Jörg Romeis - Academia.edu (original) (raw)

Papers by Jörg Romeis

PLoS ONE, 2011

The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator in many cr... more The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator in many cropping systems. Its larvae and adults are predaceous, feeding on aphids, thrips, lepidopteran larvae and plant tissues, such as pollen. Therefore, this species is exposed to insecticidal proteins expressed in insect-resistant, genetically engineered cotton expressing Cry proteins derived from Bacillus thuringiensis (Bt). A tritrophic bioassay was conduced to evaluate the potential impact of Cry2Ab-and Cry1Ac-expressing cotton on fitness parameters of C. maculata using Bt-susceptible and -resistant larvae of Trichoplusia ni as prey. Coleomegilla maculata survival, development time, adult weight and fecundity were not different when they were fed with resistant T. ni larvae reared on either Bt or control cotton. To ensure that C. maculata were not sensitive to the tested Cry toxins independent from the plant background and to add certainty to the hazard assessment, C. maculata larvae were fed artificial diet incorporated with Cry2Ab, Cry1Ac or both at .10 times higher concentrations than in cotton tissue. Artificial diet containing E-64 was included as a positive control. No differences were detected in any lifetable parameters between Cry protein-containing diet treatments and the control diet. In contrast, larvae of C. maculata fed the E-64 could not develop to the pupal stage and the 7-d larval weight was significantly negatively affected. In both feeding assays, the stability and bioactivity of Cry proteins in the food sources were confirmed by ELISA and sensitive-insect bioassays. Our results show that C. maculata is not affected by Bt cotton and is not sensitive to Cry2Ab and Cry1Ac at concentrations exceeding the levels in Bt cotton, thus demonstrating that Bt cotton will pose a negligible risk to C. maculata. More importantly, this study demonstrates a comprehensive system for assessing the risk of genetically modified plants on non-target organisms.

Environmental Toxicology and Chemistry, 2014

The effects of insect-resistant genetically engineered rice producing Cry1C protein derived from ... more The effects of insect-resistant genetically engineered rice producing Cry1C protein derived from Bacillus thuringiensis (Bt) on Chrysoperla sinica (Tjeder) (Neuroptera: Chrysopidae) were assessed in laboratory bioassays. Survival and development of C. sinica larvae were not adversely affected when the larvae were fed a diet containing purified Cry1C protein at 200 µg/g fresh weight, representing a worst-case exposure scenario; in contrast, C. sinica larvae were adversely affected when the diet contained avidin or potassium arsenate. Life table parameters of C. sinica adults did not differ when the adults were fed with Bt or non-Bt rice pollen together with a 2-M sucrose solution. Life table parameters of C. sinica adults also did not differ when the adults were fed an artificial diet with or without purified Cry1C protein at a nominal concentration that was approximately 20 times higher than that in rice pollen; in contrast, C. sinica adults were adversely affected when the diet contained potassium arsenate. In all bioassays with lacewings, the bioactivity and stability of the Cry1C protein in the diet and Cry1C protein uptake by the lacewings were confirmed by enzyme-linked immunosorbent assay (ELISA) and by bioassays with a Cry1C-sensitive lepidopteran. These results demonstrate that neither larvae nor adults of C. sinica are sensitive to Cry1C protein at concentrations higher than those encountered in the field, demonstrating that the growing of Bt rice producing Cry1C protein is unlikely to pose a risk to C. sinica.

