Microbe-mediated alterations in floral nectar: consequences for insect parasitoids

Floral nectar is frequently colonized by microbes among which bacteria and yeasts are the most abundant. These microbes have the ability to alter nectar characteristics with consequences for the whole community of flower-visiting insects. Recent research carried out on natural enemies of insect herbivores has shown that microbe-mediated changes in nectar traits can influence the foraging behavior and life history traits of parasitoids. The production of microbial volatile organic compounds can affect the attraction of parasitoids to nectar, while changes in sugar and amino acid composition can impact their longevity. Future research should focus on understanding the effects of nectar microbial colonization on parasitoid reproduction, with a specific emphasis on the interactions among different microbial taxa known to co-occur in floral nectar. Overall, this review highlights the importance of considering the role of nectar-inhabiting microbes in shaping the interactions between parasitoids and their food resources

Genetic characterization of Pepino mosaic virus isolates from Belgian greenhouse tomatoes reveals genetic recombination

Over a period of a few years, Pepino mosaic virus (PepMV) has become one of the most important viral diseases in tomato production worldwide. Infection by PepMV can cause a broad range of symptoms on tomato plants, often leading to significant financial losses. At present, five PepMV genotypes (EU, LP, CH2, US1 and US2) have been described, three of which (EU, LP and US2) have been reported in Europe. Thus far, no correlation has been found between different PepMV genotypes and the symptoms expressed in infected plants. In this paper, the genetic diversity of the PepMV population in Belgian greenhouses is studied and related to symptom development in tomato crops. A novel assay based on restriction fragment length polymorphism (RFLP) was developed to discriminate between the different PepMV genotypes. Both RFLP and sequence analysis revealed the occurrence of two genotypes, the EU genotype and the CH2 genotype, within tomato production in Belgium. Whereas no differences were observed in symptom expression between plants infected by one of the two genotypes, co-infection with both genotypes resulted in more severe PepMV symptoms. Furthermore, our study revealed that PepMV recombinants frequently occur in mixed infections under natural conditions. This may possibly result in the generation of viral variants with increased aggressivenes

Associative learning and memory retention of nectar yeast volatiles in a generalist parasitoid

Understanding how animals learn is crucial to interpreting animal behaviour. Flower-visiting insects, such as bees and parasitoids, are excellent animal models to study visual and olfactory learning, including memory phenomena. The diversity of resources flower-visiting insects exploit predisposes them to learn and remember the colours, shapes and odours associated with rewarding experiences (e.g. flowers), allowing them to focus on the most rewarding resources. Recent research has shown that nectar-living microbes release volatile organic compounds (VOCs) that contribute to overall flower scent. Nevertheless, little is known about the extent to which nectar microbiota mediate insect learning of floral preferences. In this study, we investigated whether VOCs produced by nectar microbes serve as a learning cue to parasitoids and how long any developed preference is maintained. Experiments were performed using the generalist aphid parasitoid Aphidius ervi and three nectar yeasts, including the nectar specialist Metschnikowia reukaufii and the generalist species Hanseniaspora uvarum and Sporobolomyces roseus. Results showed that naïve parasitoids had an innate preference for nectar fermented by the nectar specialist M. reukaufii, but not by the other two yeasts which had either a neutral (H. uvarum) or deterrent (S. roseus) effect. When parasitoids were conditioned with yeast-fermented nectar, they were strongly attracted to their odours 2 and 24h after conditioning, but not after 48h. Furthermore, when parasitoids were conditioned to one yeast-fermented nectar, they also showed increased attraction to other yeast-fermented nectars. This generalization suggests that their learning ability may have broader ecological consequences. However, this generalized response to other yeast VOCs lasted for only 2h. We conclude that parasitoids show conditioned responses to the scent of yeast-fermented nectar, and yeasts, therefore, may play an important but understudied role in shaping their foraging behaviour

Parafermionic algebras, their modules and cohomologies

We explore the Fock spaces of the parafermionic algebra introduced by H.S. Green. Each parafermionic Fock space allows for a free minimal resolution by graded modules of the graded 2-step nilpotent subalgebra of the parafermionic creation operators. Such a free resolution is constructed with the help of a classical Kostant's theorem computing Lie algebra cohomologies of the nilpotent subalgebra with values in the parafermionic Fock space. The Euler-Poincar\'e characteristics of the parafermionic Fock space free resolution yields some interesting identities between Schur polynomials. Finally we briefly comment on parabosonic and general parastatistics Fock spaces.Comment: 10 pages, talk presented at the International Workshop "Lie theory and its applications in Physics" (17-23 June 2013, Varna, Bulgaria

Accounting for seasonality in a soil moisture change detection algorithm for ASAR Wide Swath time series

A change detection algorithm is applied on a three year time series of ASAR Wide Swath images in VV polarization over Calabria, Italy, in order to derive information on temporal soil moisture dynamics. The algorithm, adapted from an algorithm originally developed for ERS scatterometer, was validated using a simple hydrological model incorporating meteorological and pedological data. Strong positive correlations between modelled soil moisture and ASAR soil moisture were observed over arable land, while the correlation became much weaker over more vegetated areas. In a second phase, an attempt was made to incorporate seasonality in the different model parameters. It was observed that seasonally changing surface properties mainly affected the multitemporal incidence angle normalization. When applying a seasonal angular normalization, correlation coefficients between modelled soil moisture and retrieved soil moisture increased overall. Attempts to account for seasonality in the other model parameters did not result in an improved performance

