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Spodoptera frugiperda (J.E. Smith) is a crucial agricultural pest owing to its global impact on >300 crops. Among these, the corn strain of S. frugiperda causes significant damage to maize (Zea mays L.). However, limited research exists on the influence of maize nutrients on the metamorphosis of S. frugiperda and the underlying mechanisms. In this study, the effects of different growth stages of maize leaves, namely, tender leaves (tender) and mature leaves (mature), on various aspects of larval development, including body weight, body length, developmental age, pupation rate, and eclosion rate, were investigated. Additionally, we measured the levels of 20-hydroxyecdysone (20E) and three types of juvenile hormone (JH; i.e., JH I–III) in S. frugiperda larvae fed on tender or mature. The results revealed that larvae fed on Tender exhibited significantly prolonged instar duration, reduced body weight and length, and decreased pupation and eclosion rates, with the emergence of abnormal adults. Analysis of nutritional components in maize leaves revealed significantly higher levels of amino acids, soluble sugars, and sterols in mature than in tender. Hormone analysis in S. frugiperda larvae revealed higher 20E titers in individuals feeding on mature during prepupal and pupal stages. We demonstrated the crucial role of sterols in regulating the level of 20E and pupation rate of S. frugiperda. Based on these findings, we propose that isoleucine, arginine, glutamic acid, sucrose, campesterol, and β-sitosterol serve as key nutrients influencing the development of S. frugiperda. Moreover, β-sitosterol is a significant factor influencing the interaction between maize leaves and S. frugiperda. Our research results provide a reference for the control strategy of S. frugiperda based on breeding insect-resistant varieties by altering host nutrition. [ABSTRACT FROM AUTHOR]

Pyriproxyfen (PPF) has been shown to affect the pupal stage and ecdysone levels in holometabolous insects, such as silkworms and mealworms. It remains unknown whether it affects hemimetabolous insects with their hormone levels in insects lacking a pupal stage. In this laboratory study, bioassays were conducted to investigate the effects of varying doses of PPF on Aphis craccivora Koch (Hemiptera: Aphididae). Ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) was used to determine the types and titers of juvenile hormone (JH) and 20-hydroxyecdysone (20E). Additionally, the effects of PPF on A. craccivora reproduction and molting, as well as its influence on relevant gene expression, were examined. The results revealed LC50 and LC90 values of 3.84 and 7.49 mg/l for PPF, respectively, after 48 h of exposure. The results demonstrated a significant reduction in the titer of JH III and a significant increase in the titer of 20E following treatment with PPF. However, there was no significant decrease observed in the titer of JH III skipped bisepoxide (JH SB3). A sublethal concentration of PPF was found to inhibit Krüppel homolog 1 (kr-h 1) gene expression and reduce aphid reproduction, but it did not significantly impact ecdysone receptor expression and aphid molting. The results of this study demonstrate that PPF exhibits a lethal effect on aphids, thereby providing an effective means of control. Additionally, sublethal concentrations of PPF have been found to inhibit the JH in aphids, resulting in a decline in their reproductive ability and achieving the desired control objectives. [ABSTRACT FROM AUTHOR]

Juvenile hormone III (JH III) is a crucial hormone synthesized exclusively as R -stereoisomer in most insects. Herein, we established a mature Tris-HCl culture system for essential biochemical reactions and applied stable instrumental detection methods to analyze JH III, methyl farnesoate (MF) and juvenile hormone acid (JHA) using UPLC-MS/MS. Our results revealed that the R -JH III terminal synthesis pathway in Apis mellifera follows the "esterify then epoxidize" sequence, with precise methyl-(2 E ,6 E )-farnesoate titer regulation and its spatial cis-trans isomerism, achieving selective R -JH III synthesis. Furthermore, we observed that the preferred generation of S / R -JH III chiral enantiomers varied depending on the spatial cis-trans isomerism of different MFs. Our results suggest that S -JH III could theoretically exist in insects, offering a novel perspective for understanding the synthesis mechanism of diverse complex juvenile hormones in different insect species.