Soil Insecticides Research Articles

Evaluation of Foliar Insecticide Treatments for the Control of Foliar Insects in Potatoes in Virginia, 2014

The objective of this experiment was to assess the efficacy of foliar and soil insecticides for the control of CPB and PLH. The trial consisted of 12 treatments arranged in an RCB design with four replicates. Potatoes were planted on 14 April 2013 at the Virginia Tech Eastern Shore AREC near Painter, VA. Plots were 2 rows wide and 20 ft (6.1 m) long with unplanted guard rows on each side. Rows were planted on a 3 ft row center (0.9 m) with 11 inches (0.3 m) between plants, in a 6 tier field design with 8 ft …

Estimation of efficacy functions for products used to manage corn rootworm larval injury

AbstractMaize, Zea mays L., is an economically important crop grown throughout the world. Corn rootworm, Diabrotica spp. (Coleoptera: Chrysomelidae), larvae constitute a significant economic threat to maize production in the United States, where yield losses and management costs associated with corn rootworm species exceed $1 billion annually. Furthermore, the introduction of the western corn rootworm, D. virgifera virgifera LeConte, into maize‐producing regions of Europe has made managing corn rootworm larval injury an international concern. Larvae injure maize plants by feeding on root tissue and are the primary target of management activities. Products commonly used to protect root systems from injury include chemical insecticides (seed or soil applied) and genetically modified maize hybrids expressing toxins derived from Bacillus thuringiensis Berliner (Bt). The confirmation of field‐evolved resistance to various Bt toxins in populations of the western corn rootworm presents a significant management challenge. We performed a meta‐analysis to provide a broad understanding of the relative efficacy of the primary products currently being used to manage corn rootworm larval injury, including insecticidal seed treatments, soil insecticides and Bt hybrids (with and without the addition of soil insecticide). Our analysis is unique in the breadth of locations and years included – we analysed 135 individual trials conducted from 2003 through 2014 at multiple sites in both Illinois and Nebraska. Panel data were produced by pairing the mean node‐injury rating for each treatment of a given trial with the mean node‐injury rating for untreated maize. Linear regression models were developed to estimate the relationship between the potential for corn rootworm larval injury and product performance. For a given level of injury potential, the parameters estimated reveal differences in the degree of root protection offered by the various product categories analysed. Implications for developing long‐term, integrated, and sustainable practices for managing this important pest of maize are discussed.

Environmental fate of the insecticide cypermethrin applied as microgranular and emulsifiable concentrate formulations in sunflower cultivated field plots

A field dissipation and transport study of the insecticide cypermethrin applied as microgranular (MG) and emulsifiable concentrate (EC) formulations has been conducted in field sunflower cultivations and bare soil plots with two different slopes (1% and 5%). The dissipation of insecticide in soil (on planting rows) was monitored for a period of 193days. Cypermethrin residual concentrations in the upper soil layer (0–10cm), 2days after soil application (DASA), ranged from 0.53 to 0.73μgg−1 when the maximum values were observed 7 DASA, ranged from 1.06 to 1.23μgg−1. The dissipation rate was better described by first-order kinetics. The average half-life in cultivated (tilled and planted) plots was 23.07 and 24.24days for soil slopes 5% and 1%, respectively. In uncultivated (tilled but not planted) plots the respective values were 22.01 and 22.37days. The insecticide was found below the 10cm soil layer occasionally in few samples at low concentrations (<0.02μgg−1). In runoff water it was detected once (7days after foliar application, at levels below LOQ), when in sediment it was detectable for seven samplings. The maximum values were observed 7days after foliar application, when they reached 0.097 and 0.143μgg−1 in cultivated plots with soil slopes 1% and 5%; and 0.394 and 0.500μgg−1 in uncultivated plots, respectively. The amount of cypermethrin which was transferred by the sediment remained at low levels (less than 0.01% of the totally applied active ingredient), even in plots with 5% inclination. The insecticide was detected in leaves and stems of the sunflower plants after the foliar application up to the day of harvest. On the contrary, in roots it was detectable during the whole cultivation period. No residues were detected in flowers or seeds.

