Examining historical rates of leafcutting bee cell pathogens to establish baseline infectivity rates for alfalfa seed growers

The alfalfa leafcutting bee (Megachile rotundata) is one of the primary pollinators for the alfalfa seed industry. The alfalfa leafcutting bee is a solitary cavity nesting bee. Female Megachile rotundata bees will construct and provision individual brood cells lined with cut leaves (cocoon) and will gather nectar and pollen to place within the constructed cocoon. The female bee will lay a single egg within the constructed cocoon and leave the egg to undergo larval stage development and pupation into the adult stage. During this time multiple pathogens and parasitoids can prey on the developing larvae, resulting in the loss of the future adult bee. A major concern for commercial alfalfa seed growers is the presence of invertebrate pests and fugal pathogens. In the present study, we used historical data from the Parma Cocoon Diagnostic Laboratory to determine baseline rates of pathogen and parasite infection of Megachile rotundata cells and used this analysis to determine historical infection rates and cutoffs for management practices. Additionally, using a Faxitron (X-ray) analysis for Megachile rotundata cell obtained in 2020, we compared the presence of chalkbrood, pathogens, and parasitoids in samples collected from both growers stocks and newly purchased Canada bees. The results of the investigation demonstrate historical averages of the presence of chalkbrood, pathogens, and parasitoids. We also show a significant increase in chalkbrood and predators in 2007-2011 and a significant difference in chalkbrood and predators between bee samples obtained from Canada and grower stocks.

Behavior of the Biological Control Agent Bacillus thuringiensis subsp. aizawai ABTS-1857 and Salmonella enterica on Spinach Plants and Cut Leaves

Fresh produce has been identified as an important vehicle for the transmission of foodborne pathogens. This study evaluated the behavior of vegetative cells and spores of Bacillus thuringiensis, one of the main biological control agents (BCAs) used in the world, and Salmonella enterica on spinach plants (pre-harvest) and spinach cut leaves (post-harvest) at 12°C, experimentally inoculated as single or co-cultures. The results evidenced that spray-inoculated commercial BCA containing Bacillus thuringiensis subsp. aizawai ABTS-1857 (BTa ABTS-1857) spores persisted well on spinach leaves in both pre- and post-harvest simulations. However, when BTa ABTS-1857 vegetative cells were spray-inoculated, more than 2 log reductions in the counts of B. thuringiensis were observed during 20 days pre- and 5 days post-harvest simulations, respectively. The counts of S. Montevideo on the spinach cut leaves during post-harvest storage at 12°C for 5 days remained unchanged, whereas 1 log reduction was noted during pre-harvest. Moreover, during pre-harvest simulation, when co-inoculated with BTa ABTS-1857 vegetative cells or spores, additional 0.5 or 1.0 log reductions were detected on the counts of S. Montevideo in the spinach leaves on the 10th day. These results were obtained under laboratory conditions, and further findings in longitudinal studies from farm (in the agricultural field) to retail (end of shelf life) will contribute to understanding of the role of B. thuringiensis as a BCA on growth/survival of Salmonella spp. in fresh produce.

Expression Level of Mature miR172 in Wild Type and StSUT4-Silenced Plants of Solanum tuberosum Is Sucrose-Dependent

In potato plants, the phloem-mobile miR172 is involved in the sugar-dependent transmission of flower and tuber inducing signal transduction pathways and a clear link between solute transport and the induction of flowering and tuberization was demonstrated. The sucrose transporter StSUT4 seems to play an important role in the photoperiod-dependent triggering of both developmental processes, flowering and tuberization, and the phenotype of StSUT4-inhibited potato plants is reminiscent to miR172 overexpressing plants. The first aim of this study was the determination of the level of miR172 in sink and source leaves of StSUT4-silenced as well as StSUT4-overexpressing plants in comparison to Solanum tuberosum ssp. Andigena wild type plants. The second aim was to investigate the effect of sugars on the level of miRNA172 in whole cut leaves, as well as in whole in vitro plantlets that were supplemented with exogenous sugars. Experiments clearly show a sucrose-dependent induction of the level of mature miR172 in short time as well as long time experiments. A sucrose-dependent accumulation of miR172 was also measured in mature leaves of StSUT4-silenced plants where sucrose export is delayed and sucrose accumulates at the end of the light period.

