Biology subjects

Marion-Poll, F.

Publications and source records attributed to Marion-Poll, F..

6 recordsLinked to original sources

bioRxiv2025

The Hidden Sweet Tooth of the Black Soldier Fly (Hermetia illucens)

The black soldier fly Hermetia illucens (BSF) is increasingly studied for its ability to convert organic waste into protein, offering solutions for waste valorisation and livestock feeding. While egg production depends on adult performance, the biology of adult BSF remains poorly understood. In particular, growing evidence suggests that adults can feed and benefit from sugar supplementation but the behavioural and molecular bases of sugar detection remain unknown. To fill this gap, we tested whether adult BSF can detect and prefer sugar by using behavioural assays, binary-choice feeding tests and proboscis extension responses. We also described numerous gustatory sensilla on the proboscis with scanning electron microscopy, and characterized the responses to sugar in some of them with electrophysiological recordings. These experiments were complemented by an analysis of the gustatory receptor (GR) gene repertoire and the expression levels of sugar-responsive receptors. All the experimental tests conducted in this study converge to show that the adults can detect and consume sucrose, with females responding more strongly than males. Genome analysis identified 28 GRs, a surprisingly small number for a generalist fly, including only three putative sugar-specific GRs homologous to those of the eight known sugar GRs in Drosophila. Moreover, one of these GRs show a general high level of expression including in the head and in the antennae whereas the two others display tissue-specific patterns of expression. We also identify a high number of GR pseudogenes, including four putative sugar receptor pseudogenes, indicating multiple gene loss events and substantial reduction of the GR repertoire compared to other dipteras sharing a similar ecological niche. We conclude that although BSF possesses a reduced set of GR genes, including only three putative sugar-responsive GRs, adults have retained a strong sensitivity to sugars in their environment. The set of behavioural, morphological, and electrophysiological tools developed here provides a foundation for deeper investigations into feeding behaviour in this species of growing agroecological importance.

animal behavior and cognition↗

bioRxiv2025

How does selection for flowering in maize shapes defenses components against the European Corn Borer ?

Understanding how selection for flowering time affects maize susceptibility to the European corn borer (ECB, Ostrinia nubilalis) is essential in the context of climate change and increasing pest pressures. We investigated the consequences of divergent selection for flowering time on maize defense and susceptibility traits using two genetic backgrounds (MBS847 and F252). Three complementary approaches were combined: leaf palatability tests, ECB field incidence dynamics surveys, and biochemical analyses of maize stem walls. In the MBS847 background, early-flowering families exhibited lower content of defense compounds, higher leaf palatability, and higher field infestation compared to late-flowering families. In contrast, no significant differences were observed between early and late populations in the F252 background. Differences in susceptibility between families were associated with variation in stem biochemical composition, including fiber components which influence stem rigidity and resistance to ECB. Our results indicate that selection for flowering time can modify plant defense traits and susceptibility in a genetic-background-dependent manner. These findings highlight the interaction between plant phenology, biochemical defenses, and insect herbivory, with implications for breeding and adaptation under changing environmental conditions.

ecology↗

bioRxiv2025

Drosophila Sociality Influences Immune Peptide Load and Apoptosis-induced Tumor Suppression independently of the Antitumor Peptide Defensin

Patients social environment might influence cancer outcome. This potentially happens in Drosophila, as we previously reported that the social context influences the growth of intestinal tumors. To uncover the underlying social-induced physiological mechanisms, we performed RNA-seq of isogenized beheaded tumorous Drosophila. Importantly, expression of several immune peptides varied according to the social-induced tumor growth effect. Furthermore, ectopic expression in tumors of the apoptotic-inhibitor p35 suppressed the social-induced effect. Next, we challenged the immune peptide Defensin, previously reported to suppress imaginal disc tumor growth through a cell-death/JNK-dependent network. Nonetheless, the social-induced tumor suppression was maintained upon Defensin overexpression or JNKK-knockdown in tumors, and in defensin mutants. Surprisingly, tumor growth was reduced in the latter, indicating that Defensin sustains the growth of these intestinal tumors. In summary, our study indicates that the social context affects the immune response and that a given immune peptide may have opposite effects depending on tumor type.

