Susceptibility of Different Instars of European Corn Borer (Lepidoptera: Crambidae) to Diet Containing Bacillus thuringiensis

Huang, Fangneng; Buschman, Lawrent L.; Higgins, R. A.

doi:10.1093/jee/92.3.547

Cited by 50 publications

(52 citation statements)

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“…However, there was a large decrease in the number of larvae recovered in nonBt stalks between weeks 4-8, such that by week 8 there were no longer any differences in the number of larvae recovered from stalks among the three treatments. Increased survival in the stalks of Bt plants is consistent with a general decline in Bt titer of Event 176 plants during senescence, and decreased sensitivity of later instar larvae (Huang et al, 1999).…”

Section: Field Experimentssupporting

confidence: 54%

Larval distribution and survival of second generation European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) on Event 176 Bt Corn

et al. 2003

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European corn borer Ostrinia nubilalis H . ubner (Lepidoptera: Crambidae) larvae that have completed development on Event 176 Bt corn hybids have either survived exposure to sublethal doses of Cry1Ab Bt toxin or exploited plant tissues that do not express the toxin. To evaluate the impact of such exposure on larval establishment and survival, Event 176 plants with and without tassels and a non-Bt isoline were infested with O. nubilalis egg masses during anthesis. On the non-Bt plants, larval establishment occurred primarily on pollen collecting in the leaf axils, silks and ears. In contrast, almost no larvae were recovered from leaf axils of the Bt treatments and at least 50% fewer larvae were recovered from the silks and ears during the first 2 weeks after infestation relative to the non-Bt plants. The larvae recovered from Bt treatments weighed significantly less than those observed in the non-Bt isoline at 4 weeks after infestation. By the eighth week, the larval weights of all three treatments were similar in three of four different field tests, suggesting that second generation larvae have the ability to compensate for initial exposure to sublethal doses of Bt toxin. In laboratory assays involving exposure of neonate larvae to silks of Event 176 and non-Bt corn, survival of neonate O. nubilalis was not different although larval weights were significantly reduced (2-to 6-fold). These results suggest that second generation larvae completing development on Event 176 corn do not completely avoid exposure to the Bt toxin, although those that do survive are able to compensate for these sublethal effects. The implication of these results is that Event 176 hybrids do not appear to satisfy requirements for high dose that are recommended for resistance management purposes. r

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Section: Field Experimentssupporting

confidence: 54%

Larval distribution and survival of second generation European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) on Event 176 Bt Corn

et al. 2003

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“…For the purposes of this evaluation, we use the EPA (1998) deÞnition of high dose (toxin 25 times the concentration needed to kill susceptible larvae). Bioassays with Dipel (commercial formulation of B. thuringiensis endotoxins) suggest that third instars are Ͼ25 times more tolerant than neonates (Huang et al 1999). Thus, if B. thuringiensis hybrids effectively control third instars, they would satisfy the EPA deÞnition of high dose.…”

Section: Resultsmentioning

confidence: 99%

“…4). Huang et al (1999) suggest that ultrahigh dose and high dose should be deÞned in terms of larval stage. The results from this study suggest that hybrids with a B. thuringiensis dose sufÞcient to kill third-instar O. nubilalis could be considered high-dose plants, and hybrids with a B. thuringiensis dose sufÞcient to kill fourth-instar O. nubilalis could be considered ultrahigh-dose plants.…”

Section: Resultsmentioning

confidence: 99%

Late-Instar European Corn Borer (Lepidoptera: Crambidae) Tunneling and Survival in Transgenic Corn Hybrids

Walker¹,

Hellmich²,

Lewis³

2000

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Field studies were conducted in 1996 and 1997 to determine injury by and survival of late-instar European corn borer, Ostrinia nubilalis (Hu¨ bner), on genetically altered Bacillus thuringiensis Berliner corn, Zea mays L. Cry1Ab events 176, Bt11, MON810, and MON802; Cry1Ac event DBT418; and Cry9C event CBH351 were evaluated. Plants of each corn hybrid were manually infested with two third-, fourth-, or Þfth-instar O. nubilalis. Larvae were held in proximity to the internode of the plant above the ear with a mesh sleeve. Larvae were put on the plants during corn developmental stages V8, V16, R1, R3, R4, R5, and R6. This study shows that not all B. thuringiensis hybrids provide the same protection against O. nubilalis injury. Hybrids with B. thuringiensis events Bt11, MON810, MON802, and CHB351 effectively protected the corn against tunneling by late-instar O. nubilalis. Event 176 was effective in controlling late-instar O. nubilalis during V12 and V16 corn developmental stages; however, signiÞcant tunneling occurred by fourth instars during R3 and R5. Event DBT418 was not effective in controlling late-instar O. nubilalis during corn vegetative or reproductive stages of development. Whether the B. thuringiensis hybrids satisÞed high-and ultrahigh-dose requirements is discussed. KeywordsOstrinia nubilalis, Bacillus thuringiensis, resistance management, high-dose strategy

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“…Another factor not considered was the relative susceptibility of different developmental stages of monarchs (1). Toxicity of Bt proteins has been shown to vary considerably throughout larval development of European corn borer, Ostrinia nubilalis (Hübner) (10). A similar response by monarch larvae could have important implications for risk assessment depending on synchrony of monarch larval development and corn anthesis.…”

mentioning

confidence: 99%

Monarch larvae sensitivity to Bacillus thuringiensis - purified proteins and pollen

Hellmich

Siegfried

Sears

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

234

157

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Laboratory tests were conducted to establish the relative toxicity of Bacillus thuringiensis (Bt) toxins and pollen from Bt corn to monarch larvae. Toxins tested included Cry1Ab, Cry1Ac, Cry9C, and Cry1F. Three methods were used: (i) purified toxins incorporated into artificial diet, (ii) pollen collected from Bt corn hybrids applied directly to milkweed leaf discs, and (iii) Bt pollen contaminated with corn tassel material applied directly to milkweed leaf discs. Bioassays of purified Bt toxins indicate that Cry9C and Cry1F proteins are relatively nontoxic to monarch first instars, whereas first instars are sensitive to Cry1Ab and Cry1Ac proteins. Older instars were 12 to 23 times less susceptible to Cry1Ab toxin compared with first instars. Pollen bioassays suggest that pollen contaminants, an artifact of pollen processing, can dramatically influence larval survival and weight gains and produce spurious results. The only transgenic corn pollen that consistently affected monarch larvae was from Cry1Ab event 176 hybrids, currently <2% corn planted and for which re-registration has not been applied. Results from the other types of Bt corn suggest that pollen from the Cry1Ab (events Bt11 and Mon810) and Cry1F, and experimental Cry9C hybrids, will have no acute effects on monarch butterfly larvae in field settings.

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Susceptibility of Different Instars of European Corn Borer (Lepidoptera: Crambidae) to Diet Containing Bacillus thuringiensis

Cited by 50 publications

References 0 publications

Larval distribution and survival of second generation European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) on Event 176 Bt Corn

Larval distribution and survival of second generation European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) on Event 176 Bt Corn

Late-Instar European Corn Borer (Lepidoptera: Crambidae) Tunneling and Survival in Transgenic Corn Hybrids

Monarch larvae sensitivity to Bacillus thuringiensis - purified proteins and pollen

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