Agriotes sordidus

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Agriotes sordidus
Agriotes sordidus.png
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Infraorder: Elateriformia
Family: Elateridae
Genus: Agriotes
Species:
A. sordidus
Binomial name
Agriotes sordidus
(Illiger 1807) [1]
Synonyms [2]

Agriotes sordidus is a species of click beetle, family Elateridae, found in south-western Europe, mainly in Spain, Portugal, France, south-western Germany and northern Italy. In the north the distribution extends to southern England, the Netherlands and the Upper Rhine valley of Germany. There are also records from northern Africa and the Canary Islands. [2] [5] A. sordidus is a serious agricultural pest in France as well as in parts of Germany and Italy with the polyphagous larvae (wireworms) damaging maize, other cereals and various other crops like alfalfa. They feed on the roots and the lower stems of seedlings and can cause plant mortality. The adults feed on the leaves, but cause little damage. [6] [7] Pest populations can be monitored using pheromone traps or by baiting wireworms in the soil. In maize fields, trapping of more than two A. sordidus larvae in standard soil traps within 10 days indicates likely economic damage and the need for control action. In order to reduce the environmental impact of soil insecticides, non-chemical management options should be applied as much as possible. These include crop rotation or timing tillage and irrigation in a way so that the eggs and young larvae are desiccated in the top layer of the soil. [8] [9] The adult beetles of A. sordidus have a length of 8–9 mm and a blackish brown coloration. They can be separated from other similar species like Agriotes rufipalpis , A. obscurus , and A. sputator by a combination of features like the shape of the pronotum, the densely punctured thorax, the shape and ridges on the elytra, as well as the coloration. [10] [11] The larvae can be identified by the tip of the abdomen and by other features. [7] [5]

Contents

Distribution

Distribution range of Agriotes sordidus in Europe and North Africa. Agriotes sordidus distribution.png
Distribution range of Agriotes sordidus in Europe and North Africa.

Agriotes sordidus was originally described from a specimen collected near Coimbra in Portugal. [1] The type locality of Agriotes hispanicus, which is regarded as a synonym of A. sordidus, was given as "Algesiras", the French name of Algeciras at the southern tip of Spain, not far from Gibraltar. [4] Most subsequent records of A. sordidus are from France including Corsica. Other records are from southern England, Belgium, parts of the Netherlands, southern and western Germany (extending in the north until the Upper Rhine valley), Switzerland, Italy and coastal parts of north-western Africa, including from east to west: Tunisia, Algeria, Morocco and parts of the Canary Islands. [2] [12] [5] [13] [14]

Agriotes sordidus was also reported from north-western Hungary in 2023. [15] However, these records were disputed, based on comparison with specimens from Italy and Spain. [16]

Description

The adult beetles of Agriotes sordidus are 8–9 mm long. They can be identified by the following combination of characters: [10] [11]

The species most similar to Agriotes sordidus are A. rufipalpis , A. sputator , A. medvedevi and A. obscurus . The adults of A. rufipalpis can be separated by the more elongated pronotum ("distinctly longer than wide"), when compared to A. sordidus ("slightly longer than wide"). [16] Both species have different distribution ranges, with A. rufipalpis being confined to south-eastern Europe. In addition, the larvae of both species are indistinguishable and both species are attracted to the same pheromone. [7] A. sputator can be distinguished by the structure of the male genitalia. [16] A. medvedevi differs from A. sordidus mainly by the head being less densely punctured with smooth areas in between the punctures. A. obscurus is broader than A. sordidus with a less domed pronotum and with the elytra usually having a lighter color. [10] [11]

Morphological features of Agriotes obscurus larvae - top row: tip of abdomen, bottom left: mandible, bottom right: frontoclypeus Agriotes sordidus larval-features.png
Morphological features of Agriotes obscurus larvae - top row: tip of abdomen, bottom left: mandible, bottom right: frontoclypeus

The morphology of the Agriotes sordidus larvae is characterized by an unusual shape of the abdominal tip and the shape of the mandibles and the frontoclypeus, see illustrations on the right. The tip of the abdomen, the ninth segment, has a subconical shape, shrinking abruptly in the apical fourth. The base of the apical spike has a square, bulge-like structure. The indicated angle on the mandible between the apical tip and the subapical tooth is much larger than 90°, on average around 150° with a range of 130° to 170°. The indicated angle on the frontoclypeus is a right angle. [7] Further, the larvae can be reliably identified with molecular methods. [17]

