|Scientific Name||Leptinotarsa decemlineata (Say)|
|Common Names||English: Colorado potato beetle; German: Kartoffelkäfer; French: Doryphore; Spanish: Dorifora|
The adult beetle has a stout, very convex, oval body 10-14 mm (3.93 - 5.46 inch)in length. The pronotum is brownish-red with black spots; the elytra show the well-known black and yellow stripes (decemlineata means „with ten stripes“). The larvae have a soft, plump, orange-red to dark red body with a black head and legs. They reach a length of ca. 12 mm (0.47 inch). The eggs are ovoid, ca. 1.5 mm (0.06 inch) in length, bright orange-yellow in color and therefore easily noticeable.
This species is easily confused with its close relative L. juncta.
All larval stages and the adults of L. decemlineata feed almost continuously on the foliage and young shoots of their host plants. Potato beetles possess a very efficient detoxification system, which allows them to feed on plants with high contents of poisonous alkaloids.
Massive infestations can lead to leaf skeletonising and ultimately, to complete defoliation. This may kill heavily-attacked plants, but in any case, yield will be greatly reduced. Losses in potato are most severe if the incidence of last instar larvae, the most voracious stage, peaks during the time of tuber formation.
Damage will often appear in distinct patches within fields, as the insects hardly move from the plant they hatched on - unless all of its leaves have been devoured.
Potato beetles can spread diseases transmitted by mechanical injury, e.g. Bacterial Ring Rot and Potato Spindle Tuber Disease.
The adults appear from hibernation in May, feed on young leaves for 5-10 days, mate, and then immediately start with oviposition. Over a period of 4-5 weeks, each female lays up to ca. 1,000 eggs in clusters of 20-50 on the undersides of leaves. The larvae hatch 3-14 days later. They molt three times, and the four larval instars last 2-4 weeks. The larvae drop to the soil where they build a round cell up to 20 cm deep to pupate there. Pupation lasts a further two weeks, but the completely-developed beetles stay in the soil at least one more week before emerging. Only a few of them use their ability to fly to find new food sources.
There are 1-3 generations each year. In October, the adults burrow 20-40 cm (7.87 - 15.75 inch) deep into the soil, where they overwinter.
L. decemlineata probably originates from Mexico, but it got its common name from a conspicuous occurrence on its wild host Solanum rostratum in western USA. It has been accidentally introduced to potato-growing countries throughout the world. In 1877 it reached Europe, where it became widespread in the 1940s.
Additional Crop Information
Solanaceae, especially potato, but also eggplant, tomato, pepper and tobacco.
Leptinotarsa decemlineata it is not considered a major threat in most areas of the United States, but it is among the most serious pests of potatoes in the countries it has been introduced into. Losses of 50% are not uncommon.
Useful non-chemical contribution to Integrated Weed Management
Crop rotation and the destruction of harvest residues are essential to delay initial infestation. Crops should be separated from previously-infested ones by at least several hundred metres, as the latter will be a source of emerging beetles in the spring.
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