Pests
Phthorimaea operculella Zeller - Potato Tuber Moth
Systematic position.
Class Insecta, order Lepidoptera, family Gelechiidae, genus Phthorimaea.Synonyms.
Gnorimoschema operculella Zell., Phthorimaea terella Wlk., Gelechia solanella Boisd.Biological group.
Oligophagous pest of solanaceous plants.Morphology and biology.
Moth is small, light gray. Wings of quiet moth are roof-like. Forewings are widely lanceolate; wingspan 12-15 mm. A longitudinal, blackish stripe and dark points form along median crease. Hindwings almost as wide as forewings, with folded external edge and a fringe longer than it is wide. Antennae are gray with well-designated joints. Last abdominal segment is almost equal to 1/3 the length of the abdomen in the male. In female, the anal segment is of usual length. The apex of male abdomen is strongly pubescent, covered in dense, hairy bunches. Egg oval, 0.4-0.6 mm in length, to 0.4 mm in width, at first pearl-white, later yellow and dark. Older larva flesh-colored or yellowish green, with a pale longitudinal stripe along the median of its back, 10-13 mm in length, 1.5 mm in width. Pupa is brown, 5.5-6.5 mm in length. The abdominal apex has a small cremaster and chaetae. It develops in a silky cocoon of grayish silvery color that reaches 10 mm in length. In field conditions, the adult larva or pupa winters under crop residues in upper layer of ground; in storehouses, the pest winters during all stages of development. In nature, moth emergence takes place at the end of April or in May, and imago is found until the end of October. Moths are active after sunset and at dawn. They can live 30 days, laying eggs in groups of 2-3 or individually on the lower sides of plant leaves, sometimes on leafstalks, stems, exposed potato tubers, lumps of soil in field, on potato tubers at buds and on bags in storehouses. Female fecundity is 150-200 eggs, 165 on average. Embryonic development lasts 3-10 days. Hatching caterpillars actively move in search of forage. Caterpillars form tunnels under epidermis of leaves and stalks, eating away parenchyma. One larva makes 3-4 tunnels, gradually filling them with excrement. The larvae more often penetrate tubers through buds. They create twisting tunnels in fruits and tubers. Web-like interlacing of leaves and damage to stalks and sprouts occur more often in top part of plants. Larval development continues for 11-14 days while caterpillars pass through 4 instars. Pupation occurs inside hidden cocoons located in various shelters (under dust, on bags, in floor cracks). Pupal stage lasts 6-8 days. In storehouses, the pest reproduction proceeds continuously.Distribution.
The Potato Tuber Moth originated in Southern and Central America. Most of the species distribution area falls along equatorial and tropical climatic belts. It has penetrated into Europe since the beginning of 20th century (Italy, Spain, Portugal). It is now widely distributed all over the world, registered in more than 70 countries in North and South America (and on adjacent islands); in Asia (Japan, Vietnam, Korea, China, India, Pakistan, Iran, Iraq, Afghanistan, Syria, Turkey, Cyprus, Sumatra, and Java); in Africa (Algeria, Kenya, Congo, Morocco, Sierra Leone); in Australia, New Zealand and on islands of Oceania; in Europe (Spain, Portugal, France, Italy, Greece, Albania, Bulgaria, republics of the former Yugoslavia, Ukraine, Moldova, Georgia). In the Russian Federation, the species is distributed in the south of the European region only, i.e., in the Krasnodar Territory (since 1981) and sparsely throughout the Rostov Region; it is also found in the Primorskii Territory of the Far East. It is assumed that the Potato Moth distribution area is limited naturally to an average annual isotherm of 10°C. The pest can acclimatize itself in the Rostov and Astrakhan Regions.Ecology.
Polyvoltine species. The Potato Moth develops 3-4 generations in the Krasnodar Territory and 4-5 generations in Southern Ukraine. Lifecycle from egg to imago lasts 22-30 days in summer and to 2-4 months in winter. Lethal temperatures for all stages of the pest are below -4 and above +36°C. Optimum conditions for moth development are temperatures of 22-26°C and air humidity levels of 70-80%. Caterpillars can tolerate sharp temperature fluctuations, remaining alive even when tubers freeze. Moth vitality is manifested in a wide range of positive temperatures from 8-35°C. The Potato Moth has no diapause in ontogenesis, which allows its continuous development under suitable temperature conditions and forage presence (in potato storehouses). Possessing high ecological plasticity, the pest can adapt for a life in temperate climates with a sum of active temperatures (above 0°C) of 4,000°C or less. Caterpillars of the pest are oligophages, specializing in feeding on plants of the family Solanaceae only. The Potato Tuber Moth has a significant amount of parasites and predators. In all developmental stages, it spreads mainly by transportation of potato tubers, fresh fruits of tomato and eggplant, and on tobacco packages and boxes taken from infected farms and areas.Economic significance.
A dangerous pest of solanaceous cultures, particularly potato. It also damages eggplant, tomato, pepper, and tobacco. Tobacco leaves are severely injured during drying. It prefers to eat such weeds as datura, ground-cherry, nightshade, henbane, belladonna, and nicandra. Potato storehouses are a basic reservation of the moth, where the significant part of damaged tubers undergo rotting; thus, losses reach 25-80%. In southern regions of Ukraine, the moth invasion of potato plants reaches 75%, and tuber damage reaches 60%. Quarantine actions include the inspection of cargo and vehicles from countries in which the pest is distributed; disinfecting vehicles and industrial cargo; monitoring with pheromone traps 3-5 km around primary import stations; and strict quarantine of solanaceous cultures arriveing from the infected regions. Control measures include mowing and destruction of potato tops 5-7 days before their drying; rapid harvest and removal of all potato tubers from field; potato tuber fumigation with bromic methyl according to instructions; regular elimination of nightshade weeds; insecticide treatments in fields in zones of wide and limited distribution of the pest according to regular recommendations; and the use of bio-preparations.Related references.
Kudina, Zh.D. & Semenenko, A.V., eds. 1981. Temporary methodical instructions on revealing and control of the Potato Tuber Moth. Kiev: Urozhai, MSKH Ukrainian SSR, 23 p. (in Russian).L.vovskii, A.L. & Piskunov, V.I. 1999. Fam. Gelechiidae - wing-emarginated moths. In: Kuznetsov, V.I., ed. Insects and mites - pests of agricultural crops. Lepidoptera. St. Petersburg: Nauka. V. 3, part 2, p. 46-93 (in Russian).
Omelyuta, V.P., ed. 1990. Revealing of potato tuber moth and its control (recommendations). Authors collective. Moscow: VO Agropromizdat, VASKHNIL, UkrNIIZR. 17 p. (in Russian).
Shutova, N.N. 1970. Potato tuber moth. Moscow: Kolos, 10 p. (in Russian).
Shutova, N.N., Smetnik, A.I. 1986. Quarantine pests, diseases and weeds. In: Shamonin A.I., Smetnik A.I., eds. Plant quarantine in the USSR. Moscow: Agropomizdat, p. 143-248 (in Russian).
Vasyutin, A.S., ed. 2000. Quarantine phytosanitary state of the Russian Federation for January 1, 2000. Moscow: MSKH RF, 96 p. (in Russian).
Vasyutin, A.S., ed. 2004. Reference-book on quarantine phytosanitary state of the Russian Federation for January 1, 2004. Moscow: MSKH RF, 102 p. (in Russian).
Vasyutin, A.S., Kayumov, M.K., Mal.tsev, V.F. 2002. Quarantine of plants. Moscow, 536 p. (in Russian).