Samung, Y. | Search bioRxiv

bioRxiv2025

Influential landmarks

Geometric morphometrics based on two-dimensional landmarks is a powerful tool for distinguishing morphologically similar or cryptic taxa, an important asset in the fight against medically and veterinary important arthropods. While it is commonly assumed that increasing the number of landmarks should improve discriminatory power by capturing more shape information, our findings challenge this assumption. In terms of shape discrimination, we demonstrate that small subsets of landmarks can outperform full sets of landmarks. Examples are given in 6 insect families: Culicidae, Glossinidae, Muscidae, Psychodidae, Reduviidae and Tabanidae. In all of these examples where landmark-based geometric morphometry was effective in separating morphologically close taxa, the total number of landmarks was not as effective as some significantly smaller subsets. To find such performing subsets, we used a random approach. Thus, for each number of landmarks (subsets), we examined a random sample of their many possible combinations. This random search was compared to a simpler approach, called the hierarchical method, based on the contribution of each landmark to the overall distance between shapes. Both procedures have been integrated into the XYOM online software, providing accessible tools for efficient landmark selection and improved morphometric analysis. Author summaryLandmark-based geometric morphometrics describes shape in direct relation to the number of landmarks used. It is commonly assumed that increasing the number of landmarks allows for more information about shape, and when discriminating between groups or taxa, this strategy is expected to improve classification accuracy. Our results challenge this assumption. We demonstrate that subsets of landmarks, as small as three or four, can outperform the species classification obtained by the full set of landmarks, and we propose two methods for identifying them. We analyze the possible causes of these counter-intuitive results and the perspectives they could open for morphometric studies.

bioinformatics↗

bioRxiv2024

Comprehensive intra-host infection kinetics reveals high arbo-flavivirus transmission potential by neglected vector species, Aedes scutellaris

BackgroundDengue virus (DENV) and Zika virus (ZIKV) are primarily transmitted by Aedes mosquitoes. As most studies on vector competence have focused on Aedes aegypti and Aedes albopictus while neglecting other Aedes species, it is possible that the transmission risks might be underestimated. it is necessary to examine additional species that could potentially serve as competent vectors. This is particularly important considering the potential expansion of their geographical range due to climate change or species-specific vector reduction interventions. Methodology/Principal FindingsIn this study, we examined the infection kinetics and transmission potential of Aedes scutellaris from Thailand, comparing to Ae. aegypti and Ae. albopictus. Our findings demonstrated that Ae. scutellaris and Ae. albopictus had lower rates of midgut infection compared to Ae. aegypti due to smaller blood meal sizes during feeding. However, once the infection has established Ae. scutellaris exhibited efficient replication of ZIKV and DENV1-4 in the midguts, secondary organs, and salivary glands. Notably, Ae. scutellaris had a low salivary gland escape barrier, with comparable transmissibility as Ae. aegypti when inoculated with the same viral load. ConclusionThis study highlights the potential of Ae. scutellaris as a vector for DENV and ZIKV and emphasizes the importance of considering neglected mosquito species in arbovirus transmission and surveillance efforts. Author SummaryDengue and Zika are viral infections caused by arthropod-borne flaviviruses, and spread primarily through the bite of infected Aedes mosquitoes. Most research on DENV and ZIKV transmission has primarily focused on Aedes aegypti and Aedes albopictus while other Aedes species are overlooked, thus the epidemiology of the transmission might be underestimated. With climate change together with species-specific mosquito population reduction interventions these neglected Aedes species could become increasingly important in sustaining virus transmission. In this study, we examined Aedes scutellaris, a mosquito species that co-habitats with Ae. aegypti and Ae. albopictus, to assess its ability to transmit DENV and ZIKV using a combination of blood feeding and intrathoracic injection methods. Our findings show that although Ae. scutellaris had lower initial infection rates due to smaller blood meals, DENV and ZIKV were able to replicate and transmit at levels comparable to Ae. aegypti when exposed to similar virus loads. This highlights the need to study a broader range of species to improve virus control and outbreak prevention strategies.

microbiology↗