The study assessed the impact of climate change, aphid infestation and drought stress on winter wheat (Triticum aestivum L.) and the performance of English grain aphid (Sitobion avenae) under abiotic stress in controlled environmental conditions. To understand wheat and aphid interactions under different climatic condition, wheat plants were grown in controlled climatic chambers simulating present (400 ppm CO2, 19.8 degrees C, RH 69.2%) and future (700 ppm CO2, 23.4 degrees C, RH 67.5%) scenarios, combined with biotic stress (aphid) and abiotic stress (drought). Climate change effects combined with other stress factors are expected to alter crop physiology and insect biology. The results showed that aphid performance was significantly enhanced under future climatic conditions, with higher fecundity (56%), and a shortened or faster developmental time. As for wheat structural growth, above-ground biomass improved by up to 80% under future climate. However, its physiological efficiency, water content and photosynthetic efficiency were significantly reduced under the combined biotic and abiotic stresses. The study demonstrates that climate change may increase wheat plant growth under controlled conditions, yet it simultaneously boosts the shift in pest attacks and intensifies stress impacts, which eventually threaten wheat productivity. The findings emphasize the improvement of wheat varieties and pest-resistant strains capable of withstanding future climatic conditions.

In our investigation, we have developed innovative statistical models tailored to predict specific phenological stages of winter oilseed rape (WOSR) cultivation in Luxembourg. Leveraging extensive field observations and meteorological data, our modeling approach accurately forecasts critical growth stages of WOSR, including inflorescence emergence (BBCH 51), initial flowering (BBCH 60), and cessation of flowering (BBCH 69), capitalizing on accumulated heat units. Our findings challenge conventional assumptions surrounding base temperatures, advocating for a specific base temperature of 3 °C for winter oilseed rape emergence, consistent with prior research. Validation via leave-one-out cross-validation yields promising outcomes, with average Root Mean Square Error (RMSE) values below 1, surpassing analogous studies. Particularly noteworthy is our model’s performance in predicting crucial growth stages, notably BBCH 60, pivotal for pest control. Despite advancements, hurdles persist in forecasting late-stage phenological events influenced by leaf senescence and anticipated climate change impacts, likely accelerating WOSR development and introducing new risks. In response, cultivar selection strategies informed by individual development rates and temperature sensitivities emerge as vital mitigation measures. As climate variability intensifies, precision agriculture assumes paramount importance in optimizing resource allocation and ensuring sustainable WOSR cultivation practices. Our study advocates for proactive integration of predictive modeling into adaptive management frameworks, empowering stakeholders to make informed decisions taking climatic dynamics into account.

1. Population genetics is a valuable tool for assessing the impact of human -altered landscapes on genetic connectivity in various species. However, when applied to insects, challenges arise due to potentially large effective population sizes (Ne), high dispersal capacities and the recency of anthropogenic impacts. 2. This study assessed the population genetic structure of two pollinators across a human -altered landscape in Luxembourg. Samples from the ashy mining bee (Andrena cineraria, N = 201) and the greater bee fly (Bombylius major, N = 637) were genotyped at 25 microsatellite loci, including a genotyping-by-ampliconsequencing approach for A. cineraria. 3. Despite high statistical power of FST > 0.002 in B. major and FST > 0.0025 in A. cineraria, no deviations from genetic homogeneity were detected. For both species, there was no evidence for isolation -by -distance or genetic clustering. Genetic homogeneity was most likely the result of high levels of gene flow that compensate for the effects of genetic drift. 4. Estimates of Ne ranged between several thousand to tens of thousands, although precision was low. Simulations highlighted that genetic lag times can substantially affect our ability to detect recent (<50 generations) population differentiation when Ne is very large. Lag times were shorter with data from 25,000 simulated di -allelic loci, but only when sample sizes remained high. 5. Insect genetic studies should consider lag times due to large Ne and ensure sample size and markers offer adequate power to reject the null hypothesis of no landscape effect on genetic connectivity.

Thrips are significant pest of crops, vegetables, and fruiting trees, and various species of thrips can infest citrus at fruit formation as well as new leaf sprouts. Thrips presence and damage can significantly reduce the export value of fruits, making them a major concern for citrus growers. Field studies were conducted to investigate the biodiversity and abundance of citrus thrips on an early fruiter citrus cultivar in experimental and commercial orchards of Morocco. In this study, we investigated the abundance, economic importance, dynamics, and seasonal fluctuations of citrus thrips in relation to citrus phenology. We identified four species of thrips that infest citrus orchards, including Frankliniella occidentalis, Pezothrips kellyanus, Scirtothrips sp, and Aeolothrips sp. Our results showed that the quantitative peak of thrips occurred during the blooming stage, and that the number of thrips caught on sticky traps during bloom could be a suitable predictive method for estimating final fruit damage. The population dynamics of thrips species were found to depend on several biotic and abiotic factors, including temperature, rainfall, and chemical interventions. We also observed that some citrus varieties were more susceptible to thrips attacks than others, with Washington navel and Maroc late being the most infested orchards with infestation rates of 32% and 24%, respectively. Our findings provide important insights into the abundance, economic importance, and seasonal fluctuations of citrus thrips, which can inform the development of effective control strategies to mitigate their damage in citrus orchards.