Development of an indirect spectrophotometric method for determination of methamidophos insecticide in soil, water and vegetable samples

A simple and rapid indirect spectrophotometric method for determination of methamidophos in water, soil and vegetable samples has been described. Methamidophos reacts with acid produced from p-dimethylaminobenzaldehyde (p-DMAB) as a result of Cannizaro’s reaction. The resultant adduct undergoes condensation reaction in acidic medium forming a yellow colored product. Absorbance of the colored product was measured at 405 nm and pH 3 against a reagent blank. The Beer’s law range is obeyed in the range 1-30 µg mL-1 with molar absorptivity of 2.8 ×103 L mol-1 cm-1. The limit of detection and quantification were found to be 0.20±0.03 and 0.60±0.04 µg mL-1 respectively. The proposed method was effectively applied for determination of methamidophos in various samples with percent recoveries in the range of 96±0.08 to 102±0.06 %. KEY WORDS: Spectrophotometric, Methamidophos, p-Dimethylaminobenzaldehyde (p-DMAB), Cannizaro’s reaction Bull. Chem. Soc. Ethiop. 2015, 29(2), 311-318DOI: http://dx.doi.org/10.4314/bcse.v29i2.13

Risk Assessment of Genetically Engineered Maize Resistant to Diabrotica spp.: Influence on Above-Ground Arthropods in the Czech Republic.

Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize), confers resistance to corn rootworms (Diabrotica spp.) and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009–2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G) and two non-Bt reference hybrids (KIPOUS and PR38N86). Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (P<0.05). Multivariate analysis showed that the abundance and diversity of plant dwelling insects was similar in maize with the same genetic background, for both Bt (MON88017) and non-Bt (DK315) untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability.

Residues of Fungicides and Insecticides in Rice Field

The use of pesticides assists in integrated programs that aim high yield and quality grains in irrigated rice (Oryza sativa L.). However, the use of pesticides can pose risk to rice quality as well as the environment and general population. Therefore, the objective of this study was to investigate the dissipation and persistence of fungicides (azoxystrobin and difenoconazole) and the insecticides (lambda‐cyhalothrin and thiamethoxam) in irrigation water, soil, rice plant, panicle, and rice grain. The study was conducted in the field during the 2011/2012 crop season, with fungicides and insecticides applied to the aerial parts of the rice plants, the samples were collected in different moments during a 40‐d monitoring period after the application of the pesticides. Laboratory analyses to detect pesticide residues were determined by ultra‐high performance liquid chromatography and by gas chromatography. Pesticide residues were detected in irrigation water and rice plants during the 40 d of monitoring. Azoxystrobin, difenoconazole, and thiamethoxan were transported into the environment due to overflowed water from the rice field, however pesticide residues were not detected in soil. Azoxystrobin, difenoconazole, thiamethoxan, and lambda‐cyhalothrin residues were detected in rice hull, however, no residues were detected in neither brown nor polished rice grain.

Evaluation of soil‐applied insecticides with Bt maize for managing corn rootworm larval injury

AbstractThe western corn rootworm, Diabrotica virgifera virgifera LeConte, is considered one of the most significant insect pests of maize in North America. Larvae of other secondary subterranean pests such as grape colaspis, Colaspis brunnea (F.), and Japanese beetle, Popillia japonica Newman, can also injure maize seedlings and cause yield loss. In the past decade, maize hybrids containing Bt proteins have been used to manage the western corn rootworm; additionally, seeds are commonly treated with a neonicotinoid and fungicide combination to control secondary pests. Recently, soil‐applied insecticides have been used in conjunction with rootworm Bt hybrids (and seed‐applied insecticides) in areas with perceived risk for increased rootworm larval or secondary pest damage. We conducted a series of trials from 2009 to 2011 that examined multiple rootworm Bt hybrids and their near‐isolines, along with two soil‐applied insecticides, to determine whether the Bt plus insecticide combination resulted in an increased level of efficacy or yield. We also sampled for Japanese beetle and grape colaspis larvae to determine their potential for reducing yield. Densities of secondary pests in our trials were low and likely had no effect on maize yield. The addition of a soil‐applied insecticide to rootworm Bt hybrids improved efficacy only once across 17 location‐years, when overall corn rootworm injury was highest; an improvement in yield was never observed. Our results suggest that the use of a soil‐applied insecticide with a rootworm Bt hybrid should only be considered in scenarios with potentially significant rootworm larval populations. However, potential negative consequences related to trait durability when soil insecticides are used with rootworm Bt maize should be considered.

