RESUMEN
BACKGROUND: The incompatible insect technique (IIT) has been used for Aedes mosquito population suppression to curb the transmission of dengue. However, its wide application is limited owing to the low output of male mosquitoes and the risk of population replacement from the release of fertile Wolbachia-infected females. This study aims to improve IIT efficiency for broader adoption. RESULTS: We assessed the impact of 10% pyriproxyfen (PPF) sticky powder exposure on Wolbachia (from Culex molestus)-transinfected Aedes albopictus Guangzhou line (GUA line) (GC) mosquitoes. We found that the exposure caused chronic toxicity in adult mosquitoes without affecting the cytoplasmic incompatibility (CI)-inducing capability of males. The PPF-contaminated GC females exhibited significant sterilization and the ability to disseminate lethal doses of PPF to breeding sites. Subsequently, we conducted a field trial combining PPF with IIT aiming to suppress the Ae. albopictus population. This combined approach, termed boosted IIT (BIIT), showed a notable enhancement in population suppression efficiency. The improved efficacy of BIIT was attributed to the dispersion of PPF particles in the field via the released PPF-contaminated male mosquitoes. During the BIIT field trial, no Wolbachia wPip-positive Ae. albopictus larvae were detected, indicating the effective elimination of the risk of Wolbachia-induced population replacement. Additionally, the field trial of BIIT against Ae. albopictus resulted in the suppression of the nontarget mosquito species Culex quinquefasciatus. CONCLUSION: Our results highlight the remarkable efficiency and feasibility of combining IIT with PPF in suppressing mosquito populations, facilitating the widespread implementation of IIT-based management of mosquito-borne diseases. © 2024 Society of Chemical Industry.
RESUMEN
BACKGROUND: Mosquito-borne arboviruses are expanding their territory and elevating their infection prevalence due to the rapid climate change, urbanization, and increased international travel and global trade. Various significant arboviruses, including the dengue virus, Zika virus, Chikungunya virus, and yellow fever virus, are all reliant on the same primary vector, Aedes aegypti. Consequently, the occurrence of arbovirus coinfection in mosquitoes is anticipated. Arbovirus coinfection in mosquitoes has two patterns: simultaneous and sequential. Numerous studies have demonstrated that simultaneous coinfection of arboviruses in mosquitoes is unlikely to exert mutual developmental influence on these viruses. However, the viruses' interplay within a mosquito after the sequential coinfection seems intricated and not well understood. METHODOLOGY/PRINCIPAL FINDINGS: We conducted experiments aimed at examining the phenomenon of arbovirus sequential coinfection in both mosquito cell line (C6/36) and A. aegypti, specifically focusing on dengue virus (DENV, serotype 2) and Zika virus (ZIKV). We firstly observed that DENV and ZIKV can sequentially infect mosquito C6/36 cell line, but the replication level of the subsequently infected ZIKV was significantly suppressed. Similarly, A. aegypti mosquitoes can be sequentially coinfected by these two arboviruses, regardless of the order of virus exposure. However, the replication, dissemination, and the transmission potential of the secondary virus were significantly inhibited. We preliminarily explored the underlying mechanisms, revealing that arbovirus-infected mosquitoes exhibited activated innate immunity, disrupted lipid metabolism, and enhanced RNAi pathway, leading to reduced susceptibility to the secondary arbovirus infections. CONCLUSIONS/SIGNIFICANCE: Our findings suggest that, in contrast to simultaneous arbovirus coinfection in mosquitoes that can promote the transmission and co-circulation of these viruses, sequential coinfection appears to have limited influence on arbovirus transmission dynamics. However, it is important to note that more experimental investigations are needed to refine and expand upon this conclusion.