This study provides the first documented discovery of symptoms caused by the cicada Stictocephala bisonia (buffalo treehopper) in Luxembourgish viticulture. Symptoms were found in 2022 in red grapevine cultivars, also in 2023 symptoms on vine plants occurred and two adults of the buffalo treehopper were caught. A characterisation of the resulting symptoms and a discussion on the species’ potential pest status depending on annual meteorological conditions are provided.

Biological control by augmentative release of parasitoids is an established practice for controlling an economi-cally very important insect pest group, whiteflies (Aleyrodidae), in protected cropping systems worldwide. One of the two most used parasitoids is Encarsia formosa. Anthropogenic climate change will modify multitrophic interactions between organisms, and sensitive biocontrol systems are not an exception. At the same time, there is a knowledge gap in our understanding of the performance of E. formosa as a biocontrol agent in mid-future climate. In the present study, we evaluate the parasitization rate, development time, and longevity of this important biocontrol agent by performing climatic chamber simulation driven by physically consistent, regionally downscaled, numerical future climate projections. The parasitoid shows 8.6 days accelerated development, 15-fold higher parasitization rate, and 38% shorter longevity under the tested future climate conditions. Challenges in conclusively assessing life parameters of this parasitoid, and the implications on whitefly biocontrol in the future are discussed.

Whiteflies of the Bemisia tabaci species complex are among the most damaging insect pests in agriculture worldwide, causing damage by feeding on crop plants and by vectoring plant viruses. The species complex consists of over 35 cryptic species that differ in many aspects of their biology including the optimal environment, geographic distribution, and host range. Global warming and associated climate change resulting from human activities is expected to contribute to biological invasions. Bemisia tabaci species show fast adaptability to changes in agroecosystems and have a long record of biological invasions. Climate change driven increase in B. tabaci importance in agricultural systems of Europe has been predicted, but so far not experimentally tested. The present study evaluates the development of B. tabaci MED (=Mediterranean) in a climatic chamber simulation of the future climate in Luxembourg, chosen as a representative region for the Central Europe. Future climate predictions for the period 2061-2070 were derived from a multimodel ensemble of physically consistent regional climatic models. Results show a 40% shorter development time of this important pest in future climatic conditions, with an increase in fecundity by a third, and insignificant difference in mortality. Accelerated development, combined with its already established year-round presence in European greenhouses and predicted northward expansion of outdoor tomato production in Europe, means faster population build-up at the beginning of the outdoor cropping season with the potential of reaching economic importance. Benefits of simulating hourly diurnal cycle of physically consistent meteorological variables versus previous experiments are discussed.

Climate change (CC) poses one of the foremost challenges for humanity in the 21st century [...].

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.

Whiteflies (Aleyrodidae) cause high economic losses in agricultural systems worldwide. Heavy reliance on insecticide use for whitefly control has led to the resistance development towards nearly all used groups of insecticides. A more sustainable, widely used, and irreplaceable control measure in protected cropping systems is biological control by augmentative release of parasitoids. All commercially available whitefly parasitoids are wasps from the genera Encarsia and Eretmocerus, with one of the most used parasitoid species being Eretmocerus eremicus. Biocontrol by these highly specialized natural enemies is sensitive to changes in environmental conditions. Ongoing anthropogenic climate change could affect multitrophic interactions between organisms, and biocontrol systems are not an exception. At the same time, little is known about the development of E. eremicus under projected future climate conditions. The present study evaluates the longevity of this important biocontrol agent by performing climatic chamber simulation driven by physically consistent, regionally downscaled, multi-model ensemble projections of the future climate for Luxembourg. Results show a reduction of its longevity up to 50% under future climate. The median survival in the projected future climate was found to be 13 days, which is 9 days less than under present climate. Implications on the efficacy of the whitefly biocontrol practices in future climate conditions are discussed.

