Influence of Panicle Maturity on Infestation of Grain Sorghum by Corn Earworm and Sorghum Webworm (Lepidoptera: Noctuidae) in Georgia

1991 ◽  
Vol 26 (4) ◽  
pp. 419-424
Author(s):  
J. R. Chamberlin ◽  
J. N. All
Keyword(s):  
Helicoverpa Zea ◽  
Paired Comparison ◽  
Larval Density ◽  
Field Tests ◽  
Grain Sorghum ◽  
Corn Earworm ◽  
Egg Parasitism ◽  
Low Levels ◽  
Sorghum Webworm ◽  
Lepidoptera Noctuidae

The influence of panicle maturity on oviposition by the corn earworm, Helicoverpa zea (Boddie), and sorghum webworm, Celama sorghiella (Riley), was investigated on grain sorghum in Georgia during 1986 and 1987. Stage of panicle development, density of corn earworm and sorghum webworm, and egg parasitism by Trichogramma spp. were recorded at 2–3 day intervals in three field tests. Sorghum webworm and corn earworm began oviposition as panicles emerged from the boot. Oviposition peaked 4–8 days later, near the time panicles began anthesis, but then declined quite rapidly. Oviposition by sorghum webworm ceased approximately 10–12 days after panicle emergence began. Corn earworm oviposition continued at low levels until sampling was terminated 14 - 17 days after panicles began emgergence. Rainfall appeared to mediate effects of panicle maturity on oviposition. Corresponding peaks in larval density were not observed for corn earworm or sorghum webworm, possibly because of heavy parasitism by Trichogramma spp. A paired comparison procedure was used to determine preference of small, medium, and large corn earworm larvae for panicles of different maturity. Early instars preferred newly flowered panicles and concentrated feeding on pollen filled anthers. Late instars preferred panicles in the soft-hard dough stages, while intermediate instars exhibited no significant preference. These data suggest that corn earworm oviposition is concentrated at anthesis because pollen enhances larval development and survival.

Predation of Corn Earworm (Lepidoptera: Noctuidae) Eggs and Young Larvae by Orius insidiosus (Say) (Heteroptera: Anthocoridae) on Grain Sorghum in a Greenhouse

1994 ◽  
Vol 29 (1) ◽  
pp. 10-17 ◽  
Author(s):  
D. A. Jacobson ◽  
T. J. Kring
Keyword(s):  
Larval Density ◽  
Grain Sorghum ◽  
Corn Earworm ◽  
Fourth Instar ◽  
The Other ◽  
Orius Insidiosus ◽  
First Instar ◽  
Egg Density ◽  
Lepidoptera Noctuidae ◽  
Individual Adult

Individual adult, fourth- and second-instar Orius insidiosus (Say) were caged for 24 h on branches of grain sorghum panicles with combinations of 0, 2, or 4 corn earworm eggs and 0, 2, or 4 first instar earworms, excepting 0 eggs and 0 larvae. Individual adult O. insidiosus also were caged for 24 h with 2 second-instar corn earworms. In cages with corn earworm eggs and first instars, predation by all stages of O. insidiosus on one stage of corn earworm was not significantly influenced by the number of the other stage available. The number of corn earworm eggs shriveled or missing, indicative of predation by O. insidiosus, was highest for cages with O. insidiosus adults (65% for either egg density). In cages with fourth-instar O. insidiosus, the percentage of corn earworm egg shriveled or missing was 45% with 2 eggs available and 32% with 4 eggs available. At all densities of eggs, the number of eggs shriveled or missing in cages with second-instar O. insidiosus was not significantly higher than in control cages. The number of first-instar corn earworms shriveled or missing was highest with fourth-instar O. insidiosus (≈ 52% loss at either larval density). Approximately 47% of larvae at both densities were shriveled or missing in cages with adult O. insidiosus. As was the case with eggs, the number of corn earworm larvae shriveled or missing in cages with second-instar O. insidiosus was not significantly different from that for the controls. Predation on second-instar corn earworms by adult O. insidiosus was not significant.

Efficacy of Predators Attacking Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) Eggs on Grain Sorghum in the Field

1995 ◽  
Vol 30 (2) ◽  
pp. 251-257 ◽  
Author(s):  
D. A. Jacobson ◽  
T. J. Kring
Keyword(s):  
Helicoverpa Zea ◽  
Grain Sorghum ◽  
Corn Earworm ◽  
Predator Population ◽  
Effective Technique ◽  
Fine Mesh ◽  
Arthropod Predators ◽  
Mesh Cage ◽  
Disruption Method ◽  
Lepidoptera Noctuidae

