Tri-Trophic Studies Using Cry1Ac-Resistant <I>Plutella xylostella</I> Demonstrate No Adverse Effects of Cry1Ac on the Entomopathogenic Nematode, <I>Heterorhabditis bacteriophora</I>

Abstract

The potential impacts on natural enemies of crops that produce insecticidal Cry proteins from Bacillus thuringiensis (Bt) are an important part of an environmental risk assessment. Entomopathogenic nematodes are important natural enemies of lepidopteran pests, and the effects of Bt crops on these nontarget organisms should be investigated to avoid disruption of their biological control function. The objective of this study was to investigate the effects of Cry1Ac-expressing transgenic Bt broccoli on the entomopathogenic nematode, Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), under tri-trophic conditions. Using Cry1Ac-resistant Plutella xylostella L. (Lepidoptera: Plutellidae) larvae as hosts, we evaluated the potential impact of Cry1Ac-expressing Bt broccoli on several Þtness parameters of H. bacteriophora. Virulence, reproductive potential, time of emergence, and preference of H. bacteriophora for the host (P. xylostella) were not signiÞcantly affected when Cry1Ac-resistant P. xylostella larvae were reared on leaves of Cry1Ac or non-Bt broccoli. Also the aforementioned parameters of the subsequent generation of H. bacteriophora did not differ between nematodes obtained from P. xylostella reared on Cry1Ac broccoli compared with those obtained from P. xylostella reared on non-Bt broccoli. To the best of our knowledge, the current study provides the Þrst clear evidence that Cry1Ac does not affect important Þtness parameters of H. bacteriophora.

Transmission Success of Entomopathogenic Nematodes Used in Pest Control

“…There is an increasing use of GMO plants in crops, many of them producing their own insecticidal proteins. In a recent study, no significant effects on the virulence, reproduction and host preference of H. bacteriophora were found when diamondback moth ( Plutella xylostella ) was reared on broccoli leaves genetically modified to produce CrylAc proteins [ 184 ]. Additional levels continue to be added to the inter-organismal interactions in which EPNs are implicated—most recently, the insect host’s endosymbionts.…”

Multidimensional approaches for studying plant defence against insects: from ecology to omics and synthetic biology

“…Despite the scientific consensus that the genetically engineered crops on the market are safe, concurrent concerns over issues related to its risk assessment and biosafety have to be handled carefully (Gilbert, 2013;Ronald, 2014). Two recently published independent studies claimed that GM Bt crops had no negative effects on two beneficial insect predators or on a beneficial, entomopathogenic nematode (Gautam et al, 2014;Tian et al, 2014). As an alternative to introducing foreign genes into the plant genome, enhancing the existing plant defensive proteins has also shown significant promise (Morton et al, 2000;Campbell et al, 2011).…”