Control Of Corn Earworm Research Articles

Bt Trait Efficacy Against Corn Earworm, Helicoverpa zea, (Lepidoptera: Noctuidae) for Preserving Grain Yield and Reducing Mycotoxin Contamination of Field Corn.

The corn earworm, Helicoverpa zea (Boddie), causes persistent ear damage to corn grown in the southeastern United States region. Increased levels of ear damage have been associated with mycotoxin contamination in addition to yield loss. Corn hybrids expressing proteins from the Bacillus thuringiensis (Bt) may provide corn earworm control. A selection of hybrids expressing various Bt traits were evaluated in field experiments across Georgia over two years to assess their efficacy for corn earworm control, grain yield and quality protection, and grain mycotoxin mitigation. Ear damage was significantly reduced only by Bt hybrids expressing the Vip3Aa20 protein. The remaining Bt hybrids expressing Cry proteins provided only marginal control. Ear damage had a variable effect on grain yield and was not correlated with grain aflatoxin contamination. In contrast, grain fumonisin contamination was positively associated with earworm damage. These results indicate Bt hybrids that effectively reduce corn earworm damage may also assist in reducing fumonisin contamination and possibly yield loss.

Insecticidal control of corn earworm in Minnesota sweet corn, 2023

Insecticidal control of corn earworm in Minnesota sweet corn, 2023

Efficacy of insecticides Spear Lep and Heligen for control of corn earworm in sweet corn, Virginia, 2023

Efficacy of insecticides Spear Lep and Heligen for control of corn earworm in sweet corn, Virginia, 2023

Chlorantraniliprole Residual Control and Concentration Determination in Cotton.

Studies were conducted in 2020 and 2021 at the Delta Research and Extension Center in Stoneville, MS, to determine the residual concentrations of chlorantraniliprole in cotton (Gossypium hirsutum, L.) leaves, as well as the concentrations in petals and anthers that developed after the time of application. Foliar applications of chlorantraniliprole were applied at four rates for leaves and two rates for petals and anthers at the second week of bloom. Additional bioassays were conducted to determine mortality of corn earworm (Helicoverpa zea, Boddie) in anthers. For the leaf study, plants were partitioned into three zones consisting of top, middle, and bottom zones. Leaf samples from each zone were analyzed for chemical concentrations at 1, 7, 14, 21, and 28 days after treatment (DAT). Residual concentrations, although variable, persisted through all sampling dates, rates, and zones tested. In this study, chlorantraniliprole remained detectable up to 28 DAT. Results from the cotton flower petal and anther studies detected concentrations of chlorantraniliprole in petals at 4, 7, 10, and 14 DAT, but no concentrations were detected in anthers. Therefore, no mortality of corn earworm was recorded in the anther bioassays. A series of diet-incorporated bioassays were conducted using concentrations previously found in the petal study to determine baseline susceptibilities of corn earworms and predicted mortality. Results from the diet-incorporated bioassays showed similar susceptibility in field and lab colony corn earworms. Concentrations of chlorantraniliprole could provide up to 64% control of corn earworm when feeding occurs on the petals.

Evaluation of Selected Insecticides for Control of Corn Earworm in Grain Sorghum, 2018

Evaluation of Selected Insecticides for Control of Corn Earworm in Grain Sorghum, 2018

Effects of Carriers, Emulsifiers, and Biopesticides for Direct Silk Treatments on Caterpillar Feeding Damage and Ear Development in Sweet Corn.

In the northeastern United States, control of Lepidopteran pests of sweet corn, particularly corn earworm [Helicoverpa zea (Boddie)], is difficult using organic methods. The direct application of corn oil and Bacillus thuringiensis (Bt) to corn silk has been shown to reduce ear damage from corn earworm in past studies; these studies sought to optimize this method by evaluating additional carrier and biopesticide mixtures that comply with the United States Federal Insecticide, Fungicide, and Rodenticide Act and National Organic Standards. Carriers, which are liquids used to dissolve the biopesticide and deliver it into the tip of the ear, may have phytotoxic or insecticidal properties. Experiments conducted from 2001 to 2005 evaluated caterpillar damage and ear development effects from carriers (vegetable and paraffinic oils and carrageenan), biopesticides (Bt, spinsosad, and neem), and three emulsifiers in various combinations when applied directly to the tips of the ears 5-7 d after silk initiation. There were no effects of emulsifiers on ear quality, except for slight reduction in caterpillar damage in one of the two years. There were no differences among corn, soy, canola, and safflower oils in corn earworm control or tip development. The carrageenan carrier had the least effect upon ear development as measured by the length of nonpollinated kernels at the tip, compared to corn oil or paraffinic oil (JMS Stylet Oil), which caused the greatest tip damage as well as an oily discoloration. The carrier-pesticide combinations with the best ear quality overall were spinosad in carrageenan or corn oil, and Bt in carrageenan.

