g62-encyclopaedia-of-pests-and-natural-enemies-in-field-crops
g62-encyclopaedia-of-pests-and-natural-enemies-in-field-crops
g62-encyclopaedia-of-pests-and-natural-enemies-in-field-crops
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Pollen beetle (Meligethes spp.)Crops affectedCereals✔ Oilseeds✔ Vegetable brassicasPotatoesCarrotsAlliumsPeasField beansSugar beetLettuceImportanceIn oilseed rape, adult <strong>and</strong> larval feed<strong>in</strong>g can lead tobud abortion <strong>and</strong> reduced pod set. This damage rarelyresults <strong>in</strong> reduced yields for w<strong>in</strong>ter <strong>crops</strong> but spr<strong>in</strong>g<strong>crops</strong> can be more vulnerable as the susceptible green/yellow bud stage <strong>of</strong>ten co<strong>in</strong>cides with beetle migration.Adults are occasional <strong>pests</strong> <strong>of</strong> cauliflower <strong>and</strong>broccoli, feed<strong>in</strong>g on the curds or florets <strong>in</strong> midsummerwhen new adults emerge from oilseed rape<strong>crops</strong> <strong>and</strong> move <strong>in</strong>to other areas to feed.Risk factorsCrops are usually most at risk when the weather isdry <strong>and</strong> warm (above 15°C).The damage-susceptible stage <strong>of</strong> the oilseed rape crop is green to yellow bud.Oilseed rape will usually compensate for early damage by produc<strong>in</strong>g more <strong>and</strong>larger seeds on lower racemes. Backward <strong>crops</strong> <strong>and</strong> those suffer<strong>in</strong>g from pigeondamage are at greater risk.In vegetable brassicas, the risk <strong>of</strong> <strong>in</strong>festation is higher if horticultural <strong>crops</strong> are closeto <strong>field</strong>s <strong>of</strong> oilseed rape.© Dewar Crop Protection© Emily GrahamPollen beetle (Meligethes spp.)Life cycleJan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec1 2 134 51 Adults overw<strong>in</strong>ter <strong>in</strong> sheltered spots.2 Adults migrate <strong>in</strong>to oilseed rape <strong>crops</strong> whentemperatures exceed 15°C. They feed on pollen<strong>in</strong>side buds or <strong>in</strong> open flowers.3 Eggs are laid <strong>in</strong> buds.4 Larvae feed on pollen before pupat<strong>in</strong>g.5 Adults emerge <strong>and</strong> feed on a variety <strong>of</strong> plants.Once the crop starts flower<strong>in</strong>g, the beetles move tothe open flowers, becom<strong>in</strong>g poll<strong>in</strong>ators rather than<strong>pests</strong>.Identification <strong>and</strong> symptomsThe adults are small (approx. 2.5 mm), metallicgreenish-black <strong>and</strong> have clubbed antennae.Females bite slits <strong>in</strong> the base <strong>of</strong> oilseed rape buds <strong>and</strong>lay their eggs <strong>in</strong>side.The larvae are creamy white, with a black head, threepairs <strong>of</strong> legs <strong>and</strong> dark brown spots <strong>and</strong> short bristlesalong the back. They grow to 3–4 mm long.Adults <strong>and</strong> larvae attack buds <strong>and</strong> flowers, result<strong>in</strong>g <strong>in</strong>withered buds <strong>and</strong> reduced pod set.© Dewar Crop ProtectionPollen beetles on oilseed rapePollen beetles on oilseed rapeBl<strong>in</strong>d stalks on oilseedrape due to pollenbeetle damage27Pests: BeetlesPests: Beetles28
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