Biological Control, 2010

Bt maize varieties expressing the insecticidal protein Cry3Bb1 against larvae of the Western corn... more Bt maize varieties expressing the insecticidal protein Cry3Bb1 against larvae of the Western corn rootworm (Diabrotica virgifera virgifera; Coleoptera: Chrysomelidae) may harm non-target beetles due to the spectrum of activity of the protein. We have conducted studies to assess the prey-mediated effects of Cry3Bb1-expressing Bt maize (event MON88017) on the ladybird beetle Stethorus punctillum (Coleoptera: Coccinellidae). This species specifically consumes spider mites that are known to contain high amounts of Bt toxin when feeding on Bt maize. The developmental and reproduction life-history parameters did not differ for spider mites, Tetranychus urticae (Acari: Tetranychidae), fed Bt maize or non-Bt maize. Similarly, larval survival and development, adult survival, and adult dry weight did not differ for S. punctillum fed with spider mites reared on Bt or non-Bt maize for over 2 months. Female beetles that were fed T. urticae from Bt maize had a shorter pre-oviposition period, increased fecundity, and increased fertility relative to females fed spider mites from non-Bt maize. The reasons for these effects are unclear but may be due to unidentified differences in plant characteristics. T. urticae contained 56% of the Cry3Bb1 concentration in Bt maize leaves. Beetle larvae and adults that had consumed Bt maize-fed spider mites contained toxin concentrations that were six and 20 times lower, respectively, than Cry3Bb1 levels in their spider mite prey. Thus, the toxin was diluted at higher trophic levels. The results indicate that S. punctillum is not harmed by feeding on spider mites containing Cry3Bb1. Consequently, detrimental effects on this predator when preying in Cry3Bb1-expressing Bt maize fields are unlikely.

Roots of maize plants attacked by larvae of the Western corn rootworm (Diabrotica virgifera virgi... more Roots of maize plants attacked by larvae of the Western corn rootworm (Diabrotica virgifera virgifera) commonly emit β-caryophyllene. This volatile sesquiterpene has been shown to attract entomopathogenic nematodes, potential biological control agents against this serious pest. Transgenic maize expressing coleopteran-specific insecticidal Cry3Bb1 protein from Bacillus thuringiensis (Bt) is another available control option. To improve efficacy of Bt maize and reduce the probability of resistance development, a combination of both methods could lead to a more sustainable system, as Bt maize kills or deters neonate larvae and nematodes would be capable of infecting older larvae surviving the Cry3Bb1 exposure. In the present study, we examined the emission of βcaryophyllene of two different Bt lines and their corresponding non-transformed near isolines after induction by a bacterial elicitor or by D. v. virgifera larvae. All maize lines were similarly capable of emitting β-caryophyllene after roots were incubated with coronatine, although variation was high. Emission after feeding by D. v. virgifera larvae was lower and less reliable compared with coronatine. The two Bt maize/control lines showed rather low β-caryophyllene levels compared to a highly attractive control line. Whether or not the emission levels in the varieties tested would be enough for successful nematode attraction and consequently effective biological control remains to be shown.

Environmental Entomology

et al. 2009a. Setting the record straight: a rebuttal to an erroneous analysis on transgenic inse... more et al. 2009a. Setting the record straight: a rebuttal to an erroneous analysis on transgenic insecticidal crops and natural enemies. Transgen. Res. 18: 317Ð 322.

The green lacewing, Chrysoperla rufilabris (Burmeister), is considered an important natural preda... more The green lacewing, Chrysoperla rufilabris (Burmeister), is considered an important natural predator due to its wide geographic distribution and its voracious larval feeding capacity. Its larvae feed on soft-bodies arthropods in many different crop habitats. Thus, C. rufilabris may be exposed to insecticidal proteins from Bacillus thuringiensis (Bt) when they are expressed in genetically engineered crops. Laboratory experiments were conducted to evaluate the prey-mediated impacts of Bt broccoli (expressing Cry1Ac), Bt cotton (expressing Cry1Ac/Cry2Ab) and Bt maize (expressing Cry1F) on several fitness parameters of C. rufilabris over two generations using Bt-resistant cabbage lopper, Trichoplusia ni, and Bt-resistant fall armyworm, Spodoptera frugiperda (JE Smith), larvae as prey. ELISA and sensitive-insect bioassays confirmed that C. rufilabris were exposed to bioactive Bt proteins. Development time of larval and pupal stages, female fecundity and egg hatching rate of C. rufilabris...

Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) is a solitary, larval endoparasitoid, ... more Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) is a solitary, larval endoparasitoid, and important natural enemy of noctuid moths. C. marginiventris attacks 1st and 2nd instars and its larvae feed on host hemolymph and tissue and emerge from the host to pupate. Thus, C. marginiventris may be exposed to Bt proteins when their host larvae feed on Bt crops. To eliminate host quality mediated-effects that occur when susceptible hosts fed Bt crops become sub-optimal, we used Bt-resistant fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) larvae as hosts and evaluated the potential impact of Cry1F expressing corn (Mycogen 2A517) on several fitness parameters of C. marginiventris over three generations. Survival, parasitism, development time of larval and pupal stages, adult longevity and offspring sex ratio of C. marginiventris were observed. Our results demonstrated there were no differences when resistant S. frugiperda larvae reared on either Bt or control...

The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator that suppr... more The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator that suppresses pest populations in many cropping systems. Its larvae and adults are polyphagous, feeding on aphids, thrips, lepidopteran eggs and larvae as well as plant tissues. Thus, C. maculata may be exposed by several means to insecticidal proteins expressed in genetically engineered crops expressing insecticidal proteins from Bacillus thuringiensis (Bt). We evaluated the potential impact of Cry1F expressing corn (Mycogen 2A517) on several fitness parameters of C. maculata over two generations using Bt-resistant Spodoptera frugiperda (JE Smith) larvae as prey. Survival, duration of larval and pupal stages, adult weight and female fecundity of C. maculata were not different when they were fed resistant S. frugiperda larvae reared on either Bt or control corn leaves for both generations. ELISA and sensitive-insect bioassays showed C. maculata were exposed to bioactive Cry1F protein. However, t...

Geocoris punctipes (Say) and Orius insidiosus (Say) are generalist predators found in a wide rang... more Geocoris punctipes (Say) and Orius insidiosus (Say) are generalist predators found in a wide range of crops, including cotton (Gossypium hirsutum L.) and maize (Zea mays L.), where they provide important biological control services by feeding on an array of pests, including eggs and small larvae of caterpillars. A high percentage of cotton and maize in the United States and several other countries are transgenic cultivars that produce one or more of the insecticidal Cry proteins of Bacillus thuringiensis Berliner (Bt). Here we quantify effects of three Cry proteins on the life history of these predators over two generations when they are exposed to these Cry proteins indirectly through their prey. To eliminate the confounding prey quality effects that can be introduced by Bt-susceptible prey, we used Cry1Ac/Cry2Ab-resistant Trichoplusia ni (Hü bner) and Cry1 F-resistant Spodoptera frugiperda (J.E. Smith) in a series of tri-trophic studies. Survival, development, adult mass, fecundity, and fertility were similar when predators consumed larvae feeding on Cry1Ac/Cry2Ab cotton or Cry1 F maize compared with prey feeding on isogenic or near-isogenic cotton or maize. Repeated exposure of the same initial cohort over a second generation also resulted in no differences in life-history traits when feeding on non-Bt-or Bt-fed prey. Enzyme-linked immunosorbent assay showed that predators were exposed to Bt Cry proteins from their prey and that these proteins became increasingly diluted as they moved up the food chain. Results show a clear lack of effect of three common and widespread Cry proteins on these two important predator species. The use of resistant insects to eliminate prey quality effects provides a robust and meaningful assessment of exposure and hazard.

Ecosystem functioning might be affected by cultivation of genetically engineered (GE) plants thro... more Ecosystem functioning might be affected by cultivation of genetically engineered (GE) plants through effects on non-target organisms contributing to important ecosystem services. The number of commercialized transgenic events and the cultivation areas are steadily increasing worldwide. Therefore, the careful execution of ecological risk assessments for new GE plants is crucial. Until now, only few studies assessed the potentially adverse effects of GE crops on the survival and fitness of dipteran species. This, despite the fact that Diptera play important roles in the agricultural ecosystem as predators, parasitoids, pollinators and decomposers. We propose Drosophila melanogaster Meigen 1830 (Drosophilidae) to be tested in the pre-market risk assessment as a surrogate species for the order of Diptera. We are developing two different study systems for this species to assess toxicity of insecticidal proteins and GE plant tissues. This involves the development of skills and experience ...

