Effects Of Two Rice Black-Streaked Dwarf Viruses On Vector And Non-Vector Planthoppers And Their Natural Enemies

Rice black-streaked dwarf virus (RBSDV) and Southern rice black-streaked dwarf virus (SRBSDV), transmitted by the small brown planthopper (SBPH), Laodelphax striatellus (Fallen) and white-backed planthopper (WBPH), Sogatella furcifera (Horvath) respectively, caused devastating diseases in rice and maize, had a great threat to rice production every year in China. And both of them, had great effects on the communities of arthropods in rice paddy ecosystems by changing the morphological and physiological-biochemical characteristics of rice plants. In this paper, the changes of nutrition substances and volatile profiles of rice plants infected with RBSDV and SRBSDV, the effects of rice plants infected by RBSDV and SRBSDV ecological fitness of vector and non-vector planthoppers and their natural enemies were determined. The major findings are as follows:1. The individual and total amino acid contents in rice plants infected with RBSDV were higher than those in healthy rice plants. And the content of soluble sugar in rice plants infected by RBSDV was about three times higher than that in healthy plants (P<0.001). However, there was no significant difference between the rice plants infected with SRBSDV and the control.2. The non-vectors, brown planthopper (BPH), Nilaparvata lugens (Stal) and WBPH, benefited from RBSDV-infected rice plants. The BPH population increased on the RBSDV-infected plants and the activities of defensive enzymes and detoxification enzymes in BPH were markedly higher than those on the healthy rice plants. The similar results were record on WBPH, though there was no obvious difference. There were similar trends in rice paddy field with natural condition.3. There were no significant changes on the developmental duration, body weight of female adults of WBPH infected with SRBSDV and the control. However, the fecundity of female adults and the hatchability of eggs of WBPH decreased significantly when both of the female and male were infected with SRBSDV, and there was no markedly difference when only the female or the male infected with the virus. The feeding behavior of WBPH changed after being infected with SRBSDV. It had a higher phloem sap ingestion frequency, while the total feeding time did not change obviously.4. The vector, WBPH, feeding on the SRBSDV-infected rice plants, had a higher fecundity than those on healthy plants (P=0.042), and the population of next generation improved. However, the longevity of non-vector, BPH, was shortened. There was no significant effect on the BPH population, though the hatchability of BPH eggs increased obviously (P=0.010). The starvation tolerance of WBPH and the sensitivity of BPH to temperature on the SRBSDV-infected rice plants decreased.5. The parasitic capability of Anagrus nilaparvatae was enhanced on the RBSDV-infected plants, while no difference was recorded in its ecological fitness. The "Y"-tube olfactometer was used to evaluate the preference of Anagrus nilaparvatae to various odors from rice plants infected with SRBSDV and the healthy plants and the results showed that Anagrus nilaparvatae preferred the plants with BPH eggs to the clean plants. However, when there were enough BPH eggs, no obvious difference was found between the healthy rice plants and SRBSDV-infected plants. Furthermore, the longevity of Anagrus nilaparvatae was not affected by the honeydew from healthy plants or infected plants.6. There were differences in the kinds and contents of the volatiles between SRBSDV-infected plants and healthy plants. In total,24kinds of volatile compounds were identified which were aldehydes, alcohols, alkanes and esters, respectively, and there were20kinds of them in RBSDV-infected rice plants and23in the healthy plants. In addition, octanal, undecane (H), methyl salicylate and hexadecane were absent in the RBSDV-infected plants, and tridecanal only existed in it.