Corn Earworm Larvae Research Articles

Bioactivity of Boldo (Peumus boldusMolina) (Laurales: Monimiaceae) onSpodoptera frugiperda(J.E. Smith) andHelicoverpa zea(Boddie) (Lepidoptera: Noctuidae)

Insecticidal properties of powdered boldo, Peumus boldus Molina, were evaluated against larvae of fall armyworm, Spodoptera frugiperda (J. E. Smith), and corn earworm, Helicoverpa zea (Boddie). Bioassays assessed development, feeding preferences, and mortality of neonate and third instars. For both species, most mortality (65 and 67.5%, respectively) was obtained with 8% boldo concentration incorporated into an artificial insect diet, and the LC50 and LC90 for fall armyworm were 6.8 and 25.9 g boldo kg-1 diet and 3.8 and 35.6 g boldo kg-1 diet for corn earworm. With increased concentration of boldo, larvae were shorter, weighed less, and had anatomical abnormalities, and fewer pupated. Concentrations of 4 and 8% boldo resulted in fewer adults of both species. In feeding preference tests, neonates selected the diet with the least concentration of boldo powder, and larvae fed less with higher concentrations. In tests for insect preference, the greatest concentrations of boldo resulted in the greatest indexes of feeding inhibition and growth, while the least indexes resulted in increases in larval weight and greater efficiency of conversion of ingested food in the diet percentage used to produce new larval biomass.

Constitutive Expression of the Maize Genes B1 and C1 in Transgenic Hi II Maize Results in Differential Tissue Pigmentation and Generates Resistance to Helicoverpa zea

Anthocyanin biosynthesis in maize protects tissues from biotic and abiotic stresses. Constitutive expression of the maize B1 and C1 genes, which induces anthocyanin biosynthesis, resulted in transgenic plants with varied phenotypes. Some colored leaves were substantially resistant to thrips damage, while only leaves with the highest levels of cyanidin, the predominant anthocyanidin detected in all colored transgenic tissues, were resistant to corn earworm (CEW) larvae. Colored anthers were resistant to CEW feeding, and reductions in CEW growth were significantly correlated to levels of cyanidin in the anthers. Cyanidin chloride and cyanidin-3-glucoside chloride added to insect diet slowed the growth of CEW larvae. Attempts to produce 3'5'-hydroxylated anthocyanins in colored maize with the expression of a petunia F3'5'H hydroxylase gene were unsuccessful.

EVALUATION OF VOLIAM XPRESS FOR CONTROLLING CORN EARWORM ON SWEET CORN, 2009

Selected insecticides were evaluated for corn earworm (CEW) management in a test at the Macon Ridge Research Station (Franklin Parish) in 2009. Sweet corn seed was planted to a Gigger silt loam on 26 May. Plot size was four rows (centered on 40 inches) by 30 ft. Treatments were arranged in a RCB design with four replications. Insecticides were delivered using a John Deere high clearance sprayed calibrated to apply 9.5 gpa of total spray solution using Teejet TX-8 hollow cone nozzles (2/row) at 48 psi. Treatments were initiated when 40 percent of the plants across the test area had developed to the R1 (ear silks visible) stage. Insecticides were applied four times on 1, 5, 9, and 15 Jul. Treatments were evaluated by removing 10 ears in the R3-R4 (milk/soft dough) stages from the middle two rows of each plot on 15 and 21 Jul. The number of CEW larvae and length of kernel damage (cm) from the ear tip were recorded for each ear. Data were subjected to ANOVA and means separated using LSD. Rainfall of 1.1, 0.8, and 0.25 inches were recorded during the test period.