Evaluation of Selected Insecticides for Control of Corn Earworm in Grain Sorghum, 2016*

Evaluation of Selected Insecticides for Control of Corn Earworm in Grain Sorghum, 2016*

Insecticidal Control of Corn Earworm and European Corn Borer in Minnesota Sweet Corn, 2016*

Insecticidal Control of Corn Earworm and European Corn Borer in Minnesota Sweet Corn, 2016*

Evaluation of Selected Insecticides for Control of Caterpillar Pests in Grain Sorghum, 2015: Table 1

Selected insecticide treatments were evaluated for control of corn earworm, sorghum webworm, and fall armyworm in grain sorghum at the Research and Education Center at Milan (Milan, TN). Grain sorghum was planted on 17 Jun. The test was arranged in a RCB design with four replicates. Individual plots were 12.5 × 30 ft. Treatments were applied with a high clearance sprayer calibrated to deliver 9.4 GPA at 40 PSI with 8001 flat fan nozzles. Foliar applications were made on 19 Aug, prior to infestation by caterpillar pests. The …

Evaluation of Selected Insecticides for Control of Corn Earworm in Grain Sorghum, 2015: Table 1

Selected insecticide treatments were evaluated for control of corn earworm in grain sorghum at the Research and Education Center at Milan, TN. Grain sorghum was planted on 13 May. The test was arranged in an RCB design with four replicates. Individual plots were 12.5 × 30 ft. Treatments were applied with a high clearance sprayer calibrated to deliver 9.4 GPA at 40 psi with 8,001 flat fan nozzles. Foliar application was made …

Sweet Corn Insecticide Efficacy Trial, 2014

The objective of the study was to evaluate the efficacy of insecticidal materials for control of corn earworm (CEW) on sweet corn under desert growing conditions during the spring season. Sweet corn, “Xtra-Tender 1278” was direct seeded on 21 March 2014 at the University of California Desert Research and Extension Center, Holtville, CA, into single row beds on 40-inch centers. Stand establishment and crop maintenance was achieved using furrow irrigation. Plots were two beds in width (6.67 ft) by 50 ft in length. Five replications of each treatment were arranged in an RCB …

Enhancing biological control of corn earworm, Helicoverpa zea and thrips through habitat management and inundative release of Trichogramma pretiosum in corn cropping systems

Conservation-(habitat management) and augmentative biological control (field releases of natural enemies) are important pest biological control methods in agricultural systems. When these methods are employed at a critical stage of the crop and pest phenology, they can be effective and economically viable to suppress the target pest below its economic threshold. Field experiments consisting three treatments: (1) corn intercropped with sunn hemp (habitat management: conservation biological control), (2) corn monoculture with release of Trichogramma pretiosum (inundative biological control), and (3) corn monoculture as a control were conducted. This study aimed to compare the effectiveness of (I) conservation- and inundative biological control (biocontrol-enhanced treatments) with corn monoculture in terms of improving parasitism of Helicoverpa zea eggs by T. pretiosum, (II) conservation biological control with corn monoculture on predation of H. zea eggs and thrips by Orius spp. Results showed parasitism of H. zea eggs on corn silks was greater in the biocontrol-enhanced treatments compared to the monoculture control, and was greater in the T. pretiosum released treatment compared to the habitat management. Abundance of Orius spp. in relation to prey availability was greater in the habitat management treatment compared to the monoculture control. Proportion of corn ears damaged in Trichogramma release plots was lower than other treatments. These results suggest that inundative release of T. pretiosum is a potentially more viable management tool for H. zea control in corn compared to the habitat management with sunn hemp as an intercrop.