Whiteflies are among the most important global insect pests in agriculture; their sustainable control has proven challenging and new methods are needed. Bacterial symbionts of whiteflies are poorly understood potential target of novel whitefly control methods. Whiteflies harbour an obligatory bacterium, Candidatus Portiera aleyrodidarum, and a diverse set of facultative bacterial endosymbionts. Function of facultative microbial community is poorly understood largely due to the difficulty in their selective elimination without removal of the primary endosymbiont. Since the discovery of secondary endosymbionts, antibiotic rifampicin has emerged as the most used tool for their manipulation. Its effectiveness is however much less clear, with contrasting reports on its effects on the endosymbiont community. The present study builds upon most recent method of rifampicin application in whiteflies and evaluates its ability to eliminate obligatory Portiera and two facultative endosymbionts (Rickettsia and Arsenophnus). Our results show that rifampicin reduces but does not eliminate any of the three endosymbionts. Additionally, rifampicin causes direct negative effect on whiteflies, likely by disrupting mitochondria. Taken together, results signify the end of a rifampicin era in whitefly endosymbiont studies. Finally, we propose refinement of current quantification and data analysis methods which yields additional insights in cellular metabolic scaling.

Psyllids (superfamily Psylloidea), also known as jumping plant lice, are a group of plant-sap sucking Hemiptera having significant pest status for crops, forest trees and ornamental plants. Only seven species of psyllids have been recorded in Luxembourg so far. An additional group of seven species has been recorded exclusively, based on the findings of their galls or specific plant deformations; but no mention exists in literature on the actual collection of the inducing insect in Luxembourg. To fill this knowledge gap, field collections were carried out during the years 2019-2020. In addition, samples from 1999-2000 stored in the wet collection of the Musée National d'Histoire Naturelle de Luxembourg were studied. This research, in combination with information coming from literature, allowed us to list 48 species of the families Aphalaridae (5 species), Liviidae (5), Psyllidae (24) and Triozidae (14), though the presence of one species within the last family (Triozarhamni) needs to be confirmed. Brief information on geographical distribution, biology and (if available) illustrations of diagnostic characters are provided on the psyllid species detected in Luxembourg so far.

The red gum lerp psyllid, Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae), is an invasive pest of Eucalyptus trees worldwide, responsible for serious damage, including the death of plants. Knowledge about the incidence of climatic factors on the insect development are essential to define useful strategies for controlling this pest. To this aim, G. brimblecombei has been sampled by two different methods from April 2012 to February 2013 in eastern Sicily on Eucalyptus camaldulensis in nine different sites, where the main climatic data (air temperature, relative humidity, and precipitation) have been also registered. The Glycaspis brimblecombei population showed a similar trend in all nine sites, positively correlated only with air temperature, but a negative correlation has emerged with precipitation and relative humidity. The results show the need for a deeper understanding of the role played by other abiotic (such as different concentrations of CO2) and biotic (e.g., the antagonistic action of natural enemies, competition with other pests, etc.) factors. The greater sensitivity, even at low densities of psyllid, of sampling methods based on the random collection of a fixed number of leaves compared to methods based on the collection of infested leaves in a fixed time interval has been also outlined.

The European commission directive EC 128/2009 calls for monitoring pests and pathogens of major crops. The monitoring data may be analysed for trends over time, including tests for a potential loss of biodiversity in the domain of plant pests and pathogens. The monitoring programs carried out in Luxembourg since 2007 provided evidence for an increasing role of yellow rust and a decreasing role of brown rust on winter wheat. Vast inter-annual variability was observed at the level of Fusarium head blight and mildew symptoms on winter wheat as well as at the level of Ceutorhynchus counts in oilseed rape, but no trend towards extinction could be demonstrated. Septoria leaf blotch was present in winter wheat at high levels towards the end of all seasons. The maximum number of Brassicogethes aeneus individuals found per main stem and season on oilseed rape increased slightly but significantly between 2007 and 2017. Substantial evidence for highly dynamic changes in the pest populations was found, but no evidence for the vanishing of the monitored species could be demonstrated.

Reducing the use of pesticides in agricultural systems is a prerequisite for sustainable agriculture and, therefore, knowledge on the factors that influence the regional insect pest densities is necessary. Based on multi-site and multi-annual observations of the cabbage stem weevil [Ceutorhynchus pallidactylus (Marsham, 1802)] in winter oilseed rape (Brassica napus Linnaeus) and the corresponding meteorological measurements, a statistical relationship for forecasting the abundance was derived. The model explains 84% of the variation of the data set. The remaining 16% might be explained by the landscape effects and agricultural practices, such as crop protection. Based on the statistical relationship between the mean winter air temperature and the abundance of the cabbage stem weevil in the winter oilseed rape, risk maps were derived as a forecast tool for practical farming.

The ornamental use of boxwood (Buxus sempervirens L.) is threatened by the gall‐forming psyllid Psylla buxi (L.) (Hemiptera, Psylloidea). Individuals of P. buxi were found as well as its symptoms for the first time in the Grand Duchy of Luxembourg in several locations, which indicates that this pest species has spread and is already established on boxwood across the country.