Impact of Western Bean Cutworm (Lepidoptera: Noctuidae) Infestation and Insecticide Treatments on Damage and Marketable Yield of Michigan Dry Beans.

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), recently expanded its range from the western United States into the Great Lakes region of the United States and Canada, threatening eastern dry bean production. Our objectives were to better understand the relationship between cutworm infestation and damage in dry beans, and to determine the best method and timing of insecticide application to reduce pick. Infesting with at least one egg mass per 1.5 m, or as few as two larvae per 0.3 m, of row resulted in significantly more pod damage and pick than in uninfested plots. By 14 d after hatch, larvae were no longer on plants during the daytime; direct observations revealed that fifth instars climbed plants to feed between 2100 and 0600 hours, illustrating the impractically of using larval counts to make management decisions. There was a strong linear relationship between pod damage and percent pick, making scouting for pod damage a viable alternative to egg or larval scouting. Aldicarb soil insecticide or thiamethoxam-treated seed did not reduce cutworm damage. Instead, plots treated with these insecticides had significantly more pick than control plots, perhaps related to increased canopy growth or fewer natural enemies. The pyrethroid λ-cyhalothrin provided excellent control of cutworm when sprayed up to 18 d after infestation. Pick was similar among plots sprayed once up to 18 d after infestation or sprayed four separate times. In a field study, λ-cyhalothrin residue on field-treated foliage was 100% effective at controlling caterpillars up to 14 d after application.

THE OCCURRENCE OF ENTOMOPATHOGENIC FUNGI IN SOILS FROM CULTIVATED PERENNIAL RYEGRASS (LOLIUM PERENNE L.)

An important role in the agricultural agrocenosis is attributed to entomopathogenic fungi. They limit the occurrence of certain populations of soil pests and insects overwintering in the soil environment, or held in the pupation. Fungi are the only pathogens of arthropods witch have the ability to infect plant pests directly by body. However, bacteria are the largest group of microorganisms inhabiting the soil. The aim of this study was to compare the species composition and the severity of the occurrence of entomopathogenic fungi in soils of monoculture crops perennial ryegrass (Lolium perenne L.). The material consisted of soil samples taken from the experimental research conducted in two experimental stations of the Central Research Centre for Cultivar. The fungi isolated from soil insecticides using a method developed by the selective medium.

논 및 밭토양 중 살충제 Clothianidin의 잔류특성

Abstract BACKGROUND: The current study purposed to analyse the dissipation levels of a neonicotinoid insecticide and clothianidin in paddy and upland soils and clarify the effects of soil moisture on degradation and persistence of the insecticide. METHODS AND RESULTS: In order to achieve the research purposes, clothianidin 8% SG was applied to the paddy and upland fields at the rate of 0.024 kg a.i./10a, while the analytical standard was treated at 0.25 mg/kg soil under laboratory conditions. Based on the multiple first-order kinetics, total clothianidin in soils was dissipated with DT 50 of 6.7-16.1 and 6.9-8.2 days in the paddy and upland fields, respectively, whereas the figures under the laboratory condition became larger showing 56.3 and 19.6 days.CONCLUSION: As affected by soil moisture, some differences in degradative pathways were observed. Flooding of soil caused evidently demethylation and delayed cyclization of a major metabolite, thiazolylmethylguanidine (TMG) and methylaminoimidazole(MAI), compared to the aerobic upland condition. More than 80% and 50% of the parent compound was dissipated by the 24th day after the final application in both soils and, transformation products had constituted most of soil residues after that.Key words: Clothianidin, Degradation, Persistence, Soil, Water

Persistência de inseticidas e parâmetros microbiológicos em solo sob sistemas de manejo

