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Start Over Creator Skuhravý, Václav

2. Hálky na rostlinách

Creator:
Skuhravá, Marcela and Skuhravý, Václav
Type:
article and TEXT
Language:
Czech
Description:
Hálky (cecidie) jsou novotvary na rostlinách způsobené živými organismy. Hálkotvorný organismus využívá hálku jako ochranu před nepříznivými vlivy prostředí i jako zdroj potravy. Podněcuje buňky rostlinného pletiva k množení a napadené buňky zvětšují svůj objem. Hálky se vyskytují na všech orgánech rostlin: na kořenech, stoncích, listech, květních i listových pupenech, květenstvích, plodech i semenech. Podle tvaru hálky a jejího umístění na rostlině lze určit pravděpodobného původce. Vztah hálkotvorného organismu k hostiteli se označuje jako parazitismus. Cecidologie jako nauka o hálkách je součástí biologie. and Galls (cecidia) are new formations on plants produced by living organisms. A gall-inducing organism uses gall as a shelter against the unfavourable environmental conditions and as food or nutrients. It stimulates the cells of plant tissues to proliferate and the attacked cells to increase their size. Galls occur on all plant organs. The relationship be­tween the gall-inducing organism and its host plant is usually regarded as parasitism.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/

7. The role of plant phenology in the host specificity of Gephyraulus raphanistri (Diptera: Cecidomyiidae) associated with Raphanus spp. (Brassicaceae)

Creator:
Vitou, Janine, Skuhravá, Marcela, Skuhravý, Václav, Scott, John K., and Sheppard, Andy
Type:
article, model:article, and TEXT
Subject:
Cecidomyiidae, Gephyraulus raphanistri, Brassicaceae, Raphanus raphanistrum, host-plant specificity, biological control, and host-plant phenology
Language:
English
Description:
Recent host records for Gephyraulus raphanistri (Kieffer), a flower-gall midge, show restriction to Raphanus raphanistrum throughout Europe. Gephyraulus raphanistri has never been reported infesting commercially grown Brassica crops. Historical records showing a broad host range appear to have resulted from confusion with new or as yet undescribed Gephyraulus spp. and Contarinia nasturtii (Kieffer), a known gall-former of Brassica and other related genera. This study tested host specificity of G. raphanistri in the field in Europe by manipulating host plant phenology of actual and potential hosts in the genera Raphanus and Brassica as part of a risk assessment of the insect as a potential biological control agent of R. raphanistrum, one of the most important weeds of crops in Australia. Raphanus raphanistrum raphanistrum (wild radish), R. raphanistrum landra (coastal wild radish), Raphanus sativus (radish) and Brassica napus (oilseed rape cultivar) were phenologically synchronised for initial flowering and planted out in a flowering time and species block design near a natural population of R. r. landra hosting a natural population of G. raphanistri. Three generation peaks in gall formation were observed in the experiment, with galls developing on all test plants with an apparent preference for R. r. landra. The high field specificity of this gall midge is driven by the synchrony of oviposition and flower availability, not host physiological incompatibility or behavioural unacceptability. Commercially grown Brassica spp. are not suitable hosts for G. raphanistri because in the field they differ in flowering phenology from Raphanus raphanistrum. The overlap in the flowering phenology of the crop and weed in Australia makes this insect unsuitable as a biological control agent.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public