Borer Eggs Research Articles

Ability of Orius insidiosus (Hemiptera: Anthocoridae) to Search for, Find, and Attack European Corn Borer and Corn Earworm Eggs on Corn

The ability of Orius insidiosus (Say) to search for, find, and destroy eggs of European corn borer, Ostrinia nubilalis (Hubner), and corn earworm, Helicoverpa zea (Boddie), was investigated in the field. Mobility of O. insidiosus on individual corn plants, attack rates on corn borer and corn earworm eggs, and searching capacity on corn plants were studied. Egg position on the corn plant and predator density affected egg mortality. Mortality rates rose with increased predator numbers. O. insidiosus searched in the corn silks first, followed by searching on the corn leaves but not in the tassel.

Influence of Temperature and Humidity on European Corn Borer (Lepidoptera: Pyralidae) Egg Hatchability

European corn borer, Ostrinia nubilalis (Hubner), egg hatch was studied under several temperature and humidity regimes. Percentage of hatch was severely decreased, regardless of the humidity, at 36 and 39°C. Hatch ranged from 74.0 to 0.5% at vapor pressure deficits of 7.5–32.5 mb over the temperature range of 24–33°C in 3°C increments. European corn borer egg hatch was affected similarly, from oviposition to larval eclosion, by a 12-h stress period of 14.5, 17.5, and 20.5 mb (at 30°C). Two separate aspects of the egg chorion or two processes in egg hatch are hypothesized to be disrupted by the stressful conditions as evidenced by three plateaus in percentage of eggs hatching as the length of exposure to stress increased. Percentage of hatch remained relatively stable at about 68% with exposure to 33.9-mb stress for ≤24 h. As the length of stress increased to 36–60 h, the percentage was about 22%. The percentage of hatch fell to only 2.7% at 72 and 84 h of consecutive exposure. Finally, the effect of environmental conditions on egg hatch was additive whether the eggs experienced constant stress or experienced periods of stress alternated with periods of moderate conditions. Results of this study suggest that environmental stresses (i.e., “stress units”) may accumulate and affect survival of European corn borer eggs in a manner analogous to temperature units and insect development.

Statistical analysis of occupancy rates for overdispersed populations by redistribution procedures: Application to the european corn borer EGG masses distribution

SummaryStandard statistical analyses of distributions of individuals from contingency tables are generally invalid if the individuals are not distributed independently of each other. In this paper, we discuss a method of testing hypotheses about classification category occupancy rates for overdispersed population or for population whose individuals are distributed by groups rather than lonely. These methods are based on population redistribution simulations and provide valid, exact and powerful tests in situations for which classical methods are not appropriate. Illustrations are given from the European Corn Borer eggs data.

Interaction Between Spray Distribution and Systemic Activity of Insecticides for Control of European Corn Borer (Lepidoptera: Pyralidae) in Peppers and Snap Beans

Interactions between spray distribution and insecticide mode of action in relation to control of European corn borer, Ostrinia nubilalis (Hubner), on bell peppers ( Capsicum annuum L.), sweet banana peppers ( Capsicum annuum L.), and snap beans ( Phaseolus vulgaris L.) were investigated. Multiple treatments were applied using either a conventional boom sprayer or an air-curtain sprayer. Materials evaluated were fenvalerate (local activity) and acephate (systemic activity). Spray droplet distribution was evaluated with UV-spectrophotometric analysis of sprayed dyes. European corn borer egg massey were sampled weekly during the experiment, and crop injury was evaluated at harvest. Spray deposition with the air-curtain sprayer was much higher on the undersides of the leaves and on fruit than with the conventional boom application. Variability of spray deposition between samples also was reduced. Faceplate and fenvalerate significantly reduced banana pepper and bell pepper injury from European corn borer. However, significant reductions in injury due to air-curtain application occurred only with fenvalerate on bell peppers. Systemic activity of the acephate compensated, at least partially, for poor spray distribution with the conventional boom application. Virtually no injury occurred to the snap beans even in artificially infested, untreated plots. Total mortality caused by glandular trichomes was observed when larvae were introduced onto snap bean plants in the laboratory.