O objetivo deste trabalho foi avaliar a degradação dos inseticidas bifentrina, permetrina e tiametoxam em um solo sob sistemas de integração lavoura-pecuária (SILP), plantio direto (SPD) e convencional (SC), e sua relação com atributos microbiológicos (carbono da biomassa microbiana, respiração basal e atividade das enzimas -glucosidase e fosfatase ácida). O experimento foi realizado utilizando solos incubados (0-10cm) com umidade a 75% da capacidade de campo e 28ºC por 51 dias. Além de aumentos de matéria orgânica, biomassa e atividade microbiana, o sistema SILP também favoreceu a degradação mais rápida dos três inseticidas no solo, em comparação aos outros sistemas avaliados. Dentre os inseticidas avaliados, o tiametoxam apresentou degradação lenta no solo, com valores de meia-vida (TD50) entre 46 e 89 dias. Os valores de TD50 para bifentrina ficaram entre 14 e 44 dias e para permetrina entre 9 e 47 dias, considerando todos os sistemas avaliados.

Evaluation of leaching potential of three systemic neonicotinoid insecticides in vineyard soil

Dinotefuran (DNT), imidacloprid (IMD), and thiamethoxam (THM) are commonly used neonicotinoid insecticides in a variety of agriculture operations. Although these insecticides help growers control pest infestation, the residual environmental occurrence of insecticides may cause unintended adverse ecological consequences to non-target species. In this study, the leaching behavior of DNT, IMD, and THM was investigated in soils collected from an active AgriLife Research Extension Center (AREC) vineyard. A series of column experiments were conducted to evaluate the leaching potential of insecticides under two experimental scenarios: a) individual pulse mode, and b) mixed pulse mode. In both scenarios, the breakthrough pattern of the insecticides in the mostly acidic to neutral vineyard soil clearly demonstrates medium to high leachability. Of the three insecticides studied for leaching, DNT has exhibited high leaching potential and exited the column with fewer pore volumes, whereas IMD was retained for longer, indicating lower leachability. Relative differences in leaching behavior of neonicotinoids could be attributed to their solubility with the leaching pattern IMD<THM<DNT showing strong correlation with increasing aqueous solubility 610mg/L<4100mg/L<39,830mg/L. Triplicate column study experiments were conducted to evaluate the consistency of the breakthrough pattern of these insecticides. The repeatability of the breakthrough curves shows that both DNT and IMD are reproducible between runs, whereas, THM shows some inconsistency. Leaching behavior of neonicotinoid insecticides based on the leachability indices such as groundwater ubiquity score, relative leaching potential, and partitioning between different environmental matrices through a fugacity-based equilibrium criterion model clearly indicates that DNT may pose a greater threat to aquatic resources compared to IMD and THM.

A multi-year field study to evaluate the environmental fate and agronomic effects of insecticide mixtures

A mixture of insecticides used in corn production was monitored over a three-year period in a field study to determine how long each persists in the environment, where each insecticide travels within the corn field, and the efficacy of using soil-applied insecticides with genetically modified corn. The genetically modified corn contained the insecticidal Cry1Ab and Cry3Bb1 proteins (Bt corn) and the Cry1Ab protein was found to persist only during the corn growing season in soil, runoff water, and runoff sediment with highest concentrations measured during pollination. Very low concentrations of Cry1Ab proteins were measured in soil collected in the non-Bt corn field, and no Cry1Ab proteins were detected in shallow groundwater or soil pore water. Clothianidin, a neonicotinoid insecticide used as a seed coating, was detected in all matrices and remained persistent throughout the year in soil pore water. Tefluthrin, a pyrethroid insecticide applied at planting to control corn rootworm larvae (Diabrotica spp., Coleoptera: Chrysomelidae) populations, was consistently detected in soil, runoff water, and runoff sediment during the corn growing season, but was not detected in groundwater or soil pore water. Tefluthrin did not have an effect on root damage from corn rootworm larvae feeding to Bt corn, but did prevent damage to non-Bt corn. A slight reduction in grain yield was observed in the non-Bt, no tefluthrin treatment when compared to all other treatments, but no significant difference in grain yield was observed among Bt corn treatments regardless of soil insecticide application. In the current study, the use of tefluthrin on Bt corn did not significantly affect crop damage or yield, and tefluthrin may travel off-site in runoff water and sediment.

