Combined influence of Bt rice and rice dwarf virus on biological parameters of a non-target herbivore, Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae)

Abstract

The advent of genetically modified (GM) Bt rice creates the possibility of interactions among Bt crops, crop pathogens and non-target herbivores. In particular, information on how pathogen-infected Bt-expressing plants will influence non-target herbivores is necessary to predict the sustainability of GM cropping systems. Laboratory bioassays were conducted to evaluate the potential combined impacts of rice dwarf virus (RDV) and two Bt rice lines, T1C-19 (Cry1C) and T2A-1 (Cry2A), on non-target green rice leafhopper (GRLH), Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae). In the first experiment, GRLHs feeding preference tests on Bt rice lines compared to a parental control rice line, MH63, were conducted. As rice plants were uninfected with RDV, GRLHs generally preferred the control MH63 line over the two Bt lines during the initial 8 h, with no significant preference during the following 64 h. As rice plants were infected with RDV, there were no clear preferences between the Bt rice lines and the control MH63 line. In the second experiment, we assessed the combined influence of RDV-infection status and Bt rice lines on GRLH biological parameters. Egg duration, adult weights, and male adult longevity were significantly affected on RDV-infected Bt rice. Other parameters, egg hatching rate, nymph survival and fecundity were not significantly influenced. We infer that interaction effect among two testing Bt rice lines and RDV will not lead to enlarged pest populations, thus demonstrating that growing these two Bt rice lines will poses negligible risk to GRLH in sustainable rice agroecosystems. Long-term field experiments to monitor the population dynamics of GRLHs at large scale need to be carried out to confirm the current results.

Cry1C rice doesn’t affect the ecological fitness of rice brown planthopper, Nilaparvata lugens either under RDV stress or not

“…Meanwhile, BPH showed no feeding and oviposition preference between Bt rice T1C-19 and its non-Bt parental rice MH63 under RDV-free or RDV infection status (Fig. 1a), which is similar to the previous study on GRLHs 19 . In general, our results indicated www.nature.com/scientificreports/ that rice type and RDV infection status had no effect on feeding and oviposition preference of BPH (Figs.…”

“…Southern rice black-streaked dwarf virus (SRBSDV)-infected T1C-19 or T2A-1 had little effects on the ecological adaptability of the non-vector insect BPH 18 . Main biological parameters of vector insect GRLHs such as egg hatching rate, nymph survival and female fecundity were also not affected by RDV (rice dwarf virus)-infected T1C-19 and T2A-1 19 .…”

“…Rice dwarf virus (RDV), a member of the genus Phytoreovirus in the family Reoviridae, is mainly transmitted by GRLHs in a persistent-propagative manner 19 . GRLHs acquire the virus by feeding on RDV-infected rice plants for a few minutes to several days.…”

Rice dwarf virus infection alters green rice leafhopper host preference and feeding behavior

“…The field was founded in 2010 and RDV-infection has not been reported for this site. Stock cultures were maintained on TN1 (Taichung Native 1) seedlings for 3–4 generations within 80-mesh cages (50 cm 3 ) in the climate chamber under our standard conditions, 27 ± 1ºC, 75 ± 5% relative humidity, a 14L:10D photoperiod and light intensity of 3, 500–4, 000 lux [ 22 ].…”

“…To obtain viruliferous GRLHs, non-viruliferous nymphs were confined with RDV-infected TN1 rice seedlings for 2 d (acquisition access period), and then transferred individually to one RDV-free TN1 rice seedling cultured in Kimura solution B [ 23 ] in a plastic tube (D = 2.5 cm, H = 25 cm), which was given a reference number. Two days later (inoculation period), each rice seedling was separately transplanted in the glasshouse with its reference number and was replaced with new rice seedlings age 10 ± 2 d for the same leafhopper [ 22 ]. Ten days later (virus latent period), the GRLHs were individually collected according to their reference number from plants with characteristic RDV symptoms [ 24 ].…”