The monitoring showed that the pest species formation on the winter wheat developed gradually during vegetation.
In different periods of plants development, the phytophages complex consisted of the species that migrated from other biotops and those having wintered on the fields.

It was investigated that the biggest threat for the winter wheat was the com-bug, the bugs of Pentatomid family (Homoptera series), greenbugs (Aphididae family), flower thrips (Haplothrips tritici Kurd.), cereal chafer (Anisoplia austriaca Hrbst.), turnip dart (Agrotis segetum Schiff), frit flies (Cecidomyidae and Cloripidae families), leafhoppers: Deltocephalus striatus (Psammotettix striatus L.), Macrosteles sexnotatus (Macrosteles laevis Rib.), smaller brown plant hopper (Laodelphax striatella Fall.).

The following insects were always in the biocenosis of a wheat field: click beetles (genus Agriotes L.), bugs of Miridae family (Miridae), tarnished plant bugs (Lygus), corn ground beetle (Zabrus tenebrioides Goeze.), cereal leaf beetle (Oulema lichenis Voet.), striped flea beetle (Phyllotreta vittula Redt.), corn sawfly (Cephus pygmaeus L.).

The dominating entomophages were the following: seven-spot ladybird (Coccinella septempunctata L.) and two-spot (Adonia dipunctata L.); predatory thrips (Aeolothrips intermedius Bagn.), predatory ground beetles (Caradidae), common green lacewing (Chrysoperla larnea St.) and hoverflies (Syrphidae). The entomophages did not play any essential role in the limitation of pest number.

Each stage of crop formation is supplied by a certain pest insect species.

As our research shows, the most frequent on average during germination and stooling were the plant louse (17 insects per plant). The made up to 40 % of the total pest entomocomplex. In the same period, the leafhopper was observed with the density about 18 insects per m². They also wintered on the winter crop. In the stooling period, the number of plant louse and leafhopper did not exceed the threshold number.

The leafhoppers stayed on the field during the vegetation with the highest density during grain ripening – 49,4 insects per m² which is not higher then threshold (150 insects per m²).

The migration of com bugs from their wintering places to the wheat fields was observed in the first decade of May. The bugs of the family Pentatomid (Bishop’s Mitre Shieldbug, Aelia rostrate, Carpocoris fuscispinus, sloe bug) migrated from the perennial cereal grasses to the winter wheat after the earing. The beginning of larvae rebirth was at the blossoming phase. In this period their density was 2,8 insects per m². The bug’s larvae and imago of Pentatomidae family and com bugs were nourishing from the not rape grain. Their density however was 6,1 insect per m² and did not exceed the threshold of 8-10 insect per m².

During 2014 and 2015 the population of wheat by the Anisoplia austriaca coincided with the phase of wax ripeness. Thus the nourishing conditions were favourable for them. The insects populated the edges of the wheat field with the highest number of them. In general, the insects density was during two years in the phase of full ripeness about 4,2 insect per m² which was not higher than threshold. Population of cereal leaf beetle imago on the wheat fields started beginning of May, which coincided with the phase of stem elongation. The period of nourishment of cereal leaf beetle larvae lasted about one month and coincided with earing, blossoming and ripening. The highest density of the insect was during grain formation – 4,9 insects per m².

The first colonies of aphids on the winter wheat were observed at the end of stem elongation. Their number was not big. The weather condition was favourable for the aphid population growth. Their maximum number was observed in the period of milky ripeness (29,4 insects per stem). At the end of the first decade of July, the abrupt decrease of aphid population began, the masses of them died so that only single insects could be observed on the unripe ears before harvesting. The aphid death was due to the hardening of plants tissue, nourishment deterioration and activity of natural enemies.

The systematic observation of crops for pest population is prerequisite for decision about the need of pest control chemicals application. The main objects for chemical treatment in summer period were aphids and bugs larvae. Beginning second decade June 2014 and 2015, the winter wheat was sprayed against the pest. The efficiency of the following insecticides was studied: Actara 240 SC, s.c. (tiametoxam) 0,15 1/ha, Bi-58 new 40 % e.c. (diametoat) 1,5 1/ha, Karate 050 EC, e.c. (lambda-cyhalotrin) 0,20 1/ha in conditions of agricultural cooperative Rozaliivski.

Before the experiment, the aphid density was on average during two years 28,4 insects per plant. On the third day after spraying by Actara 240 SC, the insects density decreased by 84,5 % and after Karate 050 EC by 88,3 %. The high start efficiency showed Bi-58 new – 91,3 %. Further on the efficiency of Actara 240 SC and Karate 050 EC increased and exceed 90 % on the day 7.

The efficiency of Bi-58 new 40 % decreased after some time and went down to 85,3 % on the day 7. High technical efficiency was shown also by synthetic pyrethroid Karate 050 EC and neonicotinoid Actara, 93,1 and 89,3 % respectively. Thus, at aphid population on winter wheat with the density exceeding the threshold, it could be recommended to apply the following preparations: Actara 240 SC, s.c. (tiametoxam) 0,15 1/ha, Bi-58 new 40 % e.c. (diametoat) 1,5 1/ha, Karate 050 JEC, e.c. (lambda-cyhalotrin) 0,20 1/ha as the technical efficiency of these insecticides is ranging between 85,3 and 93,7 % on the day 7.

The industrial efficiency analysis of the above preparations showed that they reliably protect the winter wheat against aphid and favour the yield increase.

The yield obtained during two years ranged on average from 15,3 to 16,9 centner/ha. The highest yield was obtained by application of Actara 240 SC – 66,5 centner/ha. Good results and essential yield increase were achieved also by other preparations used. The check yield of winter wheat without application of insecticides was the lowest – 49,6 centner/ha.

Key words: winter wheat, monitoring, phytophages, cereal aphids, bugs, insecticides.