Biology subjects

Diallo, S.

Publications and source records attributed to Diallo, S..

5 recordsLinked to original sources

bioRxiv2025

Clove-derived eugenol induces strong avoidance behaviour in the invasive fruit fly, Drosophila suzukii

The success of invasive species often relies on sensory adaptations that allow them to exploit new environments. Unlike most of its relatives, the spotted-wing drosophila (Drosophila suzukii) lays eggs in ripening fruit, making it a serious and rapidly spreading agricultural pest worldwide. Spice plants produce volatiles that repel many insects, making them a potential source of D. suzukii behavioural modulators. Here, we examined whether volatiles from clove (Syzygium aromaticum) could alter the behaviour and fitness of D. suzukii. Behavioural assays revealed strong aversion: adults avoided grapes treated with clove extract, while gravid females laid significantly fewer eggs on treated fruit in both no-choice and choice assays. Clove exposure adversely impacted fitness, resulting in slower larval growth, reduced adult weight, decreased emergence rate, and shortened lifespan. Gas Chromatography-mass spectrometry analyses identified eugenol as the predominant volatile. Consistent with this, synthetic eugenol elicited strong avoidance not only in grapes but also across various host fruits, including apple, banana, blueberry, guava, mango, orange, papaya, raspberry, strawberry, and tomato. Furthermore, molecular docking and single-sensillum recordings indicated that eugenol binds most strongly to DsuzOR88a, followed by DsuzOR69a and DsuzOR23a odorant receptors. Subsequently, cheminformatic screening of 1,000 eugenol analogues revealed several structural variants predicted to interact strongly with OR88a, offering additional candidate repellents. By combining behavioural, analytical chemistry, electrophysiological, and cheminformatic approaches, our study demonstrates that clove, through its major volatile eugenol, disrupts host use and reduces fitness in D. suzukii. These results highlight the ecological role of plant-derived repellents in insect-plant interactions and position eugenol as a promising natural compound for sustainable fruit pest management.

ecology↗

bioRxiv2024

Identification of the trail-following pheromone receptor in termites

Chemical communication is the cornerstone of eusocial insect societies since it mediates the social hierarchy, division of labor, and concerted activities of colony members. The chemistry of social insect pheromones received considerable attention in both major groups of social insects, the eusocial Hymenoptera and termites. By contrast, current knowledge on molecular mechanisms of social insect pheromone detection by odorant receptors (ORs) is limited to hymenopteran social insects and no OR was yet functionally characterized in termites, the oldest eusocial insect clade. Here, we present the first OR deorphanization in termites. We selected four OR sequences from the previously annotated antennal transcriptome of the termite Prorhinotermes simplex (Rhinotermitidae), expressed them in Empty Neuron Drosophila, and functionally characterized using single sensillum recording (SSR) and a panel of termite semiochemicals. In one of the selected ORs, PsimOR14, we succeeded in obtaining strong and reliable responses to the main component of P. simplex trail-following pheromone, the monocyclic diterpene neocembrene. PsimOR14 showed a narrow tuning to neocembrene; only one additional compound out of 67 tested (geranylgeraniol) generated non-negligible responses. Subsequently, we used SSR in P. simplex workers and identified the olfactory sensillum specifically responding to neocembrene, thus likely expressing PsimOR14. We report on homology-based modelling of neocembrene binding by PsimOR14 and show how different ligands impact the receptor dynamicity using molecular dynamics simulations. Finally, we demonstrate that PsimOR14 is significantly more expressed in worker antennae compared to soldiers, which correlates with higher sensitivity of workers to neocembrene.

animal behavior and cognition↗

bioRxiv2023

Silver nanoparticle biosynthesis utilizing Ocimum kilimandscharicum leaf extract and assessment of its antibacterial activity against certain chosen bacteria

