Parasitism and Suitability of <i>Trichogramma chilonis</i> on Large Eggs of Two Factitious Hosts: <i>Samia cynthia ricini</i> and <i>Antheraea pernyi</i>

• Published in: Insects
• Main Authors: Yue-Hua Zhang, Ji-Zhi Xue, Talha Tariq, Tian-Hao Li, He-Ying Qian, Wen-Hui Cui, Hao Tian, Lucie S. Monticelli, Nicolas Desneux, Lian-Sheng Zang
• Format: Article
• Language: English
• Published: MDPI AG 2023-12-01
• Subjects: parasitoid; mass rearing; fitness; eri silkworm; biological control
• Online Access: https://www.mdpi.com/2075-4450/15/1/2

<i>Trichogramma</i>, an effective biological control agent, demonstrates promise in environmentally sustainable pest management through its parasitic action toward insect eggs. This study evaluates the parasitism fitness and ability of <i>T. chilonis</i> with regard to two factitious host eggs, aiming to develop a cost-effective biological control program. While <i>T. chilonis</i> demonstrated the ability to parasitize both host eggs, the results indicate a preference for ES eggs over COS eggs. The parasitism and emergence rates of <i>T. chilonis</i> regarding ES eggs (parasitism: 89.3%; emergence: 82.6%) surpassed those for COS eggs (parasitism: 74.7%; emergence: 68.8%), with a notable increase in the number of emergence holes observed in the ES eggs compared to the COS eggs. Moreover, the developmental time of <i>T. chilonis</i> for ES eggs (10.8 days) was shorter than that for COS eggs (12.5 days), resulting in a lower number of dead wasps produced. Notably, no significant difference was observed in the female ratios between the two species. A comprehensive analysis was conducted, comparing the size and shell thickness of the two factitious hosts. The ES eggs exhibited smaller dimensions (length: 1721.5 μm; width: 1178.9 μm) in comparison to the COS eggs (length: 2908.8 μm; width: 2574.4 μm), with the ES eggshells being thinner (33.8 μm) compared to the COS eggshells (47.3 μm). The different host species had an effect on the body length of the reared parasitoids, with <i>T. chilonis</i> reared on COS hosts exhibiting a larger body length (female: 626.9 µm; male: 556.7 µm) than those reared on ES hosts (female: 578.8 µm; male: 438.4 µm). Conclusively, the results indicate that ES eggs present a viable alternative to COS eggs for the mass production of <i>Trichogramma</i> species in biological control programs.