Spatio-Temporal Modelling Informing Wolbachia Replacement Releases in a Low Rainfall Climate

Abstract

Releases of Aedes aegypti carrying Wolbachia bacteria are known to suppress arbovirus transmission and reduce the incidence of vector-borne diseases. In planning for Wolbachia releases in the arid environment of Jeddah, Saudi Arabia, we collected entomological data with ovitraps across a 7-month period in four locations. Herein, we show that mosquito presence in basements does not differ from that of non-basement areas of buildings. In modelling mosquito presence across the study sites, we found the spatial structure to be statistically significant in one of the four sites, while a significant spatial structure was found for egg production data across three of the four sites. The length scales of the spatial covariance functions fitted to the egg production data ranged from 143 m to 574 m, indicating that high productivity regions can be extensive in size. Rank-correlation analyses indicated that mosquito presence tended to persist from the dry to wet season, but that egg production ranks at locations could reverse. The data suggest that, in Jeddah, the quality of the local environment for breeding can vary over time. The data support the feasibility of dry season releases but with release numbers needing to be flexible depending on local rates of invasion.

Modeling Sustained Transmission of Wolbachia among Anopheles Mosquitoes: Implications for Malaria Control in Haiti

“…Our simulation results indicated that releasing Wolbachia -infected mosquitoes in the dry season was more effective than in the wet season when fewer uninfected mosquitoes were in the wild for competition. This observation agrees with a previous statistical study [ 40 ] as well as a field study [ 41 ]. We note that mathematical models simplify field conditions, and this conclusion (and many others) depends on our model parametrizations.…”

Mitochondrial DNA variation in Aedes aegypti (Diptera: Culicidae) mosquitoes from Jeddah, Saudi Arabia

“…Mosquitoes were sampled from ovitraps from 3 suburbs in Jeddah (Al-Rawabi, As-Salamah 01, and Al-Safa-09), which overlap with the study described in Pagendam et al (2022). Ovitraps were placed 20 m apart, left for 2 wk and returned to the laboratory where larvae were reared to adulthood.…”

“…This has involved the integration of an Australian mitochondrial background carrying Wolbachia wAlbBQ into a nuclear genomic background that is of Jeddah origin. While information relevant to mosquito density, movement and Wolbachia fitness in Jeddah has been established (Endersby-Harshman et al 2021, Pagendam et al 2022, Schmidt et al 2023, Ross et al 2023), no mitochondrial variation data exists. A better understanding of the mitochondrial variation present in Jeddah, and its uniqueness relative to the Australian mitochondria, is needed for future releases.…”

Revisiting Wolbachia detections: Old and new issues in Aedes aegypti mosquitoes and other insects

“…( 2023 ) who detect two “natural” infections of Wolbachia in Jeddah, Saudi Arabia. Wolbachia releases have taken place in Jeddah following a detailed characterization of w MelM and w AlbB Wolbachia strains for release (Ross et al., 2023 ) and preparatory work at sites (Endersby‐Harshman et al., 2021 ; Pagendam et al., 2022 ). With two strains being released, it is not surprising that the authors identified two clades of Wolbachia in Jeddah.…”