Effect of rice lines transformed with Bacillus thuringiensis toxin genes on the brown planthopper and its predator Cyrtorhinus lividipennis

Abstract

Five transgenic rice lines, each containing an insecticidal toxin gene from Bacillus thuringiensis (Bt) under control of a different promoter, were tested for effects on two non‐target insects: the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae), and its predator Cyrtorhinus lividipennis (Hemiptera: Miridae). Bt toxin was detected by ELISA in the honeydew of N. lugens that fed on rice lines with the CaMV 35S and actin promoters. Nilaparvata lugens produced greater volumes of acidic honeydew (derived from xylem feeding) on all five Bt rice lines than on non‐transgenic control lines. The amount of honeydew derived from phloem feeding did not differ between Bt and control lines. There were no differences between N. lugens reared on Bt and control lines in any of the five fitness parameters measured (survival to the adult stage, male and female weight, and male and female developmental time). There were no differences between C. lividipennis reared on N. lugens nymphs from Bt and control lines, in any of the three fitness parameters examined (survival to the adult stage and male and female developmental time). Our results indicate that N. lugens and its natural enemies will be exposed to Bt toxins from rice lines transformed with some Bt gene constructs, but that this exposure might not affect N. lugens and C. lividipennis fitness.

Impacts of SixBtRice Lines on Nontarget Rice Feeding Thrips Under Laboratory and Field Conditions

“…These results were in agreement with previous reports that Bt insecticidal protein could be detected in Bt rice-fed N. lugens (Bernal et al 2002, Chen et al 2005) and in Bt rice-fed C. medinalis (Chen et al 2009). Similarly, Bt insecticidal protein could also be transferred from Bt maize to nontarget herbivores such as the aphid Rhopalosiphum padi L. (Hemiptera: Aphididae) (Raps et al 2001) and the thrip Frankliniella tenuicornis (Uzel) (Thysanoptera: Thripidae) (Obrist et al 2005).…”

“…For example, none of the development and reproduction parameters were differed when measured in the brown planthopper, N. lugens, and the white-backed planthopper, S. furcifera reared on Bt rice MSA and MSB expressing a fusion protein of Cry1Ab/CpTI and non-Bt rice (Fu et al 2003). Similarly, there was no difference in any of the Þve Þtness parameters (survival to the adult stage, male and female weight, and male and female developmental time) between N. lugens reared on Bt rice and control lines (Bernal et al 2002). Tan et al (2006) also reported that Bt rice B1 and B6 signiÞcantly affect neither oviposition behavior nor fecundity of the white-backed planthopper.…”

“…Effects of Bt rice on nontarget herbivores have been focused on several piercing-sucking species including the planthoppers, Nilaparvata lugens (Stål), Sogatella furcifera (Horvath), and Laodelphax striatella (Fallé n) (Homoptera: Delphacidae), and the leafhoppers Nephotettix cincticeps (Uhler) and N. virescens (Distant) (Homoptera: Cicadellidae) because Bt proteins may be ingested by these nontarget insects and transported to their natural enemies through tritrophic interactions (Chen et al 2005(Chen et al , 2006b(Chen et al , 2009Bai et al 2006). No adverse effects on the Þtness and population densities of the planthoppers and leafhoppers were observed under laboratory and Þeld conditions in previous studies (Bernal et al 2002;Liu et al 2002Liu et al , 2007Chen et al 2003Chen et al , 2004Chen et al , 2006bFu et al 2003;Bai et al 2006;Zhou et al 2006;Tan et al 2006), except one case in which N. cincticeps actually performed better on Bt rice KMD1 and KMD2 under laboratory and Þeld conditions (Zhou et al 2005). However, the impact of Bt rice on nontarget organisms was evaluated either in the laboratory or in the Þeld with transplants.…”

Field evaluation of effects of transgenic cry1Ab/cry1Ac, cry1C and cry2A rice on Cnaphalocrocis medinalis and its arthropod predators

“…Likewise, the relative abundance of the four natural enemy arthropods within the predator guild was similar in the non-transgenic and transgenic Bt rice fields. Therefore, although the densities of C. medinalis were significantly lower in the transgenic Bt rice, the lower predator populations did not result from ap- plication of Bt rice, a similar result to previous reports [10,18,31]. In most cases (75%), the population dynamics of C. medinalis adults were not affected by rice line, rice line×sam-pling date, rice line×year, rice line×sampling date×year, and no consistent effects of rice line, rice line×sampling date, rice line×year, rice line×sampling date×year on the population dynamics of C. medinalis adults were observed at different experiment sites.…”

Ecological compatibility of GM crops and biological control

“…Each crop genotype interacts differently with gene promoters and the products they regulate, making it difficult to generalize where the transgenic toxins will ultimately reside in the plant. For instance, Cry toxins are not found in the phloem tissues of some maize events ), but these toxins are detectable in the phloem of some rice, oilseed rape, and other maize events (Raps et al, 2001;Bernal et al, 2002a;Burgio et al, 2007). The end result is that numerous factors influence whether non-prey foods will be contaminated with insecticides from GM crops.…”