Exclusion and insecticidal disruption studies were conducted to evaluate the efficacy of predators of corn earworm, Helicoverpa zea (Boddie), eggs on grain sorghum panicles in southwest and northeast Arkansas. Sets of three grain sorghum plants in a field were selected and one of three different treatments were applied to each plant in the trio. One panicle was fitted with an open cage with a large mesh that allowed colonization by most arthropod predators (particularly Orius insidiosus (Say)), but prevented feral H. zea moths from ovipositing on the panicles. The other two panicles in each trio were sprayed with mevinphos (Phosdrin) to erradicate predators, then one of these panicles was fitted with a cage of fine mesh that excluded all predators (total exclusion). The third panicle was covered with only a large mesh cage (insecticidal disruption). Ten H. zea eggs were placed on each of the panicles and the number that were shriveled or missing (indicative of predation) were recorded after 24 and 48 h. Predator densities also were evaluated on these and adjacent panicles. Tests were replicated in two locations over two years. When predator densities were highest, an average of 8.7 O. insidiosus (all stages) were found per panicle in open cages. Differences in the numbers of eggs shriveled or missing were significant in these treatments, with 62% missing from open cages, 27% from insecticidal checks, and only 15% from total exclusion cages. Because O. insidiosus represented 94% of the total predator population, the results indicated the importance of O. insidiosus as a predator of H. zea eggs on grain sorghum. The insecticidal disruption method appeared to be an effective technique for evaluating the efficacy of predators of H. zea eggs on grain sorghum panicles.

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.

INFESTAÇÃO DE MILHO CRIOULO, CONVENCIONAL E TRANSGÊNICO PELA LAGARTA-DO-CARTUCHO E PELA LAGARTA-DA-ESPIGA E PARASITISMO DE OVOS

2017 ◽  
Vol 16 (3) ◽  
pp. 351
Author(s):  
CAMILA CORRÊA VARGAS ◽  
ROSANA MATOS DE MORAIS ◽  
LUIZA RODRIGUES REDAELLI
Keyword(s):  
Zea Mays ◽  
Spodoptera Frugiperda ◽  
Helicoverpa Zea ◽  
Genetically Modified ◽  
Fall Armyworm ◽  
Corn Earworm ◽  
Trichogramma Pretiosum ◽  
Hybrid Corn ◽  
Egg Parasitism ◽  
Santa Maria

RESUMO - O objetivo foi avaliar a infestação, o parasitismo de ovos e danos da lagarta-do-cartucho, Spodoptera frugiperda (J. E. Smith), e da lagarta-da-espiga, Helicoverpa zea (Boddie), em cultivares de milho: variedade crioulo (Lombo Baio), híbrido convencional (Semilha S395) e híbrido geneticamente modificado (Bt) (TC1507 Herculex I ®, Cry1F). O experimento foi conduzido em Santa Maria-RS, no período de segunda safra de 2014. O delineamento foi de blocos ao acaso, com três tratamentos e quatro repetições. Foram registrados os danos, o número de lagartas, de posturas e o parasitismo em ovos da lagarta-do-cartucho, dos 9 aos 72 dias após a emergência das plantas (DAE). A infestação da lagarta-da-espiga e o parasitismo de ovos foram registrados dos 67 aos 101 DAE. Os danos causados pela lagarta-do-cartucho foram semelhantes entre milho crioulo e convencional, os quais foram mais elevados do que no milho geneticamente modificado Bt. O número médio de lagartas-do-cartucho foi maior em milho crioulo. A média do número total de lagartas-da-espiga foi semelhante entre milho crioulo e convencional e superior à do Bt. Foi registrado o parasitismo de ovos para a lagarta-da-espiga por Trichogramma pretiosum Riley, nas três cultivares avaliadas, com porcentagens semelhantes entre milho crioulo e convencional e superior em milho Bt. Palavras-chave: Spodoptera frugiperda, Helicoverpa zea, Trichogramma pretiosum, Zea mays, manejo de pragas. INFESTATION IN INLANDRACE, CONVENTIONAL AND TRANSGENIC CORN BY FALL ARMYWORM AND CORN EARWORM, AND EGG PARASITISM  ABSTRACT - The objective of the work was to estimate the infestation and eggs parasitism of fall armyworm (J. E. Smith) and corn earworm (Boddie), in three corn varieties: landrace (LomboBaio), conventional hybrid (Semilha S395) and genetically modified hybrid (Bt) (TC1507 Herculex I ®, Cry1F). The experiment was carried out in Santa Maria-RS, during the second-season corn crop, in 2014. The experimental design was a completely randomized block with three treatments, and four replicates. We evaluated the damages, number of larvae, number of eggs and fall armyworm egg parasitism from 9 to 72 days after emergence (DAE). The infestation of corn earworm and the eggs parasitism were measured from 67 to 101 DAE. Fall armyworm damage was similar between landrace and conventional hybrid, and both higher than those of genetically modified hybrid Bt. Average number of fall armyworm larvae was higher in landrace cultivar. The average of total number of corn earworm larvae was similar on landrace and conventional hybrid, both higher than Bt hybrid. Corn earworm eggs parasitism by Trichogramma pretiosum Riley was recorded in the three evaluated cultivars and similar parasitism percentage was observed between landrace and conventional hybrid, which was higher in Bt maize. Keywords: Spodoptera frugiperda, Helicoverpa zea, Trichogramma pretiosum, Zea mays, pest management.

scholarly journals Corn Earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)

EDIS ◽  
1969 ◽  
Vol 2002 (7) ◽  
Author(s):  
John L. Capinera
Keyword(s):  
Helicoverpa Zea ◽  
Cooperative Extension ◽  
Cooperative Extension Service ◽  
Corn Earworm ◽  
Extension Service ◽  
University Of Florida ◽  
Agricultural Sciences ◽  
Lepidoptera Noctuidae

This document is EENY-145, one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: July 2000. https://edis.ifas.ufl.edu/in302

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