Economics of long-term IPM for western corn rootworm

We used a published biological model and published economic algorithm to evaluate western corn rootworm (Diabrotica virgifera virgifera) IPM for growers over a 15 year period beginning after significant adoption of insecticidal corn (Zea mays). The primary focus of our analysis was the economic evaluation (grower profit) of transgenic insecticidal corn expressing Cry34/35Ab1 as event 59122 and its refuge planted continuously year after year (continuous corn). We chose the reference scenario for economic comparison to be the use of soil insecticides on continuous, conventional corn. The model simulated the evolution of rootworm resistance to transgenic insecticidal (Bt) corn; but did not simulate resistance to soil insecticides. We evaluated refuge sizes of 5–50% for single-trait Bt corn and 5–20% for pyramided Bt corn with two traits targeting western corn rootworm. We considered the role of block and blended (seed mixture) refuges for insect resistance management (IRM). Results demonstrated that, for pyramided Bt corn, block refuges planted in the same location within a field year after year gave the greatest overall profit for grower. If growers relocated their block refuge annually (which is the most common practice), then a 5% blended refuge gave the greatest return. For single-trait Bt corn, 10–20% blended refuges gave greater economic return compared to block refuges ranging from 5% to 50%. Single-trait Bt corn with 5–20% block refuge (with no insecticide) was superior to soil insecticide use alone in all cornfields.

Effect of repeated applications of buprofezin and acephate on soil cellulases, amylase, and invertase

The impact of repeated applications of buprofezin and acephate, at concentrations ranging from 0.25 to 1.0 kg ha(-1), on activities of cellulases, amylase, and invertase in unamended and nitrogen, phosphorous, and potassium (NPK) fertilizer-amended soil planted with cotton was studied. The nontarget effect of selected insecticides, when applied once, twice, or thrice on soil enzyme activities, was dose-dependent; the activities decreased with increasing concentrations of insecticides. However, there was a rapid decline in activities of enzymes after three repeated applications of insecticides in unamended or NPK-amended soil. Our data clearly suggest that insecticides must be applied judiciously in pest management in order to protect the enzymes largely implicated in soil fertility.

Impact of coleopteran-active Bt corn on non-target nematode communities in soil and decomposing corn roots

Genetically engineered corn expressing crystalline proteins for insect control and encoded by genes derived from soil bacterium Bacillus thuringiensis (Bt) are widely adopted in the United States. Among the seven different events of Bt corn available commercially, YieldGard® Rootworm (event MON863) expresses a variant of the cry3Bb1 protein in the root tissue to control corn rootworm larvae. Nematodes reside in the rhizosphere and are potentially exposed to Cry3Bb1 toxins exudated from roots of Bt corn. We test the hypothesis that coleopteran-active Bt corn does not affect non-target soil nematodes. Experimental treatments were: 1) a Bt hybrid, 2) a non-Bt isoline treated with a conventional soil insecticide, and 3) a non-Bt isoline without insecticide. Nematodes were extracted from soil samples collected prior to planting (May), at peak anthesis (August), and after harvest (October) in 2003 and 2004, enumerated and identified to genus. A total of 73 nematode genera were encountered in soil and litter combined. During the growing season, maturity index values and relative abundance of fungivorous nematodes were greater in the Bt hybrid than the non-Bt isoline with or without insecticide. Nematode trophic diversity values were greater in the Bt hybrid than non-Bt isoline with insecticide and this effect continued through the following spring. Abundance of nematode predators increased two weeks after insecticide was applied to non-Bt isoline, but decreased without insecticides on either Bt or the non-Bt isoline. In decaying roots of corn treatments, maturity index values and the relative abundance of nematode predators was greater in the Bt hybrid than non-Bt isoline with insecticide. Effects at the overall community structure and nematode genera varied more by seasonal phenology than corn treatment. The isoline with insecticide had more non-target effects on nematode communities than the Bt hybrid. This treatment increased the relative abundance of predaceous nematodes temporarily but eventually reduced successional maturity by harvest time, which continued to decline during the winter in both soil and decaying corn roots.

Environmental fate of soil applied neonicotinoid insecticides in an irrigated potato agroecosystem.

