SummaryThe beekeepers of Luxembourg were asked for: 1. the honey bee (Apis mellifera) colony losses they experienced over winter; and 2. aspects of their beekeeping practice in May 2011 and 2012. Results on the magnitude of the winter losses in the managed bee colonies of Luxembourg are reported for the first time, and some factors potentially related to the losses such as varroa control methods, agricultural land use at the level of municipalities and the hive types employed were investigated. The number of managed honey bee colonies lost in Luxembourg was 938 out of 5,580 in winter 2010/11 and 1,172 out of 5,382 in winter 2011/12, corresponding to national loss rates of 16.8% and 21.8%, respectively. Elevated loss rates were observed in the Northern municipalities in both years. The losses reported from apiaries employing the hive types Dadant 10 or Dadant 12 were significantly lower compared to apiaries employing the hive type Deutsch Normal and losses with Dadant 12 were lower compared to hive type Al... ResumenEl número de colonias de abejas manejadas perdidas en Luxemburgo fue de 938 de un total de 5,580, en el invierno de 2010/11 y de 1,172 de 5,382, en el invierno de 2011/12, correspondiendo a una tasa de pérdida nacional del 16.8% y 21.8% anual, respectivamente. Las pérdidas de colonias por apiario promediaron 17.2 ± 1.0% durante el invierno 2010/11 y 24.7 ± 1.3% durante el invierno 2011/12. La mediana de las pérdidas por apiario fueron 7.8% durante el invierno 2010/11 y 14.3% durante el invierno 2011/12. Las pérdidas de colonias por apicultor promediaron 21.5 ± 1.4% durante el invierno 2010/11 y 31.0 ± 1.9% durante el invierno 2011/12. La mediana de las pérdidas por apicultor fueron 15.6% y 22.2% en 2010/11 y 2011/12, respectivamente. Las tasas de pérdidas más elevadas se observaron en los municipios del norte de Luxemburgo en los dos años. Las pérdidas reportadas en apiarios que emplean colmenas de tipo Dadant 10 o Dadant 12 fueron significativamente más bajas en comparación con las explotaciones a...

The efficiency of plant-growth-promoting rhizobacteria (PGPR) may not be consistently maintained under field conditions due to the influence of soil microbial communities. The present study aims to investigate their impact on three PGPR-based biofertilizers in wheat. We used the PGPR Paenibacillus sp. strain B2 (PB2), PB2 in co-inoculation with Arthrobacter agilis 4042 (Mix 2), or with Arthrobacter sp. SSM-004 and Microbacterium sp. SSM-001 (Mix 3). Inoculation of PB2, Mix 2, and Mix 3 into non-sterile field soil had a positive effect on root and aboveground dry biomass, depending on the wheat cultivar. The efficiency of the PGPR was further confirmed by the protection they provided against Mycosphaerella graminicola, the causal agent of Septoria leaf blotch disease. PB2 exhibited protection of ≥37.8%, while Mix 2 showed ≥47.9% protection in the four cultivars tested. These results suggest that the interactions between PGPR and native soil microbial communities are crucial for promoting wheat growth and protection. Additionally, high-throughput sequencing of microbial communities conducted 7 days after PGPR inoculations revealed no negative effects of PB2, Mix 2, and Mix 3 on the soil microbial community structure. Interestingly, the presence of Arthrobacter spp. appeared to mitigate the potential negative effect of PB2 on bacterial community and foster root colonization by other beneficial bacterial strains.

The cabbage stem weevil (Ceutorhynchus pallidactylus(Mrsh.)) (Col., Curculionidae) is a serious pest of winter oilseed rape (Brassica napusL.var. oleiferaMetzg.) in central and northern Europe. Although host-plant resistance is a key tool in integrated pest management systems, resistant genotypes are not yet available for this species. Resynthesized rapeseed lines (B. oleraceaL.×B. rapaL.) are broadening the genetic diversity and might have potential as sources of resistance to pest insects. The host quality, of nine resynthesized rapeseed lines and six genotypes ofB. napusto cabbage stem weevil, was evaluated in laboratory screening tests and in a semi-field experiment. In dual-choice oviposition tests, femaleC. pallidactyluslaid significantly fewer eggs on five resyntheses and on swede cv ‘Devon Champion’ than on the moderately susceptible oilseed rape cv ‘Express’, indicating a lower host quality of these genotypes. Results of laboratory screenings were confirmed in a semi-field experiment, in which twelve genotypes were exposed toC. pallidactylusfemales. The number of larvae was significantly lower in two resyntheses and in cv ‘Devon Champion’ than in oilseed rape cv WVB 9. The total, as well as individual, glucosinolate (GSL) content in the leaves differed substantially among the genotypes tested. The amount of feeding by larvae ofC. pallidactylus, as measured by a stem-injury coefficient, was positively correlated with the indolyl GSL compounds 3-indolylmethyl and 4-methoxy-3-indolylmethyl, and with the aromatic GSL 2-phenylethyl, whereas it was negatively correlated with 4-hydroxy-3-indolylmethyl. Thus, the composition and concentration of GSL compounds within the plant tissue might be a key factor in breeding for pest resistance in oilseed rape.