Evaluation of Leaf Consumption and Determination of Economic Injury Level Caused by Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Brassica oleracea var. acephala (Brassicales: Brassicaceae)

2019 ◽  
Vol 112 (4) ◽  
pp. 1805-1811
Author(s):  
Angélica Massarolli ◽  
Bruna Camila Gualda Bersani ◽  
Fernando Henrique Dalla Roza ◽  
Alessandra Regina Butnariu ◽  
Mônica Josene Barbosa Pereira ◽  
...  
Keyword(s):  
Pest Control ◽  
Plutella Xylostella ◽  
Yield Reduction ◽  
Economic Injury Level ◽  
Control Cost ◽  
Collard Greens ◽  
Market Values ◽  
Leaf Consumption ◽  
Economic Injury ◽  
The Mean

Abstract Plutella xylostella (L.) is a microlepidopteran found in all brassica-producing regions of the world. However, no economic injury level (EIL) has been established for this pest in collard greens. Therefore, studies evaluating the EIL of P. xylostella in this crop based on the number of caterpillars per plant can assist pest monitoring and the most effective time for pest control, ensuring profits and the use of pesticides only when required. The present study assessed leaf consumption of caterpillars at different levels of infestation and determinined the EIL for P. xylostella in collard greens. Based on the yield reduction index of collard greens for P. xylostella, EIL was estimated for different scenarios of pest control costs, setting the market value of the bunch of collard greens, and, alternatively, with prices varying and the control cost fixed. In simulated scenarios for 7 d after infestation, the number of caterpillars per plant was always below 1.38, whereas for 10 d, the maximum number was 1.25 caterpillars per plant. When simulating scenarios with different market values for the bunch of collard greens the lower the price of the collard greens bunch, the higher the mean number of caterpillars per plant to compensate the application cost. The mean number of caterpillars per plant ranged from 4.59 to 0.38 in the evaluation for 7 d, and from 4.17 to 0.35 caterpillars per plant for 10 d according to the price of the bunch of collard greens.

Determination of an Economic Injury Level for Old World Bollworm (Lepidoptera: Noctuidae) in Processing Tomato in Brazil

2020 ◽  
Vol 113 (4) ◽  
pp. 1881-1887
Author(s):  
Nayara C M Sousa ◽  
Miguel Michereff Filho ◽  
Paloma A Silva ◽  
Jorge B Torres
Keyword(s):  
Helicoverpa Armigera ◽  
Control Program ◽  
Yield Reduction ◽  
Economic Injury Level ◽  
Field Cage ◽  
Tomato Plants ◽  
Processing Tomato ◽  
Economic Injury ◽  
Helicoverpa Armígera ◽  
Lepidoptera Noctuidae

Abstract Tomato plants host various herbivores, including the Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), recently introduced into South and Central America. It is a harmful pest for tomato crops, damaging mainly the flowers and fruits. The assessment of losses and the establishment of economic injury level (EIL) and economic threshold (ET) are core steps toward establishing a control program. We determined losses caused by H. armigera on processing tomato and estimated EIL/ET values. Trials were run during two growing seasons using tomato plants caged in the field. The field cage experiment consisted of six densities of H. armigera second instar larvae (0, 1, 3, 6, 12, and 24 larvae per row meter) at two infestations periods spaced 15 d apart with the first infestation done 90 d after transplanting. The larvae were placed individually on the third upper fully developed leaf. The number of healthy and damaged fruits, size, and weight of the fruits were measured. Yield losses as a function of infestation of 1–24 larvae per row meter ranged from 4 to 34% and resulted in a yield reduction of 1.22–12.77 kg per row meter. The EIL ranged from 1.41 to 1.72 and from 2.11 to 2.58 larvae per row meter of plants in 2017 and 2018 cropping seasons, respectively. Helicoverpa armigera causes significant reduction of tomato yield. These EIL values will enable better control decision-making in processing tomato.

Idioscopus clypealis (mango leafhopper).

