Wireworms, the larvae of click beetles (Coleoptera: Elateridae), have had a centuries-long role as major soil insect pests worldwide. With insecticidal control options dwindling, research on click ...beetle biology and ecology is of increasing importance in the development of new control tactics. Methodological improvements have deepened our understanding of how larvae and adults spatially and temporarily utilize agricultural habitats and interact with their environment. This progress, however, rests with a few pest species, and efforts to obtain comparable knowledge on other economically important elaterids are crucial. There are still considerable gaps in our understanding of female and larval ecology; movement of elaterids within landscapes; and the impact of natural enemies, cultivation practices, and environmental change on elaterid population dynamics. This knowledge will allow generation of multifaceted control strategies, including cultural, physical, and chemical measures, tailored toward species complexes and crops across a range of appropriate spatial scales.
Click beetle larvae (Elateridae), commonly known as wireworms are burrowing insects found commonly in many habitats. Some species can be a significant agricultural pest, reducing crop yields and ...quality of harvestable parts such as Agriotes spp. which are common in Europe and parts of North America. X-ray Computed Tomography (CT) has previously been demonstrated as a viable method for investigating wireworm interaction in soils with living plants. In this study, we used X-ray CT to visualise and quantify wireworms, their burrow networks and the root architecture of maize, barley and bare soil over a 96-hour time period order to monitor the typically cryptic behaviour of these organisms. Components within these CT scans were subsequently segmented and volume, size and complexity data collected. Wireworm burrow volume was significantly greater in bare soil compared to maize and barley planted columns, suggesting a behavioural difference in the wireworms elicited by the presence of root structures. Burrow volume was significantly greater at 96 h compared to 24 h. Burrow networks with maize were significantly shallower and less complex in structure compared to their barley and bare soil counterparts. Burrow network depth did not vary significantly over time. The presence and species of crop roots caused differences in wireworm behaviour, leading to variation in both the volume and structure of the burrow networks. Further work is needed to determine the specific type of behaviour of wireworms (e.g. random searching behaviour) and the mechanisms that influence it (e.g. CO2 and Volatile organic compound gradients).
•Wireworm burrow volume was greater in bare soil compared to maize and barley.•Burrow volume significantly increased over time.•Burrows in maize columns were shallower and less complex than barley and bare soil.•Burrow network depth did not vary significantly over time.
•S. carpocapsae and S. bicornotum showed the best efficacy in laboratory studies.•The highest mortality rate (%75) was obtained by S. bicornotum at 1000 IJs.•Field performance of EPNs were quite ...similar to those in laboratory studies.•The maximum mortality rate (55%) was achieved by H. indica in field studies.
In the present study, the virulence of some local entomopathogenic nematode (EPN) isolates (S. carpocapsae E-76, S. feltiae KCS-4-S, H. bacteriophora FLH-4-H, S. bicornotum MGZ-4-S and H. indica 216-H) recovered from the surveys conducted in Adana, Kayseri, and Kahramanmaras provinces on the 5th or 6th larval instar of Agriotes spp. (Coleoptera: Elateridae) were investigated under laboratory and field conditions. Laboratory studies were carried out in 100 ml plastic containers including autoclaved soil at different temperatures (25 and 30 °C) and concentrations (25, 50 and 100 IJs/cm2). The infective juveniles of S. carpocapsae E-76 and H. indica 216-H isolates were applied at the concentration of 1x106 IJs/m2 with a back pack sprayer with a 0.5 mm nozzle in the field trial. In the laboratory studies, the mortality rates generally increased with the increasing temperatures, concentrations and exposure times. The highest mortality rate (65%) was achieved by two isolates (S. bicornotum MGZ-4-S and S. carpocapsae E-76) at the highest concentration (100 IJs/cm2) 21 days after inoculation at 25 °C. The most efficient isolate at 30 °C was S. bicornotum MGZ-4-S and caused 75% mortality 21 days after treatment. In the field study, S. carpocapsae E-76 performed better than H. indica 216-H isolate and caused 55% mortality on the larval instar of wireworms. The current study suggests that some of the EPN isolates tested have good potential for the biological control of wireworm. However, further studies are needed to enhance the effectiveness of EPN isolates.