Toward the Development of Novel Pest Management Agents Based upon Insect Kinin Neuropeptide Analogues

Insect kinin neuropeptides share a common C-terminal pentapeptide sequence Phe(1)-Xaa(1)(2)-Xaa(2)(3)-Trp(4)-Gly(5)-NH(2) (Xaa(1)(2)= His, Asn, Phe, Ser or Tyr; Xaa(2)(3)= Pro, Ser or Ala) and have been isolated from a number of insects. They have been associated with the regulation of such diverse processes as hindgut contraction, diuresis, and the release of digestive enzymes. In this review, the chemical, conformational, and stereochemical aspects of the activity of the insect kinins with expressed receptors and/or biological assays are reviewed. With this information, both nonselective and selective biostable analogues have been designed that protect peptidase-susceptible sites in the insect kinin sequence and demonstrate significant retention of activity in both receptor and biological assays. C-terminal aldehyde insect kinin analogues modify the activity of the insect kinins, leading to inhibition of weight gain and mortality in corn earworm larvae and selective inhibition of diuresis in the housefly. Promising mimetic analogue leads in the development of selective agents capable of disrupting insect kinin-regulated processes have been identified that may provide interesting tools for arthropod endocrinologists and new pest insect management strategies in the future.

Effect of Red Imported Fire Ant, Solenopsis invicta1,on Abundance of Corn Earworm, Helicoverpa zea2, on Maize in Texas

Predator exclusion was used to measure the impact of the red imported fire ant, Solenopsis invicta Buren, on abundance of corn earworm, Helicoverpa zea (Boddie), eggs and larvae feeding on ears of maize, Zea mays L., and on corn earworm pupae in the soil in north-central Texas. Large field plots were treated with Amdro® Fire Ant Bait insecticide to selectively suppress fire ant abundance without impacting other arthropods or their behavior. Abundance of corn earworm eggs, larvae and pupae were determined in maize in which abundance of fire ants was significantly reduced and compared with the abundance of corn earworm life stages in maize with extant populations of fire ants. Fire ants had little or no measurable effect on abundance of corn earworm eggs or larvae on ears of maize in the three fields studied during two years. The mean total number of foraging fire ants and abundance of corn earworm pupae in the soil were significantly and negatively related. This result suggests that fire ants prey on pre-pupal corn earworm larvae as they crawl on the soil surface or prey on pupae in cells in the soil. The role of red imported fire ant as both a pest and beneficial in production of maize in central Texas is discussed.

Feeding Behavior and Growth of Corn Earworm (Lepidoptera: Noctuidae) Larvae on Bacillus thuringiensis-Treated (Dipel 4L) and Untreated Meridic Diet

The effect of Dipel 4L in artificial diet on feeding behavior, occurrence on a specific diet, and growth of corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), was assessed in short-term tests. Third-, fourth-, and fifth-stage laboratory-reared and feral corn earworm larvae were evaluated. Arenas used for each assay included a non-Dipel diet, Dipel-containing diet, and a combination of the two diets. Larval activity was observed immediately after exposure to diet and at 6 and 18 h for third instars and at 6, 8, and 24 h for fourth and fifth instars, respectively. Feral and laboratory-reared third, fourth, and feral fifth instars avoided Dipel-treated diet when more suitable food was available. Third and fourth instars consistently preferred non-Dipel-containing diet when presented a choice of foods. Corn earworm growth was delayed when larvae were subjected to Dipel-treated diet in choice and no-choice assays compared with larvae provided untreated diet. Larvae presented a choice of diets grew more rapidly than those presented Dipel-treated diets in no choice arenas. Larval feeding frequency and weight gain were superior when larvae were supplied untreated diet than when restricted solely to a Dipel-treated diet. Larvae presented a choice of diets spent more time feeding and fed more frequently on untreated diet than Dipel-treated food. These data indicate that corn earworm presented a choice of Bacillus thuringiensis (Bt) and non-Bt diets may have an increased probability of completing development compared with those restricted to Bt-laced sources.

