Gregor Claus

Mr. Gregor Claus

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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 October 2021 in Insects
Verified
Journal Article
Open access
PDF file
TBTim Belien
Tim Belien
SRStijn Raymaekers
Stijn Raymaekers
MEMaxime Eeraerts
Maxime Eeraerts
VMVeerle Mommaerts
Veerle Mommaerts
GCGregor Claus
Gregor Claus
DBDany Bylemans
Dany Bylemans
Recently, the concept of Integrated Pest Management (IPM) was further extended into Integrated Pest and Pollinator Management (IPPM). Implementation of IPPM strategies entails the combination of actions for pest and pollinator management providing complementary or synergistic benefits for yield and/or quality of the harvest. The aim of this study was to examine IPPM elements (i.e., mixed hedgerow, nesting boxes for mason bees, Osmia spp.) and demonstrate their impact in the practical context of modern commercial fruit cultivation in a 4-year case study in an intensive ‘Conference’ pear orchard. The outcomes of visual observations during transect walks and molecular analysis of pollen collected by mason bees, showed the importance of additional floral resources for the presence of mason bees and other pollinating insects in the orchard environment. Pear quality assessments indicated that insect-mediated pollination had a significant positive impact, with a tendency for higher quality pears in the close vicinity of Osmia nesting boxes. However, despite the fact that pear pollen was also detected in Osmia spp. nest cells, the amount and frequency of pear pollen collection for their nest built-up turned out to be rather low. In the same intensive pear orchard studied for pollination effects, we simultaneously demonstrate the impact of a mixed hedgerow to enhance integrated pest control.

1 June 2021 in Ecotoxicology and Environmental Safety
Verified
Journal Article
Open access
GCGregor Claus
Gregor Claus
MPMatti Pisman
Matti Pisman
PSPieter Spanoghe
Pieter Spanoghe
Guy SmaggheGuy Smagghe
Guy Smagghe
MEMaxime Eeraerts
Maxime Eeraerts
Risk assessment of pesticides involves ecotoxicological testing. In case pesticide exposure to bees is likely, toxicity tests are performed with honey bees (Apis mellifera), with a tiered approach, for which validated and internationally accepted test protocols exist. However, concerns have grown regarding the protection of non-Apis bees [bumble bees (Bombus spp.), solitary and stingless bees], given their different life cycles and therefore distinct exposure routes. Larvae of solitary bees of the genus Osmia feed on unprocessed pollen during development, yet no toxicity test protocol is internationally accepted or validated to assess the impact of pesticide exposure during this stage of their life cycle. Therefore, the purpose of this study is to further validate a test protocol with two solitary bee species (O. cornuta and O. bicornis) to assess lethal and sublethal effects of pesticide exposure on larval development. Larvae were exposed to thiacloprid (neonicotinoid insecticide) mixed in a new, artificial pollen provision. Both lethal (developmental and winter mortality) and sublethal endpoints (larval development time, pollen provision consumption, cocoon weight, emergence time and adult longevity) were recorded. Effects of lower, more environmentally realistic doses were only reflected in sublethal endpoints. In both bee species, thiacloprid treatment was associated with increased developmental mortality and larval development time, and decreased pollen provision consumption and cocoon weight. The test protocol proved valid and robust and showed that for higher doses of thiacloprid the acute endpoint (larval mortality) is sufficient. In addition, new insights needed to develop a standardized test protocol were acquired, such as testing of a positive control for the first time and selection of male and female individuals at egg level.

6 June 2018
Verified
Book Chapter
Open access
PDF file
GCGregor Claus
Gregor Claus
WVWouter Vanhove
Wouter Vanhove
Patrick Van DammePatrick Van Damme
Patrick Van Damme
Guy SmaggheGuy Smagghe
Guy Smagghe
Cocoa (Theobroma cacao L.) is mainly pollinated by ceratopogonid midges (Forcipomyia spp.). However, other insect species will also pollinate cocoa flowers when these midges are scarce. In Côte d'Ivoire, inadequate pest control practices (insecticide spraying, mostly against the mirids Distantiella theobromae and Sahlbergella singularis) and landscape degradation as a result of deforestation and cocoa monoculture, have decreased overall pollinator population levels and, as a result, pollination services to cocoa trees. The current low average Ivorian cocoa yield of 538 kg per ha (in 2016) is the result of global agricultural mismanagement (deteriorated soils, lack of fertilizers, inadequate or absent pest control, absence of shade trees and intercrops). However, there is also an evidence of a pollination gap that could cause low cocoa yield. More research is needed to understand: (i) which agro-ecological efforts to enhance cocoa pollination can improve yield, and (ii) which strategies are effective in enhancing cocoa pollination. In this chapter, we briefly describe the cocoa sector. Next, the cocoa flower and pollinator biology and phenology are presented, followed by an overview of current environmental and management constraints to cocoa pollination in the context of Côte d'Ivoire, the largest cocoa producer in the world. We conclude with exploring possibilities to enhance pollination in the Ivorian small-scale cocoa sector.