Cotton-and maize-producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuri... more Cotton-and maize-producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis (Bt), have been commercialized since 1996. Bt plants are subjected to environmental risk assessments for nontarget organisms, including natural enemies that suppress pest populations. Here, we used Cry1F-resistant Spodoptera frugiperda (J.E. Smith) and Cry1Ac and Cry2Ab-resistant Trichoplusia ni (H€ ubner) as prey for the assassin bug, Zelus renardii (Kolenati), a common predator in maize and cotton fields. In tritrophic studies, we assessed several fitness parameters of Z. renardii when it fed on resistant S. frugiperda that had fed on Bt maize expressing Cry1F or on resistant T. ni that had fed on Bt cotton expressing Cry1Ac and Cry2Ab. Survival, nymphal duration, adult weight, adult longevity and female fecundity of Z. renardii were not different when they were fed resistant-prey larvae (S. frugiperda or T. ni) reared on either a Bt crop or respective non-Bt crops. ELISA tests demonstrated that the Cry proteins were present in the plant at the highest levels, at lower levels in the prey and at the lowest levels in the predator. While Z. renardii was exposed to Cry1F and Cry1Ac and Cry2Ab when it fed on hosts that consumed Bt-transgenic plants, the proteins did not affect important fitness parameters in this common and important predator. Bt plants not toxic to Zelus renardii H.-H. Su et al.

The bigeyed bug, Geocoris punctipes, is an abundant predator in many cropping systems. Its nymphs... more The bigeyed bug, Geocoris punctipes, is an abundant predator in many cropping systems. Its nymphs and adults are active predators that attack a wide variety of pests, including aphids, soft-bodied insect larvae, and insect eggs in cotton, soybean and other crops. Thus, G. punctipes may be exposed by multiple routes to insecticidal proteins expressed in genetically engineered crops producing insecticidal proteins from Bacillus thuringiensis (Bt). We evaluated the potential impact of Cry1Ac and Cry2Ab expressing cotton (BollGard II) on several fitness parameters of G. punctipes over two generations using Bt-resistant Trichoplusia ni larvae as prey. Duration of the nymphal stage, adult weight, female fecundity and egg hatching rate of G. punctipes were not different when they were fed resistant T. ni larvae reared on either Bt or control cotton leaves for both generations. Our results demonstrate that Cry1Ac and Cry2Ab expressing cotton does not affect important fitness parameters of G...

We compared the longevity of the aphid parasitoid Aphidius ervi fed on honeydew from Aulacorthum ... more We compared the longevity of the aphid parasitoid Aphidius ervi fed on honeydew from Aulacorthum solani, Macrosiphum euphorbiae, and Myzus persicae on potato. As controls, separate parasitoid cohorts were provided with a sucrose solution or water only. All honeydews studied were found to enhance parasitoid longevity as much as the sucrose solution. HPLC analysis of the honeydews showed little differences

Journal of agricultural and food chemistry, Jan 18, 2015

The honey bee, Apis mellifera, is commonly used as a test species for the regulatory risk assessm... more The honey bee, Apis mellifera, is commonly used as a test species for the regulatory risk assessment of insect-resistant genetically engineered (IRGE) plants. In the current study, a dietary exposure assay was developed, validated, and used to assess the potential toxicity of Cry1C and Cry2A proteins from Bacillus thuringiensis (Bt) to A. mellifera larvae; Cry1C and Cry2A are produced by different IRGE crops. The assay, which uses the soybean trypsin inhibitor (SBTI) as a positive control and bovine serum albumin (BSA) as a negative control, was used to measure the responses of A. mellifera larvae to high concentrations of Cry1C and Cry2A. Survival was reduced and development was delayed when larvae were fed SBTI (1 mg/g diet) but were unaffected when larvae were fed BSA (400 µg/g), Cry1C (50 µg/g), or Cry2A (400 µg/g). The enzymatic activities of A. mellifera larvae were not altered and their midgut brush border membranes (BBMs) were not damaged after being fed with diets containin...