Feeding Behavior and Growth of Corn Earworm (Lepidoptera: Noctuidae) Larvae on <I>Bacillus thuringiensis</I>-Treated (Dipel 4L) and Untreated Meridic Diet

The effect of Dipel 4L in artificial diet on feeding behavior, occurrence on a specific diet, and growth of corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), was assessed in short-term tests. Third-, fourth-, and fifth-stage laboratory-reared and feral corn earworm larvae were evaluated. Arenas used for each assay included a non-Dipel diet, Dipel-containing diet, and a combination of the two diets. Larval activity was observed immediately after exposure to diet and at 6 and 18 h for third instars and at 6, 8, and 24 h for fourth and fifth instars, respectively. Feral and laboratory-reared third, fourth, and feral fifth instars avoided Dipel-treated diet when more suitable food was available. Third and fourth instars consistently preferred non-Dipel-containing diet when presented a choice of foods. Corn earworm growth was delayed when larvae were subjected to Dipel-treated diet in choice and no-choice assays compared with larvae provided untreated diet. Larvae presented a choice of diets grew more rapidly than those presented Dipel-treated diets in no choice arenas. Larval feeding frequency and weight gain were superior when larvae were supplied untreated diet than when restricted solely to a Dipel-treated diet. Larvae presented a choice of diets spent more time feeding and fed more frequently on untreated diet than Dipel-treated food. These data indicate that corn earworm presented a choice of Bacillus thuringiensis (Bt) and non-Bt diets may have an increased probability of completing development compared with those restricted to Bt-laced sources.

Expression of a Maize Myb Transcription Factor Driven by a Putative Silk-Specific Promoter Significantly Enhances Resistance to Helicoverpa zea in Transgenic Maize

Hi II maize (Zea mays) plants were engineered to express maize p1 cDNA, a Myb transcription factor, controlled by a putative silk specific promoter, for secondary metabolite production and corn earworm resistance. Transgene expression did not enhance silk color, but about half of the transformed plant silks displayed browning when cut, which indicated the presence of p1-produced secondary metabolites. Levels of maysin, a secondary metabolite with insect toxicity, were highest in newly emerged browning silks. The insect resistance of transgenic silks was also highest at emergence, regardless of maysin levels, which suggests that other unidentified p1-induced molecules likely contributed to larval mortality. Mean survivor weights of corn earworm larvae fed mature browning transgenic silks were significantly lower than weights of those fed mature nonbrowning transgenic silks. Some transgenic pericarps browned with drying and contained similar molecules found in pericarps expressing a dominant p1 allele, suggesting that the promoter may not be silk-specific.

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.

Antibiosis to Corn Earworm, Helicoverpa zea Boddie, by Cowpea Genotypes

ABSTRACT Corn earworm (Helicovrpa zea Boddie) is a pest of cow-pea in many regions of the United States. The larvae chew round holes in cowpea pods to feed on the developing grains, and thus, affect the yield and seed quality. Studies were conducted to identify antibiosis to corn earworm (CEW) in diverse cowpea genotypes which had been identified to provide better yields in the Delmarva (Delaware, Maryland and Virginia) peninsula region. A series of bioassays were performed to evaluate the newly formed terminal trifoliolates of field grown cowpea for antibiosis to CEW. Results showed significant differences in larval weights in all bioassays. The genotypes which gave the lowest larval weights were Mississippi Silver and Quick pick Pinkeye, while the genotype, Champion, provided the largest weights of larvae in virtually all tests. Therefore, this genotype could probably be used as a susceptible check for future cowpea antibiosis studies to CEW. Results also indicate that some genotypes of cowpea that provided consistently lower weights of larvae, including Mississippi Silver and Quick pick Pinkeye, have higher levels of antibiosis to corn earworm larvae than genotypes Champion and Dixielee. These superior genotypes need to be evaluated for multiple pest resistance and other desirable agronomic traits. The antibiosis could be integrated with other methods of cowpea pest management to reduce the amount of insecticides for the management of CEW and other insect pests of cowpea.

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.

Characterization of a digestive carboxypeptidase from the insect pest corn earworm (Helicoverpa armigera) with novel specificity towards C-terminal glutamate residues.

