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The rice stripe virus (RSV) is transmitted by the small brown planthopper Laodelphax striatellus in a persistent and circulative–propagative manner. During the last few decades, RSV has caused serious disease outbreaks in rice fields in China. The results of long-term coevolution have led to complex and diverse relationships between viruses and vector insects, and understanding these interactions is critical for the management of diseases and vector organisms. In this study, three groups of comparative experiments were performed to investigate the effects of RSV infection on the reproductive parameters, vitellogenin (Vg), and Vg receptor (VgR) expressions of L. striatellus. The results showed that RSV infection promoted the fecundity, hatchability, and Vg and VgR expressions of L. striatellus but had no effect on the preoviposition period and oviposition period. Furthermore, the RNA interference of the nucleocapsid protein (CP) gene and the injection of the CP antibody in RSV-viruliferous L. striatellus reduced the fecundity, hatchability, and Vg and VgR expressions, further strengthening the hypothesis that RSV may manipulate the reproductive behavior of insect vectors to promote its own transmission. The results of this study can further reveal the interaction mechanism of virus–vector insects in reproduction and virus transmission, and provide new insights for the control of insect-borne viruses.

Laodelphax striatellus is a notorious sap-feeding insect that also serves as a vector of rice stripe virus (RSV) and is responsible for a significant decline in rice yield. Pesticide application remains a crucial strategy for controlling insect pests. In recent years, the utilization of biopesticides has gained attention due to their eco-friendliness and suitability for controlling insect pests and pathogens in agriculture. The present study aimed Figureto evaluate the potential efficacy of a microbial pesticide, decoyinine (DCY), as a seed priming agent in rice against SBPH’s biology, feeding behavior, and RSV transmission ability in the laboratory. Here, we revealed that the body weight of females and males and honeydew extraction of RSV-virulent SBPH were (22.50%, 25.0%, and 23.25%, respectively) significantly lower than non-virulent SBPH. Meanwhile, the fecundity of RSV-virulent SBPH females was significantly higher (8.24%) than non-virulent SBPH. However, nymphal survival and RSV transmission (horizontal and vertical) were found to be non-significantly affected by DCY application. Furthermore, DCY-primed rice seedlings significantly prolonged the time period and frequency of the electrical penetration graph (EPG) feeding waveforms (np, N2, and N3), and also reduced the time period of the waveform (N4-b) for both RSV-virulent and non-virulent SBPH strains with reduced RSV inoculation. The recent study provides new insights for DCY application in rice against SBPH by reducing fecundity, body weight, and honeydew contents, which might contribute to modern integrated pest management.

The brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae) is one of the most destructive rice pests in Asia. The microbial metabolite decoyinine (DCY) has been extracted from Streptomyces hygroscopicus. Recent studies have suggested that treating rice seeds with DCY could improve the growth and yield of rice. To further assess the effects of priming the seeds of different rice varieties with DCY on rice seedling resistance against BPH, an age-stage, two-sex life table and choice test were applied to investigate the individual fitness, population parameters, and preference behavior of BPHs in this study. The results indicated that feeding on rice seedlings grown from seeds primed with DCY significantly affected BPHs’ adult longevity, oviposition period, fecundity, as well as the net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), doubling time (DT), and population size in terms of BPH. The honeydew excretions and the weights of BPHs fed on DCY-pretreated rice plants were remarkably lowered. The two-way ANOVA results also showed that there were significant differences in the biological parameters, honeydew excretions, and of BPH weights owing to DCY treatment, rice variety, and the interactions between DCY treatment and rice variety. Additionally, the feeding and oviposition preferences of BPHs for the pretreated rice plants were reduced. Our results imply that the priming of seeds with DCY can improve rice resistance against BPH, which could facilitate the utilization of seed priming as a new avenue for effective crop protection.

Rice stripe virus (RSV) is transmitted by the small brown planthopper (SBPH), Laodelphax striatellus, in a circulative-propagative manner. Multiple studies have proved that RSV can manipulate vector insects to facilitate its transmission and can alter the gene expressions in viruliferous SBPH. However, to the best of our knowledge, nobody has investigated the gene expressions in the head of SBPH after RSV acquisition. In this study, to investigate the genes and gene functions regulated by RSV infection in the head of SBPH, we used RNA sequencing to compare the transcriptional profiles between SBPH head samples that acquired RSV or not. Compared with the non-viruliferous SBPH, a total of 336 differentially expressed genes (DEGs) were identified in the head samples of viruliferous SBPH groups, including 186 up-regulated and 150 down-regulated genes. Here, we focused on DEGs that may be involved in RSV replication or transmission, primarily genes associated with the nervous system, cytochrome P450s, sugar metabolism, the olfactory system, and cuticular process, as well as genes that have been previously reported to affect virus transmission in insect vectors including ubiquitin-protein ligase (E3), ecdysone response gene (E74A), and vitellogenin receptor (VgR). Finally, we verified the accuracy of the transcriptome sequencing results using qRT-PCR by selecting 16 DEGs. Our results can contribute to the understanding of the effects of RSV infection on gene regulation in the head of SBPH and provide insight into the control of plant virus transmission and insect vectors.