Evaluation of the fitness of RNA interference (RNAi) based Aedes aegypti (Linnaeus) transgenic mosquitoes

Abstract

Dengue is an arboviral disease caused by four serotypes of the Dengue Virus (DENV). An innovative approach to dengue control involves developing transgenic mosquitoes using the RNA interference (RNAi) mechanism. A previous study designed and engineered a polycistronic cluster of nine synthetic small RNAs targeting all four DENV serotypes into the Aedes aegypti genome to develop RNAi-based Transgenic Mosquitoes (TM). Genomic integration of the construct was confirmed through the expression of a red fluorescence marker in mosquito eyes, followed by genomic PCR. This study evaluated the fitness of the developed TM in comparison to Aedes aegypti Wild-type Mosquitoes (WM) under laboratory conditions. Fecundity and hatchability were assessed using 40 adult females and males (n = 40, r = 3). Flight ability and longevity were evaluated using 30 female and male TM and WM (n = 30, r = 3). Male mating success was assessed by mating one adult male TM or WM with five female WM (r = 20). Standard wing length of male and female mosquitoes was measured in both TM and WM (n = 40). Data analyses were conducted using IBM® SPSS Statistics version 26.0. No significant differences were observed in fecundity, hatchability, standard wing length, male flight ability, or male mating success between TM and WM (Student’s t-test; P > 0.05). However, a significant difference was detected in the flight ability of female TM compared to WM (Student’s t-test; P < 0.05). There were no significant differences in adult longevity between male TM (63.86 ± 0.85 days) and WM (63.60 ± 1.7 days), or between female TM (66.03 ± 4.0 days) and WM (66.62 ± 2.7 days) (Student’s t-test; P > 0.05). Overall, the absence of significant differences in most fitness parameters between TM and WM suggests that this RNAi-based transgene construct exerts only a minor impact on mosquito fitness.