Carboxypeptidases were purified from guts of larvae of corn earworm (Helicoverpa armigera), a lepidopteran crop pest, by affinity chromatography on immobilized potato carboxypeptidase inhibitor, and characterized by N-terminal sequencing. A larval gut cDNA library was screened using probes based on these protein sequences. cDNA HaCA42 encoded a carboxypeptidase with sequence similarity to enzymes of clan MC [Barrett, A. J., Rawlings, N. D. & Woessner, J. F. (1998) Handbook of Proteolytic Enzymes. Academic Press, London.], but with a novel predicted specificity towards C-terminal acidic residues. This carboxypeptidase was expressed as a recombinant proprotein in the yeast Pichia pastoris. The expressed protein could be activated by treatment with bovine trypsin; degradation of bound pro-region, rather than cleavage of pro-region from mature protein, was the rate-limiting step in activation. Activated HaCA42 carboxypeptidase hydrolysed a synthetic substrate for glutamate carboxypeptidases (FAEE, C-terminal Glu), but did not hydrolyse substrates for carboxypeptidase A or B (FAPP or FAAK, C-terminal Phe or Lys) or methotrexate, cleaved by clan MH glutamate carboxypeptidases. The enzyme was highly specific for C-terminal glutamate in peptide substrates, with slow hydrolysis of C-terminal aspartate also observed. Glutamate carboxypeptidase activity was present in larval gut extract from H. armigera. The HaCA42 protein is the first glutamate-specific metallocarboxypeptidase from clan MC to be identified and characterized. The genome of Drosophila melanogaster contains genes encoding enzymes with similar sequences and predicted specificity, and a cDNA encoding a similar enzyme has been isolated from gut tissue in tsetse fly. We suggest that digestive carboxypeptidases with sequence similarity to the classical mammalian enzymes, but with specificity towards C-terminal glutamate, are widely distributed in insects.

Developmental Delay and Evidence for Reduced Cannibalism in Corn Earworm (Lepidoptera: Noctuidae) Larvae Feeding on Transgenic Bt Sweet Corn

Developmental Delay and Evidence for Reduced Cannibalism in Corn Earworm (Lepidoptera: Noctuidae) Larvae Feeding on Transgenic Bt Sweet Corn

Influence of Cry1Ab Protein and Hybrid Genotype on Fumonisin Contamination and Fusarium Ear Rot of Corn

Fusarium ear rot of corn (Zea mays L.) is associated with feeding damage from the European corn borer (ECB), Ostrinia nubilalis Hübner, and the corn earworm (CEW), Helicoverpa zea Boddie. Specific transformation events encoding for Cry1Ab protein from Bacillus thuringiensis Berliner (Bt) may reduce Fusarium ear rot and fumonisin concentration in grain by minimizing damage from certain insects. The objective of this study was to determine if effects from Cry1Ab protein in kernels and silks on fumonisin concentration in grain vary depending on the genotype of the hybrid or the predominant insect species. Four Bt corn hybrids and their corresponding nontransgenic, near‐isogenic hybrids were compared for ear rot severity and fumonisin concentration in grain in four environments. Treatments included inoculation with F. verticillioides (Sacc.) Nirenb. (Syn = F. moniliforme J. Sheld.) and F. proliferatum (Matsushima) Nirenb., infestation with ECB larvae, infestation with CEW larvae, and controls. Cry1Ab protein from the Mon810 transformation event was associated with reduced ear rot severity when hybrids were not inoculated with Fusarium spp., regardless of whether hybrids were infested or not infested with insects. Cry1Ab protein was associated with reduced fumonisin concentration in grain when ECB was the predominant insect, but not when CEW was the predominant insect. Cry1Ab protein was not associated with reduced fumonisin concentration in grain for the most resistant hybrid pair in this study. Results suggest that Bt hybrids can reduce fumonisin concentration in grain during seasons when ECB is favored, but not during seasons when CEW is favored. Hybrid genotype was an important factor in reducing fumonisin concentration in grain.

