Cannibalism of Helicoverpa zea (Lepidoptera: Noctuidae) from Bacillus thuringiensis (Bt) Transgenic Corn Versus Non-Bt Corn

2006 ◽  
Vol 99 (3) ◽  
pp. 728-732 ◽  
Author(s):  
Charles F. Chilcutt
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
Bt Corn ◽  
Transgenic Corn ◽  
Lepidoptera Noctuidae

Field Evaluation of Transgenic Corn Containing a Bacillus thuringiensis Berliner Insecticidal Protein Gene Against Helicoverpa zea (Lepidoptera: Noctuidae)

1996 ◽  
Vol 31 (3) ◽  
pp. 340-346 ◽  
Author(s):  
Steven R. Sims ◽  
Jay C. Pershing ◽  
Barbara J. Reich
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
Negative Relationship ◽  
Field Evaluation ◽  
Corn Earworm ◽  
Insecticidal Protein ◽  
Transgenic Corn ◽  
First Instar ◽  
Transgenic Lines ◽  
Lepidoptera Noctuidae

Twelve independently transformed lines of transgenic corn (Zea mays L.) expressing the CryIA(b) insecticidal protein from Bacillus thuringiensis var. kurstaki were field tested to evaluate their resistance to the corn earworm, Helicoverpa zea (Boddie). Silks of the primary (=top) ears of transgenic [CryIA(b) positive] and isoline control plants [no CryIA(b) protein] were artificially infested with first-instar H. zea larvae and the length of ear penetration was measured after 19 d. Eight of the 12 lines had significantly less ear damage than their respective isoline controls; 3 transgenic lines reduced H. zea feeding damage by > 75% and stunted surviving H. zea larvae. Concentration of the CryIA(b) protein (μg/g fresh weight) in silks of the transgenic lines, determined using ELISA, ranged from 0.0 to 1.28 μg/g. Within transgenic lines, there was a weak (P < 0.06) negative relationship between the concentration of CryIA(b) protein in fresh silks and the length of H. zea ear penetration.

Influence of Transgenic Corn Expressing Insecticidal Protein of Bacillus thuringiensis Berliner on Natural Populations of Corn Earworm (Lepidoptera: Noctuidae) and Southwestern Corn Borer (Lepidoptera: Crambidae)

2006 ◽  
Vol 41 (3) ◽  
pp. 221-231 ◽  
Author(s):  
Kerry C. Allen ◽  
Henry N. Pitre
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
Larval Growth ◽  
Natural Populations ◽  
Corn Earworm ◽  
Bt Corn ◽  
Transgenic Corn ◽  
Diatraea Grandiosella ◽  
Corn Hybrids ◽  
Corn Borer

A 2-yr study was conducted to measure the influence of transgenic corn, Zea mays L., expressing the CrylAb endotoxin of Bacillus thuringiensis (Berliner) (Bt) by means of Event MON810 on natural populations of Helicoverpa zea (Boddie) and Diatraea grandiosella (Dyar). The studies were conducted at Leland and Morgan City, MS, in 1999 and at Morgan City in 2000. Although total numbers of H. zea larvae were not significantly different on transgenic corn hybrids compared with their near-isogenic parent lines, fewer large larvae were found on the transgenic hybrids. Differences in H. zea larval growth were noticeable when larvae fed on Bt corn vs non-Bt corn. The delay in larval growth for insects within a single generation, which could possibly result in asynchronous mating between insecticide resistant and susceptible insects, was observed for larvae feeding on plants expressing the Bt toxin. Diatraea grandiosella caused limited damage to the transgenic corn hybrids compared with their near-isogenic parent lines. Yields were not significantly greater for the Bt corn hybrids compared with their near-isogenic parent lines. Yields were not significantly greater for the Bt corn hybrids compared with the near-isogenic, non-Bt corn parents; however, there was a trend toward higher yields for Bt hybrids compared with their near-isogenic non-Bt parents.

Toxicity of Transgenic Corn Tissues Expressing Insecticidal Protein of Bacillus thuringiensis Berliner to Southwestern Corn Borer (Lepidoptera: Crambidae) in the Laboratory

2005 ◽  
Vol 40 (3) ◽  
pp. 307-315 ◽  
Author(s):  
Kerry C. Allen ◽  
Henry N. Pitre
Keyword(s):  
Bacillus Thuringiensis ◽  
Tissue Type ◽  
Bt Corn ◽  
Transgenic Corn ◽  
Laboratory Studies ◽  
Negative Effects ◽  
Diatraea Grandiosella ◽  
Corn Borer ◽  
Bt Toxin ◽  
Southwestern Corn Borer

