Survey study on fruit pollination practices and their impact on honeybee health in the Flemish region (2012-2013)

Background: The purpose of this study was to examine if there is a difference in honeybee mortality between bees that are used for pollination or come into contact with commercial fruit plantations on the one hand, and bees that never forage on commercial fruit plantations at the other hand. Therefore we conducted a survey amongst Flemish beekeepers. Results: The majority of surveyed beekeepers (>60%) indicated that their bees come into contact with commercially grown fruit. However, no significant differences in colony losses between different beekeeper groups with a different ‘fruit contact status’ were obtained. Different contact distances to commercially grown fruit, or differences between beekeepers who had or who had not delivered pollination services were not found to be significant factors in predicting colony loss rates. Also specific foraging history on apple (in which a preflowering treatment with the neonicotinoid imidacloprid was allowed and common practice in Flemish pome fruit growing at the timing of this survey) did not significantly correlate with higher colony losses. On the other hand, for several other factors including presence of Varroa and Nosema, significant correlations with colony losses were found.Conclusions: Based on the data of this survey study no detrimental effects of commercially fruit production and its current crop protection schedules on fruit crop foraging/pollinating honeybees could be identified.Keywords: honeybee, survey, mortality, fruit, pollination, foragin

Marking Drosophila suzukii (Diptera : Drosophilidae) with fluorescent dusts

The marking of Drosophila suzukii can be an important instrument for studying the ecology and behaviour of this economically important fruit pest, aiding the development of new Integrated Pest Management (IPM) tools or strategies. There is, however, a need for a cost-effective methodology that provides an easily detectable and stable mark. Whereas fluorescent pigment powders are often used in entomological research, the pigments (series, dyes), application techniques, or doses need to be evaluated for each studied species in terms of their efficacy and possible adverse effects on the performance of the insect. The effectiveness of different application techniques and dyes (RadGlo® TP-series) and their effect on the survival of adult D. suzukii were investigated in the laboratory. Furthermore, the influence of the marking on the behaviour of the flies was examined in laboratory trap assays (olfaction) and a field recapture study (general orientation). The persistence and detectability of the marks was evaluated both on living flies (for different application techniques) and dead flies under trapping/storage conditions. The use of fluorescent powders to mark D. suzukii flies yielded a clearly detectable and highly persistent mark, without any adverse effects on the survival and behaviour of the flies

Olfactory preference of Drosophila suzukii shifts between fruit and fermentation cues over the season : effects of physiological status

Worldwide monitoring programs of the invasive fruit pest Drosophila suzukii Matsumura (Diptera: Drosophilidae), using fermentation baits like apple cider vinegar (ACV), revealed a counterintuitive period of low trap catches during summer, followed by an autumn peak. In this study, we demonstrate that ACV baited traps indeed provide a distorted image of the D. suzukii population dynamics as it is possible to capture higher numbers during this "low capture period" with synthetic lures. It was hypothesised that the preference of D. suzukii populations for fermentation cues like ACV is most pronounced during autumn, winter and spring, while the flies prefer fresh fruit cues during summer and that this seasonal preference is related to the changing physiology of the flies over the season. To test this hypothesis, the preference between fermentation cues (ACV) and host fruits (strawberries) and the effect of physiology (sex, seasonal morphology and feeding, mating and reproductive status) was investigated both in olfactometer laboratory experiments and a year-round field preference experiment. In olfactometer experiments we demonstrated that protein deprived females, virgin females with a full complement of unfertilised eggs and males show a strong preference for fermentation cues while fully fed reproductive summer morph females generally prefer fruit cues. These findings indicate that D. suzukii is attracted to fermentation volatiles in search of (protein-rich) food and to fruit volatiles in search of oviposition substrates. Winter morph and starved females displayed indiscriminating olfactory behaviour. In the field preference experiment, the hypothesised seasonal shift between fermentation and fruit cues was confirmed. This shift appeared to be highly temperature-related and was similarly observed for summer and winter morphs

Control of phytophagous mites on strawberry in Europe by predatory phytoseiid mites or heat treatment

julkaisu ilmestynyt jälkikäteen, v. 2006vo

Effect of Arbuscular Mycorrhizal Fungi on Pratylenchus penetrans Infestation in Apple Seedlings under Greenhouse Conditions

A major problem in fruit cultivation in Flanders is replant disease due to a lack of uncultivated soils available for new plantings. Replant disease can cause poor growth and affect time to full production, however Arbuscular Mycorrhizal Fungi (AMF) can prove their usefulness with regard to these problems. To further investigate the effect of AMF on nematodes, different AMF species were amended to potted apple seedlings in the presence of the nematode Pratylenchus penetrans. Generally, apple seedlings grew better in the presence of nematodes when mycorrhiza were inoculated into the soil. Moreover, a positive correlation (R2 ≥ 0.88) was found between the percentage root length colonization of the roots of apple seedlings, by AMF species, and nematode reduction in the soil of the seedlings. Indigenous AMF could colonize the roots of apple seedlings the most efficiently, resulting in a higher biocontrol effect. Besides, a synergistic effect was observed when two AMF strains were applied together leading to a significant growth response of the seedlings

Identification of Blackberry (Rubus fruticosus) Volatiles as Drosophila suzukii Attractants