Nectar-Inhabiting Bacteria Affect Olfactory Responses of an Insect Parasitoid by Altering Nectar Odors

Floral nectar is ubiquitously colonized by a variety of microorganisms among which yeasts and bacteria are the most common. Microorganisms inhabiting floral nectar can alter several nectar traits, including nectar odor by producing microbial volatile organic compounds (mVOCs). Evidence showing that mVOCs can affect the foraging behavior of insect pollinators is increasing in the literature, whereas the role of mVOCs in altering the foraging behavior of third-trophic level organisms such as insect parasitoids is largely overlooked. Parasitoids are frequent visitors of flowers and are well known to feed on nectar. In this study, we isolated bacteria inhabiting floral nectar of buckwheat, Fagopyrum esculentum (Polygonales: Polygonaceae), to test the hypothesis that nectar bacteria affect the foraging behavior of the egg parasitoid Trissolcus basalis (Hymenoptera: Scelionidae) via changes in odors of nectar. In behavioral assays, we found that T. basalis wasps are attracted toward nectar fermented by 4 out of the 14 bacterial strains isolated, which belong to Staphylococcus epidermidis, Terrabacillus saccharophilus (both Firmicutes), Pantoea sp. (Proteobacteria), and Curtobacterium sp. (Actinobacteria). Results of chemical investigations revealed significant differences in the volatile blend composition of nectars fermented by the bacterial isolates. Our results indicate that nectar-inhabiting bacteria play an important role in the interactions between flowering plants and foraging parasitoids. These results are also relevant from an applied perspective as flowering resources, such as buckwheat, are largely used in agriculture to promote conservation biological control of insect pests

Weight loss and outcomes in subjects with progressive pulmonary fibrosis: data from the INBUILD trial

BACKGROUND: Lower body mass index (BMI) and weight loss have been associated with worse outcomes in some studies in patients with pulmonary fibrosis. We analyzed outcomes in subgroups by BMI at baseline and associations between weight change and outcomes in subjects with progressive pulmonary fibrosis (PPF) in the INBUILD trial. METHODS: Subjects with PPF other than idiopathic pulmonary fibrosis were randomized to receive nintedanib or placebo. In subgroups by BMI at baseline (< 25, ≥ 25 to < 30, ≥ 30 kg/m2), we analyzed the rate of decline in FVC (mL/year) over 52 weeks and time-to-event endpoints indicating disease progression over the whole trial. We used a joint modelling approach to assess associations between change in weight and the time-to-event endpoints. RESULTS: Among 662 subjects, 28.4%, 36.6% and 35.0% had BMI < 25, ≥ 25 to < 30 and ≥ 30 kg/m2, respectively. The rate of decline in FVC over 52 weeks was numerically greater in subjects with baseline BMI < 25 than ≥ 25 to < 30 or ≥ 30 kg/m2 (nintedanib: - 123.4, - 83.3, - 46.9 mL/year, respectively; placebo: - 229.5; - 176.9; - 171.2 mL/year, respectively). No heterogeneity was detected in the effect of nintedanib on reducing the rate of FVC decline among these subgroups (interaction p = 0.83). In the placebo group, in subjects with baseline BMI < 25, ≥ 25 to < 30 and ≥ 30 kg/m2, respectively, 24.5%, 21.4% and 14.0% of subjects had an acute exacerbation or died, and 60.2%, 54.5% and 50.4% of subjects had ILD progression (absolute decline in FVC % predicted ≥ 10%) or died over the whole trial. The proportions of subjects with these events were similar or lower in subjects who received nintedanib versus placebo across the subgroups. Based on a joint modelling approach, over the whole trial, a 4 kg weight decrease corresponded to a 1.38-fold (95% CI 1.13, 1.68) increase in the risk of acute exacerbation or death. No association was detected between weight loss and the risk of ILD progression or the risk of ILD progression or death. CONCLUSIONS: In patients with PPF, lower BMI at baseline and weight loss may be associated with worse outcomes and measures to prevent weight loss may be required. TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT02999178

From diverse origins to specific targets: Role of microorganisms in indirect pest biological control

Integrated pest management (IPM) is today a widely accepted pest management strategy to select and use the most efficient control tactics and at the same time reduce over-dependence on chemical insecticides and their potentially negative environmental effects. One of the main pillars of IPM is biological control. While biological control programs of pest insects commonly rely on natural enemies such as predatory insects, parasitoids and microbial pathogens, there is increasing evidence that plant, soil and insect microbiomes can also be exploited to enhance plant defense against herbivores. In this mini-review, we illustrate how microorganisms from diverse origins can contribute to plant fitness, functional traits and indirect defense responses against pest insects, and therefore be indirectly used to improve biological pest control practices. Microorganisms in the rhizosphere, phyllosphere and endosphere have not only been shown to enhance plant growth and plant strength, but also promote plant defense against herbivores both above-and belowground by providing feeding deterrence or antibiosis. Also, herbivore associated molecular patterns may be induced by microorganisms that come from oral phytophagous insect secretions and elicit plant-specific responses to herbivore attacks. Furthermore, microorganisms that inhabit floral nectar and insect honeydew produce volatile organic compounds that attract beneficial insects like natural enemies, thereby providing indirect pest control. Given the multiple benefits of microorganisms to plants, we argue that future IPMs should consider and exploit the whole range of possibilities that microorganisms offer to enhance plant defense and increase attraction, fecundity and performance of natural enemies. © 2020 by the authors. Licensee MDPI, Basel, Switzerland