cancer biology↗

bioRxiv2024

Taste evolution in an herbivorous drosophilid

Plant secondary metabolites pose a challenge for generalist herbivorous insects because they are not only potentially toxic, they also may trigger aversion. On the contrary, some highly specialized herbivorous insects evolved to use these same compounds as token stimuli for unambiguous determination of their host plants. Two questions that emerge from these observations are how recently derived herbivores evolve to overcome this aversion to plant secondary metabolites and the extent to which they evolve increased attraction to these same compounds. In this study, we addressed these questions by focusing on the evolution of bitter taste preferences in the herbivorous drosophilid Scaptomyza flava, which is phylogenetically nested deep in the paraphyletic Drosophila. We measured behavioral and neural responses of S. flava and a set of non-herbivorous species representing a phylogenetic gradient (S. pallida, S. hsui, and D. melanogaster) towards host- and non-host derived bitter plant compounds. We observed that S. flava evolved a shift in bitter detection, rather than a narrow shift towards glucosinolates, the precursors of mustard-specific defense compounds. In a dye-based consumption assay, S. flava exhibited shifts in aversion toward the non-mustard bitter, plant-produced alkaloids caffeine and lobeline, and reduced aversion towards glucosinolates, whereas the non-herbivorous species each showed strong aversion to all bitter compounds tested. We then examined whether these changes in bitter preferences of S. flava could be explained by changes in sensitivity in the peripheral nervous system and compared electrophysiological responses from the labellar sensilla of S. flava, S. pallida, and D. melanogaster. Using scanning electron microscopy, we also created a map of labellar sensilla in S. flava and S. pallida. We assigned each sensillum to a functional sensilla class based on their morphology and initial response profiles to bitter and sweet compounds. Despite a high degree of conservation in the morphology and spatial placement of sensilla between S. flava and S. pallida, electrophysiological studies revealed that S. flava had reduced sensitivity to glucosinolates to varying degrees. We found this reduction only in I type sensilla. Finally, we speculate on the potential role that evolutionary genetic changes in gustatory receptors between S. pallida and S. flava may play in driving these patterns. Specifically, we hypothesize that the evolution of bitter receptors expressed in I type sensilla may have driven the reduced sensitivity observed in S. flava, and ultimately, its reduced bitter aversion. The S. flava system showcases the importance of reduced aversion to bitter defense compounds in relatively young herbivorous lineages, and how this may be achieved at the molecular and physiological level.

evolutionary biology↗

bioRxiv2020

A semi-automated design for high-throughput Lepidoptera larvae feeding bioassays

Lepidopteran pests cause considerable damage to all crops over the world. As larvae are directly responsible for these damages, many research efforts are devoted to find plant cultivars which are resistant or tolerant to pest attacks. However, such studies take time, efforts and are costly, especially when one wants to not only find resistance traits but also to evaluate their heritability. We present here a high throughput approach to screen plants for resistance or chemicals for their deterrence, using a leaf-disk consumption assay, which is both suitable for large scale tests and economically affordable. To monitor larvae feeding on leaf disks placed over a layer of agar, we designed 3D models of 50 cages plates. One webcam can sample simultaneously 3 of such plates at a rate of 1 image/min, and follow individual feeding activities on each leaf disk and the movements of 150 larvae. The resulting image stacks are first processed with a custom program running under an open-source image analysis package (Icy) to measure the surface of each leaf disk over time. We further developed statistical procedures running under the R software, to analyze the time course of the feeding activities of the larvae and to compare them between treatments. As a test case, we compared how European corn borer larvae respond to quinine, considered as a bitter alkaloid for many organisms, and to NeemAzal containing azadirachtin, which is a common antifeedant against pest insects. We found that increasing doses of azadirachtin reduce and delay feeding. However, contrary to our expectation, quinine was found poorly effective at the range of concentrations tested. The 3D printed model of the cage and the camera holder, the plugins running under Icy, and the R scripts are freely available, and can be modified according to the particular needs of the users.

animal behavior and cognition↗

bioRxiv2017

The use of salivary α-amylase as an evolutionary solution to host selection in parasitoids

Foraging parasitoids use chemical signals in host recognition and selection processes. Thereby, chemicals from the herbivore hosts play a crucial role. When different herbivores are present in the same plant or field, the perception of specific volatiles and contact compounds emitted from the host itself enable the parasitoids both to differentiate between hosts and non-hosts and to estimate the health status of its host. During the host feeding process, contact between the parasitoid and its host is very crucial, and oral secretions from the host play a key role during the first contact for such evaluation by the parasitoid. Using an integration of behavioral observations, biochemical and sensory physiological approaches we demonstrate that female parasitoids of Cotesia flavipes recognize their host and oviposit in reaction to an -amylase, which is present in the oral secretions of the larvae of their host, Chilo partellus. This activity was also mediated by a purified -amylase synthetized from Drosophila melanogaster. Using this synthetized enzyme, we further demonstrate that the conformation of the enzyme rather than its catalytic site is responsible for this activity. This enzyme is activating gustatory neurons of the terminal antennal sensilla chaetica of C. flavipes females. -amylases are therefore good candidates for an evolutionary solution to host selection in parasitoids, thus opening new avenues for investigations in hosts-parasitoids interactions.

evolutionary biology↗