Brassicogethes

Audisio & Cline, 2009

pollen beetles

Species Guides

4

Brassicogethes is a of pollen beetles in the Nitidulidae, Meligethinae. in this genus are primarily associated with Brassicaceae plants, with several species recognized as significant agricultural pests of oilseed rape (canola). The most economically important species is Brassicogethes aeneus, which causes substantial yield losses in oilseed rape crops across Europe. The genus was established in 2009, with species previously classified under Meligethes.

Brassicogethes viridescens by (c) Christian Back, some rights reserved (CC BY), uploaded by Christian Back. Used under a CC-BY license.Brassicogethes viridescens by (c) Jonas V., some rights reserved (CC BY), uploaded by Jonas V.. Used under a CC-BY license.Meligethes-aeneus-04-fws by Francisco Welter-Schultes. Used under a CC0 license.

Pronunciation

How to pronounce Brassicogethes: //brəˌsɪkoʊˈɡɛθ.iːz//

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Identification

Members of Brassicogethes can be distinguished from related by their association with Brassicaceae plants and subtle morphological characters. The genus was separated from Meligethes based on phylogenetic and morphological evidence. -level identification typically requires examination of genitalia and other detailed morphological features.

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Habitat

Agricultural landscapes dominated by oilseed rape (Brassica napus) ; also found in semi-natural including grassy and woody field margins, prairies, and lands where Brassicaceae plants occur. occurs in woody and sheltered habitats away from crop fields.

Distribution

Europe, with documented in Estonia, France, Czech Republic, UK, and the southwestern Alps (Italy/France border region). Distribution closely follows the of oilseed rape and presence of native Brassicaceae vegetation.

Seasonality

Active during spring and summer. emerge from sites in spring to colonize oilseed rape fields at the green bud stage. Summer presence documented in various wherever flowering plants are available.

Diet

feed on oilseed rape buds, causing damage primarily at the green bud stage. Larvae feed on pollen: first instar larvae develop inside buds, while second instar larvae feed exclusively on pollen from open flowers. Adult plant associations extend to diverse flowering plants beyond larval , including yellow-flowered in spring and various weeds in summer.

Host Associations

  • Brassica napus - plant (oilseed rape)primary agricultural , damage buds and larvae feed on pollen
  • Descurainia tanacetifolia - larval plantdocumented for B. salvan in the southwestern Alps
  • Brassicaceae - -level association-level association with mustard plants

Life Cycle

Overwinters as in woody and sheltered . In spring, adults migrate to oilseed rape fields, seeking food and oviposition sites. Oviposition occurs into buds. First instar larvae develop inside buds; second instar larvae feed on pollen from open flowers. occurs in soil. Multiple hymenopteran attack larvae, including Tersilochus heterocerus, Phradis interstitialis, and Phradis morionellus. These parasitoids are , koinobiont endoparasitoids that overwinter in pupal cocoons in soil near .

Behavior

undertake post-hibernation movements averaging approximately 1.2 km to reach oilseed rape fields. Abundance is typically higher near field edges (within 2 m of adjacent ) and declines with distance into fields. Spring from sites to crops is a critical behavioral phase. Adults have been observed in alternative habitats including prairies, lands, and field margins, particularly where yellow flowers are present in spring.

Ecological Role

Agricultural pest causing significant yield losses in oilseed rape, with potential losses up to 80% reported on spring oilseed rape. Serves as for hymenopteran that provide services. The relationship between Brassicogethes and its parasitoids is influenced by landscape complexity, with semi-natural supporting parasitoid . Presence of >18% semi-natural habitat within 1 km has been associated with effective biological control through maintained rates.

Human Relevance

Major economic pest of oilseed rape (canola) production in Europe, with B. aeneus being the most significant . Management relies heavily on application, though resistance has developed widely across European . Resistance monitoring and insect resistance management strategies have been implemented, including reduction of pyrethroid use. Subject of agriculture research using computer vision (YOLOv4 architecture) for real-time detection and site-specific application. Conservation concern exists for rare species such as B. salvan, which has been proposed for Endangered status under IUCN criteria.

Similar Taxa

  • MeligethesBrassicogethes was previously classified within Meligethes; separated based on phylogenetic and morphological evidence in 2009. Both contain pollen beetles with similar overall , requiring detailed examination for differentiation.
  • XenostrongylusBoth are rapeseed pests in the Nitidulidae, but Xenostrongylus variegatus primarily feeds on leaves while Brassicogethes aeneus targets flowers; mouthpart differ substantially between the two .

More Details

Taxonomic history

The Brassicogethes was established by Audisio & in 2009, reclassifying previously placed in Meligethes. This separation was based on molecular phylogenetic analysis and morphological characters.

Genetic population structure

Brassicogethes aeneus shows low genetic differentiation across Europe, with significant isolation by distance only at the continental . Estonian show significant differentiation from the rest of Europe. Demographic analyses suggest recent population expansion, possibly associated with increased oilseed rape area.

Conservation status

While B. aeneus is a widespread pest, some Brassicogethes are of conservation concern. B. salvan, rediscovered in the southwestern Alps in 2016 after being known only from 1912 specimens, has been proposed for Endangered (EN) status under IUCN criteria due to its restricted range and specific requirements.

Insecticide resistance

Widespread resistance has been documented in European B. aeneus , with resistance ratios up to 500-fold for deltamethrin documented in Czech populations. Notably, the kdr mutation commonly associated with pyrethroid resistance in other insects has not been detected in this , indicating alternative resistance mechanisms.

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