Molecular Soil Biology 2024, Vol.15, No.3, 140-150 http://bioscipublisher.com/index.php/msb 146 biological control methods, such as the use of entomopathogenic nematodes and beneficial bacteria, have been found to be more selective, targeting WCR larvae while minimizing harm to non-target species. These biological agents can coexist with beneficial soil organisms, thereby preserving the ecological functions they perform. 7.3 Environmental concerns and mitigation measures The environmental concerns associated with the use of soil insecticides for WCR management are multifaceted. The persistence and mobility of these chemicals in the soil can lead to contamination of water bodies through runoff and leaching, posing risks to aquatic ecosystems and human health. Additionally, the development of insecticide resistance in WCR populations necessitates the use of higher doses or more potent chemicals, exacerbating environmental impacts (Meinke et al., 2021). To mitigate these concerns, integrated pest management (IPM) strategies that combine chemical, biological, and cultural control methods are recommended. Crop rotation, for instance, has been shown to effectively reduce WCR populations without the need for insecticides, thereby minimizing environmental impacts. Furthermore, the adoption of biological control agents, such as entomopathogenic nematodes and beneficial bacteria, offers a sustainable alternative that can reduce reliance on chemical insecticides while promoting soil health and biodiversity (Jaffuel et al., 2019). Implementing these IPM strategies can help balance effective WCR management with environmental conservation. 8 Integrated Pest Management (IPM) Strategies 8.1 Role of soil insecticides within an IPM framework Soil insecticides play a crucial role within an Integrated Pest Management (IPM) framework for controlling the Western Corn Rootworm (WCR). These insecticides are often used as a complementary tactic alongside other management strategies to manage annual densities of WCR and mitigate crop injury. Historically, the extensive use of soil and foliar insecticides has led to the evolution of resistance in WCR populations, necessitating their integration with other IPM tactics to delay resistance development and maintain their efficacy. Field studies have shown that soil-applied insecticides can significantly reduce WCR larval density and root damage, leading to increased maize yield. However, the over-reliance on chemical control methods alone can lead to resistance, making it essential to incorporate these insecticides within a broader IPM strategy that includes crop rotation, biological control, and other cultural practices (Blandino et al., 2017). 8.2 Combining chemical, biological, and cultural control methods Combining chemical, biological, and cultural control methods is essential for effective WCR management within an IPM framework. Crop rotation has been identified as one of the most effective cultural practices for reducing WCR populations below damage thresholds without the need for insecticides. Biological control methods, such as the application of entomopathogenic nematodes and beneficial soil organisms like arbuscular mycorrhizal fungi and Pseudomonas bacteria, have shown promise in reducing WCR damage and enhancing maize yield. These biological agents can be used in conjunction with chemical treatments to provide a more sustainable and environmentally friendly approach to pest management. For instance, the combined application of soil insecticides and biological agents has been found to be as effective as chemical treatments alone, offering a viable alternative for WCR control6. Integrating these methods can optimize pest control, reduce the risk of resistance development, and minimize environmental impacts (Meinke et al., 2021). 8.3 Case studies of successful IPM programs for WCR management Several case studies have demonstrated the success of IPM programs in managing WCR populations and improving maize yield. In Italy and Croatia, long-term surveys and field research have shown that crop rotation, both structural and flexible, effectively keeps WCR populations below damage thresholds without the need for insecticides (Furlan et al., 2022). Another successful example is the use of entomopathogenic nematodes and beneficial soil organisms in Missouri, USA, where these biological agents significantly reduced root damage and increased grain yield in WCR-infested maize fields (Figure 3) (Jaffuel et al., 2019). Additionally, a meta-analysis of insecticide efficacy trials in Indiana, USA, highlighted the importance of integrating neonicotinoid seed treatments with other IPM strategies to manage WCR effectively while reducing costs and minimizing non-target
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