European Corn Borer Larvae Research Articles

Insect Control in Late-Planted Snap Beans, 1989

Abstract 'Tenderlake' snap beans were planted in 4 row plots 15 ft long on 25 Jul at the Plateau Experiment Station, Crossville. Twelve treatments were replicated 4 times in a randomized complete block design with 5 ft alleys between blocks. Rows were 38 inches apart. Foliar insecticides were applied on 8 Aug using a 2.5 gal compressed CO2 hand sprayer at 57 gal/acre and 50 psi. Pre-treatment counts of Mexican bean beetle larvae (MBBL) averaged 49/15 row ft. European corn borer larvae (ECBL) were counted prior to harvest. The middle 2 rows from each plot were harvested using a mechanical 2-row picker on 9 Sep. A subsample (ca 1000 g) of beans from each plot was rated for pods damaged by MBBL and ECBL and expressed as a percent.

Control of European Corn Borer on Field Corn in West Central Nebraska, 1987

Abstract Dipel ES and Lorsban 4 E were applied 1 Jul through a center pivot irrigation system to whorl stage field corn. Treatments were applied in a 0.5 inch irrigation in 2 replications arranged in a randomized complete block design. Ten plants from each plot were split from stalk to tassel in search of European corn borer larvae and/or cavities on 23 Jul. Pretreatment European corn borer infestation levels were moderate with an average of 52% of the plants with larvae and an average of 0.62 larvae/ infested plant. The purpose of this trial was to evaluate different rates and formulations of Dipel ES when applied by chemigation to control European corn borer larvae.

First Generation European Corn Borer Control, 1988

Abstract A corn field near Delmont, SD, was chosen for evaluating 29 European corn borer (ECB) treatments. On 5 May the crop was sown with a 38 inch row spacing. Preapplication counts indicated a uniform distribution of first-, second-, or third-instar ECB larvae in 30% of those corn stalks sampled. Treatments (2 untreated controls, 2 liquid, and 25 granular compounds) were established to evaluate their efficacy in controlling first brood ECB larvae. Granular compounds were applied on 18 Jun to single row plots (0.9 cm by 30.5 m) in a randomized complete block design with 4 replications. Granules were placed in the whorl of corn plants from a highboy using a pneumatic applicator powered by a 3.5 hp engine. Noble metering units were mounted on a modified chain driven apparatus which regulated the amount granular insecticide released. Liquid compounds were applied with a 3.0 gal COa backpack sprayer. Insecticide application rates were computed on a broadcast basis using a band width of 12 inches applied directly in the whorl. These rates may be different from those reported by other investigators where treatments are computed on a linear area basis (linear ft of row) to establish corn rootworm application rates. The broadcast application rates are approximately 0.33 of the rootworm application rates. At the 48th day postapplication, 20 corn stalks were randomly chosen from each plot. Plants were split vertically and examined for ECB tunnelling damage. The number and length of ECB cavities were recorded.

Second Generation European Corn Borer Control, 1988

Abstract A corn field near Delmont, SD was chosen for evaluating 4 European corn borer (ECB), treatments which were applied 3 Aug using a central pivot injector (Zimmatic low-pressure irrigation system delivering 0.25 inches of water.) Rows were spaced 76.2 cm apart with approximately 23,000 plants/acre. Preapplication counts indicated a uniform distribution of first-, second-, or third-instar ECB larvae in and above the primary ear of 30% of corn stalks sampled. The experiment was arranged in a completely random design with 4 samples of 20 stalks each. Stalks were split from the base to the tassel and examined for second generation ECB tunnelling (in or above primary ear) damage. The number and length of ECB cavities were recorded and analyzed using the General Linear Model (GLM) procedure with means being compared by Duncan’s Multiple Range Test.

