Journal of Mosquito Research 2024, Vol.14, No.2, 67-75 http://emtoscipublisher.com/index.php/jmr 71 Poulin and Lefebvre (2018) revealed that the impact of Bti on non-target organisms in wetland ecosystems, especially Chironomidae populations, may indirectly affect high-trophic-level organisms such as birds and bats that rely on these non-target organisms as food sources, thereby having a negative impact on ecosystem service functions. This impact is mainly reflected in the change of food web structure, which may weaken the self-purification capacity and biodiversity of wetland ecosystems. Kästel et al. (2017) emphasized that the sensitivity of non-target organisms to Bti varies with age, such as chironomid larvae, and the changes in their population structure after Bti treatment may affect ecosystem service functions, such as the decomposition of organic matter in water bodies and nutrient cycling processes. These changes may lead to the weakening of ecosystem service functions, affecting water purification and soil fertility maintenance. Although Bti is highly effective and target-specific as a mosquito control tool, its long-term and large-scale application needs to consider its potential impact on ecosystem services. Future research should pay more attention to the impact of Bti application on ecosystem services, especially in biodiversity-rich and ecologically sensitive areas, to promote the rational and sustainable use of Bti. 3 Challenges and Management Strategies 3.1 Risk of mosquito resistance to Bti developing Bacillus thuringiensis var. israelensis (Bti) for mosquito control worldwide, the emergence of mosquito resistance to Bti has attracted the attention of the scientific community. Although Bti is considered a relatively safe biological control method for non-target organisms, the emergence of resistance not only reduces the control effect of Bti, but may also force the use of more chemical insecticides, thereby bringing additional environmental and health risks. Bonin et al. (2015) found 16 QTL regions associated with Bti resistance in a study of dengue and yellow fever vector mosquitoes, Aedes aegypti, through quantitative trait loci (QTL) and mixed analysis. Four of these QTL regions were revealed in different analysis methods, explaining 29.2% and 62.2% of the phenotypic variance in the cross between the two QTLs. This study not only reveals the complexity of Bti resistance that may involve simultaneous variation in multiple genes, but also provides important genetic markers for in-depth understanding and management of resistance. Becker et al. (2018) conducted a study on Aedes vexans in the Upper Rhine Valley region of Germany, where Bti has been used for mosquito control for 36 years. They found that despite using almost 5,000 tonnes of the Bti formula during this long-term application, no increase in resistance to Bti was detected between Aedes vexans larvae in treated and untreated areas. This finding has important implications for assessing the sustainability of long-termBti use and monitoring resistance development. Stalinski et al. (2016) revealed that the impact of Bti on mosquitoes may involve changes in mosquito physiological responses. They found that the gene expression levels of 11 alkaline phosphatases (ALPs) were significantly changed in Bti-treated mosquito larvae, and that in four Bti-resistant Cry toxin or Bti-treated mosquito strains, these The activity of ALPs is reduced. This indicates that ALPs plays a key role in the toxicological effects of Bti toxins, and its changes may be related to the development of mosquito resistance to Bti. 3.2 Strategies to manage and delay the development of resistance Managing and delaying the development of resistance to Bacillus thuringiensis var. israelensis (Bti) is key to ensuring its continued effectiveness. Multi-toxin strategy and gene deposition, bioassay and genetic analysis, application of refuge and rotation strategies, and synergistic effects of Cyt1Aa and Bin toxins can effectively delay the development of mosquito resistance to Bti through these integrated management strategies, ensuring the long-term effectiveness and sustainability of Bti as a biological control measure.
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