No-till agriculture, combined with the practices of continuous soil cover by retaining crop residues and of crop rotation, including cover crops, represents a relatively widely adopted management ...system that aims to increase soil organic matter content as well as long-term sustainability. However, its impacts on wireworm populations in the soil and risk of damage to crops are uncertain, and current recommendations may unjustifiably limit grower options. Consequently, this study examined the effects of no-tillage soil management on the population dynamics of Agriotes wireworm pests (Coleoptera: Elateridae) by bait sampling, maize plant damage assessments, and pheromone trapping (adults) within three farms in northeastern Italy, from 2011 through 2016, as compared to conventional tillage. The four-year cropping rotation consisted of winter wheat (Triticum aestivum), oilseed rape (Brassica napus), maize (Zea mays), and soybean (Glycine max) under both tillage treatments. The nature and intensity of damage caused by wireworms to maize early stages was assessed each year. Wireworms and beetles comprised of four different species (A. brevis, A. sordidus, A. ustulatus, and A. litigiosus) were captured, with the numerically dominant species (A. sordidus) accounting for over 90% of all captures. All species responded similarly to tillage practices. No effects of tillage operations were associated with beetle captures (P > 0.28) and larval densities (P > 0.45). No differences were observed between tillage treatments in wireworm feeding maize damage scores (P > 0.17; means for no-till and conventional tillage maize were 3.82 and 4.14 percent damage, respectively). These results suggest that switching from a conventional tillage system to a no-till maize production may not cause an increase of wireworm damage to maize, even though no-till conditions have been historically associated with increased wireworm damage risk. Possible causes of these results are discussed.
•No effects of tillage were associated with wireworm densities and beetle captures.•Wireworm feeding damage scores did not differ between treatments.•Switching from conventional to no tillage did not increase wireworm maize damage risk.
Wireworms, the larvae of click beetles (Coleoptera: Elateridae), can cause substantial losses in marketable yield of potatoes, yet control options are limited. The entomopathogenic fungus Metarhizium ...brunneum (Ascomycota; Hypocreales) isolate ART2825 is highly virulent against two of the most detrimental wireworm species, Agriotes obscurus L. and A. lineatus L., but field application of this isolate during potato cultivation has never succeeded. In this study, we integrated the fungus into the agricultural crop rotation prior to potato cultivation, with the aim of better adapting the application strategy to the fungus’ ecological and environmental requirements. Application preceded sowing of cover crops in late summer. We hypothesized that higher temperatures and undisturbed development for several months would support the establishment of the entomopathogen and enhance biocontrol efficiency in the following season. In two subsequent seasons, we quantified (1) fungal establishment in the soil, (2) efficiency of treated soils against wireworms in vitro, and (3) levels of wireworm damage in field potatoes. Spore concentration was enhanced in treated plots and we recovered the released Metarhizium isolate from all mycosed, field-collected wireworms. Treated soils increased wireworm mortality in the laboratory, but a statistically significant reduction of potato damage was only achieved in two out of ten field trials. The application strategy shows potential for fungal enhancement and opens new avenues for biological wireworm control.
•Application enhanced fungus in soil over entire cover crop growing period.•Treated soils increased wireworm mortality in vitro.•Released Metarhizium isolate was recovered from field-collected wireworms.•Reduced damage in potato but effect needs to be improved for practical use.•Study highlights necessity of further wireworm research.
•Soil-incorporated fresh meadow turf reduces wireworm attacks on maize.•Soil-incorporated fresh meadow competes with crop early stages as a wireworm food.•The timing of meadow ploughing is an IPM ...alternative to insecticides.
The management of soil-pests still largely relies on conventional chemical insecticides despite the provisions of Integrated Pest Management (IPM). Long-term research was carried out in north-eastern Italy to assess the potential of meadow ploughing just before maize sowing to prevent wireworm damage. The research was based on the observation that no serious wireworm damage occurred in 20 years when meadows were ploughed just before maize sowing. The research hypothesis was that soil-incorporated fresh meadow turf would be a more attractive wireworm food source than seeds, emerging seedlings and young plants. Meadow plots with a sufficiently homogeneous wireworm density were alternately ploughed the previous autumn and a few days before maize sowing. The same conditions were simulated in pots into which known numbers of cage-reared wireworms had been introduced. Results showed very consistently that plant damage in plots ploughed just before maize sowing was much lower than the damage in plots ploughed in autumn-winter, and always below the economic risk threshold (15% of damaged plants). In controlled conditions, plant damage in pots with soil-incorporated fresh meadow turf was significantly lower than that observed in pots without. In both field and controlled conditions, this major effect on plant protection is likely to be caused by the incorporation of meadow turf living plant parts into the soil. Therefore, the ploughing timing of meadows in rotation may be a viable alternative to chemical insecticides when rotation includes meadow.