Toxicity of Compounds Derived from Limnanthes alba Seed to Fall Armyworm (Lepidoptera: Noctuidae) and European Corn Borer (Lepidoptera: Pyralidae) Larvae

When incorporated into artificial diet at 3% (wet weight), milled seed of Limnanthes alba var. versicolor (Greene) C. T. Mason (Limnanthaceae) caused 100% mortality in newly hatched fall armyworm larvae, Spodoptera frugiperda (J. E. Smith) within 8 d. An ether extract and subsequent ethanol extract of the seed were prepared and tested at doses equivalent to 3% ground meal. The ether extract caused slower growth in larvae (weights were 6% of weights of controls after 8 d) but caused no mortality. The ethanol extract caused 30% mortality and retarded growth in survivors (16% of control weight after 8 d). 3-Methoxybenzyl isothiocyanate (3-MBI) was isolated from the ethanol extract and accounted for its activity; the LC50 in the diet incorporation bioassay was 270 ppm. The glucosinolate from which 3-MBI is derived was similar in activity to an equimolar amount of 3-MBI. Activity of the ether extract was due to triglycerides, but the unusual lipids of L. alba were not more active than triglycerides in corn oil, which contained oleic and linoleic acids. European corn borer larvae, Ostrinia nubilalis (Hubner), were less sensitive to the materials derived from L. alba . The seed meal did not cause significant mortality (at 3% in the artificial diet), although weights of the surviving larvae were only 4% of the weight of control larvae after 8 d. The LC50 for 3-MBI was higher (780 ppm), and the ether extract caused no significant effect. Four aromatic analogs of 3-MBI were tested, but none was significantly more active in either species than the naturally occurring compound.

Mechanisms of Resistance in Corn to Leaf Feeding by Southwestern Corn Borer and European Corn Borer (Lepidoptera: Pyralidae)

No-choice and choice laboratory feeding experiments with excised corn (Zeamays L.) leaf tissue were conducted during two summers to determine the resistance mechanisms operating against southwestern corn borer, Diatraea grandiosella Dyar, and European corn borer, Ostrinia nubilalis (Hübner), larvae in selected hybrids. Two corn hybrids with leaf feeding resistance to the southwestern corn borer and two susceptible corn hybrids were used in the studies. Under no-choice conditions, southwestern corn borer larvae fed for 10 d on leaf tissue from the resistant hybrids weighed significantly less than larvae fed on tissue from one of the susceptible hybrids. In a similar test, European corn borer larvae fed on tissue of the same hybrids for the same time period weighed significantly less on the resistant hybrids than those fed on the susceptible hybrids. Significantly fewer European corn borer larvae survived on tissue from the resistant genotypes. When given a choice, significantly more larvae of both species were observed feeding on tissue from one of the susceptible hybrids than on the other hybrids. We conclude that antibiosis and nonpreference types of resistance mechanisms occur in these hybrids.

Effects of artificial and natural diets on success in tip recording and on galeal chemosensillum morphology of European Corn Borer larvae

Abstract. Larvae of Ostrinia nubilalis(Hübner) (Lepidoptera: Pyralidae) were reared on artificial diet, fresh cut corn, or switched from diet to corn for 5 days prior to tip recording. Electrophysiological responses to a standard mixed chemical stimulus were obtained from the galeal uniporous chemosensilla of the early fifth‐stadium larvae. Mouthparts of some larvae were briefly treated with protease, then recorded again. Larvae were then processed for scanning electron microscopy (SEM) of chemosensilla terminal pores. Spike:noise ratios were significantly higher for corn‐reared, switched‐to‐corn, and protease‐ treated larvae, relative to diet‐reared larvae. Morphology of the chemo‐ sensilla terminal pores, as assessed by SEM, reveals that apparent occlusion of the pore tip is significantly greater for diet‐reared larvae relative to the other groups. The data suggest an association between quality of the electrophysiological recordings and physical blockage of the terminal sensillum pore. These data should serve as a caveat for those engaged in chemosensory studies of insect herbivores.

Center-Pivot Applications of Chlorpyrifos 4E for Reducing Ear and Stalk Infestations of Second-Generation European Corn Borer Larvae (Lepidoptera: Pyralidae) in Field Corn

Applications of chlorpyrifos 4 emulsifiable concentrate (EC) at 0.56 and 1.12 kg (AI)/ha applied through a center-pivot irrigation system resulted in significantly fewer second-generation European corn borer (ECB), Ostrinia nubilalis (Hubner), larvae (and consequently a significantly higher grain yield) than the untreated control. Larval reduction was less in the ear than in the stalk. Addition of a nonemulsifiable oil (Sunoco 11N) (1.06 liters) in 1983 had no significant effect on control. In 1984, two applications of chlorpyrifos 4EC at 0.56 kg (AI)/ha applied at 6-d intervals resulted in significantly fewer ECB per plant than a single application at 1.12 kg (AI)/ha. However, yields did not differ significantly.