Effect of maysin on wild-type, deltamethrin-resistant, and Bt-resistant Helicoverpa armigera (Lepidoptera: Noctuidae).

Larvae of the Old World corn earworm, Helicoverpa armigera (Hübner), were fed diets containing lyophilized silks from maize genotypes expressing varying levels of maysin, a flavone glycoside known to be toxic to the New World corn earworm, Helicoverpa zea Boddie. Three different H. armigera colonies were tested: a wild-type colony (96-S), a colony selected for resistance to deltamethrin (Del-R), and a colony selected for resistance to the Cry1Ac protoxin of Bacillus thuringiensis (Bt-R). A colony of H. zea was also tested as a control. High-maysin silk diets significantly slowed the growth and arrested the development of larvae from all H. armigera colonies compared with low-maysin silk diets, maysin-lacking silk diets, and no-silk control diets. The effects on the H. armigera and H. zea colonies were similar across maysin levels, although H. zea is a larger insect than H. armigera and this overall size difference was observed. Among the H. armigera colonies, maysin effects were generally similar, although 7-d-old Del-R larvae were significantly smaller than 7-d-old Bt-R and 96-S larvae for one no-silk control and two maysin-containing silk treatments. The toxic effect of maysin on the Bt-R and Del-R colonies suggests that physiological mechanisms of H. armigera resistance to Cry1Ac and deltamethrin do not confer cross-resistance to maysin.

Direct Silk Applications of Corn Oil and Bacillus thuringiensis as a Barrier to Corn Earworm Larvae in Sweet Corn

Field studies were conducted in 2000 and 2001 to rate the efficacy and longevity of four pesticide treatments against corn earworm (Helicoverpa zea) larvae (CEW) in sweet corn (Zea mays). The four treatments used were 1) corn oil, 2) Bacillus thuringiensis ssp. kurstaki (Bt), 3) oil + Bt, and 4) an untreated plot. All treatments were applied on silk day 5. Silk day 1 was the first day that more than 50% of the ears had 2.5 cm (1 inch) or more silks emerging from the husk using a hand-held pump applicator. Two first-instar CEW larvae were placed directly into silk channel of selected ears on 6 different days (days 3, 6, 9, 12, 15, and 18 after first silk). The same six ears were then harvested 4 days later. Untreated ears had more live CEW and higher levels of feeding damage than the other three treatments ears for all harvest days in both years. The number of CEW found per ear was lower when Bt was included in the treatment. The use of corn oil gave the lowest damage ratings on almost all harvest days in both years. Treatments which contained oil had the highest number of marketable ears in both years, but also the highest percentage of underdeveloped kernels at the tip of the ear (6% to 9%). The oil and Bt treatments appeared to control CEW for at least 17 days, from silking through maturity. This treatment regime appears to be a promising alternative for growers to conventional pest management methods.

Expression of GFP and Bt transgenes in Brassica napus and hybridization with Brassica rapa

It is possible to monitor the movement of transgenes by tagging them with green fluorescent pro- tein (GFP). In order to develop a model to study trans- gene flow, canola (Brassica napus cv Westar) was trans- formed with two GFP constructs, mGFP5er (GFP only) and pSAM 12 (GFP linked to a synthetic Bacillus thuringiensis (Bt) cry1Ac endotoxin gene). Transformed callus sectors that fluoresced green were preferentially selected in the tissue culture process. Four independent GFP canola events and 12 events of GFP/Bt canola were regenerated through tissue culture. GFP fluorescence was macroscopically detectable throughout the entire life cycle of canola. The GFP/Bt events were insecticidal to neonate corn earworm (Helicoverpa zea) larvae and prevented herbivory damage. Fluorescence intensity at 508 nm varied between the independent transformation events, and ranged from 7.6× 10 5 to 13.8× 10 5 (counts per second) in contrast with the wild-type at 5.3 × 105 cps. Nine GFP/Bt and three GFP events were hybridized with three wild accessions of B. rapa. The resultant hybrids fluoresced green and were insecticidal to neonate corn earworm larvae to the same degree as the transgenic ca- nola parents. However, fluorescence intensities of the hemizygous F 1 hybrid lines were lower than the respec- tive original homozygous canola parents. Each F 1 hybrid line was backcrossed by hand onto the B. rapa parent, and transgenic backcrosses were produced at rates rang- ing from 15% to 34%. These data suggest that GFP can be used as a tool to monitor transgene flow from crop species to wild relatives.