The management of soil-pests relies largely on conventional insecticides. Within the framework of the EU's PURE project, data were collected to assess the risk of soil-pest damage to grain maize in ...Europe in order to implement Integrated Pest Management (IPM) of soil-pests in a more practical and sustainable manner, thus optimizing the use of soil insecticides (in-furrow or as seed-dressing) at sowing. Plant density and soil-pest damage to maize seeds and/or plants during the growing season were determined in fields with no or some risk factors. Risk assessment on a sample of sixteen experimental sites (a total of 109.95 ha of maize) located in five European countries (Germany, Hungary, Italy, Slovenia and the Netherlands) from 2011 to 2014 showed a low risk of soil-pest damage to maize. In all fields, wireworms (Agriotes spp. larvae) caused 99.5%–100% of the plant damage, meaning that damage by other soil-pests was negligible. The fields studied were divided into two groups: those with no risk and those with risk factors. According to previous research, the risk factors were Agriotes brevis Candeze and Agriotes sordidus Illiger as prevalent damaging species, soil Organic Matter content over 5%, rotation including meadows and/or double crops, as well as surrounding landscape being mainly meadows, uncultivated grass and double crops, cover crops, and poor drainage. In the fields with no risk factors, wireworm plant damage (mainly holes in the collar causing central leaf wilting) never exceeded 15%, a threshold value for potential yield reduction. Furthermore, plant damage was much lower or even negligible in the vast majority of the fields (i.e. over 90% of fields had less than 5% wireworm damage to maize plants). Risk factors, such as rotation including meadows and/or double crops, led to the percentage of cultivated land with significant wireworm plant damage being even lower than predicted (8.7% instead of 14.7%) and almost 50% of that predicted for the whole sample (2.7% instead of 4.9%). In the few cases where plant damage was higher than 15%, yield was not affected when untreated strips were compared with strips treated with soil insecticides. In all trials, the soil insecticide Tefluthrin did not significantly increase the density of healthy maize plants or grain yield. In more than 99% of cases, no economic damage to maize by soil-pests was recorded. These results demonstrate that the occurrence of risk factors may increase the risk of wireworm damage to maize crops, while the probability of damage to a field with no risk factors is always very low (less than 1%). This highlights the importance of integrating risk assessment of soil-pest damage to maize into IPM strategies, which would include: i) an “area-wide” risk assessment evaluating the possible presence of risk factors, including click beetle population monitoring with pheromone traps, and ii) “complementary field monitoring” with bait traps where risk assessment has identified the presence of risk factors. In fields with no risk factors, treating maize with soil insecticides was found to be pointless. Therefore, IPM strategies in maize that include risk assessment of soil-pest damage may lead to a significant reduction in soil insecticides use and, consequently, to a reduction in environmental impact.
•In Europe there is a high potential for implementing IPM of soil-pests.•On a land sample (110 ha) no economic damage to maize by soil-pests was found.•In low risk conditions, soil insecticide treatment is pointless.•In all trials the soil insecticide Tefluthrin didn't increase stand and yield.
A faunistic study of the family Elateridae was carried out in Backa, the
north-western district of Vojvodina Province in Serbia, focusing on their
preferred habitats and soil types. The survey ...included four locations with a
total of 1059 ha, in which 35 species, belonging to 15 genera of Elateridae,
were observed. The frequency of larval and adult forms was 58.94% and 67.40%,
respectively, proving that wireworms are regular residents of the area.
Regarding habitat preferences, it was shown that a majority of Elateridae
species prefer open biotopes and wheat crop, while marsh soil, chernozem and
alluvium were the preferred soil types of wireworms.
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