2021 ◽  
Author(s):  
R Ganeswaran
Keyword(s):  
Population Size ◽  
Indian Subcontinent ◽  
Uttar Pradesh ◽  
The Philippines ◽  
Yield Reduction ◽  
Bud Break ◽  
Flowering Stage ◽  
Flower Bud ◽  
Economic Injury ◽  
The Mean

Abstract Mango leafhoppers are major pests in the Indian subcontinent. The major damage caused is at the flowering stage and several studies have highlighted the reduction of yield which may be between 20 and 100% depending on population size. Verghese and Rao (1987) examined the critical infestation stages of I. clypealis in Uttar Pradesh, India. The mean density of cicadellids was 0.54-20.64 per panicle in 1983 and 0-6.03 per panicle in 1984. In both years, the peak population occurred when the fruit was pea sized. At the post-bloom stage a population of two adults per panicle was sufficient to cause yield reduction. It is suggested that the critical infestation stages are at post-bloom, when the fruit is marble sized, and 1 month before harvest, with corresponding critical population levels of two adults, 6-21 nymphs and 4-11 hoppers per panicle. In the Philippines, Corey et al. (1989) found that the economic injury levels for I. clypealis on two croppings of mangoes averaged 4.21, 4.30, 4.45 and 4.55 adults per panicle at 2, 10, 18 and 26 days, respectively, after flower bud break for the first cropping, and 4.79, 4.88, 5.06 and 5.18 adults per panicle for the second cropping.

scholarly journals Competitive interaction and economic injury level of Urochloa plantaginea in corn hybrids

2019 ◽  
Vol 86 ◽  
Author(s):  
Leandro Galon ◽  
Cinthia Maethê Holz ◽  
César Tiago Forte ◽  
Felipe Nonemacher ◽  
Felipe José Menin Basso ◽  
...  
Keyword(s):  
Plant Density ◽  
Integrated Management ◽  
Productivity Loss ◽  
Control Measures ◽  
Hyperbolic Model ◽  
Economic Injury Level ◽  
Control Cost ◽  
Corn Hybrids ◽  
Grain Productivity ◽  
Economic Injury

ABSTRACT Identifying the competitive ability of corn hybrids and the economic injury level (EIL) caused by Urochloa plantaginea is important for the adoption of integrated management of this weed. This work aims to evaluate the interference and EIL of U. plantaginea infesting corn hybrids. Treatments included the corn hybrids Syngenta Status VIP3, Syngenta SX8394 VIP3, Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021, as well as 12 densities of U. plantaginea for each hybrid. We used a rectangular hyperbolic model to describe the relationship between corn grain productivity loss and the explanatory variables — plant density (PD), dry mass (DM) of the aerial parts, ground cover (GC), and leaf area (LA). EIL was determined using grain productivity, control cost, corn price, and herbicide efficacy. The rectangular hyperbolic model provides a satisfactory estimate of grain productivity loss regarding the interference of U. plantaginea in corn culture. The hybrids Pioneer 30F53 YH and Pioneer P1630H presented better competitiveness and higher EIL. Sowing the hybrids Pioneer P1630H, Pioneer 30F53 YH, and Dow 135021 increased EIL, justifying the adoption of control measures for U. plantaginea at higher densities.

Idioscopus nagpurensis (mango leafhopper).

2021 ◽  
Author(s):  
R. Ganeswaran
Keyword(s):  
Related Species ◽  
Indian Subcontinent ◽  
Uttar Pradesh ◽  
The Philippines ◽  
Yield Reduction ◽  
Bud Break ◽  
Flowering Stage ◽  
Flower Bud ◽  
Economic Injury ◽  
The Mean

Abstract Mango leafhoppers are major pests in the Indian subcontinent. The major damage is caused at the flowering stage and several studies have highlighted the reduction of yield which may be between 20 and 100% depending on population size. Verghese and Rao (1987) examined the critical infestation stages of the related species I. clypealis in Uttar Pradesh, India. The mean density of cicadellids was 0.54-20.64 per panicle in 1983 and 0-6.03 per panicle in 1984. In both years, the peak population occurred when the fruit was pea sized. At the post-bloom stage a population of two adults per panicle was sufficient to cause yield reduction. It is suggested that the critical infestation stages are at post-bloom, when the fruit is marble sized, and 1 month before harvest, with corresponding critical population levels of two adults, 6-21 nymphs and 4-11 hoppers per panicle. In the Philippines, Corey et al. (1989) found that the economic injury levels for I. clypealis on two croppings of mangoes averaged 4.21, 4.30, 4.45 and 4.55 adults per panicle at 2, 10, 18 and 26 days, respectively, after flower bud break for the first cropping, and 4.79, 4.88, 5.06 and 5.18 adults per panicle for the second cropping.

