Arbuscular mycorrhizal symbiosis is the most frequent and ancestral type of mycorrhizal symbiosis. It is estimated that at least 80% of terrestrial plant species are able to form a mutualistic relation with fungi. Consequently in the context of successful plant invasions, arbuscular mycorrhizal fungi may have a favourable if not a crucial role. The mycorrhizal status of 23 invasive species is reported here for the first time. This study also tested whether the intensity of mycorrhizal colonization of the roots of invasive species is related to that of the dominant species of invaded plant community. This is partly supported by our results when total percentages of mycorrhizal colonization were compared. In addition, the effect of habitat and community characteristics on the intensity of colonization of the roots of invasive species by arbuscular mycorrhizal fungi was tested and several significant correlations were revealed. At the among-species level, the total mycorrhizal colonization decreases and the relative arbuscular colonization increases in the roots of invasive species with increasing nitrogen availability in the habitat. Both these relations are significant after phylogenetic correction, which suggests this is an evolutionary adaptation. There are also negative correlations between the relative arbuscular colonization of invading species and the light and temperature demands of the species present in the community, and a positive correlation between the relative arbuscular colonization of the invaders and soil wetness. That all these relations are revealed at the within-species level possibly reflects differences among the habitats studied.
While observational studies led to the assumption that water or moisture (W/M) is a prerequisite for diapause development, the experimental research indicates rather the opposite: usually W/M is needed as late as for the post-diapause resumption of morphogenesis. Recent examples for this type of regulation of dormancy are given: Eggs of the tettigoniid Stictophaula armata, eggs of the grasshopper Oedaleus senegalensis, adults of the bruchid Bruchidius atrolineatus, adults of the endomychid Stenotarsus subtilis (= S. rotundus). In the late diapause of the noctuid Busseola fusca and in eggs of the chrysomelid Homichloda barkeri, moisture is assumed to be the diapause terminating cue. Fall in temperature is assumed decisive for termination of pupal diapause in the saturniid Schausiella santarosensis, although the effect of intense rain after a long dry period has not yet been excluded. Effects of intense changes in environmental conditions and of gradual decrease in diapause intensity with time have often been neglected.