Wireworm Infestations Research Articles

Navigational Signals for Insect and Slug Parasitic Nematodes: The Role of Ascorbate-Glutathione System and Volatiles Released by Insect-Damaged Sweet Pepper Roots.

This study of underground multitrophic communication, involving plant roots, insects, and parasitic nematodes, is an emerging field with significant implications for understanding plant-insect-nematode interactions. Our research investigated the impact of wireworm (Agriotes lineatus L. [Coleoptera: Elateridae]) infestations on the ascorbate-glutathione system in sweet pepper (Capsicum annuum L.) plants in order to study the potential role in root-exudate-mediated nematode chemotaxis. We observed that an A. lineatus infestation led to a decrease in leaf ascorbate levels and an increase in root ascorbate, with corresponding increases in the glutathione content in both roots and leaves. Additionally, a pigment analysis revealed increased carotenoid and chlorophyll levels and a shift towards a de-epoxidized state in the xanthophyll cycle. These changes suggest an individual and integrated regulatory function of photosynthetic pigments accompanied with redox modifications of the ascorbate-glutathione system that enhance plant defense. We also noted changes in the root volatile organic compound (VOC). Limonene, methyl salicylate, and benzyl salicylate decreased, whereas hexanal, neoisopulegol, nonanal, phenylethyl alcohol, m-di-tert-butylbenzene, and trans-β-ionone increased in the roots of attacked plants compared to the control group. Most notably, the VOC hexanal and amino acid exudate cysteine were tested for the chemotaxis assay. Nematode responses to chemoattractants were found to be species-specific, influenced by environmental conditions such as temperature. This study highlights the complexity of nematode chemotaxis and suggests that VOC-based biological control strategies must consider nematode foraging strategies and environmental factors. Future research should further explore these dynamics to optimize nematode management in agricultural systems.

Evaluation of a neonicotinoid alternative to phorate for the management of soil insects in Florida sugarcane

Wireworms (Coleoptera: Elateridae) are the main soil insect pests of sugarcane (Saccharum spp. hybrids) in Florida. Melanotus communis (Gyllenhal) is the most abundant wireworm in Florida sugarcane fields, reducing stalk populations by feeding on buds of sugarcane seed pieces and on young sugarcane plants. At-planting use of the organophosphate insecticide phorate is the main wireworm management tactic in Florida; however, phorate is a hazardous and relatively expensive insecticide. Thiamethoxam is a neonicotinoid insecticide that has potential to become registered for use on sugarcane in the United States. Previous studies suggested that thiamethoxam decreases wireworm injury to sugarcane seed pieces but does not increase wireworm mortality. The present study conducted between 2018 and 2022 aimed to comprehensively evaluate thiamethoxam for wireworm control under laboratory, outdoor, and field conditions. In two laboratory bioassays, M. communis mortality associated with thiamethoxam (3–20%) was not different than mortality for the non-treated check (0–7%), whereas mortality associated with phorate attained 93–100%. In three large container experiments conducted outdoors with controlled M. communis infestations, thiamethoxam and phorate generally protected young sugarcane plant populations at comparable levels. Insecticide efficacy was mainly associated with the protection of seed-piece buds. However, the number of recovered live wireworms was 2.7–8.0 times greater in thiamethoxam treatments than in phorate treatments. In three field experiments, young sugarcane plant populations in thiamethoxam- and phorate-treated plots were not different than those in non-treated plots. However, the at-planting application of thiamethoxam decreased the number of sugarcane thrips, Fulmekiola serrata (Kobus), by 67–89% in two experiments with thrips infestations 12 weeks after planting. Although the evaluation of insecticide efficacy under natural wireworm infestations was inconclusive, this study confirmed that thiamethoxam should be considered as an alternative to phorate if registered. However, the long-term effects of low wireworm mortality associated with thiamethoxam use should be studied.