Toxicity and toxicokinetics of 6-methoxybenzoxazolinone (MBOA) in the european corn borer,Ostrinia nubilalis (H�bner)

The maize-derived secondary chemical 6-methyoxybenzoxazoii-none (MBOA) and a tritiated derivative were prepared synthetically for a detailed examination of their toxicity and toxicokinetics in the European corn borer (ECB),Ostrinia nubilalis. During feeding trials with MBOA incorporated into meridic diets (at 0, 0.5, 1.5, 2.5, and 4.0 mg/g diet), the mean time to pupation and adult emergence was significantly lengthened at concentrations of 1.5 mg MBOA/g diet and above. Increased mortality occurred at concentrations at 1.5 mg/g and above. A decrease in the sex ratio (female/ total) and fecundity was observed at concentrations of 0.5 mg/g and above. The latter observations represent new biological effects related to MBOA. In tracer studies, both uptake and excretion of MBOA administered in diets to larvae increased linearly with concentration. Body burden values indicated that the ECB larvae were capable of excreting enough compound to maintain total tissue levels at approximately 50% of the dietary concentration. Total amount of label increased with larval stage, but decreased in adults due to a large amount of label eliminated in the pupal case. In topical application studies, elimination of the label in the frass was rapid, reaching 60% by 6 hr and 82% of applied dose by 24 hr. Accumulation of label in tissues other than hemolymph was small. The results show that MBOA is toxic to ECB, but the insect has efficient methods for minimizing these effects.

A PHENOLOGY MODEL AND FIELD EVALUATION OF BEAUVERIA BASSIANA (BALS.) VUILLEMIN (DEUTEROMYCOTINA: HYPHOMYCETES) MYCOSIS OF THE EUROPEAN CORN BORER, OSTRINIA NUBILALIS (HBN.) (LEPIDOPTERA: PYRALIDAE)

AbstractA simulation model was developed to predict the timing of European corn borer, Ostrinia nubilalis (Hbn.), larval mortality following exposure to Beauveria bassiana (Bals.) Vuillemin conidia. Model response was compared with laboratory and field data collected specifically for model validation. In laboratory validation experiments, four conidial doses of a B. bassiana isolate collected from the People’s Republic of China were applied to European corn borer larvae which were then incubated at fluctuating temperatures. Simulation results compared favorably with fungal development and mycosis under laboratory conditions. Field validation experiments showed that applications of B. bassiana to European corn borer neonates in whorl-stage corn resulted in mortality levels over 60% when conidia and European corn borers were placed on the plants on the same day. When B. bassiana conidia were placed on plants prior to European corn borers, mortality decreased linearly with time. Model predictions of the timing of European corn borer mortality were found to be accurate when B. bassiana conidia were placed on corn plants at the same time or prior to European corn borers. When European corn borers were placed on plants prior to conidia, the model underestimated the time to European corn borer death. Lack of model fit in this situation is thought to be due to delayed host and pathogen interactions on the corn plant rather than poor prediction of the physiological development of the disease.

First Generation European Corn Borer Larvae, Efficacy Trials, Kansas, 1987

Abstract Naturally infested late-whorl-stage yellow held corn was treated on 13 Jun. Eighteen insecticides and 2 untreated controls were arranged in a randomized complete block design with 4 replications. All plots consisted of 4 contiguous rows, each 12 m in length with 90-cm row spacing. Sprays were applied in water (20 gal/acre) with a C02-powered system held above the canopy on a modified backpack frame. Each treated row received spray from 2 opposing nozzles suspended over the row at a 45-degree angle (dp size HC-6) and applied at 40 psi. Granular products were applied using modified electric drive Nobel applicators mounted on a self-propelled highi clearance sprayer or manually banded using a funnel and bander system. Band spreaders were positioned approximately 5 cm above the whorl and distributed products over a 20-cm band.

