Triazophos‐induced vertical transmission of rice stripe virus is associated with host vitellogenin in the small brown planthopper Laodelphax striatellus

Abstract

BACKGROUND Rice stripe virus (RSV) is one of the most serious rice diseases in East Asia. The small brown planthopper (SBPH), Laodelphax striatellus, is an economically important rice pest. SBPH transmits RSV horizontally and vertically, resulting in serious rice economic losses. Exposure to sublethal doses of insecticides can induce many physiological and cellular changes in insects. However, the mechanism underlying triazophos‐induced RSV vertical transmission remains unclear. Here, we investigated the role of vitellogenin (Vg) in triazophos‐induced RSV vertical transmission. RESULTS RSV vertical transmission rates were significantly induced by sublethal exposure to triazophos. The transcript abundance of viral RNA3 segment (RNA3) and capsid protein (CP) in the ovaries of SBPH were also significantly increased. Triazophos induced the expression level of Vg in L. striatellus (LsVg) and increased the contents of ovarian protein and fat body protein. Knockdown of Vg significantly reduced the expression levels of LsVg and Vg receptor (LsVgR), and decreased RSV accumulations in the ovaries. Double‐stranded Vg (dsVg)‐mediated down‐regulation could be rescued by exposure to triazophos. Vertical transmission rate of the dsVg‐injected group was significantly decreased compared with the dsGFP‐injected group, and triazophos significantly rescued the RSV vertical transmission rate of the dsVg‐injected group. CONCLUSION Our results indicate that triazophos‐induced RSV vertical transmission is associated with Vg. This work will help us to further elucidate sublethal doses of insecticides‐mediated effects and develop new strategies for pest control. © 2019 Society of Chemical Industry

Sublethal Effects of Imidacloprid on Fecundity, Apoptosis and Virus Transmission in the Small Brown Planthopper Laodelphax striatellus

“…Thus, our study measured the expression levels of RNA3 and CP, and they were both up-regulated significantly by the LC 10 dose of imidacloprid, whereas decreased by the LC 30 dose of imidacloprid. These results are generally consistent with the recent study which showed that after treatment with LC 20 to LC 50 of triazophos, the transcript levels of RNA3 and CP were significantly stimulated in the RSV-carrying SBPH [50]. These results showed that low concentrations of insecticides could increase RSV viral load in viruliferous SBPH.…”

“…Previous studies showed that the transcript level of Vg and VgR was up-regulated in insects exposed to sublethal doses of insecticides. In SBPH, Vg and VgR mRNA expressions were increased in the females exposed to sublethal doses of triazophos [50]. In Nilaparvata lugens, the transcript level of Vg was significantly increased by low doses of deltamethrin and triazophos [59].…”

“…Our results indicated that the vertical transmission rate of RSV in SBPH was partly stimulated by the LC 10 dose of imidacloprid, but no significant differences occurred. However, a recent study has indicated that the vertical transmission rates of RSV were significantly induced by sublethal doses of triazophos in SBPH [50]. The mRNA expression level of CP gene or viral RNA3 segment is used to reflect viral load and has been widely applied to quantify RSV accumulations in SBPH [67].…”

“…When the nymph hatched about 24 h later, they were transferred into glass cups containing new rice seedlings. When the nymphs grew to the third instar, they were used for RSV detection, and the vertical transmission rate refers to the proportion of viruliferous individuals in the total number of offspring [50].…”

Decoyinine Induced Resistance in Rice against Small Brown Planthopper Laodelphax striatellus

“…In the laboratory, SBPH was reared using the rice variety Wuyujing-3, provided by China National Rice Research Institute, Hangzhou, China. SBPH were reared continuously in the laboratory and were raised in plastic frame cages (50 cm (L): 50 cm (W): 30 cm (H)) in an artificial climate chamber (27 ± 1 • C, 70-80% (RH) and 14:10 h light: dark (L:D)) on paddy seedlings (10 ± 5 days) [52]. Cages were made of nylon mesh cloth, having a zippered entrance on one side.…”