Biology

Like other species of Agriotes, the larvae (wireworms) of Agriotes sordidus are polyphagous, feeding on the roots and stem base of cereals, grasses and various other plants. Mainly seedlings are attacked and the damage often results in plant mortality. Agriculturally important food plants include cereal crops like maize and barley as well as forage crops like alfalfa. [6] [18]

In Italy, Agriotes sordidus adults emerge from the soil around late March to early April. As demonstrated by pheromone traps, the males are active from April to August and have a distinct activity peak in May. The adults feed on leaves, but cause little damage. Eggs are laid in May or June and the larvae go through 8 to 13 instars over several years, depending on the environmental conditions. [19] In Germany, A. sordidus has a comparatively short life cycle of 2-3 years compared to other Agriotes species. [12] In Italy, the total life cycle may be completed within two years under favorable conditions, but can be longer. Temperature is an important factor and about 3900 degree days are required for the development from egg to adult. [6] [19] [8]

Pheromones and traps

Agriotes sordidus females produce geranyl hexanoate and (E,E)-farnesyl hexanoate in their pheromone glands. The released volatiles consist mainly of the former compound with only traces of the latter. In the field, geranyl hexanoate on its own attracts large numbers of A. sordidus and the addition of (E,E)-farnesyl hexanoate has no effect on the catches. Both sexes are attracted and 10–40% of the trapped adults are females. Geranyl hexanoate is also a pheromone of Agriotes rufipalpis, as well as a component of the pheromone of Agriotes obscurus . [20] [21] [22] [23]

Agriotes sordidus larvae are attracted by CO2 and other volatiles emitted by the roots of the host plant. In the case of barley, these chemical cues are a mixture of four specific aldehydes. [24] The larvae can be trapped by bait traps placed into the soil. These consist of a plastic container, about 10 cm wide, with holes and contain moistened vermiculite and wheat plus maize seeds. The traps are placed about 5 cm below the soil surface and examined after 10 days. However, the larval bait traps also attract other wireworm species and the catches need to be sorted and identified. [9]

Impact and management

Wilting young maize plants due to damage to the stem base by Agriotes larvae Agriotes damage (Poggi 2021).png
Wilting young maize plants due to damage to the stem base by Agriotes larvae

Agriotes sordidus larvae develop faster than most other pest species in the genus Agriotes. Therefore, they can reach a size that causes significant damage to crops already three to four months after they hatch from the eggs. This includes crops planted in late summer or early autumn. [8] Like other Agriotes species, A. sordidus larvae are polyphagous, feeding on the roots and the lower stems of various grasses and other plants. Among agricultural crops, cereals like maize or barley are most often attacked. Damage to other crops like alfalfa, lettuce, sunflower and potatoes has been also reported. Seedlings are preferred and these can suffer mortality due to the wireworms feeding on the roots and the stems. In Italy, a low density of A. sordidus wireworms can already cause serious damage to maize, alongside with Agriotes brevis . In France and Germany A. sordidus has also been reported as a major agricultural pest. [6] [12] [7] In Italy, the IPM threshold for maize has been determined to be 2 larvae caught in standard bait traps over 10 days. This threshold indicates that significant damage can be expected at that population level and that Integrated Pest Management (IPM) should be implemented. [9]

To prevent significant economic damage to maize and other crops by Agriotes sordidus wireworms, neonicotinoid insecticides are often applied. However, these are highly toxic to beneficial insects like honey bees. [25] In addition, an EU directive, in effect since 2014, restricts the use of pesticides and promotes the use of Integrated Pest Management (IPM). [26] An IPM approach requires:

Non-chemical control methods against Agriotes sordidus and other wireworms include: [27] [28] [8] [29]

Taxonomy

More than 10 subspecies of Agriotes sordidus have been described, reflecting the variability of this species. In addition, two species names are regarded as synonyms, apart from the basionym Elater sordidus. These are: [2]

  1. Agriotes italicus Baudi di Selve 1871 – In the original description the name of the author was misspelled as "Flaminio Baudi a Selve". Baudi described A. italicus as a footnote to the species Agriotes meticulosus Candeze, 1863 in his article "Coleopterorum messis in insula Cypro et Asia minore ..." [Beetle harvest from Cyprus island and Asia Minor ...]. He did not mention any locality in his description, but the name italicus suggests that it was not collected in Cyprus or Turkey. The original description mentions the similarity to Agriotes sordidus and a note by the editor of the publication states that it may be part of sordidus which is highly variable. [3]
  2. Agriotes hispanicus Desbrochers des Loges 1871 – This species was described as having features that are intermediate between A. sputator and A. sordidus. The differences to A. sordidus are stated as A. hispanicus being shorter, the fore femora being narrower, and the antennal segments 2 to 9 being nearly equal. [4]