Evaluation of Attribute II Bt Sweet Corn Resistance and Reduced-Risk Insecticide Applications for Control of Corn Earworm

Evaluation of Attribute II Bt Sweet Corn Resistance and Reduced-Risk Insecticide Applications for Control of Corn Earworm

Corn Earworm (Lepidoptera: Noctuidae) in Northeastern Field Corn: Infestation Levels and the Value of Transgenic Hybrids

Corn earworm, Helicoverpa zea (Boddie), is a polyphagous noctuid pest of agricultural crops across the United States that is gaining attention as a pest of field corn. Before the introduction of transgenic insect-resistant hybrids, this pest was largely ignored in field corn, but now many Bacillus thuringiensis (Bt) corn hybrids have activity against corn earworm. However, the value of control in the northeastern United States is unclear because the risk posed by corn earworm to field corn has not been well characterized. To understand the threat from corn earworm and the value of Bt hybrids in field corn, we assessed corn earworm injury in Bt and non-Bt hybrids at 16 sites across four maturity zones throughout Pennsylvania in 2010, and 10 sites in 2011. We also used corn earworm captures from the PestWatch pheromone trapping network to relate moth activity to larval damage in field corn. Corn earworm damage was less than one kernel per ear at 21 of 26 sites over both years, and the percentage of ears damaged was generally < 15%, much lower than in the southern United States where damage can be up to 30 kernels per ear. At sites with the highest damage levels, Bt hybrids suppressed corn earworm damage relative to non-Bt hybrids, but we found no differences among Bt traits. Cumulative moth captures through July effectively predicted damage at the end of the season. Currently, the additional benefit of corn earworm control provided by Bt hybrids is typically less than US$4.00/ha in northeastern field corn.

Evidence for Decreasing Helicoverpa zea Susceptibility to Pyrethroid Insecticides in the Midwestern United States

The corn earworm (CEW), Helicoverpa zea (Boddie), is a highly mobile pest of numerous field and vegetable crops in much of North America. In the Midwestern United States, CEW is a voracious pest of several high-value vegetable crops, including sweet corn, tomatoes, and snap beans, and seed corn grown for the field corn industry. Historically, synthetic pyrethroid insecticides have been cost-effective and have provided excellent control of CEW, with control of larvae in sweet corn exceeding 90%. However, since 2000 pyrethroids have only provided 35 to 45% control in field tests conducted in the Midwest, as indicated by small-plot sweet corn efficacy trials. During 2005, the four most commonly used pyrethroids averaged only 19.3 to 37.3% control of CEW (mean of 5 trials in Minnesota, Wisconsin, Illinois, and Indiana). In addition, the survival of moths exposed to the standard pyrethroid, cypermethrin, using the Adult Vial Test (AVT), indicated high survival rates (44 to 66% at 5 μg cypermethrin and up to 45% survival at 10 μg). These levels are similar to, or higher than recent AVT results from Louisiana and Texas. These states reflect two possible “source” regions of late-season CEW that likely migrate north to the Midwestern states each summer. These results, including the stability of resistance each year in the Midwest, are discussed within the context of developing and expanding a North American resistance monitoring and management network. Accepted for publication 3 June 2007. Published 19 July 2007.

Antibiosis of forage soybean as an ecological alternative for the control of corn earworm

The present study is the first to document some antibiosis type of resistance in forage soybeans. The production of forage soybean is increasing in the United States where about 500 000 acres are now grown annually in various soybean growing areas. However, production is limited by the corn earworm Helicoverpa zea Boddie, which is a major insect pest of soybean. An in vitro study of field grown soybean leaves was conducted to select forage soybean genotypes for antibiosis type resistance to corn earworm. The feeding tests were conducted on excised leaf material from a randomized complete block design. The results showed significant differences in the weight of corn earworm larvae, which were allowed to feed on different genotypes of fodder soybean. The mean larval weights on genotypes Tara, 7P116 and 8 GH 85-2 were 245.8, 242.1, and 169.3 mg, respectively. These genotypes were found to be most susceptible to corn earworm while the tall growing vegetable cultivar Moon Cake with the mean larval weight of 94.8 showed some antibiosis types of resistance.

