Molecular Soil Biology 2024, Vol.15, No.3, 140-150 http://bioscipublisher.com/index.php/msb 148 2015, all treatments resulted in significant reductions in root damage compared to the control. However, the effectiveness of these treatments varied in subsequent years. By 2016, AMF showed a slightly higher root damage level compared to the other treatments, while in 2017, AMF led to the highest root damage among all treatments. This suggests that while biological control agents can be effective, their impact may fluctuate depending on environmental conditions and WCR pressure, highlighting the need for adaptive management strategies in pest control. 9 Future Directions and Research Needs 9.1 Emerging trends in soil insecticide development and application Recent studies have highlighted the importance of developing and applying soil insecticides in innovative ways to combat the Western Corn Rootworm (WCR). For instance, the application of soil insecticides at different maize planting times has shown significant reductions in WCR larval density and root injury, leading to increased maize yield (Blandino et al., 2017). Additionally, the efficacy of various chemical control strategies, including pyrethroid, neonicotinoid, and organophosphate insecticides, has been evaluated, with seed-applied insecticides like clothianidin and tefluthrin showing promising results in increasing grain yield. However, the emergence of pyrethroid-resistant WCR populations necessitates a multitactical approach to manage resistance and prolong the effectiveness of soil insecticides. 9.2 Advances in biotechnological approaches for WCR control Biotechnological advancements offer promising alternatives to traditional chemical insecticides. RNA interference (RNAi) technology has emerged as a novel method for WCR management. This technology involves maize expressing double-stranded RNA structures that target essential genes in WCR, leading to insect death. The first in planta RNAi product targeting the WCRsnf7 gene, combined with Bt proteins, has been approved for commercial use, marking a significant step forward in species-specific pest management. Additionally, the combined application of beneficial soil organisms, such as arbuscular mycorrhizal fungi, Pseudomonas bacteria, and entomopathogenic nematodes, has shown potential in promoting plant growth and protecting against WCR infestations (Jaffuel et al., 2019). 9.3 Research gaps and priorities for future studies Despite the progress made, several research gaps and priorities need to be addressed to enhance WCR management strategies. One critical area is the need for long-term studies to evaluate the persistence and effectiveness of biocontrol agents like entomopathogenic nematodes in different soil types and climatic conditions (Modic et al., 2020). Furthermore, the impact of root pruning by WCR larvae on nutrient content in maize and its subsequent effects on plant health and yield require further investigation. Another priority is the development of integrated pest management (IPM) strategies that combine crop rotation, biotechnological approaches, and chemical control to sustainably manage WCR populations and reduce reliance on insecticides. Finally, economic evaluations of different pest management approaches, including neonicotinoid seed treatments and other prophylactic insecticides, are essential to determine their cost-effectiveness and guide decision-making for maize producers (Kahler et al., 1985). 10 Conclusion The impact of soil insecticides on Western Corn Rootworm (WCR) and maize yield has been extensively studied, revealing significant findings. Soil insecticides have been shown to effectively reduce WCR larval density and root damage, leading to increased maize yield. For instance, the application of soil insecticides at different planting times resulted in a significant reduction in WCR larval density by 43%, root injury by 65%, and an increase in grain yield by 8%. Similarly, various chemical control strategies, including pyrethroid, neonicotinoid, and organophosphate insecticides, have demonstrated significant reductions in WCR larval density and increases in grain yield, with seed-applied clothianidin and tefluthrin showing yield increases of up to 19%. However, the long-term use of insecticides has led to the evolution of resistance in WCR populations, necessitating the integration of other management tactics.
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