Pests
Caliroa cerasi L. - Pear Sawfly, Pear Slug, Pear and Cherry Slug Sawfly.
Synonyms.
Caliroa limacina Retz., Eriocampoides limacina Retz., Eriocampa adumbrata Kl.Systematic position.
Class Insecta, order Hymenoptera, family Tenthredinidae, genus Caliroa.Biological group.
Pest of the horticultural crops.Morphology and biology.
Adult is black. Body size is 4-6 mm, wing span is 6-9 mm. Antennae are 9-segmented, black. Legs are black, brownish in middle only. Wings are venation and pterostigma black; wings transparent, with slightly darkened median band. There are two biological forms: the main one which is parthenogenetic, ubiquitous and a bisexual one, rarely occurring. Sexual dimorphism is best expressed by venation of hind wings, in females possessing two central cells, which are usually absent in males. Female is larger than male by 1-2 mm. Eggs are oval, pale green. Caterpillars are yellow-green, 9-11 mm in size, with 10 pairs of legs (the anal pair is absent), the head is black, small; the anterior body part is flattened, and the body is covered with black slime. During individual development, the caterpillar molts 5-7 times. The average width of the head capsule of the first through fifth instars is 0.33, 0.55, 0.68, 0.79 and 0.97 mm, respectively. The sixth and seventh molts are due to salvation from the slime sheath, contaminated with dust and products of the sawfly metabolism, and therefore, is not followed by changes in head capsule size. Pupa is white, sheathed with oblong oval soil cocoon. Last instar caterpillars overwinter in cocoons in soil under tree crowns, at the depth of 2-5 cm in the south and 10-15 cm in the north. Adult insects emerge in May-July, depending upon the geographical zone. The flight lasts up to two months in the north and one month in the south. Females emerge with mature eggs and lay them by one inside the leaves from the underside. A visible knot is formed in the place of oviposition. One leaf may bear up to 20-30 eggs, laid by different females. Each female lays up to 75 eggs. The egg development lasts one to two weeks. Hatched caterpillars eat leaves from above, leaving veins and lower epidermis untouched. The feeding period of the caterpillars lasts 15 to 28 days. After feeding is finished, caterpillars fall from the leaf and move to the soil to pupate or overwinter. Facultative larval diapause is typical of Pear Sawfly. Winter and summer diapauses are induced by daylight length and drought, respectively.Distribution.
The species is distributed in Europe, Asia, China, Japan, North and South America, North and South Africa, Australia, New Zealand; in the territory of Former USSR, it is distributed in the European part in the north to Leningrad, Novgorod, Vladimir, Ivanovo, Perm Regions, it inhabits in the Caucasus, Volga region, Kazakhstan, Uzbekistan, Turkmenia, Kirgizia, Tadjikistan, Siberia.Ecology.
The species is found in several zones having differing numbers of generations within the area, due mainly to degree days and climatic zone. This is a univoltine species in the forest zone but in Lithuania there may be up to two generations. There are 1 to 2 generations in the forest-steppe zone and 2 generations in the steppe. In the mountain regions of Transcaucasia and Middle Asia there are 1 to 3, depending upon the sea level height. Wide forage specialization allows the pest to feed on leaves of cherry, bird-cherry, plum, peach, apricot, alycha, pear, apple, quince, hawthorn, aronia, sloe, cotoneaster, almond, shadberry and bird cherry tree, which provides it a wide area of distribution. Preference of the forage plants may vary through years. Larvae of second generation are more harmful than larvae of first generation. Overwintering sawfly caterpillars possess high cold resistance, varying within the negative temperature boundaries of 5 to 25°C. This facilitates survival of the overwintering stage in northern and eastern parts of the area. Temperatures of +23-26°C are the most favorable for sawfly development. The lower developmental threshold of embryonic stage is +11°C, and the lower developmental threshold of larval stage is lower than +10°C. The pest prefers trees exposed on the south hillsides with good insulation. Leaves are inhabited to the greater extent in the higher levels and in the south part of the crown. The sawfly prefers more shaded older cherry bush only under highly arid conditions,such as in Western Siberia. Younger larvae perish when air humidity falls to 30-40%. Dense soil is unfavorable for overwintering as it prevents larvae from moving deeply. Natural enemies are the predatory bugs, oviphages of the Trichogramma genus, different hymenopteran parasitoids (Erromenus fumatus Bris., E. exareolatas Gir., Mesoleius excavatus Prov., Pristomerus vulnerator Panz., Triphon translucens Ratz. et al.), birds, entomopathogenic bacteria (Bacillus thuringiensis Berl., Bacillus sp.) and fungi (Beauveria bassiana Bals.).Economic significance.
