The development and reproduction of the fall armyworm (FAW), Spodoptera frugiperda, which were reared on artificial diets containing nano-graphene oxide (GO), were determined based on age-stage, two-sex life table analysis. The results showed that GO had adverse effects on FAWs. Compared with the control, the duration of the egg stage and first, second, and sixth instar larval stages increased with increasing GO concentrations; however, the lifespan of male and female adults decreased with increasing GO concentrations. Weights of FAW pupae that were supplied with GO-amended diets increased by 0.17–15.20% compared to the control. Intrinsic growth, limited growth, and net reproductive rates of FAWs feeding on GO supplemented diets were significantly lower than the control, while mean generational periods (0.5 mg/g: 38.47; 1 mg/g: 40.38; 2 mg/g: 38.42) were significantly longer than the control. The expression of genes encoding vitellogenin (Vg) and vitellogenin receptor (VgR) expression was abnormal in female FAW adults feeding on GO-amended diets; the number of eggs laid decreased relative to the control, but Vg expression increased. In conclusion, GO prolonged the developmental period of FAWs, decreased fecundity, and led to a decline in the population size. The study provides a basis for the rational use of GO as a pesticide synergist for FAW control.

This study focuses on the regulatory effects of genes encoding the juvenile hormone (JH) receptor methoprene-tolerant (Met) and transcription factor krüppel homolog 1 (Kr-h1) on the reproductive capacity of Coccinella septempunctata male adults. Met and Kr-h1 expression levels were analyzed in males fed on artificial diets with and without JH by quantitative real-time PCR, and the effects of Met and Kr-h1 on male reproduction were analyzed by RNA interference technology. Met transcription levels in 5- and 10-day-old males fed with a JH-supplemented diet were lower than those without JH. Kr-h1 expression in 5-day-old adult males was lower in diets lacking JH but was higher in 10-day-old males fed on a diet lacking JH. There were no significant differences in the testes sizes of male ladybugs injected with Met-dsRNA when compared to GFP-dsRNA; however, the testis volume of ladybugs injected with Kr-h1-dsRNA was smaller than those injected with GFP-dsRNA. After males were injected with Met-dsRNA and Kr-h1-dsRNA, the mean egg production by females decreased by 12.75% and 23.10%, respectively, at 20 d postinjection. Our results show that Met and Kr-h1 have important roles in regulating reproduction by directly affecting testes development in males and egg production in females.

The effects of the gene encoding the ecdysone receptor (EcR) on the reproduction of the ladybug Coccinella septempunctata was evaluated. EcR transcription was measured by quantitative real-time PCR in ladybug adults reared on artificial diets with and without 20-hydroxyecdysone (20E). EcR expression levels in 5 d old male and female ladybugs supplied with the 20E-amended artificial diet were lower than expression levels in ladybugs reared on an artificial diet lacking 20E. However, EcR expression levels in 10 d old ladybugs supplied with the 20E artificial diet were higher than those lacking 20E supplementation. The regulatory effects of EcR were studied in female and male ladybugs by RNA interference. EcR expression in female ladybugs injected with EcR-dsRNA was significantly downregulated after 5 d but remained unaffected in 10 d old females. EcR expression levels in males microinjected with EcR-dsRNA were significantly lower at 5 and 10 d after microinjection than GFP-dsRNA-treated males. The ovary volume in females injected with EcR-dsRNA at 5 d was smaller than females microinjected with GFP-dsRNA, but volumes at 10 d were larger than in GFP-dsRNA-treated females. The testes of males injected with EcR-dsRNA were larger than those injected with GFP-dsRNA at 5 d but the testes at 10 d after injection with EcR-dsRNA were smaller than those injected with GFP-dsRNA. When females were microinjected with EcR-dsRNA and mated with noninjected males, egg production decreased by 34.80% for 20 days. When males were microinjected with EcR-dsRNA and mated with noninjected females, egg production decreased by 30.38% for 20 days. Injection of female and male ladybugs with EcR-dsRNA had no significant effect on egg hatching rates. Our results show that EcR plays an important role in the development of reproductive organs and egg development in C. septempunctata.

The gene encoding juvenile hormone transcription factor Krüppel homolog 1 (Kr-h1) was studied for its effects on ovary development and reproduction in the ladybug beetle, Coccinella septempunctata. Kr-h1 expression in C. septempunctata was evaluated in females supplied with a juvenile hormone (JH) amended diet using quantitative PCR, and the function of Kr-h1 in female reproduction was assessed using RNAi technology. Expression of Kr-h1 in females supplied with a JH diet was significantly higher at 5 and 10 d than in females not supplied with JH. At 5 and 10 d post-injection with Kr-h1-dsRNA, Kr-h1 expression levels were 30.97% and 38.32% lower, respectively, than expression in controls injected with GFP-dsRNA. Development of ovaries and vitellogenesis in ladybugs microinjected with Kr-h1-dsRNA was significantly delayed in comparison to controls. At 20 d post-injection, mean egg production decreased by 28.74% relative to controls. These results prove that Kr-h1 has a vital role in modulating ladybug fecundity by impacting ovary development and egg production.

In this study, transcriptomic and proteomic analyses were used to identify genes encoding seminal fluid proteins in Coccinella septempunctata L. A total of 65 SFPs domains containing secretory signal peptides were identified, including trypsin, Kazal_2, His_Phos_2, Peptidase_M14, lipase, Kunitz_BPTI, Ribonuc_2-5A, and Gly-co_transf_90; an additional 22 signal peptide-containing domains were identified that lacked annotations in the Pfam database. Transcript levels of the 65 SFPs accounted for 87.58% of the total expression levels of 211 specifically expressed proteins in the male reproductive tract (MRT). RNA interference (RNAi) was used to analyze the function of the SFP trypsin. RNAi-mediated knockdown of the seminal fluid trypsin gene in male C. septempunctata, followed by mating with females, significantly reduced female fecundity and egg hatching rates. This study enriches our knowledge of insect SFPs and provides a theoretical basis for the artificial rearing of C. septempunctata.