References

  1. 1 2 3 Illiger, Karl (1807). "Portugiesische Käfer (Fortsetzung)". Magazin für Insektenkunde. 6: 1–80 [7].
  2. 1 2 3 4 Zapata de la Vega, José Luis; Sánchez-Ruiz, Antonio (2012). "Catálogo actualizado de los Elatéridos de la Península Ibérica e Islas Baleares (Coleoptera: Elateridae)" (PDF). Arquivos Entomolóxicos. 6: 115–271.
  3. 1 2 Baudi a Selve, Flaminio (1871). "Coleopterorum messis in insula Cypro et Asia minore ab Eugenio Truqui congregatae recensitio (Pars quarta)". Berliner entomologische Zeitschrift. 15: 49–71 [55].
  4. 1 2 3 Desbrochers des Loges, J. (1871). "Description de Coléoptères nouveaux de l'Europe et confins et remarques diverses". Mittheilungen der Schweizerischen Entomologischen Gesellschaft. 3 (7): 337–376 [369].
  5. 1 2 3 "Agriotes sordidus (Illiger, 1807)". GBIF - Global Biodiversity Information Facility. Retrieved 23 July 2025.
  6. 1 2 3 4 Furlan, L. (2004). "The biology of Agriotes sordidus Illiger (Col., Elateridae)". Journal of applied entomology. 128 (9–10): 696–706. doi:10.1111/j.1439-0418.2004.00914.x.
  7. 1 2 3 4 5 Furlan, Lorenzo; Benvegnù, Isadora; Bilò, María Fabiana; Lehmhus, Jörn; Ruzzier, Enrico (2021). "Species identification of wireworms (Agriotes spp.; Coleoptera: Elateridae) of agricultural importance in Europe: A new "horizontal identification table"". Insects. 12 (6) 534. doi: 10.3390/insects12060534 .
  8. 1 2 3 4 Barsics, Fanny; Haubruge, Eric; Verheggen, François J. (2013). "Wireworms' management: An overview of the existing methods, with particular regards to Agriotes spp. (Coleoptera: Elateridae)". Insects. 4 (1): 117–152. doi: 10.3390/insects4010117 .
  9. 1 2 3 Furlan, Lorenzo (2014). "IPM thresholds for Agriotes wireworm species in maize in Southern Europe". Journal of Pest Science. 87 (4): 609–617. Bibcode:2014JPesS..87..609F. doi: 10.1007/s10340-014-0583-5 . PMC   4220100 . PMID   25395918.
  10. 1 2 3 "Gattung Agriotes Eschsch". Die Käfer Europas. 16 September 2023. Retrieved 25 July 2025.
  11. 1 2 3 Telfer, Mark G. "Joy's keys to Elateridae, Eucnemidae and Throscidae" (PDF). Quel est cet ANIMAL? - Quel est cet insecte?. Retrieved 4 July 2025.
  12. 1 2 3 Lehmhus, Jörn; Niepold, Frank (2013). "Neue Funde des Schnellkäfers Agriotes sordidus (Illiger, 1807) mit einem Überblick über seine aktuelle Verbreitung in Deutschland". Journal für Kulturpflanzen. 65 (8): 309–314. doi: 10.5073/JfK.2013.08.02 .
  13. ↑ "Agriotes sordidus (Illiger, 1807)". UK Beetle Recording. Retrieved 1 May 2020.
  14. ↑ "Agriotes sordidus". iNaturalist. Retrieved 28 July 2025.
  15. ↑ Nagy, Antal; Horváth, András; Szanyi, Kálmán (2023). "Distribution of economically important click beetles and the first record of Agriotes sordidus Illiger in Hungary". Journal of Central European Agriculture. 24 (4): 899–907. doi: 10.5513/JCEA01/24.4.3965 .
  16. 1 2 3 Németh, Tamás (2024). "Species of the genus Agriotes Eschscholtz, 1829 occurring in Hungary (Coleoptera: Elateridae)" (PDF). Folia Entomologica Hungarica - Rovartani Közlemények. 85: 137–146.
  17. ↑ Staudacher, K.; Pitterl, P.; Furlan, L.; Cate, P.C.; Traugott, M. (2011). "PCR-based species identification of Agriotes larvae". Bulletin of Entomological Research. 101 (2): 201–210. doi:10.1017/S0007485310000337.
