Potato Leafhopper Research Articles

Effect of Drive Row Ground Covers on Hop (Rosales: Cannabaceae) Yard Arthropod Pests in Vermont, USA.

Alternatives to pesticides are necessary for the management of hop (Humulus lupulus L.) arthropod pests. The three major arthropod pests in northeastern US hop production include two-spotted spider mite, Tetranychus urticae Koch, hop aphid Phorodon humuli (Schrank), and potato leafhopper, Empoasca fabae Harris. This 3-yr study (2012-2014) in Vermont investigated the effect of flowering ground covers on arthropod pest abundance. Hop cultivars 'Nugget' and 'Cascade' were evaluated under a strip-split plot experimental design. Ground cover treatments included 1) Control: mowed red clover (Trifolium pratense) and resident weeds, 2) Clover: red clover, and 3) Diverse: common yarrow (Achillea millefolium), beebalm (Monarda fistulosa), red clover, and annual sunflower (Helianthus annuus). Natural enemies were grouped by associated pest and indicated by our mixed model to be strong predictors of the number of hop aphid and potato leafhopper on hop plants. In year two, ground cover treatment had a significant effect on two-spotted spider mite abundance where fewer two-spotted spider mite were observed on hop plants in Diverse plots. The established, un-mowed Clover treatment was preferred by potato leafhopper over Diverse ground cover and hop plants. This revealed the potential for clover ground cover to serve as a trap crop for potato leafhopper management in northeastern hop yards. Our findings are evidence that ground covers implemented for conservation biological control may serve more specific pest management functions instead of or in addition to boosting top-down pest pressure.

Registered and Experimental Foliar Insecticides for Control of Colorado Potato Beetle and Potato Leafhopper in Potato, 2016*

Registered and Experimental Foliar Insecticides for Control of Colorado Potato Beetle and Potato Leafhopper in Potato, 2016*

Evaluating pest-regulating services under conservation agriculture: A case study in snap beans

Although conservation agriculture (CA) practices including strip-tillage (ST) and cover cropping are promoted largely for their potential benefits for soil quality, uncertainty surrounding their short-term effects on pests often constrains adoption. Quantification of ecosystem services or dis-services associated with pests is an important step in identifying research and policy priorities for improving the performance of CA practices. Using insect, weed and yield data from snap beans in a three year vegetable rotation, we estimated the value of pest-regulating services associated with the adoption of CA, and compared it to establishment and management costs associated with implementing CA.Experimental factors included tillage (full-width tillage [FWT] or ST), cover crops (winter rye [R] or none [NR]) and weed management intensity (low or high). The value of pest-regulating services associated with adoption of CA practices was estimated based on pesticide cost savings associated with reductions in pest densities given action thresholds typical of commercial snap bean production in the North Central United States. CA practices had no detectable impact on snap bean yields relative to FWT-NR, but resulted in significant tradeoffs in weed and insect abundance. For example, in at least one of two years, ST-R had lower densities of potato leafhopper, Powell amaranth and winter annual weeds, but greater densities of tarnished plant bug and large crabgrass compared to FWT-NR. CA practices had variable effects on natural enemies including ladybeetles, spiders and parasitoids, with no consistent impacts relative to FWT-NR. We estimated that CA practices resulted in net pest-regulating dis-services with costs of $33ha−1 for FWT-R, $25ha−1 for ST-NR, and $14ha−1 for ST-R. Under partial adoption of CA (ST-NR), pest-related costs were completely offset by savings in tillage costs, resulting in estimated short-term increases in net returns of $26ha−1. In contrast, complete adoption of CA (ST-R) resulted in greater pest and cover crop management costs that outweighed savings due to reduced tillage, resulting in estimated short-term losses of $165ha−1. In production systems for which effective, low-cost pesticides are unavailable (e.g. low-income countries) or prohibited (e.g. organic systems), the economic impact of pest regulation services is likely to be greater than our estimates suggest. Although CA practices provide several potential long-term ecosystem services at both the farm and landscape level, short-term impacts on pests and yields relative to the costs of implementation are likely to be the major determinant of grower adoption.

Early Spring Occurrence ofEmpoascaspp. (Hemiptera: Cicadellidae) in and Adjacent to Alfalfa Fields in Iowa

Abstract Adult Empoasca fabae (Harris) (Hemiptera: Cicadellidae) were monitored at three locations within four alfalfa fields (edge of field to 40 m into field) from mid-April to June and Empoasca spp. activity from adjacent tree and shrub species until July. Similar numbers of Empoasca spp. adults were collected from sticky traps placed on tree and shrub species in the four border areas. In three of the four fields examined, significantly more E. fabae were found at the edges of the alfalfa fields closest to the trees than at 40 m from the edge of the field during the first week of May. In subsequent samples, there was no difference in the distribution of E. fabae in the alfalfa fields (except Field 2, where there were more E. fabae near the field edge for the duration of the study). Based upon this study, Empoasca spp. (primarily E. fabae) are colonizing alfalfa fields from the field margins to the interior in early spring and may be using adjacent woody habitats (including Gleditsia, Prunus, Ulmus, Ti...