The Potential of Bt Corn as a Trap Crop for the Control of Corn Earworm, Helicoverpa zea Boddie, in Soybean

ABSTRACT Corn and soybean are two important crops in the Delmarva (Delaware, Maryland and Virginia) peninsula region. Both crops are attacked by corn earworm (CEW), Helicoverpa zea (Boddie). The larvae cause significant ear damage to corn serving as a primary nursery for CEW populations which shift to soybean later in the season. In soybean, CEW larvae cause serious yield losses if not controlled by insecticides. Many farmers in the Delmarva region have been increasing the acreage they grow with genetically engineered corn hybrids that contain insecticidal proteins expressed by the genes of Bacillus thurngiensis sub sp. kurstaki (Bt) as an alternative to the application of chemical insecticides. A study was conducted to investigate the use of Bt corn as a trap crop for the management of CEW in soybean. Bt corn was planted as a trap crop in a ten percent of the area of soybean as a peripheral trap, trap in the middle and trap in the intermittent rows in soybean. CEW moths were attracted and observed on the newly formed silks of the ears of Bt corn in all types of traps including peripheral trap, trap in the middle and trap in the intermittents rows planted in soybean. CEW eggs were also observed on the silk of transgenic corn. The moths, eggs and larvae (CEW) were hardly observed in soybean grown as a main crop. Clearly, we were able to divert the CEW adults on Bt corn from soybean. The number of CEW eggs was significantly higher in the peripheral trap and trap in the intermittent rows compared with trap in the middle of the plots, suggesting that Bt corn planted as a peripheral trap crop could be more practicable and effective for the farmers in reducing the CEW damage in soybean.

Control of European Corn Borer and Corn Earworm on Sweet Corn, 1997

Abstract ‘Jubilee’ was planted 25 Jun at the Uni-versity of Minnesota Agricultural Experiment Station at Rosemount, MN. Treatments were arranged in a RCB design with 4 replications. Plots consisted of 2 rows, 25 ft long with 30-inch row spacing. A single skip row separated each plot and 10-ft alleys separated the replications. Treatments were applied with a CO2-pressurized backpack sprayer using a single nozzle fitted with an XR-Teejet 8002 flat fan nozzle with no screen. The sprayer was calibrated to deliver 20 gpa at 34 psi, both rows of each 2-row plot were treated. Treatments were applied to the ear zone and began at 50% silk. Three applications were made 31 Aug, 5 and 11 Sep. Treatments were evaluated on 23 Sep by selecting 25 ears at random from each plot (100 per treatment) and recording the total number of larvae, larval size and location, and feeding damage (cm2).

Corn Earworm and European Corn Borer Control with Insecticides, 1997

Abstract ‘Golden Queen’ sweet corn was seeded on 22 I Apr near Calabash, NC in Brunswick Co. Single-row plots, 10 ft long on 42-inch centers, were replicated 4 times in a RCB design. Alleys of 5 ft were used I between replicates. Treatments were applied with a CO2-pressurized backpack sprayer using a single hollow-cone nozzle (18X) operating at 60 psi to deliver 54.5 gpa. Test 1 and Test 2 were in the same field with a 75 ft spacing of untreated area between the two test sites. Applications were made to both Test 1 and Test 2 twice a week on 27 and 30 Jun, and 3, 7, 10, 14, and 17 Jul. Insect-damaged ears were assayed on 21 Jul when all ears were harvested from both tests.

Selected Insecticides for Control of Corn Earworm and Green Cloverworm in Soybean in Virginia, 1997

Abstract Efficacy of selected insecticides was evaluated against CEW and GCW in soybean. ‘Hutcheson’ soybean was planted 15 June in a producer’s field in Greensville County, VA, using an 18-inch row spacing. All treatments were broadcast as foliar sprays with water on 27 August using a CO2 pressurized backpack sprayer calibrated to deliver 14.3 gpa at 18 psi through 8002VS flat fan nozzles spaced 18 inches apart on the spray boom. A RCB experimental design was used with 4 replicates; plots were 4 rows by 50 ft. Insect samples were taken using a 15-cm diameter sweep net, 15 sweeps per plot. Pre-treatment insect populations were assessed just prior to treatment application by taking several 15-sweep samples throughout the planned test area. Post-treatment samples were taken 2, 4, 8, 12, and 21 days after treatment (DAT) by comparing numbers of small (1st and 2nd instars), medium (3rd and 4th instars), large (5th and 6th instars) and total CEW larvae, and total (all sizes) GCW larvae. Data were analyzing using ANOVA and LSD statistical procedures.