Effects of Corcyra cephalonica Egg Consumption on Population Fitness and Reproduction of the Whitefly Predator Serangium japonicum (Coleoptera: Coccinellidae)

Ladybird beetle, <i>Serangium japonicum</i> (Coleoptera: Coccinellidae), is an important predatory natural enemy of whiteflies, and its mass rearing is crucial for biological control. This study evaluated the suitability of <i>Corcyra cephalonica</i> (Lepidoptera: Pyralidae) eggs as an alternative diet for adult <i>S. japonicum</i> by directly comparing it to the natural prey, <i>Bemisia tabaci</i> (Hemiptera: Aleyrodidae) nymphs. Results showed that, compared to a <i>B. tabaci</i> diet, feeding on <i>C. cephalonica</i> eggs supported normal development and significantly extended the lifespan of adult <i>S. japonicum</i>, without compromising offspring quality (hatching rate, development, survival, or predatory capacity). However, the moth egg diet significantly impaired reproduction, causing delayed ovarian development, reduced vitellogenesis, and altered gene expression: downregulation of methoprene-tolerant, Juvenile hormone acid O-methyltransferase, Vitellogenin, and Vitellogenin receptor, and upregulation of Juvenile hormone esterase and Copper/zinc superoxide dismutase. Practically, this work defines <i>C. cephalonica</i> eggs as a suboptimal but viable supplementary diet for colony maintenance, but unsuitable as a sole diet for mass-rearing reproductively robust populations. Our findings explain the physiological and molecular mechanisms underlying the "reproduction-lifespan trade-off" in <i>S. japonicum</i> induced by feeding on <i>C. cephalonica</i> eggs, providing a mechanistic basis for its rational application in the mass production of natural enemies.