Evaluation of systemic insecticides for the control of Colorado potato beetle, potato leafhopper, and aphids in potato, 2014: Table 1.

Evaluation of systemic insecticides for the control of Colorado potato beetle, potato leafhopper, and aphids in potato, 2014: Table 1.

Registered and experimental foliar insecticides to control Colorado potato beetle and potato leafhopper in potato, 2014: Table 1.

Registered and experimental foliar insecticides to control Colorado potato beetle and potato leafhopper in potato, 2014: Table 1.

Effects of Chlorpyrifos andLambda-andGamma-Cyhalothrin on Suppression of Aster Leafhoppers,Macrosteles quadrilineatus(Hemiptera: Cicadellidae) in Spring Wheat1

ABSTRACT Unexpected outbreaks of the aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), in wheat in the spring of 2012 across the Northern Plains of the U.S. prompted extensive applications of insecticides to suppress their populations. Aster leafhoppers are infrequent pests of wheat in the Northern Plains early in the spring, and data on insecticide efficacy for aster leafhoppers in wheat were unavailable at the time of the outbreak. Thus, our goal was to test several insecticides commonly used against key pests in wheat for their efficacy against aster leafhoppers. We examined the effects of chlorpyrifos and lambda- and gamma-cyhalothrin in greenhouse and field. These insecticides are not currently registered for suppression of aster leafhoppers in wheat, but they are used frequently to control potato leafhoppers in alfalfa. We found that all insecticides reduced numbers of aster leafhoppers four days after application (DAA) in the field, but not seven and 14 DAA, likely due ...

European Corn Borer Control in Snap Bean, 2015: Table 1

European corn borer control (ECB) using foliar-applied insecticides was evaluated in a research snap bean field near Geneva, New York (GPS coordinates: 42.865500, -77.029667). On 25 June 2015, processing snap bean seeds were planted at a density of 23 seeds per m using a precision vacuum planter (Monosem Inc.). All seeds (including the non-insecticide control) were treated with thiamethoxam (Cruiser 5FS) and mefenoxam and fludioxonil (ApronMaxx) to protect seedlings against seed corn maggot, early infestations of potato leafhoppers and diseases. Natural ECB pressure in the research field is rarely high enough to sufficiently evaluate insecticide treatments on snap bean. To increase ECB pressure at the …

Survey of Northeastern Hop Arthropod Pests and Their Natural Enemies

The commercial production of hops ( Humulus lupulus L.) in the northeastern United States is on the rise due to demand from local breweries. Several arthropod pests are economically damaging to hop yield and quality. Due to climate and landscape differences between traditional and resurging hop-growing regions, there is a need for region-specific integrated pest management (IPM). We first review hop pest and natural enemy biology and management strategies. Then the phenology, abundance, and peak date of arthropod pests scouted in seven Vermont hop yards is reported. Documentation of natural enemy abundance is also reported. Our 3-yr survey indicated that hop aphid ( Phorodon humuli (Schrank)) populations were highest in the continually cool, wet season. Potato leafhopper ( Empoasca fabae (Harris)) was a pest with an unpredictable arrival date and of special concern for first-year hop plants. Twospotted spider mite ( Tetranychus urticae Koch) was a pest of concern in hot, dry conditions and after some broad-spectrum pesticide applications aimed at leafhoppers. This survey was the first step toward developing appropriate IPM tactics for modern day northeastern hop production. Further research should be focused on adjusting arthropod pest thresholds, disease management, and developing alternative control options for both arthropod and disease management.

SURVEY AND POPULATION DENSITY OF SOME INSECT AND MITE PESTS INFESTING CHICORY PLANT (CICHORIUM INTYBUS L.) IN GIZA GOVERNORATE, EGYPT

the present investigation was carried out at the experimental farm of Agricultural Research Centre, Giza Governorate, Egypt throughout two successive seasons (2010 and 2011) on chicory plants. Obtained results clearly indicated the following: 1) Twenty seven species of insects and mites were surveyed on Chicory plants during the two successive growing seasons. 2) Eight insects and mites considered important pests. 3) The spider mite Tetranychus urticae Koch proved to be the most abundant species during the two growing seasons showing the highest population density general mean recording 26. 47, 15.60 movable stages/sample in the two seasons, respectively. The lowest density was obtained with the phytophagous mite Bryobia sp. 4) Six insect pests their population density general means were intermediate, these insects were the aphid Uroleucon ambrosiae (Thomas), the white fly B. tabaci (Genn.), Thrips tabaci Lind., the potato leaf hopper Empoasca decipiens (Paoli), the sugar cane mealy bug Saccharicoccus sacchari (Cockerell) and the sugar beet fly Pegomyia mixta (Will) during two seasons.