Early Detection of Wireworm (Coleoptera: Elateridae) Infestation and Drought Stress in Maize Using Hyperspectral Imaging

The objective of our research was to test hyperspectral imaging as a method for early detection and discrimination of biotic and abiotic stress in maize. We investigated the individual and combined effects of wireworm feeding and drought stress on leaf spectral responses and on various morphological and physiological traits of maize plants, selecting two hybrids with different tolerance to drought. Physiological parameters were determined at three time points (14, 21 and 28 days after adding wireworms and changing watering regime), along with hyperspectral imaging. Most of the differences in physiological characteristics between treatments were detected on day 21, when drought was the main cause of the negative physiological outcome, while the presence of wireworms only caused lower relative chlorophyll content, resulting in lower combined stress damage in some treatments. The morphological data showed greater wireworm damage to hybrid ZP341 and a greater negative effect of combined stress on hybrid FuturiXX. Hyperspectral imaging detected pest infestation and drought stress before they were detected by classical methods, with the highest overall accuracy on day 14 (84.7%) and the lowest on day 28 (67%). It can therefore be used as a method for early detection of wireworm infestation and/or drought in maize.

A decision support system based on Bayesian modelling for pest management: Application to wireworm risk assessment in maize fields

Protecting crops against pests is a major issue in the current agricultural production system. In particular, assessing the risk to crops can promote integrated pest management (IPM) strategies that encourage natural control mechanisms and advocate the use of pesticides as a last resort. In this study, we focused on wireworms, major soil-dwelling insect pests inflicting severe economic damage on various crops (including maize, potatoes and cereals) across Europe and North America. We have developed an original hierarchical Bayesian model that explicitly accounts for biological knowledge and uncertainty in field observations, rather than relying solely on statistical correlations, to predict the level of wireworm infestation. The model was calibrated and validated using a substantial dataset originating from an agro-environmental survey carried out over three consecutive years (2012–2014) in France, which provides the wireworm abundance in 419 maize fields, together with information on the landscape context, field history, weather conditions, soil characteristics and farming practices associated to each field. Model outcomes show good agreement with current knowledge from literature and field expertise in terms of the effects of variables on wireworm abundance, and provide fairly good predictive capacity. Subsequently, the model was encapsulated as a software (R shiny application) to predict the risk of wireworm infestation in any field of interest, and can be used by farmers or agricultural advisors as a decision support system for the implementation of IPM strategies. The conceptual framework that we implemented can be adapted to a wide range of similar situations involving other crops and pests.

Three years of surveillance associates agro-environmental factors with wireworm infestations in Manitoba, Canada.

Wireworms, the soil-dwelling larvae of click beetles, are a major threat to global agricultural production. This is largely due to their generalist polyphagous feeding capabilities, extended and cryptic life cycles, and limited management options available. Although wireworms are well-documented as economically important pests in the Canadian Prairies, including Manitoba, there are gaps in knowledge on species distributions, subterranean behaviour and life cycles, feeding ecology and damage capacity, and economic thresholds for crop yield loss. We carried out 3 years (2018-2020) of intensive surveillance of larval populations across Manitoba. A total of 31 fields (24 in ≥ 2 consecutive years) were surveyed in early spring using standardized bait trapping approaches. Wireworms were present in 94% of surveyed sites, but the catch within fields varied year to year. While Hypnoidus bicolor predominated (94% of larvae), several other pest species were identified. We then explored the relationships between wireworm trap numbers and agro-environmental factors. The larval catch tended to decrease under conditions of low soil temperatures and increased clay content, coupled with high soil moisture and precipitation during the trapping period. Treatment and cultural methods appeared less influential; however, wheat production in either of the previous two growing seasons was associated with increased wireworm catch. Our models failed to predict a relationship between wireworm catch and crop yields, although infestations were rare in our region. Our findings better infer the risks posed by wireworms to crop production in the Canadian Prairies, and the agro-environmental factors that represent the greatest contributors to these risks. This information should be incorporated into future integrated pest management (IPM) strategies for wireworms. © 2021 Her Majesty the Queen in Right of Canada Pest Management Science © 2021 Society of Chemical Industry Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Linking variety-dependent root volatile organic compounds in maize with differential infestation by wireworms

