## 2 Host Diversity for _Cordyceps militaris_ Cultivation  
The cultivation of _C. militaris_, a fungus known for its significant medicinal properties, involves utilizing various host species, ranging from natural insect hosts to artificial substrates. The choice of host species plays a critical role in influencing fungal growth, bioactive compound production, and overall yield. Traditionally, _C. militaris_ parasitizes various insects, particularly those belonging to the orders Lepidoptera, Coleoptera, and Hymenoptera. These natural hosts provide unique biochemical environments that facilitate fungal development and the synthesis of key metabolites, essential for the fungus's therapeutic effects [19]. However, the reliance on natural insect hosts presents ecological and ethical concerns, prompting the exploration of alternative substrates that could sustain large-scale cultivation while maintaining or enhancing bioactive compound production (Table 1). Lepidoptera hosts, such as the ghost moth, are particularly rich in lipids and proteins, which are conducive to substantial fungal growth and high cordycepin levels--a compound known for its anti-cancer and immunomodulatory properties [2]. Similarly, Coleoptera, like beetles, contribute a chitinous exoskeleton that supports the production of chitinase, an enzyme crucial for fungal structural integrity and immune-enhancing effects [38; 39]. Hymenoptera, including wasps and bees, provide unique fatty acids and sterols that may enhance the pharmacological value of _C. militaris_ extracts [40]. Despite the benefits of these natural hosts, their overharvesting raises sustainability concerns, necessitating the development of alternative substrates such as grains, synthetic media, and plant-based materials. Grains like rice and wheat offer a more sustainable and consistent output, although they typically yield lower levels of key metabolites such as cordycepin compared to insect hosts [37; 41]. Synthetic media, tailored with specific nutrients, allow precise control over growth conditions, facilitating a better understanding of metabolic pathways involved in bioactive compound synthesis [42; 43]. The choice of host species not only impacts the yield of bioactive compounds but also affects the quality and consistency of _C. militaris_ products (Table 2). For example, silkworm pupae are a preferred host due to their nutrient-rich profile, which enhances the production of cordycepin and polysaccharides, compounds known for their anti-inflammatory and \begin{table}
\begin{tabular}{c c c} \hline \hline
**Host Type** & **Impact on Fungal Growth and Bioactive Compounds** & **Ref.** \\ \hline Lepidoptera & Rich in lipids and proteins, conducive to substantial fungal & [33] \\ (e.g., ghost moth) & growth and high levels of cordycepin & [34] \\ \hline Coleoptera & Chitinous exoskeleton aids in producing chitinase, affecting & \\ (e.g., beetles) & anti-inflammatory and anti-tumor activities & [35] \\ \hline Hymenoptera & Supplies unique fatty acids and sterols, enhancing & [36] \\ (e.g., wasps, bees) & pharmacological value & [36] \\ \hline Grains & More sustainable and consistent but yields lower levels of key & [37] \\ (e.g., rice, wheat) & metabolites like cordycepin compared to natural hosts & [37] \\ \hline Synthetic media & Tailored with specific nutrients to control growth conditions, & [38] \\  & enhancing understanding of metabolic pathways & [38] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Impact of host diversity on _C. militaris_ growth and bioactive compound production. immune-boosting properties [44]. In contrast, other hosts like cicadas and beetles present different advantages and challenges. Cicadas are effective in supporting high-quality production, whereas beetles, due to their tougher exoskeletons, may yield lower levels of cordycepin but could produce unique peptides or secondary metabolites [45].