1 July 2021 in Food Research International
Verified
Journal Article
Open access
KNKaat Neckermann
Kaat Neckermann
GCGregor Claus
Gregor Claus
SBSiegrid De Baere
Siegrid De Baere
Gunther AntonissenGunther Antonissen
Gunther Antonissen
SLSarah Lebrun
Sarah Lebrun
VDVéronique Delcenserie
Véronique Delcenserie
Mycotoxin intoxication is in general an acknowledged and tackled issue in animals. However, in several parts of the world, mycotoxicoses in humans still remain a relevant issue. The efficacy of two mycotoxin detoxifying animal feed additives, an aflatoxin bentonite clay binder and a fumonisin esterase, was investigated in a human child gut model, i.e. the in vitro Simulator of the Human Intestinal Microbial Ecosystem (SHIME®). Additionally, the effect of the detoxifiers on gut microbiota was examined in the SHIME. After an initial two weeks of system stabilisation, aflatoxin B1 (AFB1) and fumonisin B1 (FB1) were added to the SHIME diet during one week. Next, the two detoxifiers and mycotoxins were added to the system for an additional week. The AFB1, FB1, hydrolysed FB1 (HFB1), partially hydrolysed FB1a and FB1b concentrations were determined in SHIME samples using a validated ultra-performance liquid chromatography-tandem mass spectrometry method. The short-chain fatty acid (SCFA) concentrations were determined by a validated gas chromatography-mass spectrometry method. Colonic bacterial communities were analysed using metabarcoding, targeting the hypervariable V1-V3 regions of the 16S rRNA genes. The AFB1 and FB1 concentrations significantly decreased after the addition of the detoxifiers. Likewise, the concentration of HFB1 significantly increased. Concentrations of SCFAs remained generally stable throughout the experiment. No major changes in bacterial composition occurred during the experiment. The results demonstrate the promising effect of these detoxifiers in reducing AFB1 and FB1 concentrations in the human intestinal environment, without compromising the gastrointestinal microbiota.


15 February 2021 in International Journal of Food Contamination
Verified
Journal Article
Open access
PDF file
EDEdelbis Lopez Davila
Edelbis Lopez Davila
MHMichael Houbraken
Michael Houbraken
JRJasmine De Rop
Jasmine De Rop
GCGregor Claus
Gregor Claus
AWAbukari Wumbei
Abukari Wumbei
PSPieter Spanoghe
Pieter Spanoghe
Background: Vegetables and rice produced in Cuba may contain residue of pesticides that exceed the maximum residue limits (MRLs). Pesticide residues on crop samples from Sancti Spíritus province were analyzed. Based on these residue data, a risk assessment of consumer exposure was conducted.Methods: Samples collected during the 2017, 2018, and 2019 periods were analyzed using UPLC-MS/MS and GC/ECD chromatography techniques. A deterministic risk assessment was performed, using consumption data collected by the authors. Also, a probabilistic risk assessment was worked out with @RISK for the Monte Carlo simulation.Results: A broad range of pesticides were detected in the samples. Most of the detected active ingredients were insecticides and fungicides. A considerable part of the detected pesticide residues exceeded the EU and Cuban MRLs. However, the deterministic risk assessment revealed that the consumer risk of pesticide exposure is low. Only in the maximum exposure scenario children and adults were exposed to methamidophos residues in tomatoes higher than the acceptable daily intake.Conclusions: When a more realistic consumption (50th percentile) and higher (95th percentile) consumption pattern for tomatoes was assumed, the deterministic risk assessment found no chronic risk for children and adults being exposed to methamidophos present in the tomato samples. Furthermore, the probabilistic risk assessment concerning methamidophos exposure in tomato for children and adult strata showed no risk. To perform in the future a more accurate risk assessment for Cuban consumers it is important to have more detailed consumption data and an expanded dataset of the residues in different crops.