OBSERVATIONS CONCERNING THE HARMFUL ENTOMOFAUNA FROM WINTER RAPESEED CROPS IN THE CONDITIONS OF CENTRAL OF MOLDAVA, BETWEEN YEARS 2014-2017

: During 2014-2017, 22 species were identified in the yellow bowl trap type installed in winter rapeseed crops established at A.R.S.D. Secuieni. Of these, 11 species are specific to winter rapeseed crops and 11 species were accidental identified because of the proximity with different agricultural crops (maize. sunflower. grain cereals). The highest abundance was registered by Epicometis hirta Poda species which accounted 914 specimens collected during the analyzed period. The species were integrated into classes of dominance ((D1 - subrecedent species. D2 - recedent species. D3 - subdominant species. D4 - dominant species and D5 - eudominant species). Meligethes aeneus F., Ceuthorrhyncus napi Gyll. and Epicometis hirta Poda. being considered eudominant species belonging to the D5 class. The Ceuthorrhynchus napi Gyll., Meligethes aeneus F., Epicomites hirta Poda., Psylliodes chrysocephala L., Subcoccinella 24 punctata L., Oulema melanopa L. species were classified in the constancy class - C4 - euconstant species. Meligethes aeneus F., Epicometis hirta Poda and Ceuthorrhynchus napi Gyll. species recorded the highest values for the index of ecological significance (W %) and were classified in the W5 class - characteristic species. The collected entomofauna belongs to five orders: Coleoptera, Heteroptera, Lepidoptera,. Diptera and Hymenoptera. The highest number of species (17 species) and the highest number of collected speciemens (3246 specimens) belonged to the Coleoptera order.


INTRODUCTION
Rapeseed crops involves a careful plant surveillance because it is one of the most ssusceptible crop to pest attack throught the phenological development of plants. Knowing the harmful species, which by attacking the different plant organs (leaves, stem, floral buds, flowers) leads to low productions of poor quality, it is important because teoretical knowledge combined with practical knowledge ensure the establishment of the suitable treatment moment [1][2][3][4][5][6][7].
The researches conducted to identify the pest atack correlated with influence of zonal agroecological factors has led to the establishment of the climate changes impact on winter rapeseed crops entomofauna. The drought which appears more frequently in the spring and summer months, the succession of high temperatures and low

EXPERIMENTAL SETUP
The researches were conducted at the Agricultural Research -Development Station Secuieni -Neamt on the rapeseed crops. during 2014-2017 and consisted on collecting the harmful entomofauna from winter rapeseed crops, determining it and establishing of some ecological parameters represented by abundance, species dominance, constancy and index of ecological significance.
In spring, were installed yellow bowl trap type in the winter rapeseed crops, aiming to collect the harmful organisms, between the stem elongation phenophase until the end of seed ripening phenophase. The biological material was colected in Petri dishes, clear of vegetable remanins and analyzed in the laboratory at microscope, then grouped on species and orders.
The collected material was subjected to a mathematical analysis, obtaining a number of ecological parameters: abundance (A), dominance (D), constancy (C) and index of ecological significance (W), wich highlight the characteristics of the analyzed biocenoses.
The abundance (A %) represents the total number of individuals of a species in the catch from a centain place on a given date. Based on the value of this indicator, the other indicators are calculated.
The dominance (D %) shows the participation percentage of each species in the catch. Explains the relationship of a species herd with the sum of the individuals of the other associated species. This indicator is calculated according to the equation (1): where: D is dominance; A -species abundance; NA -the total number of individuals of A species; N1 -the total number of individuals of the collected species.
The constancy (C %) expresses the continuity of a species occurrence in the analyzed biotope. This characteristic is a structural indicator because it shows the participation proportion of a species in the biocenosis structure. The higher the value of the indicator, the more the species is better adapted to the conditions offered by the biotope. The constancy is calculated according to the equation ( (2) where: CA represent the constancy of A species; np·A -the number of samples in which the A species occures; Np -total number of collected samples.
The index of ecological significance (W %) represents the relationship between the structural indicator (C) and the productive indicator (D) and is calculated using equation (3): where: WA are the ecological significance index of A species; CA -constancy of A species; DA -dominance of A species.

RESULTS AND DISCUSSION
From the observations and determinations carried out on the entomofauna collected from winter rapeseed crops, it was found that it was made up of 22 species that totalized over the entire observation period (2014-2017) 3447 specimens (Table 1).
In 2016 were registered 1502 specimens and it was the year with the highest number of specimens collected, in 2015 were collected 1038 specimens, followed by the year 2014 with 618 specimens, and the lowest number of insects collected was recorded in 2017 -289 specimens.
During the analyzed period, it was found that the indentified species had values ranging from one specimen at Agriotes spp. species to 914 specimens at Epicomites hirta Poda species. The highest number of collected specimens was recorded in the following species  Table 1).
There were found other species of insects, which have been categorize as accidental species coming from proximity crops (maize. sunflower. grain cereals): Ostrinia nubilalis Hbn., Chlorops pumilionis Bjerk., Tanymecus dilaticollis Gyll., Crepidodera ferruginea Scopoli., Oscinella frit L., Oulema melanopa L., Eurygaster spp., but also entomophagus species (Subcoccinella 24 punctata L.). From Table 2, it can be noted that the collected species were classified in dominance classes as follows: -nine species belong to D1 class -subrecedent species with a spreading percentage below 1.0 %; -three species were classified to D2 classrecedent species with a spreading rate ranging from 1.2 % -2.0 %; -two species were classified in D3 classsubdominant species whose spreading rates were between 2.1 % -5.0 %; -four species belong to D4 classdominant species with spreading rates between 5.1 % -10 %; -three species were classified in D5 classeudominant species whose spread percentage was higher than 10.1%. Ostrinia nubilalis Hbn 7 Phyllotreta nigripes Fabr. 8 Eurygaster spp 9 Oulema melanopa L. Total 9 species 3 species 2 species 4 species 3 species Calculating the precentage of harmful entomofauna on dominance classes it was found that in D1 class, species with sporadic spreading were recorded 3.46 % of the collected species. From D2 class, species with low spreading, belong 4.84 % from the identified species. In D3 class, species with middle spread, were recorded 7.12 % of the total, 27.34 % belong to D4 class, dominant species, and in D5 class, eudominant species, were recorded 57.34 % from the collected species (Figure 1).   Depending on the index of ecological significance (W), the species were classified as follow (Table 4) Fig. 3. The species share from Coleoptera order in rapeseed crops.

CONCLUSIONS
During 2014-2017 were identified 22 species using the yellow bowl trap type installed in winter rapeseed crops established at A.R.S.D. Secuieni.
Of these, 11 species are specific to winters rapeseed crops and 11 species were accidental identified due to their proximity to different agricultural crops (maize, sunflower, grain cereals).
The highest abundance was recorded by Epicometis hirta Poda species with 914 specimens collected during the analyzed period.
Meligethes aeneus F., Epicometis hirta Poda and Ceuthorrhynchus napi Gyll. species recorded the highest values on the ecological significance index (W%) and were classified in W5 class -characteristic species.
The analyzed entomofauna belongs to five orders: Coleoptera, Heteroptera, Lepidoptera, Diptera and Hymenoptera. The higest number of species (17 species) and the highest number of collected speciemens (3246 specimens) belonged to the Coleoptera order