Summary Fabeae legumes such as pea and faba bean form symbiotic nodules with a large diversity of soil Rhizobium leguminosarum symbiovar viciae (Rlv) bacteria. However, bacteria competitive to form root nodules (CFN) are generally not the most efficient to fix dinitrogen, resulting in a decrease in legume crop yields. Here, we investigate differential selection by host plants on the diversity of Rlv. A large collection of Rlv was collected by nodule trapping with pea and faba bean from soils at five European sites. Representative genomes were sequenced. In parallel, diversity and abundance of Rlv were estimated directly in these soils using metabarcoding. The CFN of isolates was measured with both legume hosts. Pea/faba bean CFN were associated to Rlv genomic regions. Variations of bacterial pea and/or faba bean CFN explained the differential abundance of Rlv genotypes in pea and faba bean nodules. No evidence was found for genetic association between CFN and variations in the core genome, but variations in specific regions of the nod locus, as well as in other plasmid loci, were associated with differences in CFN. These findings shed light on the genetic control of CFN in Rlv and emphasise the importance of host plants in controlling Rhizobium diversity.

(2006, 2007, 2008). It was less important and somewhat less complicated to establish the most suitable time for spraying in the case of the chlorpyrifos + cypermethrin combination in comparison with the pyrethroids applied separately. The effectiveness of the tested insecticides was markedly influenced by the time of spraying. The effects of the pyrethroids applied singly achieved results comparable to those of the chlorpyrifos + cypermethrin combination only at the optimal spraying time. The most suitable time for spraying varied from the point when the first females appeared in yellow water traps in somewhat higher quantities to the time when a substantial proportion of caught females was able to lay eggs.

Seidenglanz M., Huňady I. (2016): Effects of faba bean (Vicia faba) varieties on the development of Bruchus rufimanus. Czech J. Genet. Plant Breed., 52: 22-29.The development of Bruchus rufimanus was assessed in randomised field trials from 2005 to 2007 with eight faba bean genotypes (SU 5/13, SU-BT, Mistral, Merkur, Stabil Merlin, Melodie, Divine). Significant differences, reproducible between the years, were found between the faba bean lines. The varieties most attractive to B. rufimanus ovipositing females were SU-BT and Divine. Merkur showed a certain level of non-preference. The highest mortality rates of eggs and first instar larvae in pod valve tissues were recorded in Merkur (34-45%) and Divine (51-55%). The highest mortality rates of larvae and pupae during their development in seeds (effect of seed coat and cotyledon tissues) were recorded in Merkur (87-90%) and Melodie (87-99%). Parasitation by Triaspis thoracicus contributed to this mortality. The highest levels of B. rufimanus parasitation were found in SU-BT (32-35%), the lowest in Melodie (3-9%). The total reduction in Bruchus rufimanus individuals during their development was relatively high in all varieties, ranging from 72% to 99%.

The effects of two pyrethroid (lambda-cyhalothrin, alpha-cypermethrin) and two neonicotinoid (acetamiprid, thiacloprid) insecticides on B. pisorum L. eggs were compared under field conditions in the Czech Republic in 2005–2007. The main objective of the study was to find out what real effects can be expected from the available insecticides registered in Europe when applied at the time of the first egg occurrence on lower pods. In general, the rates of Bruchus pisorum egg (+ first instar larvae) survival were significantly lower with all the insecticides compared in the study, in each of the three years (2005, 2006, 2007). The tested insecticides showed some ovicidal effects and also some larvicidal effects. The tested pyrethroids (lambda-cyhalothrin, alpha-cypermethrin) showed somewhat higher effectiveness in comparison with the neonicotinoids (acetamiprid, thiacloprid). Alpha-cypermethrin was the most effective in all three years. In 2006 and in 2007 this insecticide significantly reduced the rates of egg survival in comparison with acetamiprid. In contrast, acetamiprid was the least effective insecticide in each of the three years.

Seidenglanz M., Rotrekl J., Smýkalová I., Poslušná J., Kolařík P. (2010): Differences between the effects of insecticidal seed and foliar treatments on pea leaf weevils (Sitona lineatus L.) in the field pea (Pisum sativum L.). Plant Protect. Sci., 46: 19-27.Tested seed treatments (two doses of thiamethoxam, thiamethoxam + fludioxonil + metalaxyl-M; two doses of clothianidin + beta-cyfluthrin) showed high effects on pea leaf weevils (Sitona lineatus L.) which approved relatively long-lasting and sufficient protection of several bottom nodes of stipules simultaneously. The effects of foliar treatments (chlorpyrifos + cypermethrin; acetamiprid, lambda-cyhalothrin) sometimes were evident only on the node which was determined as the youngest node at the time of spraying. The effects of the compared seed and foliar treatments on the reduction of S. lineauts larvae numbers on roots were not proven as positive. It is possible to conclude that the foliar application had no real effect in this sense at all. However, positive significant effects of thiamethoxam and clothianidin + beta-cyfluthrin on root nodulation in general were recorded. Especially higher doses of the seed treatments increased overall nodulation from 43% till 363%.