Like most phytophagous insect pests, wireworms are suspected to use plant volatile organic compounds (VOCs) to locate appropriate host plants. Preliminary field observations at our study site showed strong differences in the infestation level of four varieties of maize by wireworms. We raised and tested the hypothesis that these maize varieties have differential susceptibility/attraction to wireworms because they emit different VOCs from their roots. We collected, separated, identified and quantified VOCs from the roots of two maize varieties having experienced contrasted levels of wireworm infestation in the field. We showed that the less susceptible variety released a more diverse blend of VOCs, including large amounts of hexanal, heptanal and 2,3-octenanedione. The higher diversity and concentration of VOCs could play a role on the pest repulsion, explaining the difference in susceptibility of variety with respect to the other one. Laboratory dual-choice bioassays showed that wireworms were strongly attracted to COV released by maize roots. However, when wireworms were offered both maize varieties, no preference was detected, contrasting with the field results. Therefore, VOCs may not be the only cues influencing host selection by wireworms.

Sugar beet wireworm Limonius californicus damage to wheat and barley: evaluations of plant damage with respect to soil media, seeding depth, and diatomaceous earth application

Wireworms, the larval stage of click beetles (Coleoptera: Elateridae), continue to be one of the major concerns of cereal producers, primarily due to the lack of effective pesticides and species-specific management options. To have a better understanding of species-specific interactions of one of the most damaging wireworms in the Pacific Northwest and intermountain regions of the USA, a greenhouse study was set to evaluate the damage from the sugar beet wireworm Limonius californicus to wheat and barley planted at different depths and in soil media with varying levels of organic content and texture. Overall, the evaluated wheat appeared to be more susceptible than the barley, showing greater reductions in emergence success and foliar biomass. The greatest loss of foliar biomass was observed in peatmoss-dominated medium, as indicated by a significant host plant-by-soil media interaction. Percentage of plants fed upon by L. californicus was significantly higher in the sand-dominated medium than peatmoss-dominated and 1:1 mix media. Moreover, manipulation of soil media by the addition of diatomaceous earth showed no consistent effect in protecting the planted wheat. Our findings indicated that in addition to quantifying wireworm species-specific interactions, host plant interactions with the environment in the presence of wireworm infestation should also be further studied. These relationships could influence the outcome of integrated management approaches and future risk assessment models and recovery plans.

Correlations between wireworm damages in potato fields and landscape structure at different scales

Wireworms, the larvae of click beetles are world-wide pests of arable and vegetable crops. Many studies have shown that arthropods are influenced by landscape context. Therefore, for successful wireworm risk assessment, it is important to gain more information on relationships between landscape structure and wireworm infestation level. The aim of this study was to investigate if different landscape variables are related to wireworm infestation, represented by the proportion of wireworm damaged potato tubers. Based on aerial photographs and field surveys landscape variables, such as landscape composition, landscape complexity and ecological variables were characterised around 14 randomly selected potato field plots alongside the gradient from the lower warm-dry “Weinviertel” (region 1) to the cool-humid “Waldviertel” (region 2) in the North-East of Austria at three scales (1, 9 and 25 ha). Relationships between landscape variables and wireworm damage ratings were described by Spearman correlations coefficients. Our results showed that wireworm damage was higher in region 2 than in region 1 and tended to be higher in soils with higher sand content. Among the tested landscape variables only landscape composition, especially grassy field margins were significantly positively correlated with wireworm damage at the 25 ha scale. In areas with high proportion of such grassy habitats, farmers should pay more attention to field characteristics, such as sand content in soil, and management, like crop rotation. Further investigations on appropriate management regimes for grassy landscape elements suppressing wireworm populations but ensuring the maintenance of natural pest control should be conducted.

An investigation inot the use of multiple site characteristics to predict the presence and infestation level of wireworms (Agriotes sup., Coleoptera: Elateridae) in individual grass fields

SummarySixty‐two grass fields were sampled in England and Wales over a three year period to assess the level of wireworm population present. Data on site‐specific variables including soil physical characteristics, grass duration, grass genera diversity and other abiotic factors such as field aspect, altitude, and meteorological parameters were abiotic factors such as field aspect, altitude, and meteorological parameters were collected at each site. Only grass duration and soil bulk density showed any association with wireworm infestation stauts when considered as single variates. Data from a sub‐set of 41 fields were used to develop a series of multi‐variate discriminant rules to predit wireworm presence/absece in individual fields. These were vaildated using data from the remaining 21 fields. In general, the rules tended to over‐estimate the number of wireworm‐infested fields by misclassifying uninfested fields as infestes. Multivariate models to predict wireworm populaiton levels in infested fields were also developed using multiple and generalised linear regression. The predictive accuracy of these was poor. Neither the population prediciton models nor the presence/absence rulses accounted fully for the large inte‐field variation in wireworm infestation status.