Distribution and Sampling of Southwestern Corn Borer (Lepidoptera: Pyralidae) in Preharvest Corn

Southwestern corn borer, Diatraea grandiosella Dyar, was sampled from six corn, Zea mays (L.), fields in the Texas High Plains during 1985, 1986, and 1987. Density estimates were made for eggs, small, medium, and large-sized larvae and pupae during both corn borer generations. Taylor’s power function provided significant regressions for all size categories. The distribution of southwestern corn borer eggs and small larvae was aggregated, and older stages were progressively less clumped. Binomial and sequential sampling plans for eggs and small larvae were developed using Taylor’s coefficients.

Autoradiographic Detection of Lesser Cornstalk Borer (Lepidoptera: Pyralidae) Eggs in Soil Environments

A nondestructive method of detecting lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), eggs in soil is outlined. Fourth instar larvae were fed a diet containing radioactive phosphorus (4 μ Ci/g), and eggs laid by females that emerged from these larvae contained sufficient radioactivity to expose X-ray film. Fecundity, oviposition rates, and longevity were similar for 32P-labeled adult females and unlabeled adult females. In greenhouse tests using corn planted in simulations of conventional tillage and no-tillage conditions, eggs were autoradiographically detected in soil and on plant tissue.

Dispersal and Survival of Early Instars of European Corn Borer (Lepidoptera: Pyralidae) in Field Corn

Cohorts of European corn borer, Ostrinia nubilalis (Hubner), from eggs infested on whorl-stage corn ( Zea mays L.), were intensively sampled through fourth instar in 1986 and through fifth instar in 1987. In both years, central plants in plots (4 by 2 m, 55 plants) were infested with European corn borer egg masses to simulate a first-generation infestation. In 1986, one egg mass was placed in each plot, whereas in 1987, plots received one, two, or four egg masses. In both years, >50% of the recovered larvae were on the infested plant. Mean dispersal distance increased linearly with time in both years. However, maximum dispersal distance was independent of time in both years. In 1987, egg mass density had a significant linear effect on maximum dispersal distance but no effect on mean dispersal distance. The radius encompassing 90% of the recovered larvae included the infested plant and two plants on either side within the same row. Mortality occurred mainly within the first 48 h: 75.7% in 1986 and 82.9% in 1987. A logistic regression showed that egg and larval survival were independent of egg mass density. The number of tunnels produced per larva found at 8 d after infestation (considered equivalent to scouting) was 0.592. Knowledge of European corn borer dispersal and survival could be used to improve sampling plans and the calculation of economic thresholds.

Effect of Temperature and Storage on Yellow Stem Borer (YSB) Egg Hatchability and Larval Survival

Effect of Temperature and Storage on Yellow Stem Borer (YSB) Egg Hatchability and Larval Survival

Estimation of european corn borer egg masses density by sampling of runs

SummarySpatial distributions of individuals may be considered in two ways: Firstly, individuals are situated on a continuum. Secondly, individuals are situated on discrete units, for example, insect eggs on plants. The aim of this paper is to show that sometimes, in the latter case, sampling methods based on infestation runs can be of interest in estimating population density. Analytical results are obtained under complete spatial randomness hypothesis and alternative hypotheses. Sampling procedures with limited cost are discussed and the European corn borer (ECB) case is mainly considered.

Direct Evaluation of Natural Enemies of the Southwestern Corn Borer (Lepidoptera: Pyralidae) in Texas Corn

The effect of natural enemies on survival of southwestern corn borer, Diatraea grandiosella (Dyar), eggs and larvae was measured in Texas High Plains corn using exclusion cages. Orius insidiosus (Say) and spiders were the most abundant predators on corn plants. Predation of corn borer eggs was uncommon and insignificant. Survival of first-generation larvae in whorl stage corn where predators were excluded was significantly greater than survival on plants accessible to predators in two of three years. Survival of second-generation larvae on tassel stage corn was significantly greater during both years on caged plants (excluding predators). However, during the second generation, mortality of first and second instars was replaceable by cannibalism among mature, prediapause larvae. Egg and larval parasites were not observed.