Laboratory studies were conducted to compare the response of Diatraea grandiosella (Dyar) larvae to lyophilized transgenic corn tissue expressing the Cry1Ab endotoxin protein of Bacillus thuringiensis (Berliner) (Bt) with conventional corn tissue incorporated into a BioServ™ artificial diet. Whorl leaf, stalk, shank, husk, silk or kernel tissues were tested independently in the diet. Larvae fed diet containing conventional corn weighed more and were longer in length than larvae fed diet containing Bt corn for all tissue types included in the study. The number of larvae that survived depended on the tissue type and age of the tissue. Larvae fed diet with kernel tissue expressing Bt toxin had greater weight and body length than larvae fed the other Bt tissue types. The negative effects of Bt corn tissues expressing the Cry1Ab endotoxin protein on growth of D. grandiosella was observed, even at the diluted concentrations of toxic tissues incorporated into the diet in this study.

Bollworm (Lepidoptera: Noctuidae) Development and Movement on Bacillus thuringiensis-treated Cotton Leaves

2001 ◽  
Vol 36 (1) ◽  
pp. 23-33 ◽  
Author(s):  
Muhammad Ashfaq ◽  
S. Y. Young ◽  
R. W. McNew
Keyword(s):  
Bacillus Thuringiensis ◽  
Helicoverpa Zea ◽  
Leaf Surface ◽  
Larval Mortality ◽  
Lethal Dose ◽  
Crop Protection ◽  
Pupal Weight ◽  
Larval Weight ◽  
Lepidoptera Noctuidae ◽  
Transfer Times

Larval mortality, survivorship and movement of the bollworm, Helicoverpa zea (Boddie), on and away from Bacillus thuringiensis-treated cotton leaves were investigated in the laboratory. Bacillus thuringiensis (Costar®, Novartis Crop Protection, Inc; Greensboro, NC) was applied to the upper surface of cotton leaves via a spray table in five concentrations, i.e., 0.0 (control), 0.14, 0.29, 0.58, and 1.15 kg/ha. Three-day-old H. zea larvae were released on treated leaves, kept at 30°C, and transferred to artificial diet after 12, 24, and 48 h. Significantly higher numbers of larvae were found on the lower than upper leaf surface after all three transfer times, but the numbers surviving in all treatments were similar to the control. Larval movement from the leaf to cup surface was significantly higher in B. thuringiensis-treated leaves than in the control. The mortality of larvae that were transferred from leaves to diet at 7 d after treatment was significantly higher in all treatments than in the control and highest at the highest rates (0.58 and 1.15 kg/ha). Data on survival of larvae at different locations suggest that for the first 24 h, the increase in the percentage of larvae on the inner cup surface in B. thuringiensis treatments was not due to larvae that had consumed a lethal dose, but an attempt to avoid the B. thuringiensis on the upper leaf surface. Highest larval weight was recorded in the control for all transfer times. The length of the larval period increased with the B. thuringiensis rate at the 12-h transfer. The pupal weight was reduced at the highest B. thuringiensis rates at the 48-h transfer.

Antagonism between Formulations of Different Bacillus thuringiensis Subspecies in Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae)

1998 ◽  
Vol 33 (2) ◽  
pp. 129-135 ◽  
Author(s):  
A. O. Ameen ◽  
J. R. Fuxa ◽  
A. R. Richter
Keyword(s):  
Bacillus Thuringiensis ◽  
Heliothis Virescens ◽  
Helicoverpa Zea ◽  
Insect Species ◽  
Median Lethal Concentrations ◽  
Lepidoptera Noctuidae

Interactions between formulations of the aizawai and kurstaki subspecies of Bacillus thuringiensis Berliner were evaluated by bioassay in Heliothis virescens (F.) and Helicoverpa zea (Boddie). In preliminary experiments, a formulation of subspecies aizawai, Xentari AS®, had significantly (P < 0.05) higher median lethal concentrations (LC50s) in both insect species than formulations based on subspecies kurstaki. Helicoverpa zea was significantly (P < 0.05) more susceptible than H. virescens to one formulation of subspecies kurstaki (Dipel ES®), but the two insects did not differ in susceptibility to Xentari AS® or to a second formulation of subspecies kurstaki (Dipel 6AF®). In H. virescens, Xentari AS® was additive with Dipel 6AF® and significantly (P< 0.05) antagonistic with Dipel ES® and with a third formulation of subspecies kurstaki, Dipel 48A®. In H. zea, Xentari AS® was significantly antagonistic with all three formulations of subspecies kurstaki. This suggests that certain toxin combinations from B. thuringiensis subspecies might not be effective for managing H. virescens and H. zea populations.

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