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The occurrence of honey bees was observed in fields of oilseed rape (Brassica napus subsp. napus) during the flowering period. The investigation revealed that the farmer was using different pestici...

Drastic reductions of insect diversity and abundance are observed in the highly fragmented agricultural landscapes of central Europe. Declines of pollinators may have detrimental effects on the reproduction of wild insect-pollinated plants as well as the yield of crops. In order to mitigate such impacts, sown flower strips on arable land within Agri-Environment Climate Schemes (AECS) are supported across EU countries. However, it is not clear whether sown flower strips provide equivalent benefits to wild flower-visiting insects as semi-natural habitats.Here, we apply plant-pollinator network approach to evaluate the function of sown flower strips for the communities of wild bees. We compared the structural characteristics and the robustness of plant-pollinator networks in sown flower strips and nearby semi-natural habitats. We also quantified the importance of individual plant species for bees based on simulations of plant-pollinator extinction cascades.We found that assemblages of plants and pollinators were less diverse in sown flower strips than in semi-natural habitats, more generalized, and more nested. However, we did not find any significant differences in network robustness to plant-pollinator coextinctions. Further, simulations revealed a large variation in the functional importance among plant species from both habitats.We conclude that although the analysis of network robustness suggested that plants in the sown flower strips and semi-natural habitats were functionally equivalent, this masked important differences among the two habitats. From the conservation point of view, semi-natural habitats were superior in supporting a more diverse community of solitary bees and bumblebees.

Beneficial insects, such as Apis mellifera (honey bees) and Bombus sp. (bumble bees), play important roles in the environment as pollinators, and they are directly affected by agronomical practices, such as pesticide spraying or the selection of crop cultivar. Sunflower is an important resource for these pollinators, and its yield is highly dependent on pollination. Six sunflower hybrid cultivars (ES Biba, Gonzalo, Drake, Vellox, NK Neoma, and P63LE10) were used to compare the visitation rates (VR) of pollinators during flowering in three years (2015, 2016, and 2017). From this set, cultivar P63LE10 was selected to evaluate how pesticide treatments (mixture of two insecticide products containing acetamiprid and pirimicarb, respectively, and two fungicide products containing propiconazole plus prochloraz and dimoxystrobin plus boscalid, respectively) affect pollinator visitation. The amount of pesticide residue in sunflower inflorescences was analyzed to determine the content over the duration of the experiments. The sunflower cultivar P63LE10 was significantly the most attractive to both groups of pollinators in 2017. This cultivar was visited by the highest number of honey bees also in the other years. For bumble bees, cultivar P63LE10, along with cultivars NK Neoma and Vellox, had the highest visitation rates in 2015 and 2016. In 2017, plants treated by the fungicide dimoxystrobin plus boscalid had the highest visitation rates for both groups of pollinators. For bumble bees plants treated with this fungicide were significantly more visited (VR 23.1 ± 2.1%) than these treated with insecticide with pirimicarb (16.4 ± 2%) and the untreated control (17.9 ± 1.7%), and for honey bees plants treated with dimoxystrobin plus boscalid were significantly more visited (VR 24 ± 4.5%) than all other treatments except with acetamiprid (20.5 ± 3.5%). The residues of tested pesticides were found in blooms for the whole time of the experiment (range of values for 2016 and 2017 [ng/g]: acetamiprid 144–6, 3360–56; pirimicarb 177–12, 223–10; prochloraz 380–6, 1970–912; propiconazole 324–17, 1024–1018; boscalid 216–154, 9600–1319; dimoxystrobin 452–137, 6560–911). The influence of cultivar was more important than pesticide treatment in the selection of a preferred food source by pollinators.

In experiments on winter oilseed rape during 2013–2016, we examined the influence of timing of fungicides application at BBCH 61–63 and BBCH 65–67 for fungicides containing active ingredients based upon new triazoles, strobilurins and SDH inhibitors (cyproconazole 80 g/l a.i. + azoxystrobin 200 g/l a.i., picoxystrobin 200 g/l a.i. + cyproconazole 80 g/l a.i., boscalid 200 g/l a.i. + dimoxystrobin 200 g/l a.i., protioconazole 125 g/l a.i. + fluopyram 125 g/l a.i., and prochloraz 276 g/l a.i. + tebuconazole 133 g/l a.i.) on effectiveness against Sclerotinia sclerotiorum and yield. For cyproconazole 80 g/l a.i. + azoxystrobin 200 g/l a.i. and boscalid 200 g/l a.i. + dimoxystrobin 200 g/l a.i., two applications with divided and full doses were also performed. Applications at BBCH 65–67 resulted in a statistically insignificant 4% greater effectiveness against Sclerotinia sclerotiorum. All applications increased yields, but no significant difference was determined due to application timing by growth stages. Divided applications achieved the highest effectiveness, while yield was increased especially at full dosage. In practice, however, such split applications are difficult to perform.