Population dynamics of false wireworms (Gonocephalum macleayi, Pterohelaeus alternatus, P. darlingensis) and development of an integrated pest management program in central Queensland field crops: a review

False wireworms (particularly Pterohelaeus alternatus and Gonocephalum macleayi) are major pests of seedling field crops in central Queensland. Population densities are spatially and temporally dynamic, with high densities (>2/m2) of large larvae and adults generally not persisting at a location for more than 1 year. Adult movement in summer in response to changes in habitat suitability is suggested as the cause of population changes. Natural enemies, particularly entomopathogenic fungi, may also have a role in suppressing high population densities. One-half to three-quarters of fields that have grown summer crops including sorghum, sunflower, soybeans, and mungbeans in the preceding season are infested at densities that could cause economic losses in subsequent crops sown in wide rows with a low seed-sowing rate. Winter-grown wheat results in a significantly lower infestation rate (one-quarter of the fields sampled), but winter chickpea is a suitable crop for development of false wireworm infestations. Cultivation per se does not reduce numbers of false wireworms, but stubble removal may depress densities. False wireworms feed on stubble, and crop damage may be increased in low-stubble fields (following long fallows for example) despite low false wireworm numbers, due to lack of alternative food. The dynamic nature of false wireworm population size makes prediction of pest levels difficult. The presence of false wireworms should be assessed in each fallow field before planting. Management strategies based on preplanting sampling, economic injury levels, stubble management, crop rotation, and insecticide control are discussed.

Wireworm (Coleoptera: Elateridae) Sampling for Semiarid Cropping Systems

Experiments conducted from 1977 to 1979 showed that baited traps (soaked or un soaked grain sorghum seed covered with a layer of charcoal dust and a piece (1 m2)of 6-mil clear polyethylene) were more effective for detecting wireworm, Conoderus sp., infestations than uncovered traps. This type of trap attracted wireworm larvae earlier and weekly catches were usually higher than in uncovered traps. Irrigating fields before planting improved trap performance by providing soil moisture levels necessary for bait seed germination and, possibly, by drawing wireworm larvae closer to the soil surface. In semiarid regions, wireworm infestations can be detected before planting by incorporating traps into a sound pest management program.

Mechanical Wireworm Population Sampler

ABSTRACT A mechanical wireworm population sampler was de-signed, constructed and tested for field sampling of wireworm infestations. Depending on soil conditions, this machine can separate at least 70 percent of the par-ticles in the 1 to 4 mm size range. Working details, sampling techniques and field results are discussed.

Chemical Control of Wireworms on Potatoes12

In 2 of 3 tests conducted to evaluate chemicals for control of the Pacific Coast wireworm, Limonius canus LeConte, and the Great Basin wireworm, Ctenicera pruinina (Horn), broadcast applications resulted in lower percentages of injured and culled tubers than did sidedress applications. In the 3rd test, there were no differences between broadcast, furrow, and at plant sidedress applications. Individual compounds differed in effectiveness depending on method of application in all 3 tests. Compounds that were very effective included N-2596 (S-(p-chlorophenyl)O-ethyl ethylphosphonodithioate), CGA 12223 (0-[5-chloro-1-(1-methylethyl)-lH-1,2,4-triazol-3-yl] O,O-diethyl phosphorothioate), and ethoprop. All 3 were as effective as fonofos (used as a standard) in reducing injury to tubers. Wireworm infestations (presence of wireworms or feeding on seed pieces and tubers) increased from time of planting until 16 wk; however, the highest number of wireworms per hill was found at 6 wk, but decreased thereafter. No difference in tuber injury was noted between 15–16 wk after planting and at harvest (20–21 wk).

