留尼汪大学

Pressures and threats to shallow-water coral reefs have intensified over the last decades. The ‘Deep Reef Refuge’ Hypothesis (DRRH) postulates that Mesophotic Coral Ecosystems (MCEs) may be protected from these pressures and threats and could provide larvae to shallower reefs, therefore representing a genetic source for recolonising degraded shallow habitats. Focusing on the coral genus Pocillopora in Reunion Island (southwestern Indian Ocean), we aimed to (1) characterize the vertical distribution of each molecularly identified species, (2) determine their population structuring, to seek for evidence of vertical and horizontal connectivity in depth, and (3) test whether the DRRH may apply to these coral species in Reunion Island. We used 13 microsatellite loci to assess the genetic structure in Pocillopora populations sampled along a depth gradient (at 15, 30 and 45 m depth) on three sites around the island. Among the 288 colonies sampled, four species were identified, but only one (P. aff. verrucosa) was found in sufficient number at all depths for further analyses. Its populations showed no evidence of genetic structuring among sites and depths, highlighting strong vertical and horizontal connectivity at all depths. We argue that the shallow populations of P. aff. verrucosa could benefit from the larvae produced by MCEs in Reunion Island, therefore implying that MCEs can serve as a substantial reproductive refuge for this species. Nevertheless, complementary studies are needed to confirm these results, particularly focusing on other reef-building species with contrasting life-history traits and regions.

Urban overheating is a pressing challenge for tropical island cities, where high humidity and intense solar radiation amplify heat stress. This study investigates the interplay between the urban heat island (UHI) effect and outdoor thermal comfort in R & eacute;union Island, a small tropical island in the southwest Indian Ocean. An innovative LoRa network of validated low-cost sensors was deployed in two contrasting districts: Ruisseau, a compact high-density neighborhood, and Le Port, an open mid-rise district with minimal vegetation cover. The network simultaneously monitored air temperature, humidity, wind, and solar radiation, enabling the calculation of UHI intensity and the Universal Thermal Climate Index (UTCI). Results show that UHI magnitude alone does not adequately describe heat stress in tropical cities. In Ruisseau, higher UHI intensities coincided with neutral or moderate UTCI values due to effective shading from compact morphology. In contrast, Le Port recorded lower or comparable UHI but significantly higher UTCI values, often in the strong heat stress category, driven by solar exposure and weak nocturnal ventilation. Seasonal analysis further revealed extreme and persistent heat stress during the hot-humid season, with nighttime UTCI exceeding 30 degrees C in Le Port, leaving no recovery window for residents. These findings highlight the need to prioritize outdoor thermal comfort, rather than UHI reduction alone, in tropical island planning. Strategies should co-optimize shading and ventilation while embedding thermal comfort targets into building codes and zoning. The study demonstrates the potential of low-cost sensor networks to inform climate-responsive and resilient urban design in vulnerable island contexts.

The citrus industry is threatened by a devastating bacterial disease known as Huanglongbing (HLB) or citrus greening. Current control measures largely rely on chemical suppression of insect vectors, primarily Diaphorina citri and Trioza erytreae. A promising alternative lies in the biotechnological use of viruses that specifically infect these vectors. Although much progress has been made in elucidating the virome of D. citri, there is no data on the viral population that Trioza erytreae can harbor and/or infect it. In this study, we analyzed the virome of T. erytreae from the Iberian Peninsula, Madeira, the Canary Islands, São Tomé and Principe, the Reunion Islands, and South Africa. We identified seven new insect-specific viruses (ISV) belonging to the families Narnaviridae, Totiviridae, Solemoviridae, Phenuiviridae, Flaviviridae, and Tombusviridae, the last three detected only in South African populations, four mycoviruses of the Ambiguiviridae, Botourmiaviridae, and Partitiviridae families, and three viruses known to infect citrus. Furthermore, comparison with the DNA sequence database has allowed us to identify the presence of 22 actively expressed endogenous viral elements (EVEs; virus-derived genetic material integrated into the genome of a nonviral host). Our findings provide new insights into the virome of this important insect vector and new perspectives to its potential for biocontrol strategies against HLB.

Mango is an important tropical fruit, rich in essential micronutrients. In Côte d’Ivoire, the harvested fruit is either exported to international and regional markets, processed, or remains on the local market. Nutritional flows across value chains and their resulting nutritional impact are poorly understood. The purpose of this study was to estimate the past, present, and future nutritional impact of the mango value chain in Côte d’Ivoire. We adapted the NUTRI-P-LOSS methodology that predicts nutritional postharvest losses across crop value chains, to assess nutritional flows in the mango value chain. Mango production quantities were estimated, and fruits at harvest, during ripening, and after drying, were analysed for macro- and micronutrients. Findings indicate that mango domestic nutritional contribution is likely to increase in the future, helping address vitamin A and C deficiencies and anaemia related-issues that remain prevalent, particularly among vulnerable groups such as children under five, pregnant teenagers and women (i.e. meeting requirements for vitamin C, from approximatively 60,000 people in 2000, to 1 million people in 2050). Whilst vitamin A is concentrated in dried mango, vitamin C—the fresh fruit’s primary micronutrient—is lost in drying. Therefore, increased domestic consumption of dried mango would increase vitamin A from mango but not improve the overall nutritional impact of mango on the local population (vitamins A and C, iron). Our work leads to the development of a user-friendly tool that predicts the past, present, and future nutritional impact of crop production with mango in Côte d’Ivoire as an example.

The fight against malaria vector mosquitoes is an essential strategy for eradicating this disease. Selective capture of anthropophilic Anopheles species is crucial for targeted vector control. In this study, the ability of synthetic attractants, 4-hydroxycoumarin and 7-decyloxychromone, and their combination with CO2 to selectively capture anthropophilic Anopheles species was evaluated in the field. To do this, nocturnal trappings were conducted using CDC light traps in rural area, in the highlands of Madagascar. Each night test, baited and unbaited traps were set up. The results confirm that 4-hydroxycoumarin efficiently and selectively attracts anthropophilic Anopheles (KI = 80%; SI = 5.1). 7-decyloxychromone has a similar attractive effect but with much lower selectivity (KI = 69%; SI = 1.6). The tested mixtures of products did not show any synergistic effect on selectivity for anthropophilic Anopheles species. A decrease or even elimination, in the number of anthropophilic Anopheles was observed during consecutive trapping nights. These results may indicate that using selective synthetic attractants in mass trapping could contribute to reducing malaria vector populations, offering a promising complementary approach for vector control programs.