preserving agent on entrapped representatives of the Carabidae (Coleoptera). Acta univ. agric. et silvic. Mendel. Brun., 2010, LVIII, No. 2, pp. 213-218 This paper focuses on the type of cover and preserving agent infl uence on composition of entrapped fauna of Carabidae beetles. The research took place in the northern part of the protected landscape area of Žďárské vrchy, south from Kameničky municipality in rural district of Chrudim. Epigeic fauna was monitored one month from April 30 th to June 5 th 2008 -in the period of the highest activity of most Carabidae species. Traps were located in Latin square with fi ve meter distance, using three preserving agents (formaldehyde, ethylene glycol, sodium chloride solution) and three types of covers above pitfall traps (acrylic glass cover, no cover, or wooden board put above the trap). Within the research 1123 Carabidae specimens belonging to 21 species were entrapped. The most numerous was Poecilus cupreus (915 specimens) in which also the strongest relationship to formaldehyde was detected. The redundancy analysis (RDA) from CANOCO package was used for statistical evaluation. With monitored variables, a signifi cant infl uence (T = 0.137, F = 3.020, P = 0.0240) of formaldehyde on presen ce of some Carabidae species was confi rmed (Poecilus cupreus, Amara lunicollis, Pterostichus diligens, and Bembidion guttula). Infl uence of the cover above the pitfall trap on species range in the trap was not confi rmed (T = 0.062, F = 2.574, P = 0.0710).

Over the course of three years (2016–2018), the effects of insecticides on stem-mining weevils [(Ceutorhynchus pallidactylus (Marsham, 1802), Ceutorhynchus napi (Gyllenhal, 1837)] were assessed under field conditions. The dates for spraying were determined on the basis of the recorded percentages of weevil females carrying mature eggs in their ovaries (timing I: the first females with mature eggs present in yellow water traps; timing II: more than 50% of the females with mature eggs present). Delaying the first spring insecticide application till timing II made it possible to combine the control of the stem weevil along with the control of the pollen beetle, Brassicogethes aeneus (Fabricius, 1775). However, the poor effectiveness of the tested insecticides on the stem-mining weevils, regardless of the date they were sprayed, indicates it is impossible to successfully control the insect pests with one insecticide application during the seasons with prolonged egg-laying periods.

A total of 251 pollen beetle (Brassicogethes aeneus F.) populations sampled in the Czech Republic and Slovakia were tested against both lambda-cyhalothrin and tau-fluvalinate by means of Insecticide Resistance Action Committee (IRAC) susceptibility test method 11, version 03 (glass vial test) over four (2015-2018) years. The results confirmed high levels of resistance to lambda-cyhalothrin in the pollen beetle populations of both countries. Tau-fluvalinate is less affected by resistance, but relatively high proportions of resistant populations at many localities in both countries make this insecticide almost unusable against the pest too. The results of a correlation analysis of lethal concentration (LC) values (LC 50 and at least partly of LC 90 values, too) indicate a moderate level of cross resistance against the two active ingredients in Czech populations. In Slovakian populations, the positive correlation between the LC 50 values proved to be significant only in 2018 (r = 0.66, p < 0.001). Despite certain variability in the results of the correlation analysis recorded in this study, the findings indicate another possible decrease in the susceptibility of pollen beetles to pyrethroids, in general, if tau-fluvalinate were used for their control under field conditions.