Using plants in the biological production of silver nanoparticles (AgNPs) is becoming increasingly important as a practical and environmentally benign method. In the current work, silver nanoparticles were made utilizing the significant Ocimum kilimandscharicum, and their potential to combat certain bacteria was discussed. Both aqueous and methanol plant extracts were used for reducing silver nitrate at different time intervals (30 to 150 minutes) and pH (2 to 11). The UV-visible absorption spectrum recorded for both methanol and aqueous extracts revealed successful synthesis of AgNPs. The antimicrobial activity of the AgNPs was evaluated against Escherichia coli ATCC 25922, Salmonella choleraesuius ATCC 10708, and Staphylococcus aureus ATCC 25923. 50mg/ml was the concentration of the extracts tested. The best zone of inhibition was recorded for the methanol and aqueous-mediated AgNPs, ranging from 12{+/-}1 to 16{+/-}1mm. The methanol and aqueous extract silver nanoparticles had the same Minimum Inhibitory Concentration (6.25{+/-}0.00 mg/ml), whereas the Minimum Bactericidal Concentrations were 12.5{+/-}0.00 and 25{+/-}0.00 mg/ml, respectively. The highest inhibition zone of 16{+/-}1 mm was observed against Salmonella choleraesuius with 50{+/-}0.00 mg/ml aqueous silver nanoparticles. The results show that the silver nanoparticles made with Ocimum kilimandscharicum have potent antibacterial action against those microorganisms.

pharmacology and toxicology↗

bioRxiv2020

Development of new cowpea (Vigna unguiculata) mutant genotypes, analysis of their agromorphological variation, genetic diversity and Population structure

Cowpea is one of the most important legume grain in the SubSaharian region of Africa used for human consumption and animal feeding but its production is hampered by biotic and abiotic constraints raising the need to broaden its genetic basis. For this purpose, the seeds of two cowpea varieties Melakh and Yacine were respectively irradiated with 300 and 340 Gy. The developed mutant populations were agromorphologically characterized from M5 to M7 while the genetic diversity of the last were evaluated using 13 ISSR markers. Based on agromorphological characterization, variation of flower color, pod length, seed coat color and seed weight with respectively 78.01, 68.29, 94.48 and 57.58% heritability were recorded in the mutant lines. PCA analyses allowed to identify the elite mutants based on their agromorphological traits while Pearsons correlation results revealed a positive correlation between yield component traits. Three subpopulations were identified through STRUCTURE analyses but assignment of the individuals in each group was improved using DAPC. Analysis of Molecular Variance revealed that the majority (85%) of the variance rather existed within group than among (15%) group. Finally, our study allowed to select new promising mutant genotypes which could be tested for multi local trials to evaluate their agronomic performance.

genetics↗

bioRxiv2018

Chilling, irradiation and transport of male Glossina palpalis gambiensis pupae: effect on the emergence, flight ability and survival.

BackgroundThe sterile insect technique (SIT) requires mass-rearing of the target species, irradiation to induce sexual sterility and transportation from the mass-rearing facility to the target site. Those treatments require several steps that may affect the biological quality of sterile males. This study has been carried out to evaluate the relative impact of the chilling, irradiation and transport on emergence rate, flight ability and survival of sterile male tsetse flies Glossina palpalis gambiensis.\n\nResultsChilling, irradiation and transport all affected the quality control parameters studied. The emergence rate was significantly reduced by long chilling periods and transport, i.e. from 92% at the source insectary to 78% upon arrival in Dakar. Flight ability was affected by all three parameters with 31% operational flies lossed between the source and arrival insectaries. Only survival under stress was not affected by any of the treatments.\n\nConclusionThe chilling period and transport were the main treatments which impacted significantly the quality of sterile male pupae. Therefore, the delivery of sterile males was divided over two shipments per week in order to reduce the chilling time and improve the quality of the sterile males. Quality of the male pupae may further be improved by reducing the transport time and vibration during transport.\n\nAuthor summaryTsetse fly and the disease it transmits, trypanosomosis, remain an enormous challenge in several countries in sub-Saharan Africa. The use of the Sterile Insect Technique (SIT) has become one of the components of the eradication of tsetse fly in Africa. The sterile insect technique (SIT) requires mass-rearing of the target species, irradiation to induce sexual sterility and transportation from the mass-rearing facility to the target site. In this study, we demonstrate the relative impact of the chilling, irradiation and transport on the emergence rate, the flight ability and the survival of sterile male tsetse flies Glossina palpalis gambiensis. We found that the chilling, irradiation and transport affected the emergence rate and flight ability. But the survival of the sterile male under stress was not affected by any of the treatments. Hence, the quality of the male pupae may further be improved by reducing the transport time and vibration during transport.

physiology↗