Revisiting the Economic Injury Level and Economic Threshold Model for Potato Leafhopper (Hemiptera: Cicadellidae) in Alfalfa.

The economic injury level for potato leafhopper, Empoasca fabae (Harris), in alfalfa (Medicago sativa L.) was developed over 30 yr ago. In response to increasing market value of alfalfa, farmers and consultants are interested in reducing the economic threshold for potato leafhopper in alfalfa. To address this question, caged field trials were established on two consecutive potato leafhopper susceptible crops in 2013. Field cages were infested with a range of potato leafhopper densities to create a linear regression of alfalfa yield response. The slopes, or yield loss per insect, for the linear regressions of both trials were used to calculate an economic injury level for a range of current alfalfa market values and control costs. This yield-loss relationship is the first quantification that could be used to help assess whether the economic threshold should be lowered, given the increased market value of alfalfa.

Climate Change and Phenology: Empoasca fabae (Hemiptera: Cicadellidae) Migration and Severity of Impact.

Climate change can benefit individual species, but when pest species are enhanced by warmer temperatures agricultural productivity may be placed at greater risk. We analyzed the effects of temperature anomaly on arrival date and infestation severity of potato leafhopper, Empoasca fabae Harris, a classic new world long distance migrant, and a significant pest in several agricultural crops. We compiled E. fabae arrival dates and infestation severity data at different states in USA from existing literature reviews and agricultural extension records from 1951–2012, and examined the influence of temperature anomalies at each target state or overwintering range on the date of arrival and severity of infestation. Average E. fabae arrival date at different states reveal a clear trend along the south-north axis, with earliest arrival closest to the overwintering range. E. fabae arrival has advanced by 10 days over the last 62 years. E. fabae arrived earlier in warmer years in relation to each target state level temperature anomaly (3.0 days / °C increase in temperature anomaly). Increased temperature had a significant and positive effect on the severity of infestation, and arrival date had a marginal negative effect on severity. These relationships suggest that continued warming could advance the time of E. fabae colonization and increase their impact on affected crops.

Effects of Nitrogen Fertilization on Potato Leafhopper (Hemiptera: Cicadellidae) and Maple Spider Mite (Acari: Tetranychidae) on Nursery-Grown Maples.

Although leaf nitrogen (N) has been shown to increase the suitability of hosts to herbivorous arthropods, the responses of these pests to N fertilization on susceptible and resistant host plants are not well characterized. This study determined how different rates of N fertilization affected injury caused by the potato leafhopper (Empoasca fabae Harris) and the abundance of maple spider mite (Oligonychus aceris (Shimer)) on 'Red Sunset' red maple (Acer rubrum) and 'Autumn Blaze' Freeman maple (Acer×freemanii) during two years in Indiana. N fertilization increased leaf N concentration in both maple cultivars, albeit to a lesser extent during the second year of the study. Overall, Red Sunset maples were more susceptible to E. fabae injury than Autumn Blaze, whereas Autumn Blaze maples supported higher populations of O. aceris. Differences in populations of O. aceris were attributed to differences between communities of stigmaeid and phytoseiid mites on each cultivar. Injury caused by E. fabae increased with N fertilization in a dose-dependent manner in both cultivars. Although N fertilization increased the abundance of O. aceris on both maple cultivars, there was no difference between the 20 and 40 g rates. We suggest the capacity of N fertilization to increase O. aceris on maples could be limited at higher trophic levels by the community of predatory mites.

