Optimizing artificial induction and standardized production of egg branches for <i>Cryptotympana atrata</i> in poplar plantations

The golden cicada (Cryptotympana atrata) is an economically important insect in China, but the expansion of its artificial cultivation is limited by an unstable supply of high-quality egg branches used for propagation. To develop a standardized system for egg-branch production, we evaluated the effects of nymph release density on emergence and oviposition performance in a managed poplar plantation in Henan Province (tree age: 3 years; row and column spacing: 4 m × 4 m). Four release densities were established: 48, 16, 6, and 2 nymphs per tree. We recorded emergence rates, crawling height, spatial distribution of emergence and oviposition branches, branch length, and egg number. Emergence exceeded 90% in all treatments and was highest at the greatest release density, reaching 96.35%. Mean crawling height also showed a density-associated gradient, with higher values in high-density regions. The spatial distribution of egg branches closely matched the distribution of emerged individuals, and egg-branch yield reached a maximum at the highest release density, indicating strong spatial continuity. In contrast, branch length and egg numbers per branch did not differ significantly between artificial poplar stands and wild poplar hosts, maintaining a positive relationship between branch length and egg load under both conditions. These results demonstrate that the high-density release of C. atrata nymphs in poplar plantations can improve emergence efficiency and egg-branch yield without altering key oviposition traits. A release density of 48 nymphs per tree is recommended for large-scale standardized production, providing a practical technical basis for commercial cultivation.