Chemigation Applications for Second-Generation Corn Borer Control, 1988

Abstract This experiment was conducted in furrow-irrigated corn in Finney County, Kans. Standard and simulated chemigation applications of corn borer insecticides were made to evaluate their efficacy under 2 methods of application. Untreated and miticide-treated (Di-Syston) plots were included as controls. Treatments were arranged in a randomized complete block design with 4 replicates. The plots were 4 rows wide (10 ft) and 45 ft long. The standard insecticide applications were made with a high-clearance sprayer using a 10-ft boom with 3 nozzles directed at each row (one nozzle directly over the row and 2 suspended on 18-inch drop hoses). The sprayer was calibrated to deliver 40 gal/acre with 30 psi of CO2 pressure. The simulated chemigation applications were made using 3 Delvan 100/140, 3/4-inch raindrop nozzles mounted on the high-clearance sprayer at tassel height between the rows. This system was calibrated to deliver 5,400 gal/acre on the 2 center rows (equivalent to a 0.2-inch irrigation). Chemicals were added to 200 gal of water in the main tank of the sprayer and agitated by recirculation and applied within 20 min of mixing. The treatments were applied on 4 Aug and some were retreated on 12 and 17 Aug. The timing of applications was based on the Kansas State University SWCB and ECB models and the presence of corn borer eggs in the field. Evaluations were made 21-27 Sep by dissecting 10 corn plants from each plot (5 consecutive corn plants from each of the 2 center rows). The number of larvae of each species and the length of tunneling was recorded for each plant.

Insect Control in Peppers, 1987

Abstract Green bell peppers (var. KRG-3) and sweet banana peppers (open pollinated) were transplanted as separate trials on 29 May at the MSU Entomology Field Research Farm, East Lansing. Plots were 3 rows wide (30 inches between rows) by 30 ft long (18 inches between plants) arranged in a completely randomized design with 4 replications. Treatments were applied with a tractor-mounted boom sprayer at 30 gal/ acre and 40 psi on 22 and 29 Jul and 4 Aug. Two plants from the center row of each plot were examined on a weekly basis for European corn borer (ECB) egg masses and green peach aphids (GPA). Banana and bell peppers were harvested on 10 and 11 Aug, respectively. All fruit from 27 ft of the center row were harvested (a subset of 40 banana peppers were randomly selected) and examined for ECB damage. On 11 Aug, 4 leaves per plant (4 plants per plot) were examined for GPA.

Insect Control in Peppers, 1986

Abstract Green bell peppers were transplanted on 11 Jun at the MSU Entomology Field Research Farm, East Lansing. Plots were 3 rows wide (30 inches between rows) by 30 ft long (18 inches between plants) arranged in a randomized complete block with 4 replications (= blocks). Treatments were applied with a tractor-mounted boom sprayer at 30 gal/acre and 40 psi on 4, 12, 19, and 29 Aug. Efficacy was determined by examining 2 plants from the center row of each plot on a weekly basis. Entire plants were examined for European corn borer (ECB) egg masses, 4 leaves per plant were examined for green peach aphid (GPA), and all fruit from 24 ft of the center row (up to 40 fruit) were examined for ECB damage at harvest (9 Sep).