First-Generation European Corn Borer Control in Field Corn, 1987

Abstract Seven insecticidal treatments were examined to determine their efficacy in controlling primarily first-generation (second-generation also evaluated) European corn borer (ECB) in conventionally planted field corn grown on the Vernon Delano Farm in Richmond County, Va. 'Pioneer 3389' corn was planted on a 36-inch row spacing on 28 Apr. Materials were applied either as foliar sprays or granular applications on 9 Jun. Foliar spray concentrates were applied with a CO2-powered compressed-air sprayer, using TeeJet AL8004 nozzels, at 32 psi that delivered 31.8 gal of finished formulation/acre. Granular insecticides were applied directly in the whorl by using a Spred-rite gravity flow granular applicator. Individual plots were 4 rows by 30 ft with 2-row borders and were arranged in a complete randomized block experimental design with 3 replications. Individual plots were evaluated 8 days after treatment and then periodically throughout the remainder of the growing season. All plants in 30 row-ft were inspected for the presence of ECB feeding damage, and 5 random plants/plot were split and observed for the presence of live ECB larvae on 22 Jun. Yield estimates were obtained by harvesting 1 of the 2 center rows of each plot. Yields were adjusted to 12% moisture.

Horizontal Transmission of Nosema pyrausta (Microsporida: Nosematidae) in the European Corn Borer, Ostrinia nubilalis (Lepidoptera: Pyralidae)

It was demonstrated in laboratory transmission tests that corn stalks inhabited by European corn borer (ECB), Ostrinia nubilalis (Hubner), larvae that are infected with Nosema pyrausta (Paillot), become readily contaminated, via spores in larval excrement and that contaminated feeding cavities provide a major source of infection for the healthy inhabitants of the stalk. Exposure of uninfected ECB larvae to damaged plant cavities that harbored actively feeding infected ECB larvae leads to higher frequencies of transmission than cavities that have been abandoned or are inhabited by uninfected individuals. Results also indicate that in each generation, there is a time lag following ECB oviposition before effective transmission takes place in the field, and in the second generation, ECB larvae continue to contaminate plant tissues with infectious spores until they enter diapause. This mechanism of transmission, along with larval feeding behavior and intraplant movement, contribute significantly to the horizontal spread and annual build-up of N. pyrausta within the ECB population.

Ecological Studies of the European Corn Borer (Lepidoptera: Pyralidae) in Boone County, Iowa

An ecological study of the European corn borer (ECB), Ostrinia nubilalis (Hbn.), was conducted in Boone County, Iowa, from 1950 through 1965. The average date of the beginning of first-generation pupation was 12 May, with completion 8 June. Moth flight usually began in late May, peaked during the 2nd and 3rd weeks of June, and ended in early July. First-generation oviposition was greatest during the last half of June. Most (69.0%) first-generation ECB eggs hatched; a significant number (25.5%) were lost, probably due to heavy rains and violent winds. Greatest total numbers of first-generation ECB egg masses and larvae occurred in maize planted 6–10 d after the first planting date. The average date of the beginning of second-generation pupation was 16 July, with the average completion 14 August. Peak second-generation moth flight was during the first half of August. Peak oviposition was in early to mid-August. Percentage of second-generation eggs missing was less than that of the first generation, probably because severe storms were less frequent during August than in June. Heavy second-generation infestations often occurred in early-planted maize; more than 65% of second-generation larvae were found in maize planted during the first 10 d of the planting period. Heaviest infestations were in maize planted 21–30 d after the first planting date. A small third-generation moth flight occurred in some years. Predators were much more numerous during the second-generation oviposition period than during the first-generation oviposition. More second-generation eggs were eaten by predators than were first-generation eggs. The most common parasitoid of the ECB was Lydella thompsoni Herting; this species was uncommon after 1959. Other parasitoids were recorded but were not numerous.

Tissue culture and its use in investigations of insect resistance of maize

Southwestern corn borer ( Diatraeagrandiosella Dyar), sugarcane borer ( Diatraea saccharalis (Fabricius)), and European corn borer ( Ostrinia nubilalis Hubner) larvae were reared for 7 days on callus initiated from two maize ( Zea mays L.) hybrids with resistance to leaf feeding by the southwestern corn borer and two susceptible hybrids. Mean weights for larvae from resistant and susceptible hybrids were 4.8 and 7.0 mg for the southwestern corn borer, 5.5 and 7.6 mg for sugarcane borer, and 7.2 and 10.2 mg for European corn borer, respectively. When larvae were allowed to choose among calli of the four hybrids, significantly fewer of each species chose to feed on the southwestern corn borer-resistant hybrids. Both antibiosis and larval nonpreference appeared to be operating as mechanisms of resistance to southwestern corn borer, sugarcane borer, and European corn borer.