PLoS ONE, 2011

The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator in many cr... more The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator in many cropping systems. Its larvae and adults are predaceous, feeding on aphids, thrips, lepidopteran larvae and plant tissues, such as pollen. Therefore, this species is exposed to insecticidal proteins expressed in insect-resistant, genetically engineered cotton expressing Cry proteins derived from Bacillus thuringiensis (Bt). A tritrophic bioassay was conduced to evaluate the potential impact of Cry2Ab-and Cry1Ac-expressing cotton on fitness parameters of C. maculata using Bt-susceptible and -resistant larvae of Trichoplusia ni as prey. Coleomegilla maculata survival, development time, adult weight and fecundity were not different when they were fed with resistant T. ni larvae reared on either Bt or control cotton. To ensure that C. maculata were not sensitive to the tested Cry toxins independent from the plant background and to add certainty to the hazard assessment, C. maculata larvae were fed artificial diet incorporated with Cry2Ab, Cry1Ac or both at .10 times higher concentrations than in cotton tissue. Artificial diet containing E-64 was included as a positive control. No differences were detected in any lifetable parameters between Cry protein-containing diet treatments and the control diet. In contrast, larvae of C. maculata fed the E-64 could not develop to the pupal stage and the 7-d larval weight was significantly negatively affected. In both feeding assays, the stability and bioactivity of Cry proteins in the food sources were confirmed by ELISA and sensitive-insect bioassays. Our results show that C. maculata is not affected by Bt cotton and is not sensitive to Cry2Ab and Cry1Ac at concentrations exceeding the levels in Bt cotton, thus demonstrating that Bt cotton will pose a negligible risk to C. maculata. More importantly, this study demonstrates a comprehensive system for assessing the risk of genetically modified plants on non-target organisms.

Environmental Toxicology and Chemistry, 2014

The effects of insect-resistant genetically engineered rice producing Cry1C protein derived from ... more The effects of insect-resistant genetically engineered rice producing Cry1C protein derived from Bacillus thuringiensis (Bt) on Chrysoperla sinica (Tjeder) (Neuroptera: Chrysopidae) were assessed in laboratory bioassays. Survival and development of C. sinica larvae were not adversely affected when the larvae were fed a diet containing purified Cry1C protein at 200 µg/g fresh weight, representing a worst-case exposure scenario; in contrast, C. sinica larvae were adversely affected when the diet contained avidin or potassium arsenate. Life table parameters of C. sinica adults did not differ when the adults were fed with Bt or non-Bt rice pollen together with a 2-M sucrose solution. Life table parameters of C. sinica adults also did not differ when the adults were fed an artificial diet with or without purified Cry1C protein at a nominal concentration that was approximately 20 times higher than that in rice pollen; in contrast, C. sinica adults were adversely affected when the diet contained potassium arsenate. In all bioassays with lacewings, the bioactivity and stability of the Cry1C protein in the diet and Cry1C protein uptake by the lacewings were confirmed by enzyme-linked immunosorbent assay (ELISA) and by bioassays with a Cry1C-sensitive lepidopteran. These results demonstrate that neither larvae nor adults of C. sinica are sensitive to Cry1C protein at concentrations higher than those encountered in the field, demonstrating that the growing of Bt rice producing Cry1C protein is unlikely to pose a risk to C. sinica.