Since 1995, neonicotinoid insecticides have been a critical component of arthropod management in potato, Solanum tuberosum L. Recent detections of neonicotinoids in groundwater have generated questions about the sources of these contaminants and the relative contribution from commodities in U.S. agriculture. Delivery of neonicotinoids to crops typically occurs as a seed or in-furrow treatment to manage early season insect herbivores. Applied in this way, these insecticides become systemically mobile in the plant and provide control of key pest species. An outcome of this project links these soil insecticide application strategies in crop plants with neonicotinoid contamination of water leaching from the application zone. In 2011 and 2012, our objectives were to document the temporal patterns of neonicotinoid leachate below the planting furrow following common insecticide delivery methods in potato. Leaching loss of thiamethoxam from potato was measured using pan lysimeters from three at-plant treatments and one foliar application treatment. Insecticide concentration in leachate was assessed for six consecutive months using liquid chromatography-tandem mass spectrometry. Findings from this study suggest leaching of neonicotinoids from potato may be greater following crop harvest in comparison to other times during the growing season. Furthermore, this study documented recycling of neonicotinoid insecticides from contaminated groundwater back onto the crop via high capacity irrigation wells. These results document interactions between cultivated potato, different neonicotinoid delivery methods, and the potential for subsurface water contamination via leaching.

Evaluating multiple approaches for managing western corn rootworm larvae with seed blends

AbstractCorn rootworm, Diabrotica spp., larvae represent a significant and widespread economic threat to corn, Zea mays (L.), production in the United States, where control costs and yield losses associated with these insect pests exceed $1 billion annually. Preventing root injury and associated yield loss caused by corn rootworm larvae may be accomplished by the independent use of planting time soil insecticides or transgenic Bt hybrids. However, recent reports of both confirmed and suspected Bt resistance in corn rootworm populations throughout the Corn Belt have led to significant interest in the use of these two management tactics simultaneously. Although this approach has been investigated to some extent previously, information is lacking on how the use of a soil insecticide in tandem with a Bt seed blend—Bt and refuge (non‐Bt) seed mixed into a single product—may affect root protection and yield. We describe an experiment including six trial sites conducted over a three‐year period where various seed blends and soil insecticide/seed blend combinations were evaluated. The predominant species contributing to root injury across all sites was the western corn rootworm (Diabrotica virgifera virgifera LeConte). A weighted technique is presented for evaluating root injury for seed blends that offers a reliable estimate of product performance. The addition of a soil insecticide to the seed blend treatments never resulted in significantly improved root protection and failed to provide a consistent yield benefit. Our results suggest that a soil insecticide/seed blend combination approach is not warranted. Additionally, a subanalysis performed on individual refuge and nearby Bt root systems for seed blend treatments provides insight into the spatial characteristics of root injury in seed blend scenarios.

IPM thresholds for Agriotes wireworm species in maize in Southern Europe.

Currently, integrated pest management (IPM) of wireworms is not widespread in Europe. Therefore, to estimate the densities of three major wireworm species in southern Europe (Agriotes brevis Candeze, A. sordidus Illiger, and A. ustulatus Schäller), bait traps were deployed pre-seeding in maize fields in north-eastern Italy between 1993 and 2011. Research discovered that there was a significant correlation between all three wireworm species caught in the bait traps and damage to maize plants, but damage symptoms varied. Wherever A. ustulatus was the main species caught, there was no significant damage to maize plants, but seeds were damaged. Most of the symptoms caused by A. brevis and A. sordidus were to the central leaf/leaves, which wilted because of feeding on the collar. A. brevis was the most harmful species; when more than one A. brevis wireworm was caught per trap, plant damage sometimes resulted in reduced yield. Five A. ustulatus larvae per trap caused the same damage to maize as one A. brevis. A. sordidus came second (threshold two larvae/trap). These thresholds are reliable for: (1) bare soil in which there are no alternative food sources; (2) average soil temperature 10 cm beneath the surface of above 8 °C for 10 days; (3) soil humidity near to field water capacity, but days of flooding have not been considered. The implementation of the practical method described herein may lead to effective IPM of wireworms in maize and to a significant reduction in the number of fields treated with soil insecticides.

Efficacy assessment of soil insecticides and seed treatments for the control of western corn rootworm larvae

Wirksamkeit von Bodeninsektiziden und Saatgutbehandlungen zur Bekampfung des Westlichen Maiswurzelbohrers