Forage Yield and Nutritive Value Responses to Insecticide and Host Resistance in Alfalfa

ABSTRACTThere are conflicting reports on effectiveness of glandular‐haired alfalfa (Medicago sativa L.) cultivars for reducing plant injury caused by potato leafhopper (PLH), Empoasca fabae Harris (Hemiptera: Cicadellidae). We measured forage yield and nutritive value in a glandular‐haired cultivar rated as highly resistant to PLH (54H91) and a nonglandular‐haired susceptible cultivar (54V54), both grown with and without an insecticide applied either early or late in each summer growth cycle across 3 yr. Cultivar × insecticide treatment interactions (P ≤ 0.01 and 0.14) were found for cumulative yield across years in two experiments. With the early insecticide treatment on 54H91, forage yield was up to 6% greater (P = 0.03) than without insecticide, while the susceptible 54V54 yielded 17 to 37% more (P < 0.01) with the early treatment than without insecticide. Crude protein (CP) of 54V54 in summer averaged 10 to 22 g kg−1 lower (P < 0.05) for the untreated than with early insecticide treatment, but consistent differences in forage fiber content or fiber digestibility were not observed. Cumulative forage yield across all harvests or across summer harvests in the untreated 54H91 were similar to yield of the late insecticide‐treated susceptible 54V54. The glandular‐haired alfalfa cultivar suppressed PLH abundance and reduced yield losses caused by this pest in the absence of insecticide applications. Glandular‐haired cultivars with high PLH resistance provide alfalfa growers opportunities to reduce insecticide use within an integrated pest management strategy in regions where the PLH causes significant yield losses in susceptible cultivars.

Population Dynamics of Empoasca fabae (Hemiptera: Cicadellidae) in Central Iowa Alfalfa Fields.

Adults and nymphs of Empoasca fabae Harris (Hemiptera: Cicadellidae) and adults of predatory species in the families Coccinellidae, Anthocoridae, Nabidae, Chrysopidae, and Hemerobiidae were sampled in Iowa alfalfa fields from June to September in 1999 and 2000. The relationship between each predatory taxa and E. fabae was examined using regression analysis. In 2000, all predators were found to be positively correlated with the presence of E. fabae during all periods sampled and most likely contributed to mortality. Orius insidiosus (Say) (Hemiptera: Anthoridae) was the most numerous insect predatory species; population numbers ranged from 0 to 1 and 0.1 to 3.7 adults per 0.25 m2 in 1999 and 2000, respectively. Partial life tables were constructed for E. fabae nymphs for two alfalfa-growing periods. Nymphs were grouped into three age intervals: first and second, third and fourth, and fifth instars. For the first alfalfa growing period examined, E. fabae nymphal mortality was 70% in 1999 and 49% in 2000. During the last growing period of each season (August–September), total nymphal mortality was relatively low (<25%). Adult E. fabae density ranged from 5.4 to 25.6 and 1.4–9.2 per 0.25 m2 in 1999 and 2000, respectively. E. fabae population peaks were similar for each age interval in all growing periods. This study provides further information on the population dynamics of E. fabae and its relationship with select predatory species in Iowa alfalfa fields.

Trunk injection: An alternative technique for pesticide delivery in apples

Field studies, laboratory bioassays, and residue profile analysis were used to determine the seasonal effectiveness of trunk injected pesticides against key apple disease and insect pests. Insecticides formulated for trunk injection, imidacloprid (Ima-jet™), rynaxypyr (XCL-r8™), and emamectin benzoate (TREE-age™) were injected into semi-dwarf Empire apple trees Malus domestica (Borkhausen) and evaluated for a wide range of insect pests. The fungicide compounds, propiconazole (Alamo®), phosphites (Phospho-jet), and penthiopyrad (Fontelis™), were injected into semi-dwarf MacIntosh (RedMax) apple trees M.domestica (Borkhausen) for control of apple scab fungus, Venturia inaequalis (Cooke). After the original single injection, imidacloprid was highly effective in controlling piercing and sucking pests such as the potato leafhopper, Empoasca fabae (Harris), and aphids (Aphididae), and emamectin benzoate was highly effective in controlling the oblique banded leaf roller, Choristoneura rosaceana (Harris), and potato leafhopper, E. fabae (Harris), and rynaxypyr was highly effective in controlling Oriental fruit moth, Grapholita molesta (Busck), and leafrollers all for two growing seasons. The residue profiles for insecticides showed that vascular delivery was predominantly to foliage, with fruit residues far below the EPA maximum residue limits (MRLs), and low to no residues detected in apple flower parts. Phosphites provided significant levels of apple scab control over two seasons for the single injection after the foliage recovered from the phytotoxicity damage in the first season. Propiconazole and penthiopyrad showed limited effectiveness for the control of apple scab. The residue profiles for fungicides showed phosphites to be delivered primarily to foliage, but inconsistent foliar residue levels for the other two compounds suggests possible incompatibilities may be responsible for poor product performance. These incompatibilities may include molecular or chemical properties. For example, on the molecular level such as the molecular size too large to fit through vascular tissue and chemical properties such as the viscosity of the compound resulting in poor translocation or pH.

Effects of pesticide application on arthropod pests of nursery-grown maples.

