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.
Wireworms (Coleoptera: Elateridae) are economically significant pests of potatoes (Solanum tuberosum), damaging the marketable portion of the crop by feeding and tunneling into tubers. While ...conventional potato growers use the few registered synthetic insecticides to control wireworms, certified organic growers are left with less options due to the limited effectiveness of the available insecticides. Biologically derived pesticides provide an additional alternative for both systems. Certain gram-negative proteobacteria, such as Burkholderia spp., possess insecticidal compounds. However, very little is known about their efficacy on wireworms. From 2018 to 2021, we conducted experiments in Virginia to assess the efficacy of a Burkholderia spp.-based commercial pesticide, Majestene, as a wireworm control in potatoes. In a lab experiment, soil drench application of this insecticide at a rate of 66 g a.i. per 1 liter resulted in 30% wireworm mortality and significantly reduced wireworm feeding damage on potato tubers. In the field, in-furrow applications of Burkholderia spp. at a rate of 17.66 kg a.i. per ha significantly reduced wireworm damage to tubers in 2 of 7 field experiments conducted. By comparison, the commercial standard insecticide, bifenthrin, significantly reduced tuber damage in 3 of the 7 field experiments. Our study demonstrates the prospect for proteobacteria-derived insecticides for control of wireworms and potentially other soil-dwelling insects. In conclusion, findings present growers with another option to combat wireworm pressure, especially in organic systems.
Two new flightless click beetle species,
and
, are described and illustrated from Taiwan, China. Their habitus and diagnostic characters are illustrated. The two species most resemble
, which is ...endemic to Taiwan, by the strongly protruding pronotal anterior angles accompanied by pits and the shape of aedeagus. They can be all grouped as the
-species group. A key to the species of the
-species group and an updated checklist of Chinese
with supplementary notes on type localities are provided. The discovery of two new species highlights the potential species-richness of the flightless click-beetles on Taiwan Island.
Click beetles (Coleoptera: Elateridae) represent one of the largest groups of beetle insects. Some click beetles in larval form, known as wireworms, are destructive agricultural pests. Morphological ...identification of click beetles is generally difficult and requires taxonomic expertise. This study reports on the DNA barcoding of Japanese click beetles to enable their rapid and accurate identification. We collected and assembled 762 cytochrome oxidase subunit I barcode sequences from 275 species, which cover approximately 75% of the common species found on the Japanese main island, Honshu. This barcode library also contains 20 out of the 21 potential pest species recorded in Japan. Our analysis shows that most morphologically identified species form distinct phylogenetic clusters separated from each other by large molecular distances. This supports the general usefulness of the DNA barcoding approach for quick and reliable identification of Japanese elaterid species for environmental impact assessment, agricultural pest control, and biodiversity analysis. On the other hand, the taxonomic boundary in dozens of species did not agree with the boundary of barcode index numbers (a criterion for sequence-based species delimitation). These findings urge taxonomic reinvestigation of these mismatched taxa.
In the Pacific Northwest United States, cereal crops (barley, oats, wheat) are the foundation of most dryland crop rotations. Nearly 100% of cereal producers use neonicotinoid seed treatments to ...manage wireworms, regardless of crop and pest density. However, wireworms cause variable damage to different crops, and whether neonicotinoids boost yield and economic returns across crops remains largely unknown. In a field experiment conducted on one commercial farm over two years, we examined effects of imidacloprid seed treatments on wireworm density, yield, and economic returns for barley, oat, and wheat crops. Wheat plots with imidacloprid seed treatments produced greater yields and economic returns over costs than untreated plots, even though wireworm densities were largely unaffected by treatments. However, no differences in yield and economic returns were observed between treatments in barley or oats. Wireworm densities were markedly lower in oats compared to barley and wheat, indicating not all crops provided a permissive environment for wireworms. Our results support the hypothesis that growers may benefit from moving away from applying seed treatments in all cereal crops, but rather targeting management to specific crops, although research at more commercial farm sites remains needed to test the generality of this conclusion. Our results also support the hypothesis that incorporating more tolerant cereal crops (barley and oats) into rotations to replace spring wheat may be a promising option for growers in areas with high wireworm pressure.