MODELING OF THE PREVENTION AND CONTROL OF FOREST PEST

2007 ◽  
Vol 15 (04) ◽  
pp. 539-550 ◽  
Author(s):  
WEIJIAN XU ◽  
SHIDONG CHEN ◽  
LANSUN CHEN
Keyword(s):  
Pest Control ◽  
Prevention And Control ◽  
Existence Condition ◽  
Impulsive Effect ◽  
Forest Pest ◽  
Economic Injury Level ◽  
Economic Injury ◽  
Finite Period ◽  
Pest Density ◽  
And Control

In most models of pest control, the time of prevention and control is always assumed to be unrestricted. In practice, however, it is usually required in agriculture and forestry that we control the pest density to be lower than the economic injury level in a given time. By constructing the dynamics of logistic differential equation with impulsive effect, this paper describes the process of pest control through impulsive spraying pesticide in a given time, and then the existence condition of the solution to the boundary value problem of the dynamics is obtained, with which we solve the problem of pest control on a finite period of time and discuss the governing strategies.

scholarly journals Economic Injury Level for Bermudagrass Stem Maggot (Diptera: Muscidae) in Bermudagrass Forage Production in Texas

2019 ◽  
Vol 112 (5) ◽  
pp. 2215-2221
Author(s):  
Allen E Knutson ◽  
Forrest Mitchell
Keyword(s):  
Vascular Tissue ◽  
Cynodon Dactylon ◽  
Forage Yield ◽  
Economic Injury Level ◽  
Forage Production ◽  
Market Values ◽  
Economic Injury ◽  
Stem Damage ◽  
And Control ◽  
The Impact

Abstract The bermudagrass stem maggot, Atherigona reversura Villeneuve (Diptera: Muscidae), was first reported damaging bermudagrass Cynodon dactylon (L.) Pers grown for forage in 2010 in the southeastern United States. Injury results from individual larvae feeding internally on the vascular tissue just above the terminal node of the grass stem. Injury slows plant growth and reduces forage accumulation. To address the need for economic guidelines to manage this new pest, the relationship between the percent of stems damaged by bermudagrass stem maggot and forage yield was measured in commercial bermudagrass hay fields in northcentral Texas. Yield loss was estimated to be 9.97 kg/ha (8.90 lbs /acre) for each percentage of stems with bermudagrass stem maggot damage. This relationship was used to calculate economic injury levels for a range of hay market values and control costs. The impact of stem damage on protein content, energy, and digestibility of bermudagrass hay was also investigated. Although there was a significant trend for declining forage quality with increasing stem damage, stem damage explained very little of the model’s variability.

scholarly journals Efficacy of Bt maize against European corn borer in Central Europe

2012 ◽  
Vol 48 (Special Issue) ◽  
pp. S25-S35 ◽  
Author(s):  
F. Kocourek ◽  
J. Stará
Keyword(s):  
European Corn Borer ◽  
Field Trials ◽  
Control Measures ◽  
Economic Injury Level ◽  
Bt Maize ◽  
Corn Borer ◽  
The Czech Republic ◽  
Economic Injury ◽  
Maize Plants ◽  
The Mean

The efficacy of Bt maize MON 810-YieldGard<sup>&reg;</sup> and of Trichogramma wasp against European corn borer (ECB) (Ostrinia nubilalis H&uuml;bner) was evaluated in the period of 2002&ndash;2008 in field trials on three localities in the Czech Republic. The efficacy of Bt maize on the reduction of the number of tunnels caused by ECB per 100&nbsp;maize plants before harvest was always 100% and that in Trichogramma treatment was on average 50%. The mean increase of the yield of 15% and 10% was obtained in Bt maize and Trichogramma treatments, respectively in comparison with the untreated control. The damage curve and economic injury level by ECB on maize was developed for the evaluation of the yield losses and management of the pest control. The higher economic efficacy of growing Bt maize as compared to other control measures is documented.

FLUE-CURED TOBACCO LOSSES CAUSED BY THE TOMATO HORNWORM, MANDUCA QUINQUEMACULATA (LEPIDOPTERA: SPHINGIDAE), AT VARIOUS INFESTATION LEVELS IN ONTARIO

1977 ◽  
Vol 109 (8) ◽  
pp. 1091-1095
Author(s):  
H. H. Cheng
Keyword(s):  
Feeding Habits ◽  
Maximum Yield ◽  
Leaf Size ◽  
Prediction Equation ◽  
Yield Reduction ◽  
Yield Losses ◽  
Economic Injury Level ◽  
Economic Injury ◽  
Terminal Buds ◽  
The Relationship

