Effects of Bacillus thuringiensis and Hd-73 Delta-Endotoxin on Growth, Behavior, and Fitness of Susceptible and Toxin-Adapted Strains of Heliothis virescens (Lepidoptera: Noctuidae)

1991 ◽  
Vol 20 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Fred Gould ◽  
Arne Anderson
Keyword(s):  
Bacillus Thuringiensis ◽  
Heliothis Virescens ◽  
Growth Behavior ◽  
Delta Endotoxin ◽  
Lepidoptera Noctuidae

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.

Survival Rates of Tobacco Budworm (Lepidoptera: Noctuidae) Larvae Exposed to Transgenic Cottons Expressing Insecticidal Protein of Bacillus thuringiensis Berliner

2000 ◽  
Vol 35 (2) ◽  
pp. 105-117 ◽  
Author(s):  
C. D. Parker ◽  
V. J. Mascarenhas ◽  
R. G. Luttrell ◽  
K. Knighten
Keyword(s):  
Bacillus Thuringiensis ◽  
Insecticidal Activity ◽  
Heliothis Virescens ◽  
Survival Rates ◽  
Larval Survival ◽  
Tobacco Budworm ◽  
Bt Cotton ◽  
Plant Structure ◽  
Lepidoptera Noctuidae ◽  
Insecticidal Plants

The insecticidal activity of transgenic cottons expressing endotoxin protein of Bacillus thuringiensis Berliner (Bt cotton) was quantified by measuring survival of tobacco budworm, Heliothis virescens (F.), larvae caged on different plant structures for varying lengths of exposure. Percentages of larvae surviving were measured on Bt cottons expressing Cry1Ab and CrylAc protein. Plant structure (terminal, leaf, square or boll) did not affect larval survival, and survival did not differ significantly between CrylAb and CrylAc cottons. Larvae exposed to Bt cotton for only 24 h had higher initial survival than larvae exposed for 48, 72 and 96 h. Larvae first exposed to Bt cotton at 4 d of age had higher survival than those first exposed as neonate or 2-d-old larvae. Survivorship of neonate and 4-d-old larvae exposed to CrylAc cotton was significantly reduced with only 48 h of exposure to the insecticidal plants. Seven-day-old larvae exhibited no significant reduction in survivorship with exposure to CrylAc cotton for 48 h.

Microplitis croceipes (Hymenoptera: Braconidae) Development in Tobacco Budworm (Lepidoptera: Noctuidae) Larvae Treated with Bacillus thuringiensis and Thiodicarb

1999 ◽  
Vol 34 (2) ◽  
pp. 249-259 ◽  
Author(s):  
D. W. Atwood ◽  
T. J. Kring ◽  
S. Y. Young
Keyword(s):  
Bacillus Thuringiensis ◽  
High Mortality ◽  
Heliothis Virescens ◽  
Laboratory Tests ◽  
Resistance Management ◽  
Tobacco Budworm ◽  
Microplitis Croceipes ◽  
Host Mortality ◽  
Lepidoptera Noctuidae

Bacillus thuringiensis Berliner var. kurstaki and thiodicarb were evaluated in laboratory and field assays to determine the effect on tobacco budworm larvae, Heliothis virescens (F.), and the parasitoid Microplitis croceipes Cresson. Laboratory trials were conducted using B. thuringiensis concentrations of 0, 10, 50 and 250 ppm and thiodicarb concentrations of 0, 12.5, 25, 50, 100, and 200 ppm in the diet. The test using field-treated cotton squares was conducted using B. thuringiensis and thiodicarb, independently and in combination, at rates recommended for resistance management in Arkansas. Laboratory tests indicated that tobacco budworm mortality was directly related to B. thuringiensis and thiodicarb concentrations, although B. thuringiensis only significantly increased tobacco budworm mortality at the highest concentration of exposure in the absence of parasitization. Parasitization increased host mortality at all B. thuringiensis experimental rates after 6 and 14 days. Although host mortality increased linearly with increasing thiodicarb concentration, parasitization did not significantly increase host mortality over thiodicarb alone until day 14. Emergence of M. croceipes was inversely related to B. thuringiensis and thiodicarb concentration. In assays using squares from field-sprayed cotton, thiodicarb and thiodicarb/B thuringiensis mixtures provided significantly greater tobacco budworm mortality than did B. thuringiensis application alone. In addition, no significant advantage was determined for tank mixtures with B. thuringiensis as compared to thiodicarb application alone. However, neither B. thuringiensis nor thiodicarb, alone or in combination, caused a high mortality of early third instar tobacco budworm in the absence of parasitization by M. croceipes.

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