Viability of Claviceps africana Spores Ingested by Adult Corn Earworm Moths, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)

2004 ◽  
Vol 97 (3) ◽  
pp. 764-767 ◽  
Author(s):  
Louis K. Prom ◽  
Juan D. Lopez
1996 ◽  
Vol 31 (3) ◽  
pp. 340-346 ◽  
Author(s):  
Steven R. Sims ◽  
Jay C. Pershing ◽  
Barbara J. Reich

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.


1991 ◽  
Vol 26 (4) ◽  
pp. 419-424
Author(s):  
J. R. Chamberlin ◽  
J. N. All

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.


EDIS ◽  
1969 ◽  
Vol 2002 (7) ◽  
Author(s):  
John L. Capinera

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


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kadie E Britt ◽  
Thomas P Kuhar ◽  
Whitney Cranshaw ◽  
Christopher T McCullough ◽  
Sally V Taylor ◽  
...  

Abstract Corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), has emerged as an injurious insect pest to hemp, Cannabis sativa L., a crop newly reintroduced to the United States. Growing hemp presents a potential alternative economic opportunity for farmers but can be challenging with a market that is unstable and just developing. One of the most notable production challenges is managing corn earworm, an insect pest that is particularly damaging when it feeds on flower buds produced in cannabinoid varieties, creating extensive bud tunneling and wounds that allow entry of pathogens that can aid development and presence of bud rot. Damage to seeds is of lesser concern in hemp cultivars grown for grain and minimal risk is associated with hemp grown for fiber. Our ability to research hemp has only recently been allowed as production was largely suspended following World War II and, as such, there has been limited opportunity to develop information for empirically-based pest management recommendations. Further complicating development of integrated pest management (IPM) strategies are regulatory challenges associated with providing registration support to add hemp to pesticide labels, as it was not formally recognized as a crop by U.S. regulatory agencies until late 2019. Research needs and challenges to develop effective IPM programs for corn earworm on hemp are discussed here.


1992 ◽  
Vol 27 (4) ◽  
pp. 413-420 ◽  
Author(s):  
J. E. Carpenter ◽  
B. R. Wiseman

Male and female corn earworm, Helicoverpa zea (Boddie), adults were exposed to a substerilizing dose (10 krads) of gamma radiation after which their progeny were reared on a meridic diet containing selected concentrations of dry silk collected from resistant dent corn genotypes. Significant interactions were observed between the developmental time of progeny from irradiated females and progeny from normal parents and meridic diets with increasing degrees of resistance. A significant interaction also was observed between the mean larval weights of normal and substerile larvae and diets with increasing degrees of resistance. The 9-d weight of normal larvae was significantly higher than the weight of substerile larvae at the lowest degree of resistance, but differences between the weight of normal and substerile larvae at the highest degree of resistance were not significant. Larvae from irradiated male by normal female crosses were equally competitive with normal larvae for all measured parameters. Data from this study suggest that plant resistance and inherited sterility would be compatible control strategies for the management of H. zea populations.


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