Pear Sawfly damages leaves of cherry, bird-cherry, sometimes plum, pear, apple and other fruit crops. The greatest damage is done to young gardens and nursery orchards. Caterpillars skeletonize the leaves. Heavily damaged trees suffer in winters, decreasing fruit yield quality. Soil tillage in autumn and spring are used to control the overwintering cocoons. Chemicals are applied against larvae and adults between one and 20-25 days before harvest.Reference citations:
Bondarenko N.V., Pospelov S.M. & Persov M.P. 1991. Pear Sawfly - Caliroa cerasi L. In: General and agricultural entomology. Second revised edition. Leningrad: Agropromizdat. p. 371 (in Russian).Bryantsev B.A. 1973. Pear Sawfly - Caliroa limacina Retz. In: Agricultural entomology. Second revised edition. Leningrad: Kolos. p. 226 (in Russian).
Ermolenko V.M. 1974. Family of true sawfly or Tenthredinidae. In: Vasil.ev V.P., ed. Pests of agricultural crops and afforestations. Arthropoda. V.2. Kiev: Urozhai. p. 411-468 (in Russian).
Fedorova N.A. 1968. An experience of biological control of Pear Sawfly. In: Vasil.chenko G.V., ed. Young scientists for Altai gardeners. Barnaul: Altaiskoe knizhnoe izdatel.stvo. Issue 1. p. 101-103 (in Russian).
Goderdzishvili G.S. 1980. Features of Pear Sawfly dynamics in Georgia. Proceedings of Research Institute of Plant Protection. Tbilisi. V. 31. p. 8-19 (in Russian).
Goderdzishvili G.S. 1980. Biological features of Pear Sawfly in Georgia. In: Gvritishvili M.N., ed. Materials of the Transcaucasian coordination meeting on plant protection (May, 15-16 1980). Tbilisi: Georgia SSR Research Institute of Plant Protection. p. 170-173 (in Russian).
Koltun N.E., Yarchakovskaya S.I. & Supranovich R.V. 2007. Pear Sawfly. In: Orchard diseases and pests. Minsk: Krasiko-Print. p. 19-20 (in Russian).
Onufreichik K.M. 1970. Pear Sawfly (Caliroa limacina Retz.) in Western Belarus. Biology and agrotechnics of agricultural crops. Proceedings. Gorki: Belarus Agricultural Academy. V. 64. p. 179-185 (in Russian).
Onufreichik K.M. 1975. Some ecological features of Pear Sawfly. In: Protasov N.I., ed. Rational methods of plant protection against pests, diseases and weeds. Proceedings. Gorki: Belarus Agricultural Academy. V. 140. p. 68-74 (in Russian).
Savkovskii P.P. 1976. Atlas of pests of fruit and berry crops. Kiev. Urozhai. 207 pp. (in Russian).
Talitskii V.I. 1958. Some data on Pear Sawfly biology. In: Kabluchko G.A., ed. Bulletin of scientific and technical information. Kishinev: Moldavia Research Institute of the Orcharding Winegrowing and Winemaking. N1. p. 14-16 (in Russian).
Vasil.ev V.P. & Livshts I.Z. 1984. Orchard pests. In: True sawflies (Tenthredinidae). Second revised edition. Moscow: Kolos. p. 252-253 (in Russian).
Zhelokhovtsev A.N. & Zinov.ev, A.G. 1996. A list of the sawflies and horntails (Hymenoptera, Symphyta) of the fauna of Russia and adjacent territories. Entomol. Review 75 (2): 357-359 (in Russian).
Zhelokhovtsev A.N. 1988. Order Hymenoptera. Suborder Symphyta (Chalastogastra). In: Keys to insects of European part of the USSR. V. 3. Part. 6. Leningrad: Nauka. 288 p. (in Russian).