  18. ↑ Barsics, F.; Fiers, M.; Fauconnier, M-L.; Jijakli, H.; Francis, F.; Haubruge, E.; Verheggen, F.J. (2014). "Assessing the foraging behavior of Agriotes sordidus wireworms in dual choice olfactometers". Communications in Agricultural and Applied Biological Sciences. 79 (2): 151–156.
  19. 1 2 Furlan, Lorenzo; Garofalo, Nicoletta; Toth, Miklos (2004). "Biologia comparata di Agriotes sordidus Illiger nel Nord e Centro-Sud d'Italia". Informatore Fitopatologico. 2004 (10): 49–54.
  20. ↑ Furlan, Lorenzo; Tóth, Miklós; Ujváry, István (30 August – 5 September 1997). The suitability of sex pheromone traps for implementing IPM strategies against Agriotes populations (Coleoptera: Elateridae). XIX IWGO conference proceedings. Vol. 30. Guimaraes, Portugal. pp. 173–182.
  21. ↑ Tóth, M.; Furlan, L.; Szarukán, I.; Ujváry, I. (2002). "Geranyl hexanoate attracting male click beetles Agriotes rufipalpis Brullé and Agriotes sordidus Illiger (Col., Elateridae)". Journal of applied entomology. 126 (6): 312–314. doi:10.1046/j.1439-0418.2002.00667.x.
  22. ↑ Tóth, Miklós; Furlan, Lorenzo; Yatsynin, Venyamin G.; Ujváry, István; Szarukán, István; Imrei, Zoltán; Tolasch, Till; Francke, Wittko; Jossi, Werner (2003). "Identification of pheromones and optimization of bait composition for click beetle pests (Coleoptera: Elateridae) in Central and Western Europe". Pest Management Science. 59 (4): 417–425. doi:10.1002/ps.629. PMID   12701702.
  23. ↑ Tóth, Miklós; Furlan, Lorenzo; Vuts, József; Szarukán, István; Ujváry, István; Yatsynin, Venyamin G.; Tolasch, Till; Francke, Wittko (2015). "Geranyl hexanoate, the female-produced pheromone of Agriotes sordidus Illiger (Coleoptera: Elateridae) and its activity on both sexes". Chemoecology. 25 (1): 1–10. doi:10.1007/s00049-014-0170-5.
  24. ↑ Barsics, Fanny; Delory, Benjamin M.; Delaplace, Pierre; Francis, Frédéric; Fauconnier, Marie-Laure; Haubruge, Éric; Verheggen, François J. (2017). "Foraging wireworms are attracted to root-produced volatile aldehydes". Journal of Pest Science. 90 (1): 69–76. doi:10.1007/s10340-016-0734-y.
  25. ↑ Furlan, Lorenzo; Vasileiadis, Vasileios P.; Chiarini, Francesca; Huiting, Hilfred; Leskovšek, Robert; Razinger, Jaka; Holb, Imre J.; Sartori, Erica; Urek, Gregor; Verschwele, Arnd; Benvegnù, Isadora; Sattin, Maurizio (2017). "Risk assessment of soil-pest damage to grain maize in Europe within the framework of Integrated Pest Management". Crop Protection. 97: 52–59. Bibcode:2017CrPro..97...52F. doi:10.1016/j.cropro.2016.11.029.
  26. ↑ "DIRECTIVE 2009/128/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL". European Union law. Retrieved 10 August 2025.
  27. ↑ Furlan, Lorenzo; Bonetto, Christian; Patalano, Giampiero; Lazzeri, Luca (2004). "Potential of biocidal meals to control wireworm populations". Agroindustria. 3 (3): 313–316.
  28. ↑ Furlan, Lorenzo; Bonetto, Christian; Costa, Bruno; Finotto, Andrea; Lazzeri, Luca (2009). "Observations on natural mortality factors in wireworm populations and evaluation of management options". IOBC Bulletin. 45: 436–439.
  29. ↑ Furlan, Lorenzo; Kreutzweiser, David (2015). "Alternatives to neonicotinoid insecticides for pest control: case studies in agriculture and forestry". Environmental Science and Pollution Research. 22: 135–147. doi: 10.1007/s11356-014-3628-7 .
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