A Strain of Serratia marcescens (Enterobacteriaceae) with High Virulence Per Os to Larvae of a Laboratory Colony of the Corn Earworm (Lepidoptera: Noctuidae)1

An unpigmented strain of the bacterium Serratia marcescens Bizio that is highly virulent when fed to larvae from a laboratory colony of the corn earworm, Helicoverpa zea (Boddie), was found as a contaminant in a sample of the nuclear polyhedrosis virus of the celery looper, Anagrapha falcifera (Kirby), that also infects H. zea. High rates of mortality (>70%) were obtained by feeding doses of less than 100 bacterial cells per larva. Previous reports indicated that when insects could be killed with S. marcescens administered orally, doses on the order of 105 to 106 cells per insect were required to obtain comparable levels of mortality. Its virulence may have been increased through unintentional selection during the in vivo production of the virus in corn earworm larvae. The insect colony with which high mortality was obtained was compared with another colony, and the S. marcescens strain was compared with other strains. Results indicate that the highest levels of mortality are associated with a particular combination of insect colony and bacterial strain. While the potential of this organism as a biological control agent has not been evaluated, these apparently unique interactions could make this system an interesting and potentially useful model for the study of host-pathogen virulence factors.

Ear and shank damage by corn borers and corn earworms to four events of Bacillus thuriengiensis transgenic maize

Twenty-eight transgenic maize hybrids containing the Bacillus thuringiensis (Bt) endotoxin and several of their non-Bt isolines were evaluated for control of the southwestern corn borer, Diatraea grandiosella Dyar, the European corn borer, Ostrinia nubilalis (Hübner), and the corn earworm (CEW), Heliocoverpa zea (Boddie) in the shank and ear. The Bt hybrids represented four events (Mon810, Bt11, 176, and CBH354) from seven seed companies. The maize hybrids were grown in four locations that ranged from the northern to southern length of the Texas Panhandle. A semi-arid environment with hot days-cool nights and <220 mm of rain characterize this region. Maize in this region is irrigated with furrow or moving truss application systems. Maize was infested with each species of corn borer at the tasseling growth stage using the Davis applicator. Natural infestations of corn earworm were allowed to develop. Hybrids of events Mon810, Bt11, and CBH354 provided good control of corn borers in shanks and ears. Event 176 hybrids did not provide good control in the shanks and ears because Bt is not expressed in reproductive tissue in this event. No Bt transgenic maize hybrid provided consistent control of CEW larvae on kernels. Feeding gallery length on ears from CEW feeding was sometimes shorter in Mon810 and Bt11 hybrids than in the non-Bt hybrids.

Comparison of Insect Sampling Techniques in Snap Bean

ABSTRACT Three sampling techniques including cage-aerosol, sweep net and drop cloth, were compared in their ability to sample insects on snap bean. Few significant differences among the three techniques were detected when used to sample larvae of the corn earworm (CEW), Helicoverpa zea (Boddie), the green cloverworm, Plathypena scabra (Fabricius), or the cabbage looper, Trichoplusia ni (Hubner). The sweep net caught significantly greater numbers of spotted cucumber beetles, Diabrotica undecimpunctata howardi Barber, and tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois). Both are strong fliers and escaped detection with the drop cloth. Although the drop cloth was somewhat faster to use when plants were small, differences in sample time were reduced with larger plants. Throughout the two year study the mean number of CEW larvae per min of sample time was 0.29 with the sweep net and 0.22 with the drop cloth.