Insecticides Tested for Wireworm Control on Cigar-Wrapper Tobacco1

Broadcast applications of 17 insecticidal compounds in various formulations were evaluated far control of the southern potato wireworm, Conoderus falli Lane, and the tobacco wireworm, Conoderus vespertinus (F.), on cigarwrapper tobacco. Efficiency of some treatments varied with the density of wireworm infestations and distribution of insecticide in the soil. Ethylene dibromide as recommended for nematode control did not give adequate control of a heavy wireworm infestation. Compounds which gave good results were Bayer 25141 [ O, O -diethyl O-p- (methylsulfinyl) phenyl phasphorothioate], diazinon, G5-13005 [ O, O -dimethyl phosphorodithioate S -ester with 4-(mercaptomethyl)-2-methoxy-∆2-1,3,4-thiadiazolin-5-one], Kepone® (decachlorooctahydro-1,3,4-metheno-2H-cydobuta-[cd]pentalen-2-one), N-2790 ( O -ethyl- S -phenyl-ethylphosphonodithioate), Niagara 9203 [ O, O -dimethyl phosphorothioate S -ester with 3-(mercaptomethyl)-2-benzoxazolinone], and parathion. None of the compounds were phytotoxic except Niagara 10242 (2,3-dihvdro-2,2-dimethyl-7-benzo-furanyl methylcarbamate), which caused considerable chlorosis, deformity, and necrosis in the tobacco foliage.

CONTROL OF THE EASTERN FIELD WIREWORM, LIMONIUS AGONUS (SAY), IN EARLY POTATOES IN ONTARIO BY APPLICATION OF INSECTICIDES TO THE SOIL

When applied as water suspensions at 5.0 lb. per acre for control of a very heavy population of the eastern field wireworm, dieldrin2, heptachlor, and aldrin prevented re-infestation for at least 3 years after application, and chlordane for 2 years. Only dieldrin and heptachlor gave 95 per cent, or more, marketable potatoes in the year of application. BHC containing 12, 90, and 99 per cent gamma isomer at 0.75 lb. of the gamma isomer, parathion at 5.0 lb., and DDT at 10.0 lb. per acre gave inadequate protection, or were effective for only 1 to 2 years. Against a moderate infestation of wireworms, all treatments except BHC containing 90 per cent gamma isomer and DDT protected the potatoes satisfactorily in the year of application. BHC tainted tubers up to 2 years after the insecticide was applied. Adequate protection was generally provided when the wireworm infestation averaged no more than 1 larva per bait. The insecticides were applied once in plots in one of three adjoining ranges in 1951, 1952, and 1953, respectively. Potatoes were grown in the treated ranges until 1954. The treatments were evaluated on the basis of tuber quality, and numbers of wireworms taken in whole-wheat flour baits.

A PRELIMINARY TEST OF DDT AND BENZENE HEXACHLORIDE FOR THE CONTROL OF WIREWORMS IN A SASKATCHEWAN POTATO FIELD

An inexpensive, simple, chemical control of wireworms in land to be used for vegetable production has long been sought in the Prairie Provinces. Existing methods of control (3, 4, 5, 6) are not wholly satisfactory for row crops. The cultural measures commonly advocated (6) will reduce wireworm infestations sufficiently that cereal crops can be grown without serious damage, but they are not usually sufficiently effective that potatoes or other row crops can be produced successfully. Crude naphthalene is the most satisfactory of the chemical methods recommended (3, 4, 5) but it is too costly for material, is difficult to handle and apply, and is effective only under certain conditions of soil, moisture and temperature. As a result, commercial potato production on the prairies has been restricted largely to districts and fields where wireworms are virtually absent.