Effect of height and colour of bee bricks on nesting occupancy of bees and wasps in SW England

Bee bricks are a novel solitary-bee nesting habitat made from reclaimed concrete, designed to be built into walls to provide nest sites in urban areas. We tested if cavity-nesting bees and wasps used bee bricks, and if they showed any preference for nesting in bricks of different colours or at different heights. We carried out surveys of solitary bees in 15 private urban gardens and eight rural public gardens, where the bee bricks were then placed for two years (2016-2017). Bee bricks were placed on structures that were either 1 m in height with 4 bricks (red, yellow, white and wooden control) or with three platforms where white bricks were placed at 0 m, 0.6 m or 1.0 m above the ground. The number of occupied nest holes was counted at the end of each summer. Nesting holes that were capped with mud were more common than those capped with chewed or cut leaves. The average % of holes capped with either mud or chewed leaf was greatest in red bricks and lowest in wooden controls. Only one brick out of 39 placed at ground level had capped holes, although the difference in the % of holes capped between heights was not statistically significant. Cavity-nesting bees and wasps use solitary-bee bricks for nests, but population level impacts are still untested.

Rosmarinus officinialis L. (Lamiales: Lamiaceae), a Promising Repellent Plant for Thrips Management

A number of thrips species are among the most significant agricultural pests globally. Use of repellent intercrop plants is one of the key components in plant-based ‘push–pull’ strategies to manage pest populations. In this study, the behavioral responses of three thrips species, Frankliniella occidentalis (Pergande), Frankliniella intonsa (Trybom), and Thrips palmi Karny (Thysanoptera: Thripidae) to Rosmarinus officinalis were investigated in Y-tube olfactometer bioassays and cage experiments. In addition, the major volatile compounds from rosemary were identified and the effect of the individual compounds on thrips behavior was evaluated. Females and males of the three thrips species were significantly repelled by the volatiles from cut rosemary leaves. The presence of rosemary plants significantly reduced settlement of females of the three thrips species and eggs laid by F. occidentalis females on target host plants. In total, 47 compounds were identified in the volatiles collected from the cut leaves of rosemary plants. The responses of the three thrips species to 10 major volatile compounds showed significant differences. However, α-pinene, the most abundant volatile, was repellent to F. occidentalis and F. intonsa. Eucalyptol, the second most abundant volatile, showed significant repellent activity to all the three thrips species. Our findings showed that rosemary is a promising repellent plant against the three thrips pests we tested, which could be a good candidate for ‘push’ plants in plant-based ‘push–pull’ strategies. The identified volatile compounds that accounted for the repellent activity could be developed as repellents for sustainable thrips management.

High Glucosinolate Content in Rocket Leaves (Diplotaxis tenuifolia and Eruca sativa) after Multiple Harvests Is Associated with Increased Bitterness, Pungency, and Reduced Consumer Liking

Rocket (Diplotaxis tenuifolia and Eruca sativa) leaves delivered to the UK market are variable in appearance, taste, and flavour over the growing season. This study presents sensory and consumer analyses of rocket produce delivered to the UK over the course of one year, and evaluated the contribution of environmental and cultivation factors upon quality traits and phytochemicals called glucosinolates (GSLs). GSL abundance was positively correlated with higher average growth temperatures during the crop cycle, and perceptions of pepperiness, bitterness, and hotness. This in turn was associated with reduced liking, and corresponded to low consumer acceptance. Conversely, leaves with greater sugar content were perceived as more sweet, and had a higher correlation with consumer acceptance of the test panel. First cut leaves of rocket were favoured more by consumers, with multiple leaf cuts associated with low acceptance and higher glucosinolate concentrations. Our data suggest that the practice of harvesting rocket crops multiple times reduces consumer acceptability due to increases in GSLs, and the associated bitter, hot, and peppery perceptions some of their hydrolysis products produce. This may have significant implications for cultivation practices during seasonal transitions, where leaves typically receive multiple harvests and longer growth cycles.

