Aphthona euphorbiae Schrank, Aphthona flaviceps All., Longitarsus parvulus Payk. - Flax Flea Beetles (Large Flax Flea Beetle, Yellow Flax Flea Beetle, Small Flax Flea Beetle)
Systematic position.Class Insecta, order Coleoptera, family Chrysomelidae, genera Aphthona Chevr., Longitarsus Latr.
Biological group.Pest of fiber and crown flax (Linum usitatissimum L.).
Morphology and biology.A. euphorbiae. Body slightly convex; its upper side dark-green, blue or bronze. Frons and vertex smooth and weakly punctated, elytra exhibit fine and dense punctation. Spur of hind tibia situated on the outside of apical margin. Body length reaches 1.5-2 mm. Female lays 1-3 eggs in the surface layer of soil on roots of flax seedlings or near host plants. Fertility is about 300 eggs. Eggs light-yellow, 0.62 mm in length. Development of egg lasts 11-25 days. Larva milk-white, with light-yellow head; thorax with 3 pairs of legs. Last abdominal segment is the narrowest, without apical spine. Larva eats flax roots; its development lasts 26-29 days. Pupation occurs in soil, in a cradle, at a depth of 14 cm. Adults of new generation emerge in 2.5-3 weeks and appear in southern regions at the end of June and the beginning of July. After additional feeding on flax, the beetles migrate for hibernation. A. flaviceps is close to A. euphorbiae, but has a monochromatic yellow upper-side of body. Body length reaches 1.5-2.2 mm. L. parvulus. Body highly convex; its upper side black, without metallic shine. Elytral punctation fine and sparse. 1st segment of hind tarsus at least half as long as hind tibia. Spur of hind tibia situated in the middle of apical margin. Body length reaches 1.3-1.6 mm. Biology of the last two species is similar to that of A. euphorbiae.
Distribution.A. euphorbiae: Europe, Northern Africa and Anterior Asia; inhabits the European part of the former USSR northward to Arkhangelsk Region, West Siberia, the Caucasus, Middle Asia and Kazakhstan. A. flaviceps: Mediterranean area and Eastern Europe; inhabits the Southern European part of the former USSR and Western Siberia, the Caucasus, Middle Asia and Kazakhstan. L. parvulus: Northern Africa and Asia Minor; inhabits the European part of the former USSR north to the Baltic region, southwestern Siberia, the Caucasus and Middle Asia.
Ecology.Monovoltine species. A. euphorbiae and L. parvulus are moderately mesophilous species; A. flaviceps is a more heat-loving species. Most part of population hibernates in the debris of deciduous forests; therefore, crop rotation has no influence on pest population density. Adults appear early in spring during bud blossoming of birch, under the soil moisture with levels of 25% and less. Beetles fly actively at air temperatures of about 20°C. Adults stay first on grains, crucifers, beets, and weeds. They migrate to flax after appearance of seedlings, and here their mating and oviposition occur.
Economic significance.Both larva and adult stages are harmful. Damage by adults is more significant; they eat parenchyma of cotyledons, stems, and leaves. Adults are vectors of antracnose and fusariosis. A. flaviceps is more harmful in southern regions. Damage of Flax Flea Beetles increases after drought. Control measures include the use of fertilizers to accelerate seedling development, fast sowing of flax as early as possible, autumn plowing immediately after harvesting and pre-sowing pesticide treatment of seeds.
Related references:Dubeshko, L.N. & Medvedev, L.N. 1989. Ecology of leaf beetles of Siberia and the Far East. Irkutsk: Irkutsk University. 224 p. (in Russian).
Kopaneva, L.M., ed. 1982. Keys to harmful and useful insects and mites on vegetable plants and potato in the USSR. Leningrad: Kolos. 272 p. (in Russian).
Kryzhanovskii O.L., ed. 1974. Pest insects and mites of agricultural plants. Leningrad: Nauka. V. 2. 335 p. (in Russian).
Lopatin, I.K. 1977. Leaf beetles (Chrysomelidae) of Middle Asia and Kazakhstan. Leningrad: Nauka. 289 p. (in Russian).
Lopatin, I.K. & Kulenova, K.Z. 1986. Leaf beetles (Coleoptera, Chrysomelidae) from Kazakhstan. Alma-Ata: Nauka. 199 p. (in Russian).
Palii, V.F. 1961. Fauna of pest flea beetles of the USSR. Frunze: AN Kirgiz.SSR. 101 p. (in Russian).
Palii, V.F. & Avanesova, G.A. 1975. Flea beetles (Keys to genera and harmful species). Tashkent: Fan. 111 p. (in Russian).