Biological Control, 2010

Bt maize varieties expressing the insecticidal protein Cry3Bb1 against larvae of the Western corn... more Bt maize varieties expressing the insecticidal protein Cry3Bb1 against larvae of the Western corn rootworm (Diabrotica virgifera virgifera; Coleoptera: Chrysomelidae) may harm non-target beetles due to the spectrum of activity of the protein. We have conducted studies to assess the prey-mediated effects of Cry3Bb1-expressing Bt maize (event MON88017) on the ladybird beetle Stethorus punctillum (Coleoptera: Coccinellidae). This species specifically consumes spider mites that are known to contain high amounts of Bt toxin when feeding on Bt maize. The developmental and reproduction life-history parameters did not differ for spider mites, Tetranychus urticae (Acari: Tetranychidae), fed Bt maize or non-Bt maize. Similarly, larval survival and development, adult survival, and adult dry weight did not differ for S. punctillum fed with spider mites reared on Bt or non-Bt maize for over 2 months. Female beetles that were fed T. urticae from Bt maize had a shorter pre-oviposition period, increased fecundity, and increased fertility relative to females fed spider mites from non-Bt maize. The reasons for these effects are unclear but may be due to unidentified differences in plant characteristics. T. urticae contained 56% of the Cry3Bb1 concentration in Bt maize leaves. Beetle larvae and adults that had consumed Bt maize-fed spider mites contained toxin concentrations that were six and 20 times lower, respectively, than Cry3Bb1 levels in their spider mite prey. Thus, the toxin was diluted at higher trophic levels. The results indicate that S. punctillum is not harmed by feeding on spider mites containing Cry3Bb1. Consequently, detrimental effects on this predator when preying in Cry3Bb1-expressing Bt maize fields are unlikely.

Roots of maize plants attacked by larvae of the Western corn rootworm (Diabrotica virgifera virgi... more Roots of maize plants attacked by larvae of the Western corn rootworm (Diabrotica virgifera virgifera) commonly emit β-caryophyllene. This volatile sesquiterpene has been shown to attract entomopathogenic nematodes, potential biological control agents against this serious pest. Transgenic maize expressing coleopteran-specific insecticidal Cry3Bb1 protein from Bacillus thuringiensis (Bt) is another available control option. To improve efficacy of Bt maize and reduce the probability of resistance development, a combination of both methods could lead to a more sustainable system, as Bt maize kills or deters neonate larvae and nematodes would be capable of infecting older larvae surviving the Cry3Bb1 exposure. In the present study, we examined the emission of βcaryophyllene of two different Bt lines and their corresponding non-transformed near isolines after induction by a bacterial elicitor or by D. v. virgifera larvae. All maize lines were similarly capable of emitting β-caryophyllene after roots were incubated with coronatine, although variation was high. Emission after feeding by D. v. virgifera larvae was lower and less reliable compared with coronatine. The two Bt maize/control lines showed rather low β-caryophyllene levels compared to a highly attractive control line. Whether or not the emission levels in the varieties tested would be enough for successful nematode attraction and consequently effective biological control remains to be shown.

Environmental Entomology

et al. 2009a. Setting the record straight: a rebuttal to an erroneous analysis on transgenic inse... more et al. 2009a. Setting the record straight: a rebuttal to an erroneous analysis on transgenic insecticidal crops and natural enemies. Transgen. Res. 18: 317Ð 322.

The green lacewing, Chrysoperla rufilabris (Burmeister), is considered an important natural preda... more The green lacewing, Chrysoperla rufilabris (Burmeister), is considered an important natural predator due to its wide geographic distribution and its voracious larval feeding capacity. Its larvae feed on soft-bodies arthropods in many different crop habitats. Thus, C. rufilabris may be exposed to insecticidal proteins from Bacillus thuringiensis (Bt) when they are expressed in genetically engineered crops. Laboratory experiments were conducted to evaluate the prey-mediated impacts of Bt broccoli (expressing Cry1Ac), Bt cotton (expressing Cry1Ac/Cry2Ab) and Bt maize (expressing Cry1F) on several fitness parameters of C. rufilabris over two generations using Bt-resistant cabbage lopper, Trichoplusia ni, and Bt-resistant fall armyworm, Spodoptera frugiperda (JE Smith), larvae as prey. ELISA and sensitive-insect bioassays confirmed that C. rufilabris were exposed to bioactive Bt proteins. Development time of larval and pupal stages, female fecundity and egg hatching rate of C. rufilabris...

Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) is a solitary, larval endoparasitoid, ... more Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) is a solitary, larval endoparasitoid, and important natural enemy of noctuid moths. C. marginiventris attacks 1st and 2nd instars and its larvae feed on host hemolymph and tissue and emerge from the host to pupate. Thus, C. marginiventris may be exposed to Bt proteins when their host larvae feed on Bt crops. To eliminate host quality mediated-effects that occur when susceptible hosts fed Bt crops become sub-optimal, we used Bt-resistant fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) larvae as hosts and evaluated the potential impact of Cry1F expressing corn (Mycogen 2A517) on several fitness parameters of C. marginiventris over three generations. Survival, parasitism, development time of larval and pupal stages, adult longevity and offspring sex ratio of C. marginiventris were observed. Our results demonstrated there were no differences when resistant S. frugiperda larvae reared on either Bt or control...

The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator that suppr... more The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator that suppresses pest populations in many cropping systems. Its larvae and adults are polyphagous, feeding on aphids, thrips, lepidopteran eggs and larvae as well as plant tissues. Thus, C. maculata may be exposed by several means to insecticidal proteins expressed in genetically engineered crops expressing insecticidal proteins from Bacillus thuringiensis (Bt). We evaluated the potential impact of Cry1F expressing corn (Mycogen 2A517) on several fitness parameters of C. maculata over two generations using Bt-resistant Spodoptera frugiperda (JE Smith) larvae as prey. Survival, duration of larval and pupal stages, adult weight and female fecundity of C. maculata were not different when they were fed resistant S. frugiperda larvae reared on either Bt or control corn leaves for both generations. ELISA and sensitive-insect bioassays showed C. maculata were exposed to bioactive Cry1F protein. However, t...

Geocoris punctipes (Say) and Orius insidiosus (Say) are generalist predators found in a wide rang... more Geocoris punctipes (Say) and Orius insidiosus (Say) are generalist predators found in a wide range of crops, including cotton (Gossypium hirsutum L.) and maize (Zea mays L.), where they provide important biological control services by feeding on an array of pests, including eggs and small larvae of caterpillars. A high percentage of cotton and maize in the United States and several other countries are transgenic cultivars that produce one or more of the insecticidal Cry proteins of Bacillus thuringiensis Berliner (Bt). Here we quantify effects of three Cry proteins on the life history of these predators over two generations when they are exposed to these Cry proteins indirectly through their prey. To eliminate the confounding prey quality effects that can be introduced by Bt-susceptible prey, we used Cry1Ac/Cry2Ab-resistant Trichoplusia ni (Hü bner) and Cry1 F-resistant Spodoptera frugiperda (J.E. Smith) in a series of tri-trophic studies. Survival, development, adult mass, fecundity, and fertility were similar when predators consumed larvae feeding on Cry1Ac/Cry2Ab cotton or Cry1 F maize compared with prey feeding on isogenic or near-isogenic cotton or maize. Repeated exposure of the same initial cohort over a second generation also resulted in no differences in life-history traits when feeding on non-Bt-or Bt-fed prey. Enzyme-linked immunosorbent assay showed that predators were exposed to Bt Cry proteins from their prey and that these proteins became increasingly diluted as they moved up the food chain. Results show a clear lack of effect of three common and widespread Cry proteins on these two important predator species. The use of resistant insects to eliminate prey quality effects provides a robust and meaningful assessment of exposure and hazard.

Ecosystem functioning might be affected by cultivation of genetically engineered (GE) plants thro... more Ecosystem functioning might be affected by cultivation of genetically engineered (GE) plants through effects on non-target organisms contributing to important ecosystem services. The number of commercialized transgenic events and the cultivation areas are steadily increasing worldwide. Therefore, the careful execution of ecological risk assessments for new GE plants is crucial. Until now, only few studies assessed the potentially adverse effects of GE crops on the survival and fitness of dipteran species. This, despite the fact that Diptera play important roles in the agricultural ecosystem as predators, parasitoids, pollinators and decomposers. We propose Drosophila melanogaster Meigen 1830 (Drosophilidae) to be tested in the pre-market risk assessment as a surrogate species for the order of Diptera. We are developing two different study systems for this species to assess toxicity of insecticidal proteins and GE plant tissues. This involves the development of skills and experience ...