Insecticides used against potato leafhopper, Empoasca fabae (Harris) (Homoptera: Cicadellidae), have been reported to cause problems with maple spider mite, Oligonychus aceris (Shimer) (Acarina: Tetranychidae), on nursery-grown 'Red Sunset' red maple and 'Autumn Blaze' Freeman maple. To test this, we conducted two experiments on field-grown trees in nurseries. In the first, the effects of early-season pesticide applications were examined during 2009. The second experiment was conducted in 2010 to compare effects of using threshold levels of one, three, or six leafhoppers per branch to time applications. Pesticide applications reduced abundance and damage by leafhoppers in both cultivars, but increased populations of O. aceris on Autumn Blaze during 2009. In contrast, on Red Sunset, populations of O. aceris did not increase after insecticide applications. In 2010, insecticide applications did not increase abundance of O. aceris on Autumn Blaze because use of treatment thresholds to manage leafhoppers greatly reduced numbers of trees requiring treatment for leafhoppers. Two phytoseiid mites, Neoseiulus fallacis (Garman) and Typhlodromus caudiglans (Schuster), and one stigmaeid, Zetzellia mali (Ewing), were identified as the principal predators of O. aceris on maple leaves. Insecticide applications had no significant effects on the total abundance of predatory mites on either Red Sunset or Autumn Blaze maples in 2009 or 2010. However, populations of predator Z. mali were higher during both years on Red Sunset than on Autumn Blaze. These results suggest that both early-season pesticide use and cultivar can affect the likelihood of secondary outbreaks of spider mites on maples.

Potato Leafhopper (Hemiptera: Cicadellidae) Ecology and Integrated Pest Management Focused on Alfalfa

This article summarizes the knowledge to date on biology of the potato leafhopper, Empoasca fabae (Harris), including its distribution, development, migration, agricultural host plants, and mechanics of injury to host plants. Damage to alfalfa, potatoes, soybeans, and snap beans, and treatment guidelines, are summarized. Particular attention is given to integrated pest management options in alfalfa, the host plant most frequently incurring economically damaging populations of potato leafhopper. Alfalfa scouting and economic thresholds are discussed along with cultural controls and host plant resistance.

Herbicide drift can affect plant and arthropod communities

Field edges, old fields, and other semi-natural habitats in agricultural landscapes support diverse plant communities that help sustain pollinators, predators, and other beneficial arthropods. These plant and arthropod communities may be at significant ecotoxicological risk from herbicides applied to nearby crop fields. Recent innovations in herbicide-resistant crop biotechnology may lead to major increases in the use of the herbicides dicamba and 2,4-D. These herbicides selectively affect broadleaf plants, and non-target exposures may therefore lead to a net reduction in the functional diversity and floral resources provided by semi-natural habitats. In multi-year experiments at two sites (a field edge and an old field), we exposed replicated plots to low doses of dicamba designed to simulate herbicide drift and monitored changes in plant and arthropod communities. At the field edge site, we observed a significant decline in forb cover (but not floral resources) in plots treated at doses (∼1% of the field application rate) that are substantially lower than those that have been documented to affect plant communities in previous research. We also observed declines in three herbivorous pest species (pea aphids, spotted alfalfa aphid, and potato leaf hopper), increases in one pest species (clover root curculio), and increases in beneficial seed predators (crickets) associated with dicamba exposure. In contrast, at the old field site, drift-level doses did not affect plant community structure but reduced flowering of a key species (Monarda fistulosa). Variability across sites and taxonomic groups makes it difficult to offer general conclusions about the risks of dicamba drift to plant and arthropod biodiversity. Factors including the successional age of the plant community and water stress at the time of herbicide exposure likely explain the differing responses at the two sites to simulated drift.

Modeling and Sensitivity Analysis of the Role of Biodiversity to Control Pest Damage in Agroecosystems

The paper provides a mathematical framework for cost-effective and environmentally safe strategies to minimize alfalfa damage from pests in alfalfa agroecosystems with optimal biodiversity levels and to predict outcomes for scenarios not covered by field experiments. Alfalfa is the most important forage legume world-wide and is a valuable source of nutrition for farm animals. The potato leafhopper (PLH) pest damages the alfalfa plant leading to a reduction of the productivity, a loss in nutritional value, and a decrease in milk production. The PLH pest outbreaks are also prone in monocultures. New mathematical models are shown to accurately fit results from field experiments utilizing plant diversity and enemies (pest-predator) hypotheses. The focus is on polyculture as a farming technique and the damsel bug, Nabis, a natural predator of the PLH. Mathematical methods include the Shannon diversity index, differential equations, scramble competition approaches, and sensitivity analysis to determine critical parameters.