Journal of Mosquito Research 2024, Vol.14, No.3, 124-134 http://emtoscipublisher.com/index.php/jmr 125 2 Genetic Control Techniques 2.1 Sterile insect technique (SIT) The Sterile Insect Technique (SIT) is a species-specific and environmentally benign method for insect population suppression. It involves mass rearing, radiation-mediated sterilization, and the release of a large number of sterile male insects into the wild. These sterile males mate with wild females, resulting in no offspring and thus reducing the population over time. SIT has been successfully used against various agricultural pests and is now being adapted for mosquito control. The technique's effectiveness in mosquito control has been demonstrated in several studies, showing significant reductions in mosquito populations (Wilke et al., 2012). 2.2 Release of insects carrying a dominant lethal (RIDL) The Release of Insects carrying a Dominant Lethal (RIDL) is a genetic modification of the SIT approach (Lees et al., 2015). Instead of using radiation to sterilize the insects, RIDL involves releasing insects that are homozygous for a repressible dominant lethal genetic construct. This method aims to overcome some of the technical difficulties associated with conventional SIT, such as the potential negative effects of radiation on insect fitness. RIDL has shown promise in theoretical models and preliminary field trials, suggesting it could be a cost-effective and efficient method for mosquito population suppression (Alphey et al., 2011). 2.3 Gene drive systems Gene drive systems utilize selfish genetic elements, such as homing endonuclease genes (HEGs), that can spread rapidly through a population even if they reduce fitness. These systems have the potential to drive introduced traits through a population without the need for large-scale sustained releases. Gene drive systems can target and knock out genes that are crucial for mosquito survival or reproduction, leading to population suppression or elimination. The population genetics and dynamics of these systems have been modeled to predict their impact and optimize their deployment (Alphey and Bonsall, 2014). 2.4 Wolbachia-Based Strategies Wolbachia-based strategies involve the use of the endosymbiotic bacteria Wolbachia, which can induce cytoplasmic incompatibility (CI) in mosquitoes (Pagendam et al., 2020). This incompatibility results in the production of non-viable offspring when Wolbachia-infected males mate with uninfected females. The Incompatible Insect Technique (IIT) leverages this phenomenon for population suppression. Combining IIT with SIT (IIT-SIT) has shown high efficacy in field trials, significantly reducing mosquito populations. The integration of Wolbachia-based strategies within broader Integrated Vector Management (IVM) plans has demonstrated promising results in various settings (Zhang et al., 2015). 3 Mechanisms of Action 3.1 Genetic modification Genetic modification techniques in mosquito control involve altering the genetic makeup of mosquitoes to either suppress their populations or replace them with genetically modified individuals that are less capable of transmitting diseases. These modifications can be classified into self-limiting and self-sustaining systems. Self-limiting systems, such as the Sterile Insect Technique (SIT) and Release of Insects carrying a Dominant Lethal gene (RIDL), are designed to reduce mosquito populations temporarily and require continuous releases to maintain their effects (Alphey, 2014). On the other hand, self-sustaining systems, such as those utilizing homing endonuclease genes (HEGs) and gene drives, aim to spread genetic modifications throughout the mosquito population permanently, potentially leading to long-term suppression or replacement (Williams et al., 2020). 3.2 Population suppression Population suppression strategies focus on reducing the number of mosquitoes in a given area. Traditional methods like SIT involve releasing sterilized male mosquitoes to mate with wild females, resulting in no offspring and a subsequent decline in the mosquito population. Modern genetic approaches have improved upon this by using techniques such as RIDL, where mosquitoes are genetically engineered to carry a dominant lethal gene that causes death in offspring, thereby reducing the population more effectively. Another promising method involves
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