Insecticide Efficacy Against Second-Generation Corn Borers, 1987

Abstract This experiment was conducted in late-planted furrowirrigated corn in Finney County, Kans. Treatments were arranged in a randomized complete block design with 4 replications. The plots were 4 rows wide (10 ft) and 45 ft long. The standard insecticide applications were made with a high-clearance sprayer using a 10-ft boom with 3 nozzles directed at each row (1 nozzle directly over the row and 2 suspended on 18-inch drop hoses). The sprayer was calibrated to deliver 20 gal/acre at 30 psi under C02 pressure. The simulated chemigation applications were made using 3 Delvan 100/140, %-inch raindrop nozzles mounted on the high-clearance sprayer at tassel height between the rows. This system was calibrated to deliver 5,400 gal/acre on the 2 center rows (equivalent to a 0.2-inch irrigation). Chemicals were added to 200 gal of water in the main tank of the sprayer and agitated by recirculation and applied within 20 min of mixing. The treatments of CME 13406 and Dimilin were applied on 30 Jul, earlier than the other treatments to take advantage of presumed long residual activity. The remaining treatments were applied on 8 Aug, about 4 days after target date due to wet field conditions. The timing of applications was based on the Kansas State University southwestern corn borer (SWCB) and European corn borer (ECB) models and the presence of corn borer eggs in the field. There were 12 hatched and 6 unhatched ECB egg masses and 14 hatched and 14 unhatched SWCB egg masses on 10 plants on 7 and 8 Aug. Corn borer evaluations were made 14-28 Sep by dissecting 10 corn plants in each plot (5 consecutive corn plants in each of the 2 center rows). The number of larvae of each species and the length of tunneling were recorded for each plant. Stalk rot associated with corn borer tunnels was evaluated using a rating scale of 0 to 4: 0, no visible stalk rot; 1, stalk rot present in one internode; 2, stalk rot in 2 internodes; 3, stalk rot found in 3 internodes; and 4, stalk rot in 4 or more internodes. Banks grass mites (BGM) (mostly adult females) were counted by visually searching every other leaf (one-half plant) of four plants in each plot on 18 Aug.

European Corn Borer Control in Sweet Peppers, 1986

Abstract Trials were conducted at Rock Springs, Centre County, PA. ‘Sweet Green Bell’ peppers were transplanted 16 Jun 12 inches apart. Row spacing was 3 ft. Plots were 4 rows wide X 25 ft long separated with 1 border row arranged in a randomized complete block design with 4 replicates. On 26 Jul the field was seeded with 860 European corn borer (ECB) egg masses—36/plot. Insecticides were applied with a C02 Bak-Pak sprayer equipped with drop nozzles delivering 32 gal/acre at 22 psi. Insecticides were applied 15, 22, and 29 Aug. Peppers were harvested on 11 Sep at which time 25 fruit were selected from each plot and examined for ECB infestation. Rainfall totalled 3.75 inches for Jun, 5.00 inches for Jul, 2.18 inches for Aug, and 4.94 inches for Sep. Average daily maximum and minimum temperatures (°F) were 84 and 39 for Jun, 91 and 51 for Jul, 83 and 45 for Aug, and 82 and 41 for Sep, respectively.

European Corn Borer Control in Sweet Corn, 1982

Abstract Insecticide treatments were applied to sweet corn in Fargo, ND. Each treatment was replicated 3 times in a completely randomized test. Plots consisted of 3 rows of sweet com approximately 27 m long. There were 2 guard rows on the edges of the field. Treatments were applied to the center row in each plot. Ten days prior to insecticide application, 25 plants in the center of each row were marked for treatment and infested with corn borer egg masses (in the black head stage) supplied by the Corn Insects Research Laboratory, Ankeny, Iowa. The treatments were applied in the whorl of the corn plants in late Jul. Analyses are based on data from examination of ears (harvest) and stalks (fall) for borer larvae. Analyses of variance and Duncans Multiple Range Tests were conducted with borer counts from ears, stalks and ears and stalks combined. Data were transformed by .

Fruit Insect Control, 1985

Abstract ‘Large Red Cherry’ peppers were transplanted 7 Jun, near Benson, NC. Single row plots 10 ft long on 60 in centers were arranged in a randomized complete block design replicated 4 times. Applications were made using a C02 pressurized backpack sprayer with a single hollow cone nozzle delivering 54 gal/acre at 60 psi. Fruit was harvested and plants were artificially infested with 2 European corn borer egg masses per plant on 30 Jul. Treatments were applied 2, 9, and 16 Aug. Fruit was harvested and the % of infested fruit recorded on 13 and 22 Aug.

