Effects of MON810 Bt Field Corn on Adult Emergence of Helicoverpa zea (Lepidoptera: Noctuidae)

2003 ◽  
Vol 96 (3) ◽  
pp. 925-930 ◽  
Author(s):  
T. A. Horner ◽  
G. P. Dively ◽  
D. A. Herbert
Keyword(s):  
Helicoverpa Zea ◽  
Adult Emergence ◽  
Field Corn ◽  
Lepidoptera Noctuidae

scholarly journals Impact of Simulated Corn Earworm (Lepidoptera: Noctuidae) Kernel Feeding on Field Corn Yield

2019 ◽  
Vol 112 (5) ◽  
pp. 2193-2198 ◽  
Author(s):  
B M Olivi ◽  
J Gore ◽  
F M Musser ◽  
A L Catchot ◽  
D R Cook
Keyword(s):  
Helicoverpa Zea ◽  
Zea Mays L ◽  
Corn Earworm ◽  
Corn Yield ◽  
Corn Hybrids ◽  
Field Corn ◽  
Lepidoptera Noctuidae ◽  
Economic Pest ◽  
Harvest Method ◽  
Study Manual

Abstract Corn earworm, Helicoverpa zea (Boddie) Lepidoptera: Noctuidae, has not been considered an economic pest of field corn. Historical losses estimates ranged from 1.5 to 2.5%, and a large number of foliar insecticide applications would be needed to minimize infestations. In recent years, Bt, Bacillus thuringiensis (Berliner) field corn, Zea mays (L.) Poales: Poaceae, technologies that exhibit activity against corn earworm have been introduced. However, it is unclear how much damage to corn ears (number of damaged kernels) is required to reduce yield. In this study manual damage methods were utilized to inflict defined levels of kernel damage and to impose damage at levels greater than observed with natural corn earworm infestations. Bt corn hybrids expressing the Agrisure Viptera (Vip 3A) trait were used to minimize injury from natural infestations of corn earworm. Manual kernel damage was imposed at R3 stage to mimic corn earworm feeding while avoiding interference with pollination. These methods were used in experiments where treatments were applied to individual ears and hand-harvested and in experiments where treatments were applied to all primary ears in the plot and machine-harvested. Damage of ≥60 kernels per ear was required to significantly reduce yield regardless of harvest method. Kernel damage from natural corn earworm infestations reported in other studies was much lower than 60 kernels per ear. Timely planting is a key component of all integrated pest management programs. Field corn planted during the recommended planting window for optimum yield is unlikely to experience corn earworm damage great enough to reduce yield.

Effect of Parasitoid and Host Age on Oviposition and Emergence of Microplitis croceipes (Hymenoptera: Braconidae) an endoparasitoid of Helvicoverpa zea (Lepidoptera: Noctuidae)

1993 ◽  
Vol 28 (4) ◽  
pp. 343-349 ◽  
Author(s):  
W. W. Harrison ◽  
D. A. Herbert ◽  
D. D. Hardee
Keyword(s):  
Helicoverpa Zea ◽  
Pupal Stage ◽  
Adult Emergence ◽  
Microplitis Croceipes ◽  
Host Age ◽  
Parental Age ◽  
Host Instar ◽  
Adult Wasp ◽  
Lepidoptera Noctuidae ◽  
Parasitoid Age

The effect of parasitoid age and two instars of the host Helicoverpa zea (Boddie) were investigated for the endoparasitoid, Microplitis croceipes (Cresson). Third and fourth instars of H. zea were exposed to three different age ranges (3 to 5, 6 to 8, and 12 to 15-d-old) of mated adult female M. croceipes. No significant differences were shown in rate of parasitism regardless of parasitoid age or host instar. Significant differences (P < 0.05) were found between parental age and adult wasp emergence, sex ratio, and number in pupal stage entering diapause. Six to 8-day-old parasitoids parasitizing third instar hosts yielded the highest percentage of adult emergence (47.5 ± 14%; X̄ ± SD), the highest percentage of females (79%), and the lowest percentage (4.5 ± 6%; X̄ ± SD) entering diapause during the test.

Effects of an Entomopathogenic Nematode and a Nuclear Polyhedrosis Virus on Emergence of Heliothis virescens (Lepidoptera: Noctuidae)

1995 ◽  
Vol 30 (2) ◽  
pp. 243-250 ◽  
Author(s):  
M. R. Bell
Keyword(s):  
Heliothis Virescens ◽  
Untreated Control ◽  
Helicoverpa Zea ◽  
Entomopathogenic Nematode ◽  
Adult Emergence ◽  
Similar Rate ◽  
Tobacco Budworm ◽  
Whitening Agent ◽  
Nuclear Polyhedrosis ◽  
Lepidoptera Noctuidae

Cage tests were conducted during the 1993 growing season to determine the effect of incorporating an entomopathogenic nematode (Steinernema riobravis) in soil under cotton on subsequent emergence of tobacco budworm, Heliothis virescens (L.). When soil under seedling cotton was treated with 240K nematodes per m2 on 13 May, the number of moths emerging in cages was reduced by an average of 66%, compared to the untreated control, for at least 21 days following application. When a similar rate was applied on soil under mature cotton on 12 July, the number of moths emerging in treated cages after developing as larvae on the plants was 57% less over a 39 d period compared to the untreated control. In another cage study, application of the nematodes on wild geranium, Geranium dissectum L., an early-season host of tobacco budworms and cotton bollworms, Helicoverpa zea (Boddie), reduced adult emergence by 36% compared to untreated areas, whereas a single application of baculovirus from the celery looper (600 billion polyhedra per ha) reduced the emergence by 56%. In this latter test, adult emergence was further reduced (73% less than control) when a whitening agent was added to the virus application. These studies indicate than an entomopathogenic nematode, and the use of a whitening agent with baculovirus, might be useful in tobacco budworm management programs.

Sign in / Sign up

Export Citation Format

Share Document