•Imidacloprid increased yields and economic returns of wheat crops.•No yield differences in the control or treated plots in barley and oats were observed.•Wireworm densities were not affected by imidacloprid treatments.•Wireworm densities were lower in oats compared to barley and wheat.•Neonicotinoid seed treatments should only be targeted to susceptible crops.
Fossil bioinclusions in amber are invaluable source of information on the past evolution and diversity of various organisms, as well as on the paleoecosystems in general. The click-beetles, ...Elateridae, which originated and greatly diversified during the Mesozoic, are mostly known from the adpression-like fossils, and their diversity in the Cretaceous ambers is only poorly documented. In this study, we describe a new click-beetle based on an incomplete inclusion in ajkaite, an Upper Cretaceous (Santonian) amber from the Ajka Coal Formation from Hungary. We used X-ray micro-computed tomography scanning to reconstruct its morphology because it is deposited in an opaque piece of amber. Our results suggest that the newly described Ajkaelater merkli gen. et sp. nov. belongs to subfamily Elaterinae. It represents the first Mesozoic beetle reported from Hungary, and the first Mesozoic Elateridae formally described from mainland Europe. Our discovery supports an Eurasian distribution and diversification of Elaterinae already in the Cretaceous. The paleoenvironment of the Ajka Coal Formation agrees well with the presumed habitat preference of the new fossil taxon. The discovery of a presumably saproxylic click-beetle shed further light on the yet poorly known paleoecosystem of the Santonian present-day western Hungary.
Abstract
Wireworms, the larval stage of pest click beetle species (Coleoptera: Elateridae), are pests of many crops in North America including root vegetables and cereals. There is cause for concern ...amongst growers who are facing pressure from wireworms because there are a decreasing number of effective pesticides that can be used for wireworm management. Most research on pest elaterids has focused on the wireworm stage, which is the damage causing life stage. Recently, the focus in elaterid research has shifted to the adult click beetle stage, including identification of semiochemicals and development of effective traps. However, there is still a lot to be discovered about the basic biology of click beetles, including their feeding ecology. In an effort to understand the feeding ecology of click beetles, we investigated the presence of plant DNA in the digestive tracts of Limonius californicus (Mann.), L. canus (LeConte), and L. infuscatus (Mots.) beetles collected in 3 different locations within central Washington. To examine dietary histories of beetles and wireworms, specimens were collected from natural habitats and high-throughput sequencing of the plant genes trnF and ITS was used to identify their dietary history. Results revealed that click beetles do feed on a large variety of plants, which included a large quantity of brassicaceous plants commonly found in areas surrounding wireworm infested plots. The identification of the dietary history of the click beetles allowed us to infer their landscape-scale movements thus providing a means to better understand their behavior.
Abstract
With increasingly fewer insecticides registered to control the larvae of pest click beetles (Coleoptera: Elateridae), integrative beetle management, including pheromone- and light-based ...trapping of adult beetles, must be explored as an alternative strategy. Here, we analyzed the spectral sensitivity and color preference of 9 elaterids across 6 genera in electrophysiological recordings and in behavioral bioassays. In electroretinogram recordings (ERGs), dark-adapted beetles were exposed to narrow wavebands of light in 10-nm increments from 330 to 650 nm. All beetles proved most sensitive to green (515–538 nm) and ultraviolet (UV) light (~360 nm). In 4-choice bioassay arenas with 3 light emitting diodes (LEDs; green 525 nm, blue 470 nm, red 655 nm) and a dark control as test stimuli, beetles discriminated between test stimuli, being preferentially attracted to green and blue LEDs. In field experiments, Vernon pitfall traps fitted with a green, blue or white LED captured significantly more male and female Agriotes lineatus and A. obscurus than dark control traps. When traps were baited with green or blue LEDs at light intensities that differed by 10-fold, the traps baited with higher light intensity lures captured numerically more beetles but trap catch data in accordance with light intensity did not differ statistically. Light-based trapping may be a viable tool for monitoring elaterid species known not to have pheromones.
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