Haplothrips tritici Kurd. - Wheat Thrips

Systematic position.

Class Insecta, order Thysanoptera, suborder Tubulifera, family Phloethripidae, tribe Haplothripini, genus Haplothrips.

Biological group.

This is an oligophagous pest of small grains, primarily wheat.

Morphology and biology.

The body is elongated, thin and black-brown to black. Head is 1.1-1.2 times longer than wide. The eyes are dark-brown, almost black, large, 1/3 to . of head length. 2nd antennal segment in apical part yellowish-brown; 3rd one yellow, blackened at apex, bearing two sensilla; 4th one yellowish at base and on each side; 5th segment yellowish-brown at the extreme base only. Fore tibia yellow except for the base and edges, fore tarsus yellow. Wings with 5-8 additional cilia, transparent, blackened at base. Female length is 1.5-2.2 mm and male length is 1.2-1.3 mm. Thelytoky (males occur rarely and do not participate much in reproduction) is registered in some regions, while in the others arrhenotoky (sex ratio near to 1:1) is common. Egg is pale-orange, oblong-oval, 0.5-0.6 mm long. Mature larva is bright red, with two setae at the end of abdomen. A single generation develops per year. Larvae over-winter underground and among stubble. In spring they rise to the surface where they pass through a complicated metamorphosis (pronymph, nymph I, nymph II, adult). Part of larvae metamorphosis occurs underground. Adult has immature ovaries and requires additional feeding. Female fecundity is estimated at 13-30 eggs. Eggs develop over a period of 6-11 days. First instar larva are greenish-yellow, becoming reddish after hours, and bright red after the first molt. The second molt occurs after wintering.


The species is widespread in steppe and forest-steppe regions, belonging to the Euro-Siberian faunistic complex. In the territory of the former USSR it inhabits the European part, Siberia, Kazakhstan, Central Asia. Outside the former USSR it is widespread in Western Europe, Asia Minor and North Africa.


The spring emergence of larvae from wintering places usually starts at soil temperatures of 8°C and higher. The period of metamorphosis is strongly prolonged (about one month). Adults appear at the beginning of ear formation of winter cereals, usually in May-June. During development of cereals thrip adults invade winter rye at first, then winter wheat. The most intensive flight coincides with the beginning of ear formation of spring wheat where the great bulk of adults concentrate. Flying adults migrate by way of air streams at heights of 1.5-2 m. Most often they feed behind a sheath of penultimate leaf, sucking sap from the gentlest part of ear husk. Females lay their eggs in small groups containing 4-8 eggs each or, less frequently, one at a time, on the interior sides of ear scales and ear shank. The egg-laying period lasts 25-35 days. First larvae suck sap from ear scales and flower glumes, then from caryopsis. Larval peak density occurs during the milk development stage of seeds. During the stage of early dough development the larvae start to leave ears. The main host plants are winter and spring wheat, rye, wheatgrass and some other gramineous plants; spring wheat is the most favorable for insect development. Dry and warm weather during ear emergence and flowering of wheat (the period of egg-laying and the beginning of larva feeding) promotes increased insect survival; prolonged air drought and cool rainy weather are both unfavorable for insect development. Hot dry weather at the end of summer may also be unfavorable for insect survival due to the promotion of fast grain ripening and corresponding shortening of the larva feeding period. In spring the larvae passing through metamorphosis perish because of heat and lack of moisture. In autumn and spring many larvae die during rainy weather which favors development of entomopathogenic fungi, namely Entomophora spp. and Beauveria bassiana. Predatory thrips, Aelothrips spp., as well as other predators such as bugs, ladybirds, lacewing larvae, ground beetles, staphilinids and robber flies are capable of causing a drop in thrip numbers. When preparing to hibernate the larvae can penetrate into soil to a depth of 10-20 cm or more (to 90 cm).

Economic significance.

The insect causes strong damage to wheat, especially to summer wheat, whose development is related most closely to the insect life cycle. To a lesser degree the pest harms winter rye, barley, and other cereals. Both adults and larvae are dangerous, but the latter are usually more noxious, invoking partial or complete white ear effect, drying of flag leaf, partial ear fertilization, and incomplete grain filling. During the pest outbreaks the larva density on sowing can reach 200 and more individuals per ear (Tanskii, 1962). According to Tanskii the weight losses can reach 5-7% in poorly damaged grain, but 15-31% and more in strongly damaged grain. Unlike the Sunn Pest, the flour-baking quality of grain damaged by thrips does not decrease, however the sowing quality of seeds drops notably.

Control measures.

Control measures include the following: duly short-timed two-phase harvesting, early under-winter plowing, thorough pre-sowing treatment of winter tillage, short-timed wheat sowing, maintenance of crop rotation, growing of early-ripening wheat cultivars, expansion of acreage occupied by tilled crops and chemical treatments if necessary (especially for wheat seed sowings).

Reference citations:

Dyadechko N.P. 1964. Thrips, or fringewinged insects (Thysanoptera) of the European part of the USSR. Kiev: Urozhai. 387 p. (In Russian)
Fisechko R.N. 1976 a. Allocation of wheat thrips (Haplothrips tritici Kurd.) on different varieties of spring wheat. Zashchita rastenii ot vreditelei i boleznei v Zapadnoi Sibiri. Novosibirsk: SibNIIKhim. 9-14 p. (In Russian)
Fisechko R.N. 1976 b. Bioecological features of wheat thrips in north Kulunda and Ob forest-steppe. Zashchita rastenii ot vreditelei i boleznei v Zapadnoi Sibiri. Novosibirsk: SibNIIKhim. 32-36 p. (In Russian)
Grivanov K.P. 1958. Wheat thrips. Trudy Nauchno-Proizv. Kong. po zashchite rastenii ot vreditelei i boleznei na Yugo-Vostoke. Saratov: NIISKh. 50-57 p. (In Russian)
Shurovenkov Yu.B. 1971. Wheat thrips in Transural region and its control. Moscow: Kolos. 89 p. (In Russian)
Sitchenko N.N. 1972. Thrips (Thysanoptera) as pests of cereals in conditions of Ukraine. PhD Thesis. Kiev: Ukr. Sel'skokhoz. Acad. 18 p. (In Russian)
Tanskii V.I. 1959. Wheat thrips in regions of developing virgin and long-fallow lands in North Kazakhstan. PhD Thesis. Leningrad: VIZR. 18 p. (In Russian)
Tanskii V.I. 1961. Formation of thrips (Thysanoptera) fauna of wheat sowings on new lands of North Kazakhstan. Entomol. Obozr. 40(4): 785-793. (In Russian)
Zhichkina L.N., Kaplin V.G. 2001. Features of biology, ecology and harmfullness of wheat thrips, Haplothrips tritici Kurd. (Thysanoptera) in forest-steppe of middle Volga region. Entomol. Obozr. 80(4): 830-842. (In Russian)

© Frolov A.N.


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