Evaluation of dietary effects of transgenic corn pollen expressing Cry3Bb1 protein on a non‐target ladybird beetle, Coleomegilla maculata

Abstract

A transgenic corn event (MON 863) has been recently developed by Monsanto Company for control of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae). This transgenic corn event expresses the cry3Bb1 gene derived from Bacillus thuringiensis (Berliner), which encodes the insecticidal Cry3Bb1 protein for corn rootworm control. A continuous feeding study was conducted in the laboratory to evaluate the dietary effect of MON 863 pollen expressing the Cry3Bb1 protein on the survival, larval development, and reproductive capacity of the non‐target species, Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae). First instar C. maculata (less than 24 h old) and newly emerging adults (less than 72 h old) were fed individually on a diet mixture containing 50% of MON 863 pollen, non‐transgenic (control) corn pollen, bee pollen (a component of normal rearing diet), or potassium arsenate‐treated control corn pollen. In the larval tests, 96.7%, 90.0%, and 93.3% of C. maculata larvae successfully pupated and then emerged as adults when fed on MON 863 pollen, non‐transgenic corn pollen, and bee pollen (normal rearing) diets, respectively. Among the larvae completing their development, there were no significant differences in the developmental time to pupation and adult emergence among the transgenic corn pollen, non‐transgenic corn pollen, and bee pollen diet treatments. All larvae fed on arsenate treated corn pollen diet died as larvae. For tests with adults, 83.3%, 80.0%, and 100% of adult C. maculata survived for the 30 days of the test period when reared on diets containing 50% of MON 863 pollen, non‐transgenic corn pollen, and bee pollen respectively. While the adult survival rate on MON 863 pollen diet was significantly less than that on the bee pollen diet, there was no significant difference between the MON 863 and non‐transgenic corn pollen treatments. During the period of adult testing, an average of 77, 80, and 89 eggs per female were laid by females fed on the MON 863 pollen, control corn pollen, and bee pollen, respectively; no significant differences were detected in the number of eggs laid among these treatments. These results demonstrate that when offered at 50% by weight of the dietary component, transgenic corn (MON 863) pollen expressing Cry3Bb1 protein had no measurable negative effect on the survival and development of C. maculata larvae to pupation and adulthood nor any adverse effect on adult survival and reproductive capacity. Relevance of these findings to ecological impacts of transgenic Bt crops on non‐target beneficial insects is discussed.

Ecological compatibility of GM crops and biological control

“…These include the crop genotype and phenology, the insecticidal molecule produced, the gene promoter used in the transformation event, where the transgene is inserted within the crop's genome, and extrinsic environmental and geographical factors (Fearing et al, 1997;Duan et al, 2002;Grossi-de-Sa et al, 2006;Obrist et al, 2006a). The gene promoter used to regulate toxin expression has great influence on which tissues express a transgene.…”

Laboratory evaluation of effects of transgenic Bt corn pollen on two non-target herbivorous beetles, Epilachna vigintioctopunctata (Coccinellidae) and Galerucella vittaticollis (Chrysomelidae)

“…Bt176), may have potential risks for non-target butterflies in and near cornfields, but MON810 or Bt11, expressing a low level in pollen (Ͻ0.09 mg/g being below the limit of detection by ELISA) did not possess any risk to non-target butterflies in and near cornfields (Kaplan, 2002;Mendelsohn et al, 2003). Bt corn (MON863) targeted against coleopteran pests expressed relatively high levels of the Cry3Bb1 endotoxin in corn pollen; average 77.1 mg/g (Duan et al, 2002) or 89.2 mg/g (63.1 mg/g after sieving) (Mattila et al, 2005) in fresh weight. Therefore, it is worth evaluating the effect of pollen exposure on non-target herbivorous beetles which live on wild host plants near cornfields.…”

“…In 2002, Monsanto Japan Limited submitted a petition for the import and cultivation of MON863 expressing Cry3Bb1 protein. The expression level of Bt toxin in MON863 corn pollen is relatively high, on average 77.1 mg/g (Duan et al, 2002) or 89.2 mg/g (Mattila et al, 2005) in fresh weight. At that time, a bioassay method using native non-target coleopteran species had not yet been developed in Japan, so the potential risk of pollen exposure to non-target beetles was evaluated based on an artificial diet overlay bioassay using larvae of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Yamane, 2005).…”

“…In addition, a bioassay using purified Cry3Bb1 protein did not show adverse effects on two predatory ladybird beetles, Hippodamia convergence Guerin-Meneville and Coleomegilla maculata DeGeer (Ward et al, 2005). The potential risk from MON863 corn pollen was evaluated for C. maculata, which often uses corn pollen as a food source (Duan et al, 2002;Lundgren and Wiedenmann, 2002); however, other non-target herbivorous coleopterans which live on wild plants have not been evaluated. It will be worth evaluating the effect of pollen exposure on non-target herbivorous beetles near cornfields, because MON863 expresses a relatively high level of Bt toxin in pollen.…”

Ecological Safety Assessment Of Insecticidal Proteins Introduced Into Biotech Crops

“…However, this nontarget beetle does not appear to be adversely affected by corn pollen expressing Cry3Bb. 83,84 Other studies employing targeted field monitoring for C. maculata and related aboveground arthropods as well as soil-dwelling mites, springtails, and nematodes showed no adverse effect of Cry3Bb corn. [85][86][87] …”