Clubroot disease, caused by Plasmodiophora brassicae (Wor.), has been affecting on winter oilseed rape ( Brassica napus L.) in the Czech Republic over the past 4 years. Therefore, research on P. brassicae in the Czech Republic is important for developing effective strategies to manage clubroot under Czech environmental conditions. Experiments with P. brassicae -resistant cultivars of winter oilseed rape were conducted in an infested field and greenhouse. In the greenhouse, six resistant cultivars were grown in the infested soil collected from various fields in the Czech Republic and were assessed for index of disease (ID %). The best results achieved by cultivar Mentor (2 ± 0.7%) closely followed by cultivar SY Alister (5 ± 1.1%), the worst one was cultivar CHW 241 (30 ± 3.8%). In the field experiments seven resistant cultivars were grown, and disease development was monitored monthly. The lowest index of disease brought cultivar Andromeda (3 ± 0.8%) and PT 235 (4 ± 1.5%), the highest ID has cultivar CWH 241 (46 ± 6.5%) in the first season and in the second season any cultivar achieved 25% ID. Yields were measured at the end of the cropping season. The highest yield was achieved by cultivar SY Alister (6.1 t/ha) in the first season and cultivar PT 242 (5.03 t/ha) in the second season. The inoculum level was measured across the field by (qPCR), and an infestation map was created. The highest spore concentration was found on the field entrance. Collectively, the information obtained on the effectiveness of host resistance and pathogenic diversity of P. brassicae populations from the Czech Republic may help to more effectively manage clubroot in this country.

Řicařova V., Kazda J., Singh K., Rysanek P. (2016): Clubroot caused by Plasmodiophora brassicae Wor.: a review of emerging serious disease of oilseed rape in the Czech Republic. Plant Protect. Sci., 52: 71–86. Winter oilseed rape is the second most frequently grown crop in the Czech Republic. Clubroot, caused by Plasmo diophora brassicae (Wor.), was previously a problem in production of vegetable. The disease has been spreading on winter rape ( Brassica napus L.) over the past four years. Infected stands were reported throughout the country in autumn 2011. The pathogen is probably widely spread in the whole country, its incidence depends on suitable weather conditions. Every field with clubroot is considered as contaminated for many years. The amounts of inoculum and its distribution are not sufficient yet, but this is just the initial stage of colonisation. There is a similar situation resem bling experiences from other countries (Canada, Germany) where clubroot has gradually expanded in the last 15 years.

Winter oilseed rape (Brassica napus) is an important crop in the Czech Republic and Poland. Clubroot disease caused by the pathogen Plasmodiophora brassicae is a serious and still-growing problem for oilseed rape growers in both countries. The aim of this study was to evaluate the pathotype composition of P. brassicae populations from the Czech Republic and Poland, according to the three evaluation systems, and to determine soil inoculum loads for representative fields via traditional end-point PCR as well as quantitative PCR analysis. There were considerable differences between the populations of P. brassicae from both countries, and the number of pathotypes varied depending on the evaluation system and the threshold used to distinguish susceptible vs. resistant plant reactions. This is the first study comparing the effect of different thresholds. Using an index of disease (ID) of 25 % to distinguish susceptible vs. resistant reactions, there was a total of seven pathotypes identified based on the differentials of Williams, five with the system of Some et al., and 18 with the European Clubroot Differential (ECD) set. However, based on a threshold of 50 %, there were nine pathotypes according to the evaluation system by Williams, four based on the differentials of Some et al., and 15 with the ECD set. Changing of the thresholds led to the reclassification of some pathotypes. Several pathotypes were common in both countries. High amounts of pathogen DNA were found in many of the field soils analysed by quantitative PCR. There was a weak correlation between soil pH and infestation of P. brassicae for the Polish soils.

Spitzer T., Misa P., Bilovský J., Kazda J. (2015): Management of maize stand height using growth regulators. Plant Protect Sci., 51: 223–230. Effect in reducing maize plant height using growth regulators ethephon, chlormequat chloride (CCC), CCC + ethephon, and mepiquat chloride + prohexadione-Ca was studied in field experiments during 2010 and 2011. It was found that maize plant height could be reduced by as much as 125 cm (49% of control) using a double application of ethephon (576 g a.i./ha) at growth stages BBCH 18–19 and BBCH 34–36. The other growth regulators displayed weak or no influence. An optimum level of shortening was achieved using ethephon (576 g a.i./ha) at BBCH 34–36 (reducing plant height by 40–90 cm), but it is necessary to count upon yield loss of 0.5–0.6 t/ha.

