Pests
Neocoenorhinidius pauxillus Germ. - Apple Leaf Cutter.
Systematic position.
Class Insecta, Order Coleoptera, Family Rhynchitidae, Neocoenorhinidius Legalov.Synonyms.
Coenorrhinus pauxillus Germ.Biological group.
Pest of fruit crops.Morphology and biology.
Body length reaches 1.8-3 mm. Dark-blue or blue-green with metallic shine, densely covered with long brownish hairs. Eyes round, strongly convex, length of head without rostrum is less than width of head and eyes combined. Rostrum dorso-ventrally curved angularly at antennae insertion. Rostrum of male distinctly shorter, and rostrum of female only slightly shorter than pronotum and head combined. Scutellum small, pentagonal. 9th stria of elytra ending behind the middle. Adults appear in abundance after hibernation before the beginning of apple blossoming with an average air temperature of 10°C. They feed on buds, flowers and new leaves. Oviposition begins at the end of blossoming. Female gnaws a small pit on the under side of leafstalk, or in median vein of leaf, and puts one egg inside. Average fertility reaches 100 eggs. Egg develops in 6-8 days. Hatching larvae mine leafstalk. Infested leaves grow brown and drop. Four weeks after feeding on decomposing leaf the larvae bury themselves in the soil at a depth of 15 cm. Most of the larvae go down in the soil before the middle of July, but the first pupae appear in the middle of June. Disk of pronotum of the last instar larva has no yellow spot. Larvae and adults hibernate.Distribution.
Inhabits Europe, Turkey, Iran. In the former USSR it is distributed in the European part (northward to Baltic states and eastward to Yaroslavl', Samara, Volgograd regions), everywhere in the Caucasus, in West Kazakhstan, and in Turkmenistan.Ecology.
Development of one generation lasts 1-2 years. Larvae usually perish inside dry leaves. Microbracon discoides Wesm. is a parasite of larvae.Economic significance.
Occurs more abundantly on apple, less often on pear and plum, rarely on cherry and apricot. A pest of blackthorn, hawthorn, bird cherry tree, and snowball tree. Infested tree loses up to 50% of leaves, and abscission of fruitlets is observed. Economic threshold is about 40 adults per one tree.Related references:
Grossgeim, N.A. 1928. Rhynchites bacchus L. In: Proceedings of Mleev horticultural and truck farming station. Mleev: NKZS-Ukr.SSR, N10. 143 p. (in Russian).Kryzhanovskii, O.L., ed. 1974. Pest insects and mites of agricultural plants, V. 2. Leningrad: Nauka. 335 p. (in Russian).
Legalov, A.A. 2003. Taxonomy, classification and phylogeny of the leaf-rolling weevils (Coleoptera: Rhynchitidae, Attelabidae) of the world fauna. Novosibirsk. CD-ROM and Web-site. http:// attelabidae.narod.ru/System_of_rhynchitidae.htm (in English, in Russian).
Savkovskii, P.P. 1951. Biology of Peach Weevil in Ukraine and control measures. Collection of Works on Plant Protection. Ukrainian Institute of Horticulture. Kiev & Kharkov: Selskokhozlit. N32. P. 51-83 (in Russian).
Ter-Minasyan, M.E. 1950. Roller-weevils (Attelabidae). Fauna USSR. Insecta-Coleoptera, 27(2). Moscow & Leningrad: AN SSSR, 231 p. (in Russian).
Zayanchkauskas, P.A. 1984. Insects injuring orchards of Lithuanian SSR. In: New and rare species of insects of Lithuanian SSR. Vilnius. P. 62-88 (in Russian).
Vasil'ev V.P., 1955. Pests of orchards. Kiev: AN Ukr.SSR. 265 p. (in Russian).
Vasil'ev V.P., Lifshits I.Z., 1984. Pests of orchard plants. Moscow: Kolos. 399 p. (in Russian).