The spotted wing drosophila, Drosophila suzukii, is an invasive pest species from Southeast Asia that was recently introduced in Europe and North America. As this fruit fly lays its eggs in ripening soft-skinned fruit, it causes great damage to a variety of crops, including cherries, blueberries, blackberries, raspberries, grapes, plums and strawberries. Consequently, there is a great demand for an effective and species-specific lure, which requires the development of successful attractants. Until now, there is no lure available that is species-specific and can detect the presence of D. suzukii before infestation. As blackberry (Rubus fruticosus) is one of the preferred host crops of D. suzukii, the volatile compounds of R. fruticosus berries are here identified and quantified using multiple headspace SPME (solid phase micro extraction) GC-MS (gas chromatography–mass spectrometry). Subsequently, the attractivity of 33 of the identified compounds was tested with a two-choice laboratory bioassay. Acetaldehyde, hexyl acetate, linalool, myrtenol, L-limonene and camphene came out as significantly attractive to D. suzukii. The first four attractive compounds induced the strongest effect and therefore provided the best prospects to be implemented in a potential lure. These findings could contribute towards the development of more effective attractants for monitoring and mass trapping D. suzukii

Mass trapping Drosophila suzukii, what would it take? A two-year field study on trap interference

The invasion of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) worldwide has disrupted existing or developing integrated pest management (IPM) programs in soft-skinned fruits. Currently, with a reliance on only broad-spectrum insecticides, there is a critical call for alternative control measures. Behavioural control is one of the pillars of IPM, and, in the present study, it is investigated whether mass trapping could be viable for D. suzukii management. By quantifying trap interference in 4 x 4 replicate trapping grids, an estimate of the attraction radius for a certain attractant and context can be obtained. Traps designed for dry trapping (no drowning solution, but a killing agent inside) and synthetic controlled released experimental lures were tested in a two-year field study. Apple cider vinegar (ACV) was included as a reference bait and trials were performed with 5, 10 and 15 m inter-trap spacings at different seasonal timings. Clear trap interference and, hence, overlapping attraction radii were observed both in spring and summer for both the synthetic lures and ACV. In early spring, ACV shows the most potential for mass trapping, however from June onwards, the experimental dry lures show equal or better results than ACV. Based on our findings, workable trap densities are deemed possible, encouraging further development of mass trapping strategies for the control of D. suzukii

CFD Based Analysis of the Effect of Wind in Orchard Spraying

Copyright © 2015, AIDIC ServiziS.r.l. The high velocity air jet generated from air assisted orchard sprayers offsets the effect of wind on the spray flow pattern in front of the tree and within the vicinity of the tree height. This combined with the small wind magnitude at lower heights of the boundary layer results in insignificant wind effect within this zone. Once the spray droplets pass through the trees, the velocity of the air jet is significantly reduced by the resistance of the trees increasing the chance of deflection by wind. The projection of the spray droplets also affects the extent of the wind effect and strongly depends on the outlet design of the sprayer. The classical single axial fan sprayer used in this analysis projects part of the spray beyond the tree height resulting in a higher risk of deflection by wind. The CFD modeling approach used in this work allowed studying these wind effects of spray applications in a comprehensive way. It was observed that wind blowing opposite to the spraying direction significantly deflected the spray back to the sprayer. The effect is increased with wind velocity magnitude. Wind blowing in the direction of spraying increased the amount of spray passing through the trees (resulting in increased drift potential), but also increased on-target deposition for this type of sprayer that blows a significant amount of spray over the trees. In this case, wind helps to contain the air assistance of the axial sprayer within the canopy height to some extent.status: publishe

Numerical analysis of the effects of wind and sprayer type on spray distribution in different orchard training systems

© 2015, Springer Science+Business Media Dordrecht. A computational fluid dynamics (CFD) model of airflow and spray application in orchards was validated using field trials and used to assess the effect of wind and sprayer type on spray distribution in different orchard training systems. Three air-assisted orchard sprayer designs (a cross-flow sprayer, an axial sprayer and a sprayer with individual spouts) and four different training systems of apple and pear trees were used for this analysis. The CFD model integrates the tree architecture into the model geometry, rather than using a generalized canopy profile approach. Predicted vertical on-tree deposition profiles agreed well with measurements. The lower airflow rate generated by the sprayer with individual spouts resulted in a significantly larger deflection of the spray particles under the same wind conditions. A detailed assessment was made on the most common axial sprayer. An increase in the magnitude of the wind speed for flow across the tree row resulted in an increase in the amount of spray detected in the air around the trees and in the ground deposition in front of the tree row. Environmental airflow in the direction of spraying gave the largest deposition on the tree, constraining the spray in the canopy region. A wind direction opposite to the spraying direction, however, resulted in an increase of the ground deposition and the amount of spray remaining in air. The model can be used to analyze the effects of implementation of more sustainable spray application procedures taking into account wind conditions, tree and machine characteristics.status: publishe

Spray deposition profiles in pome fruit trees: Effects of sprayer design, training system and tree canopy characteristics

Air assisted orchard sprayers are characterized by a strong airflow that carries the pesticide droplets to the target canopy and assist in moving the plant parts to allow deposition throughout the whole tree. It has been shown before that different designs of orchard sprayers result in different airflow profiles, but it is still unclear whether these differences strongly affect on-target spray distribution, and what is the role of tree architecture. Here we present an in-field analysis of the on-target deposition profiles from three distinct sprayer types in trees of four different apple and pear training systems. The results obtained showed that there was a strong relationship between the vertical leaf deposition profile and the outlet air flow pattern from the sprayers. Stronger air assistance (higher air speed) was directly correlated to a higher on-target deposition. It was also observed that directing nozzles towards the target is always an advantage irrespective of tree architecture. Tree characteristics such as total leaf cover, leaf wall porosity and tree volume strongly affected the total on-target deposition, further confirming previous claims that ground surface area alone is an incorrect measure for dose calculation in fruit trees.publisher: Elsevier articletitle: Spray deposition profiles in pome fruit trees: Effects of sprayer design, training system and tree canopy characteristics journaltitle: Crop Protection articlelink: http://dx.doi.org/10.1016/j.cropro.2014.10.016 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.status: publishe