Effect of 5-Aminolevulinic Acid (ALA) on the Biochemical and Physiological Parameters of Postharvest Quality of Polygonatum multiflorum L. All. ‘Variegatum’ Cut Foliage

Due to the dynamic development of the floriculture market, new species and varieties of plants that can potentially be used as a source of cut greenery are constantly being sought. The experiment was conducted to analyze the effect of the cultivation site (unheated foil tunnel and open field) and treatments with the Pentakeep V formulation (0.00%, 0.02%, 0.04%, and 0.06%) on the vase life and postharvest quality of Polygonatum multiflorum ‘Variegatum’ cut foliage. There was a positive effect of the cultivation in the unheated foil tunnel on the vase life and biochemical parameters, namely the electrolyte leakage (EL), thiobarbituric acid reactive substances (TBARS), chlorophyll a + b (Chl. a + b), proline, peroxidase (POD), and ascorbate peroxidase (APX), of P. multiflorum cut foliage. Foliar application of Pentakeep V formulation at concentrations of 0.04% and 0.06% contributed to a decrease in the TBARS content in the P. multiflorum cut leaves, regardless of the plant cultivation site. Additionally, it reduced proline production in cut leaves of P. multiflorum cultivated in the unheated foil tunnel, which was confirmed by the analyses carried out after the 30 days of the experiment. Furthermore, the exogenous application of ALA during P. multiflorum cultivation inhibited POD activity, irrespective of its concentration and the site of plant cultivation.

EFFECT OF PLANT AIR EXOMETABOLITES AND THEIR INFORMATION-ENERGY FIELDS ON BIOLOGICAL TESTS

The paper demonstrates that air exometabolites of plant natural and cut leaves and flowers are proved to effect the bio tests – seed germination. The degree and character of this influence quantity and character differ for various donor and acceptor plants. The biological action of products of plants transpiration remains under its accumulation in the activated carbon and frozen water. It is shown that the interaction of some plants on the others is caused by the interrelation of both aboveground organs and root systems. So,under beetroot seed generation the size of the seedlings roots in the controlled variant was 5.5 ± 0.9 cm, the stem size was 4.6 ± 06 cm. When growing sorrel and beetroot seeds together,the beetroot size of the roots was 3.1 ± 1.0 cm; the stem size was 3.1 ± 1.0 cm. It seems feasible to take into consideration this influence under combined planting of several crops.

PSIV-10 Preference evaluation of plant functional types grasses in calves

The functional types of plants (PFT) ecological approach could be used to link the preferences of ruminants. In order to investigate if ruminant preferences were associated with this approach, three PFT groups were evaluated. A group “B”, represented by Paspalum urvillei (PU-B), “C” by Nassella neesiana (NN-C) and Sporobolus indicus (SI-C) and “D” by Andropogon lateralis (AL-D). In a randomized block design with repeated measures over time, two independent cafeteria trials (autumn-winter, A-W, and spring-summer, S-S) were carried out in calves (n = 8 for A-W; n = 4 for S-S; BW=240–270 kg) arranged in four pens. In three sessions of ten minutes each, calves received 120–160 gDM of fresh cut leaves from the different species. Dry matter intake (DMI), nitrogen intake (NI) and neutral detergent fiber intake (NDFI) were measured. Data were analyzed with a mixed model that included specie and session as fixed effects and blocks as a random. The statistical analyses were performed with SAS (University Edition), data is expressed as lsmeans and was considered to differ when Tukey test presented P < 0.05. No significant differences were observed between sessions. The DMI and NI were higher in NN-C and lower in AL-D (P < 0.01) during A-W. However, in S-S, higher DMI and NI were observed in AL-D and SI-C while NN-C presented the lower DMI and NI (P < 0.01). The FDNI did not show differences in A-W meanwhile in S-S was positively associated with DMI (Table1). Interestingly, when the season changed, it was observed a change in PFT preference, in A-W calves preferred NN-C whereas in S-S preferred AL-D. However, attributes associated with preferences were maintained in both stations, for instance, higher DMI was associated with higher NI. Additional research is required on the interactions between PFT approach and the preference of animals for different species.