## 4 Selection of Host Species
### Environmental Conditions  
Environmental conditions are crucial for the cultivation and biological activity of _C. militaris_, a valued medicinal fungus. Temperature is fundamental to fungal metabolism and development, with an optimal range of 18 \({}^{\circ}\)C to 25 \({}^{\circ}\)C fostering robust growth and fruiting body production. Deviations from this range can impair metabolic activity and development, affecting polysaccharide content and cordycepin production, where higher temperatures may accelerate metabolism but degrade sensitive compounds [71]. Relative humidity (RH) should be maintained at 80-95% to prevent mycelial desiccation and support healthy fruit body development, as lower humidity leads to a dry substrate and higher moisture can encourage contaminant growth [68]. Light exposure also plays a critical role, with a required photoperiod of 12 h of light and 12 h of darkness to promote optimal morphogenesis and secondary metabolite synthesis [50]. Substrate quality, encompassing nutrient composition and physical properties like porosity and water-holding capacity, is essential for nutrient uptake and efficient gas exchange, crucial for mycelial growth [72]. The interplay between these environmental factors can compound their effects, such as the interaction between temperature and humidity influencing water evaporation and consequently mycelial growth rates and fruiting body development [73]. For commercial cultivation, understanding and optimizing these environmental conditions are paramount, as they directly impact yield, fruit body quality, and bioactive compound production. Advanced cultivation facilities often employ automated systems to monitor and adjust these parameters, ensuring consistent product quality and reducing the risk of crop failure due to environmental fluctuations. Future research should focus on refining these parameters to enhance cultivation techniques and yields, particularly in controlled environment agriculture settings, to maximize the medicinal potential of _C. militaris_.  
Traditional isolation methods for _C. militaris_ often involve culturing surface sterilized internal tissues from wild fruit bodies or infected insects on nutrient media such as potato dextrose agar (PDA) or malt extract agar (MEA). Although straightforward, these methods are prone to significant contamination risks, which can lead to variability in the genetic and metabolic profiles of the isolates, potentially compromising their utility in research and commercial applications [74]. An alternative approach involves spore isolation from mature fruit bodies, offering the advantage of selecting genetically diverse strains beneficial for breeding programs. However, this technique also presents contamination challenges from unwanted microorganisms [75]. To mitigate these risks, rigorous sterilization procedures, such as treating fruit bodies with ethanol or sodium hypochlorite followed by rinsing with sterile water, are essential. Performing the isolation process within a laminar flow hood further minimizes airborne contaminants. The use of selective media that inhibits the growth of common contaminants while promoting the growth of _C. militaris_ spores, along with the incorporation of media supplements like antibiotics or antifungal agents, can enhance the purity of the isolates [76]. Modern techniques such as single-spore iso lation, hyphal tip culture, and flow cytometry with cell sorting offer more precise and high-throughput options, ensuring genetic uniformity, minimizing contamination, and facilitating the selection of traits like high metabolic activity or stress resistance [33; 77].