Insecticide Efficacy Against Second Generation Corn Borers, 1986

Abstract This experiment was conducted in sprinkler-irrigated corn in Finney county, KS. Treatments were arranged in a randomized complete block design with 4 replications. The plots were 4 rows wide × 10 ft and 50 ft long. There were 2 sets of untreated check plots per replicate. The standard insecticide applications were made with a high clearance sprayer using a 10 ft boom with 3 nozzles directed at each row (one nozzle directly over the row and 2 suspended on 18 inch drop hoses). The sprayer was calibrated to deliver 20 gpa with 30 psi of CO2 pressure. The simulated chemigation applications were made using 3 Delvan 100/140, 0.75 inch rain drop nozzles mounted >n the high clearance sprayer at tassel height between the rows. This system was calibrated to deliver 47 gal in 2.4 min for each plot (5430 gpa). This application was equivalent to a 0.2 inch irrigation on the 2 middle rows. For the high volume applications, the chemicals were added to 200 gal of water in the main tank of the sprayer and agitated by recirculation. Treatments were applied on 28 and 29 Jul. The timing of applications was based on the Kansas State University European corn borer model and the presence of corn borer eggs in the field. Corn borer evaluations were made in late Aug by dissecting 10 corn plants in each plot (5 consecutive corn plants in each of the center 2 rows). The number of plants infested with each species of corn borer was recorded. Corn borer and stalk rot were evaluated in late Sep by dissecting 20 plants in each plot (10 consecutive corn plants in each of the 2 center rows). Stalk rot was rated using a scale of 0 to 3; 0—no visible stalk rot; 1—stalk rot present in one node; 2—stalk rot in 2 nodes; and 3—stalk rot found in 3 or more nodes. The plants dissected for stalk rot were also rated for corn borer incidence. Corn grain yields were determined by hand harvesting 20 row-ft Prom each of the 2 center rows in each plot and correcting to 15.5% moisture. Spider mites were counted by visually searching every other leaf (one half plant) of 4 plants in each plot on 7 Aug. Mites were collected from plants in each plot with a small vacuum sampler and a subsample of about 20 mites per plot was mounted for microscopic determination of mite species.

Distribution of European Corn Borer (Lepidoptera: Pyralidae) Egg Masses and Larvae on Sweet Corn in New York

Studies were conducted in commercial sweet corn fields in upstate New York to collect information for developing a sampling protocol for egg masses and larvae of European corn borer (ECB), Ostrinia nubilalis (Hubner). Information was collected on 1) aggregation of populations in portions of the field (e.g., aggregation along borders), 2) distribution of sample observations for a whole-plant sample unit, and 3) distribution of insects within the sample unit (i.e., the within-plant distribution of eggs and larvae). Analyses of data indicated that distribution of egg masses and larvae throughout a field was essentially random with no evidence to support the hypothesis that eggs were preferentially laid near field borders where mating and resting of female adults occurred. From data on dispersion of ECB on individual plants, a Poisson series is a reasonable model for characterizing distribution of ECB egg masses. Parameters of a variance-mean model for the small larvae indicate that these larvae are highly aggregated but that aggregation becomes less pronounced as larvae mature. Since control measures are most effective against egg masses and small larvae, a sampling protocol that utilizes characteristics of both stages should be employed. An index of ovipositional activity measured via incidence of egg masses on plants can be determined by inspecting plants for presence of either egg masses or small larvae. This can be accomplished by using a binomial-based sequential sampling plan.

Within-plant and Within-field Distribution of First-generation European Corn Borer (Lepidoptera: Pyralidae) Egg Masses on Field Corn in Virginia

The oviposition site selection by the European corn borer and the within-field pattern of egg mass distribution were studied on field corn in western Virginia. Nearly all egg masses were found on the lowest six leaves of the plant. The within-field distribution of egg masses was found to be a random distribution, as interpreted from the variance/ mean ratio, the method of Taylor and Green's coefficient of dispersion.