Samia ricini: The promising large host eggs outclass Antheraea pernyi for rearing Trichogramma species

Trichogramma, a globally recognized egg parasitoid, plays a pivotal role in the biological control of lepidopteran pests. However, its mass production relies heavily on the large eggs of the Chinese oak silkworm (Antheraea pernyi Guérin-Méneville, COS), which poses a limitation due to varying compatibilities among different Trichogramma species. This study investigates the potential of Eri silkworm (Samia ricini William Jones, ES) eggs as an alternative host by evaluating the performance of 6 Trichogramma species (T. chilonis, T. dendrolimi, T. japonicum, T. leucaniae, T. ostriniae, and T. pretiosum). The suitability of ES eggs for Trichogramma rearing was demonstrated through significant improvements in key fitness parameters. Notably, T. leucaniae and T. ostriniae exhibited higher parasitism rates on ES eggs (45% and 64%, respectively) compared to COS eggs (32% and 41%). Additionally, T. japonicum, which failed to parasitize COS eggs, achieved an 18% parasitism rate on ES eggs. Both T. chilonis and T. dendrolimi showed remarkable performance on ES eggs, with parasitism and emergence rates exceeding 80%. Furthermore, females reared on ES eggs demonstrated superior reproductive potential, including enhanced longevity and fecundity, compared to those reared on COS eggs. This study highlights ES eggs as a highly promising factitious host for the mass production of Trichogramma species. Their broad compatibility and ability to enhance parasitoid fitness underscore their potential to revolutionize biocontrol strategies against lepidopteran pests in agriculture and forestry.