Spitzer T., Matusinský P., Spitzerova D., Bilovský J., Kazda J. (2014): Effect of flight activity of stem weevils (Ceutorhynchus napi, C. pallidactylus) and application time on insecticide efficacy and yield of winter oilseed rape. Plant Protect. Sci., 50: 129–134. During 2010–2012, we monitored flight activity of male and female stem weevils ( Ceutorhynchus napi, C. pallidacty lus ) using yellow water traps, the effectiveness of various application dates for the insecticide thiacloprid (72 g active ingredient/ha), and the influence on yield. The first occurrence of beetles in traps was recorded after soil temperature at 5 cm reached 8°C in all experimental years. In all years, males of C. pallidactylus dominated in the traps and the times of beetles’ first occurrence. The most effective applications of thiacloprid at the stated rate were 14 days (2010), 6 days (2011), and 1 day (2012) after peak flight. Females with eggs appeared in bowls in 2010 and 2012 at first flight, while in 2011 no females were recorded. After the most effective applications, yields increased significantly in 2010 (+5% vs. the control) and in 2011 (+4%), and insignificantly in 2012 (+2%).

Oil seed rape (Brassica napus L.) is one of the most commonly grown crops in Central Europe, and the brassica pod midge (Dasineura brassicae Winn.) is one of the most important pests there. Insecticides against this pest applied during flowering may harm bees and other beneficial insects. The use of biostimulants such as nitrophenolates, which are not harmful to beneficial insects, can be an environmentally friendly way to control this pest. Nitrophenolates activate lignin synthesis in rape pods so the brassica pod midge is not able to penetrate pods. Nitrophenolates also regulate the efficiency of the photosynthetic apparatus, thus increasing yield. For these reasons nitrophenolates were tested in field conditions in Central Europe in 2005, 2007 and 2008. Nitrophenolates were applied on 10-m2 plots, and their effect was compared to that of conventional insecticides. The number of damaged pods and yield parameters were assessed; the lignin content as well as photosynthetic rate was measured. Expression of genes related to lignin biosynthesis was examined in Arabidopsis thaliana L. The application of nitrophenolates decreased pod damage caused by the brassica pod midge. Expression levels of four genes related to lignin biosynthesis were increased after the application of nitrophenolates. The yield was higher in nitrophenolate-treated plots, which was attributed to an increase in the intensity of photosynthesis, higher chlorophyll content and improved chlorophyll a fluorescence parameters. The results showed that nitrophenolates have potential as a protective agent, but a further study is required. The application of nitrophenolates holds promise for reducing chemical input into the environment.

Effects of the extract from Angelica archangelica seeds on Acyrthosiphon pisum, pea aphid mortality was tested in laboratory conditions. The total yield of the extract was 12.5%, and the undertaken analysis demonstrated a high content of furanocoumarins with a major compounds imperatorin (50.4%), bergapten (17.9%) and phellopterin (12.2%). The extract proved to be highly toxic for the aphids and LC50 was estimated as 1.1, 0.8 and 0.4 mg L−1, and LC90 as 8.7, 5.6 and 3.3 mg L−1 for 24, 48 and 72 h from application, respectively. The effect of extract application on Harmonia axyridis was studied. Topical application was found to cause only low mortality (15.2%) in the 2nd–3rd instar larvae. No significant negative effect of the extract on food intake, mortality or fertility of adults was recorded. Based on present knowledge, we can recommend extracts from A. archangelica seeds for the development and production of new botanical insecticides.

Spitzer T., Matusinsky M., Klemova Z., Kazda J. (2012): Effect of fungicide application date against Sclerotinia sclerotiorum on yield and greening of winter rape. Plant Protect. Sci., 48: 105–109. In experiments with winter rape during 2004–2008, we examined the effectiveness of fungicides containing active ingredients based upon triazoles and SBI inhibitors (group A): flusilazole 250 g/l a.i., flusilazole 125 g/l a.i. + carbendazim 250 g/l a.i., and cyproconazole 120 g/l a.i. + carbendazim 300 g/l a.i. Fungicides based upon older and newer triazoles, strobilurins, and SDH inhibitors (group B) were also used: cyproconazole 80g/l a.i. + azoxystrobin 200 g/l a.i., prothioconazole 250 g/l a.i., prothioconazole 125 g/l a.i. + tebuconazole 125 g/l a.i., and boscalid 200 g/l a.i. + dimoxystrobin 200 g/l a.i. The application of group A fungicides against S. sclerotiorum during BBCH 65-69 growth stage had demonstratively higher effectiveness, while for group B the application date had no effect. The greening (or “stay-green”) effect only occurred with group B. The correlation coefficient for greening effect and yield was r = −0.3033 for applications during BBCH 61-65 while it was r= −0.3542 for BBCH 65-69 stage, thus indicating a relatively weak relationship.