First Generation European Corn Borer Control, 1986

Abstract Naturally infested late whorl stage, yellow field corn, located near Mt. Ayr, Ringgold Co., IA was aerially treated on 19 Jun. Seven insecticides and 1 untreated check were arranged in a randomized complete block design and replicated 4 times. Plots measured 30 rows by approximately 400 yd. Weather conditions were clear with a temperature of 88°F, relative humidity of 53%, and a light, intermittent breeze from the west, southwest. All applications were made between 1:45 and 4:00 p.m. by flying both north and south on north-south rows. Pretreatment counts made on 14 Jun consisted of examining 20 plants from each of 20 randomly selected locations throughout the study site. The number of plants with shot-hole damage were recorded. Four plants from each location were dissected and the number of European corn borer (ECB) larvae recorded. Insecticide efficacy was evaluated on 22 Jul by removing 30 selected plants from each plot, dissecting them and recording the number of ECB cavities per plant. Plants used in the efficacy evaluation were selected from the ninth row in from the east side of each plot. Individual plants were selected by walking into the field 30 paces from the turn rows, then cutting every tenth plant. Efficacy data were analyzed using an AOV. The means were ranked and separated (P = 0.05) using Duncan's Multiple Range Test. All data were normalized before analysis with a SQRT (X = 1.0) transformation.

Efficacy of Insecticides Against Second Generation European Corn Borer Larvae, 1986

Abstract Naturally infested milk stage yellow field corn was treated on 19 Jul. Fourteen insecticides and 2 untreated control plots were arranged in a randomized complete block design with 4 replications. All plots consisted of 4 contiguous rows, each 10 m in length with 91 cm row spacing. Sprays were applied in water (20 GPA) with a carbon COa powered system held above the canopy on a modified backpack frame. The boom was equipped with 45° nozzles to spray 4 rows. Band spreaders were positioned approximately 5 cm above the whorl and distributed products over a 20 cm band.

Control of European Corn Borer on Sweet Corn, 1986

Abstract Sweet corn was planted 2 Jun at the University of Minnesota, Agricultural Experiment Station, Rosemount MN. Treatments were 1 row, 50 ft long, replicated 3 times, in a randomized block design. Plants were spaced at 7-8 inch intervals within rows 30 inches apart. Twenty-five first instar European corn borer larvae were placed in the silks of all ears 5 Aug. Experimental treatments were separated by 1 row of corn, untreated and not artificially infested with ECB. Insecticidal treatments were applied 2 times, 4 and 12 Aug. Foliar sprays were applied using a C02 powered hand sprayer delivering 36 gal of water/acre at 35 psi. Granular treatments were hand applied using a “shaker” in a 12 inch band over the silks. Evaluations were made 20 Aug by scoring 35 randomly selected ears per plot for presence of ECB damage to the ear.

Efficacy of Insecticides Against First Generation European Corn Borer Larvae, 1986

Abstract Naturally infested late whorl stage yellow field corn was treated on 13 Jun. Sixteen insecticides and 2 untreated control plots were arranged in a randomized complete block design with 4 replications. Granular products were applied on 2 row plots and liquid products were applied to 4 row plots all of which were 10 m long with a row width of 91 cm. Sprays were applied in water (20 GPA) using a CO2-powered backpack sprayer. The boom was equipped with 8 nozzles 45° nozzles to spray 4 rows. Granular products were applied with a modified electric drive Noble applicator. Band spreaders were positioned approximately 5 cm above the whorl and distributed products over a 20 cm band.

European Corn Borer in Sweet Corn, 1986

Abstract ‘Silver Queen’ sweet corn was planted 27 May at Rock Springs Experimental Farm, Centre County, PA. Plant spacing was 9 inches with 30 inches between rows. Plots were 3 rows x 47 ft arranged in a randomized complete block design with 4 replicates. Insecticides were applied 14, 26 Aug with a high-clearance sprayer delivering 30 gal/acre at 14 psi. Sweet corn was in pollen shedding stage at the first application and had an 8% European corn borer (ECB) infestation. On 2 Sep, 25 ears per plot were selected and examined for signs of insect feeding externally (silks and sides) and internally (kernels and ear tips). Numbers of ECB larvae were counted. Stalk damage caused by ECB was assessed by splitting 10 stalks/plot and counting the number of cavities. Rainfall totalled 3.75 inches for Jun, 5.00 inches for Jul, and 2.18 inches for Aug. Average daily maximum and minimum temperatures (°F) were 84 and 39 for Jun, 91 and 51 for Jul, and 83 and 45 for Aug, respectively.