AbstractStudies on the flue-cured tobacco losses caused by the natural tomato hornworm, Manduca quinquemaculata (Haworth), were conducted in the field at Delhi, Ont., during 1973, 1974, and 1975. The feeding habits of the larval stage were observed and data on the subsequent damage to tobacco were recorded Two to six leaves per plant, depending on leaf size, were unmarketable due to damage caused by one hornworm larva. The most severe damage by the larva was due to destruction of terminal buds.The tobacco yield was significantly related, negatively, to the tomato hornworm infestation levels. All infestation levels influenced quantitative tobacco losses, but no qualitative differences were apparent when compared with the yield in the insect-free plots. Maximum yield losses occurred at the highest level of infestation. There were no significant differences in yield losses per larva among the infestation levels or among the years. The average yield reduction per larva for all of the population densities and years was 0.70 oz of cured leaves. A prediction equation to establish the relationship between hornworm infestation levels and tobacco yield losses was calculated. A theoretical economic-injury level for the tomato hornworm on tobacco in Ontario was established.

Idioscopus nitidulus (mango leafhopper).

2021 ◽  
Author(s):  
R Ganeswaran
Keyword(s):  
Indian Subcontinent ◽  
Uttar Pradesh ◽  
The Philippines ◽  
Economic Importance ◽  
Yield Reduction ◽  
Bud Break ◽  
Flowering Stage ◽  
Flower Bud ◽  
Economic Injury ◽  
The Mean

Abstract According to Viraktamath (1989), 14 idiocerine species in three genera (Amritodus, Busoniomimus and Idioscopus) breed on mango, and of these only six are of economic importance. Mango leafhoppers are major pests in the Indian subcontinent. The major damage caused is at the flowering stage and several studies have highlighted the reduction of yield which may be between 20 and 100% depending on population size. Verghese and Rao (1987) examined the critical infestation stages of the related species I. clypealis in Uttar Pradesh, India. The mean density of cicadellids was 0.54-20.64 per panicle in 1983 and 0-6.03 per panicle in 1984. In both years, the peak population occurred when the fruit was pea sized. At the post-bloom stage a population of two adults per panicle was sufficient to cause yield reduction. It is suggested that the critical infestation stages are at post-bloom, when the fruit is marble sized, and 1 month before harvest, with corresponding critical population levels of two adults, 6-21 nymphs and 4-11 hoppers per panicle. In the Philippines, Corey et al. (1989) found that the economic injury levels for I. clypealis on two croppings of mangoes averaged 4.21, 4.30, 4.45 and 4.55 adults per panicle at 2, 10, 18 and 26 days, respectively, after flower bud break for the first cropping, and 4.79, 4.88, 5.06 and 5.18 adults per panicle for the second cropping.

scholarly journals Damage assessment and economic injury level of the two-spotted spider mite Tetranychus urticae in soybean

2020 ◽  
Vol 55 ◽  
Author(s):  
Guilherme Padilha ◽  
Rubens Alex Fiorin ◽  
Alberto Cargnelutti Filho ◽  
Henrique Pozebon ◽  
John Rogers ◽  
...  
Keyword(s):  
Grain Yield ◽  
Tetranychus Urticae ◽  
Spider Mite ◽  
Grain Weight ◽  
Economic Injury Level ◽  
Control Cost ◽  
Economic Injury ◽  
Four Levels ◽  
Two Spotted Spider Mite ◽  
Whole Plants

Abstract: The objective of this work was to quantify the reduction of soybean grain yield caused by Tetranychus urticae damage, and to propose an economic injury level (EIL) for this pest in the crop. The experimental design was set up in randomized complete blocks, with four replicates and a 4x2 factorial arrangement with four levels of mite infestation, with or without mite control. Chlorotic symptoms were evaluated using a damage scale of 1 to 4. Soybean grain yield, number of pods, number of grains, and 1,000-grain weight were quantified for each segment of plant canopy (lower, middle, and upper) and for the whole plants. The chlorophyll content in the leaves was evaluated using the SPAD index. The population density of one two-spotted spider mite per cm2 of leaf area caused the following reductions: one pod per plant, two grains per plant, 0.7 g of 1,000-grain weight, and 0.35 g of grain yield per plant or 42 kg ha-1. Based on the equation y = 4,369 - 41.99x, the EIL of one two-spotted spider mite per cm2 is determined by considering a control cost of US$ 20.00 ha-1 and a soybean crop value of US$ 350.00 Mg-1. As to chlorotic symptoms, the EIL is set between damage scores 1 (no apparent mite damage) and 2 (yellow mottling beginning to appear).

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