Pesticide-induced changes in fecundity and rice stripe virus transmission ability in Laodelphax striatellus (Homoptera: Delphacidae)

The widespread use of pesticides in rice has caused the resurgence of the small brown planthopper (SBPH), Laodelphax striatellus. In addition to inciting damage by feeding on phloem cells, SBPH also functions as a vector for rice stripe virus (RSV), which can cause serious yield losses. In general, studies focused on pesticide-induced stimulation of SBPH populations have focused on the insects; little information is available on the impact of pesticides on RSV transmission by SBPH. The present study investigated the effects of two pesticides (validamycin and triazophos) on the fecundity and RSV transmission ability of SBPH. Our results demonstrated that the fecundity of non-viruliferous (naive) or viruliferous SBPH was enhanced by exposure to triazophos at the LC20 and validamycin at 200 mg L-1. Meanwhile, the increased number of eggs produced by viruliferous females treated with pesticides was larger than those from naive females. Exposure to validamycin caused an increase in horizontal transmission of RSV; furthermore, vertical viral transmission rates of SBPH were significantly increased by exposure to triazophos. The present study provides valuable information for understanding the mechanisms underlying the resurgence of SBPH and subsequent outbreaks of RSV.