Hormonal dynamics after Plasmodiophora brassicae infection were compared in two Brassica napus cultivars&mdash, more resistant SY Alister and more sensitive Hornet, in order to elucidate responses associated with efficient defense. Both cultivars responded to infection by the early transient elevation of active cytokinins (predominantly cis-zeatin) and auxin indole-3-acetic acid (IAA) in leaves and roots, which was longer in Hornet. Moderate IAA levels in Hornet roots coincided with a high expression of biosynthetic gene nitrilase NIT1 (contrary to TAA1, YUC8, YUC9). Alister had a higher basal level of salicylic acid (SA), and it stimulated its production (via the expression of isochorismate synthase (ICS1)) in roots earlier than Hornet. Gall formation stimulated cytokinin, auxin, and SA levels&mdash, with a maximum 22 days after inoculation (dai). SA marker gene PR1 expression was the most profound at the time point where gall formation began, in leaves, roots, and especially in galls. Jasmonic acid (JA) was higher in Hornet than in Alister during the whole experiment. To investigate SA and JA function, SA was applied before infection, and twice (before infection and 15 dai), and JA at 15 dai. Double SA application diminished gall formation in Alister, and JA promoted gall formation in both cultivars. Activation of SA/JA pathways reflects the main differences in clubroot resistance.

The efficiency of the botanical insecticide (BI) NeemAzal T/S (containing 1% Azadirachtin A), on the basis of azadirachtin applied in a dose of 20 g a.i. ha−1 against Brassica pod midge (Dasineura brassicae), has been monitored for 4 years. The biological efficiency of BI was compared with the efficiency of some synthetic insecticides. It was ascertained that BI was very efficient in decreasing the number of damaged oilseed rape pods (ranging from 56.5 to 85.9% compared to untreated plants) and its efficiency was comparable with synthetic insecticides based on Chloronicotinyl (Thiacloprid) and Neonicotinoid (Acetamiprid). BI’s efficiency was, in some years, even significantly higher compared to pyrethroid (λ-cyhalothrin). The high biological efficiency of azadirachtin that we ascertained was significantly reflected in increasing potential crop yields. The yield increase of azadirachtin ranged between 9.3 and 19.4% compared to the control sample. Azadirachtin showed the highest yield for the whole time of experimentation, and in some years the yield increase was significantly higher compared to some synthetic agents.

SHAWKI M.A.-A., TITĚRA D., KAZDA J., KOHOUTKOV A J., TABORSKÝ V. (2006): Toxicity to honeybees of water guttation and dew collected from winter rape treated with Nurelle D ® . Plant Protect. Sci., 42: 9–14. The acute and chronic toxicity to honeybees, Apis mellifera L. of water guttation and dew collected from winter rape plants treated with the insecticide Nurelle D ® (a.i. chlorpyriphos + cypermethrin) was investigated. Caged bees were fed on sugar syrup containing water guttation and dew for 24 h (acute toxicity test) and for 10 days (chronic toxicity test). Bee mortality and food consumption were determined daily. A contact toxicity test was performed within 24 h on bees kept in Petri dishes (10 bees per dish) lined with filter paper saturated with the test solution. The acute Nurelle D ® contact and oral toxicity tests showed that the mortality of bees treated with water guttation and dew collected from the treated plants did not exceed 10%. A chronic toxicity test showed that adding contaminated water guttation and dew to the syrup caused an insignificant increase in bee mortality and reduced the syrup consumption significantly. The chlorpyriphos residue found in contaminated water guttation and dew were below the limit of detection (0.8 µg/kg) and the cypermethrin residue was below the detection levels.

Spitzer T., Spitzerova D., Matusinský P., Kazda J. (2014): Possibility of using seed treatment to suppress seed-borne diseases in poppy. Plant Protect Sci., 50: 78–83. In experiments using Petri dishes in the laboratory and pots in a greenhouse and climate chamber, we examined the influence of seed treatment on emergence of poppy. Four types of fungi ( alternaria spp., Dendryphion penicillatum , Fusarium spp., and p enicillium spp.) were detected on poppy seeds, with the highest infection rate being 72% for D. penicillatum . Surface disinfection decreased infection rate chiefly in D. penicillatum (by 32%) and in a lternaria spp. (by 16%). Seed treatment increased emergence by 9–10% in laboratory experiments but by only 0–6% in green house experiments. Temperature plays an important role in emergence. In climate chamber experiments at a stable temperature of 12°C, the seed treatments increased emergence by 8–16%.