The Cydia pomonella granulovirus (CpGV) GP37 has synergistic effects on the infectivity of nucleopolyhedroviruses (NPVs), however, the mechanism employed is unclear. In this study, in vitro and in vivo binding assays indicated that GP37 efficiently bound to the midgut peritrophic membrane (PM) of Spodoptera exigua larvae. Treatment with GP37 led to the damage of the PM’s compacted structure and the generation of the PM perforations, and the enhancement of the PM’s permeability. qPCR results further demonstrated that GP37 increased the ability of occlusion-derived virions (ODV) to cross the PM. R18-labeling experiments exhibited that GP37 also promoted the fusion of ODVs and insect midgut epithelia. Altogether, our present results revealed that the synergistic mechanism of GP37 to the infectivity of NPV might involve two parts. GP37 damaged the integrity of the PM after binding, which enhanced the PM’s permeability and increased the ability of ODVs to cross the PM, finally facilitating the ODVs reaching the midgut. In addition, GP37 promoted the fusion of ODVs and insect midgut epithelia. Our data expand the understanding of the mechanism used by baculovirus synergistic factors and provide a foundation for the development of high-efficiency baculoviral insecticides.

The small brown planthopper (Laodelphax striatellus (Fallén), Hemiptera: Delphacidae), is an important agricultural pest of rice, and neonicotinoid insecticides are commonly used for controlling L. striatellus. However, the sublethal effects of thiamethoxam on L. striatellus remain relatively unknown. In this study, an age-stage life table procedure was used to evaluate the sublethal effects of thiamethoxam on the biological parameters of L. striatellus. Additionally, activities of carboxylesterase, glutathione S-transferase, and cytochrome P450 monooxygenase in the third instar nymphs were analyzed. The results indicated that the survival time of F0 adults and the fecundity of female adults decreased significantly after the third instar nymphs were treated with sublethal concentrations of thiamethoxam (LC15 0.428 mg/liter and LC30 0.820 mg/liter). The developmental duration, adult preoviposition period, total preoviposition period, and mean generation time of the F1 generation increased significantly, whereas the fecundity of the female adults, intrinsic rate of increase (ri), and finite rate of increase (λ) decreased significantly. The oviposition period was significantly shorter for the insects treated with LC30 than for the control insects. Neither sublethal concentrations had significant effects on the adult longevity, net reproduction rate (R0), or gross reproduction rate (GRR) of the F1 generation. The activities of carboxylesterase, glutathione-S-transferase, and cytochrome P450 monooxygenase increased significantly after the thiamethoxam treatments. These results indicate that sublethal concentrations of thiamethoxam can inhibit L. striatellus population growth and enhance detoxification enzyme activities.

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Outbreaks of leaf spot disease occurred in Rehmannia glutinosa fields in Henan Province, China, in 2019, with the incidence ranging from 20% to 40%. R. glutinosa plants with diseased leaves were collected, and 25 isolates were obtained. Pathogenicity tests, morphological observations, and phylogenetic analyses were conducted to identify the pathogens, and the biological characteristics and control agents of the pathogens were studied. Five isolates of pathogenic fungi were isolated. Three isolates were identified as Fusarium equiseti, which is a new pathogen causing R. glutinosa leaf disease; the other two isolates were identified as Fusarium acuminatum. The mycelia of F. equiseti grew fastest on Czapek medium, and the optimal temperature and pH were 25 °C and 10.0, respectively. The mycelia of F. equiseti grew from 5 °C t o 35 °C, and the lethal temperature was 55 °C. The optimal carbon and nitrogen sources were soluble starch and peptone, respectively. Eight fungicides had inhibitory effects on the mycelial growth of F. equiseti and F. acuminatum. Prochloraz had higher activities against F. equiseti and F. acuminatum, with EC50 values of 0.139 mg·L−1 and 0.123 mg·L−1, respectively. These results provide useful information that will aid the development of management strategies to control leaf diseases of R. glutinosa caused by F. equiseti and F. acuminatum.