Studies of Wireworm Populations

ABSTRACT Twenty stations were established in a grass field of 8 acres, and twenty-nine soil samples were examined from each station in the course of 213 years. Wireworms (Agriotes sputator) were distributed among the twenty stations in a non-random manner. In this field, the wireworm distribution was correlated to a highly significant degree with nine factors (loss on ignition, organic carbon, nitrogen, Lolium, Agrostis, Chilopoda, staphylinid larvae, ants and Nematocera) and to a significant degree with three factors (altitude, pH of the soil and Diplopoda). Among these factors, three (the organic content of the soil as measured by loss on ignition, the prevalence of the grass Lolium, and the numbers of staphylinid larvae) were found by analysis to be most significantly correlated with the wireworm distribution. Sixteen stations were set up in a grass plot of 14 acre, and twenty-one soil samples were examined from each station during a period of 3 years. The distribution of wireworms at these stations was markedly non-random throughout the sampling period, some stations being consistently three or four times as heavily infested as others only 5 yd, away. Within this plot the distribution of wireworms was correlated to a highly significant degree with altitude, depth of loam and amount of soil moisture at 3 and at 9 in. depth. It was significantly correlated with the lime content of the soil. Ranunculus was prevalent on an area of low wireworm infestation. Among the factors studied in this plot, the amount of soil moisture at 3 in. depth was most important. It was negatively correlated with the distribution of wireworms. Within the plot, stations having high wireworm populations were infested almost exclusively by Agriotes sputator; those having low wireworm populations were infested about equally by A. sputator and A. ‘obscurus-lineatus’. Four square-yard samples were examined, each in eighty-one quadrats 4 in. square. Within each square yard, the wireworms were not distributed at random and independently, but were markedly aggregated. Separation of the wireworms collected from these samples into three size groups showed that the non-random distribution in square-yard samples was largely due to the small larvae, which were strongly aggregated. The medium-sized larvae were less markedly aggregated. The distribution of the large larvae under grass was not significantly different from a random distribution. To understand the factors controlling wireworm distribution it will be necessary to consider the distribution of the different larval age-groups. Two suggestions are made towards an explanation of the geographical distribution of wireworms in England. Study of the spatial distribution of wireworms raises some of the major problems of ecology and, in particular, illustrates the interdependence of spatial distribution and seasonal succession.

Wireworm Control in Maine

The wheat wireworm, Agriotes mancus Say, is a serious pest to Maine crops. An upland species of the genus Melanotus is second in importance. Certain cultural practices and immune crops have been found to be effective in checking wireworm infestations. Meadows and oat fields seem to be favorite breeding grounds for the wheat wireworm. Clover, buckwheat, and peas are resistant to the attacks of these insects and potatoes are very susceptible. Fertilizer is useful in strengthening plants to withstand wireworm attacks. Drainage is helpful in controlling the wheat wireworm and fall plowing is but partially effective.

A Study of Field Practices as Related to Wireworm Infestations (Elateridae)1

Studies conducted at Manhattan, Kansas, from 1924 to 1929, inclusive, show that the percentage of corn plants injured by wireworms is influenced by the rate, date, and method of planting corn. Corn grown on land which had been cropped continuously to com for 19 years showed less wireworm injury than that grown in various rotations. The studies indicate further that the sequence in which crops are grown in rotations, as well as the tillage methods employed in the preparation of the seed-bed, influence the amount of wireworm injury that may be expected.

The Economic Wireworms of The Pacific Northwest (Elateridae)

This paper purposes to treat in a general way the damage caused by the three species of wireworms of principal economic importance in Washington, Oregon, and Idaho, namely, the inflated wireworm, Ludilts inflatus Say, the dry-land wireworm, Ludius noxius Hyslop, and the wet-land wireworm, Pheletes occidentalis Candeze. The paper brings out interesting ecological data which show each of these species inhabits a separate region under distinct environmental conditions, as regards rainfall and moisture content of the soil. A general life history is given for the dry-land wireworm, showing the total life cycle of this species to be four Dr more years. A brief summary is given of the damage caused by the wet-land wireworm under irrigated farming conditions together with some interesting facts about the habits of this species during recent years. The final purpose of the paper is to show that more comprehensive basic ecological studies of the many species of wireworms should be made, with much more time and care given to them than in the past. With a more thorough knowledge of the many ecological factors involved in the increase of wireworm infestations and damage, there should be found some satisfactory answer to the oft repeated question, “How can we get rid of wireworms?”