Eri silkworm eggs as a superior factitious host for mass rearing Trichogramma leucaniae, the key natural enemy of soybean pod borer

Abstract

The soybean pod borer (SPB), Leguminivora glycinivorella (Matsumura), is a major constraint to soybean production, highlighting the urgent need for effective and sustainable biological control strategies in this short-lasting agroecosystem. Trichogramma leucaniae Pang & Chen has been a promise as a biocontrol agent, its conventional mass rearing on Chinese oak silkworm (Antheraea pernyi Guérin Méneville) eggs faces challenges such as inconsistent performance and declining parasitism rates over generations. Addressing these limitations, this study evaluates the adaptability of T. leucaniae to to eri silkworm (ES), Samia ricini Willian Jones eggs across ten generations (F1–F10), offering a novel approach to enhance biocontrol practices in annual soybean cropping systems. Our results demonstrate significant improvements in parasitoid performance, with parasitism and emergence rates increasing from 43.33% and 46.7% in F1 to 90.0% and 86.7% in F10, respectively. The rearing system achieved stability in critical biological parameters, including pre-emergence time, adult emergence per egg, and sex ratio, with female proportions exceeding 90.0% after F5. Notably, the number of adults unemerged/egg decreased significantly across generations, indicating enhanced rearing efficiency. Comparative analyses demonstrated that T. leucaniae reared on ES eggs exhibited comparable performance to those reared on A. pernyi eggs, while significantly outperforming those reared on rice moth (Corcyra cephalonica Stainton) eggs in parasitizing SPB eggs across various developmental stages. This study establishes ES eggs as a superior factitious host for the sustainable mass production of T. leucaniae. Our findings offer a practical solution to enhance biological control strategies of SPB in soybean agroecosystems, contributing to the broader goal of sustainable pest management in short-lasting cropping systems.

Keywords

• Leguminivora glycinivorella
• Egg parasitoids
• Host suitability
• Samia ricini
• Soybean pests