Cotton-and maize-producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuri... more Cotton-and maize-producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis (Bt), have been commercialized since 1996. Bt plants are subjected to environmental risk assessments for nontarget organisms, including natural enemies that suppress pest populations. Here, we used Cry1F-resistant Spodoptera frugiperda (J.E. Smith) and Cry1Ac and Cry2Ab-resistant Trichoplusia ni (H€ ubner) as prey for the assassin bug, Zelus renardii (Kolenati), a common predator in maize and cotton fields. In tritrophic studies, we assessed several fitness parameters of Z. renardii when it fed on resistant S. frugiperda that had fed on Bt maize expressing Cry1F or on resistant T. ni that had fed on Bt cotton expressing Cry1Ac and Cry2Ab. Survival, nymphal duration, adult weight, adult longevity and female fecundity of Z. renardii were not different when they were fed resistant-prey larvae (S. frugiperda or T. ni) reared on either a Bt crop or respective non-Bt crops. ELISA tests demonstrated that the Cry proteins were present in the plant at the highest levels, at lower levels in the prey and at the lowest levels in the predator. While Z. renardii was exposed to Cry1F and Cry1Ac and Cry2Ab when it fed on hosts that consumed Bt-transgenic plants, the proteins did not affect important fitness parameters in this common and important predator. Bt plants not toxic to Zelus renardii H.-H. Su et al.

The bigeyed bug, Geocoris punctipes, is an abundant predator in many cropping systems. Its nymphs... more The bigeyed bug, Geocoris punctipes, is an abundant predator in many cropping systems. Its nymphs and adults are active predators that attack a wide variety of pests, including aphids, soft-bodied insect larvae, and insect eggs in cotton, soybean and other crops. Thus, G. punctipes may be exposed by multiple routes to insecticidal proteins expressed in genetically engineered crops producing insecticidal proteins from Bacillus thuringiensis (Bt). We evaluated the potential impact of Cry1Ac and Cry2Ab expressing cotton (BollGard II) on several fitness parameters of G. punctipes over two generations using Bt-resistant Trichoplusia ni larvae as prey. Duration of the nymphal stage, adult weight, female fecundity and egg hatching rate of G. punctipes were not different when they were fed resistant T. ni larvae reared on either Bt or control cotton leaves for both generations. Our results demonstrate that Cry1Ac and Cry2Ab expressing cotton does not affect important fitness parameters of G...

We compared the longevity of the aphid parasitoid Aphidius ervi fed on honeydew from Aulacorthum ... more We compared the longevity of the aphid parasitoid Aphidius ervi fed on honeydew from Aulacorthum solani, Macrosiphum euphorbiae, and Myzus persicae on potato. As controls, separate parasitoid cohorts were provided with a sucrose solution or water only. All honeydews studied were found to enhance parasitoid longevity as much as the sucrose solution. HPLC analysis of the honeydews showed little differences

Journal of agricultural and food chemistry, Jan 18, 2015

The honey bee, Apis mellifera, is commonly used as a test species for the regulatory risk assessm... more The honey bee, Apis mellifera, is commonly used as a test species for the regulatory risk assessment of insect-resistant genetically engineered (IRGE) plants. In the current study, a dietary exposure assay was developed, validated, and used to assess the potential toxicity of Cry1C and Cry2A proteins from Bacillus thuringiensis (Bt) to A. mellifera larvae; Cry1C and Cry2A are produced by different IRGE crops. The assay, which uses the soybean trypsin inhibitor (SBTI) as a positive control and bovine serum albumin (BSA) as a negative control, was used to measure the responses of A. mellifera larvae to high concentrations of Cry1C and Cry2A. Survival was reduced and development was delayed when larvae were fed SBTI (1 mg/g diet) but were unaffected when larvae were fed BSA (400 µg/g), Cry1C (50 µg/g), or Cry2A (400 µg/g). The enzymatic activities of A. mellifera larvae were not altered and their midgut brush border membranes (BBMs) were not damaged after being fed with diets containin...