Abstract

This paper presents a part of the results of a study which we conducted in the Bârnova forest. Two ichneumon wasps species: Allophatnus aetnensis (Rudow, 1883) and Hoplocryptus besseianus (Seyrig, 1926) (belonging to Cryptinae subfamily) are report for the first time in the Romanian fauna

Abstract

The paper presents some aspects about the attack and biology of Apethymus filiformis (Klug.), a non-indigenous defoliator pest of the sessile oak forest stands, Quercus petraea (Matt.) Liebl., 1784. It was recorded for the first time in Romania in 1999, but misidentified as Apethymus abdominalis Lep., a synonim of A. cereus Klug., an accepted species, but not present in the Romanian fauna. We established five new host – parasitoid relationships. In the laboratory we obtained from Apethymus filiformis larvae, by rearings, five new ichneumonoid parasitoid species: Charmon extensor (Linnaeus) (Hymenoptera: Braconidae: Charmontinae), Temelucha ophtalmica (Holmgren) (Hymenoptera: Ichneumonidae: Cremastinae), Gelis cinctus (Linnaeus) (Hymenoptera: Ichneumonidae: Cryptinae), Diplazon laetatorius (Fabricius) (Hymenoptera: Ichneumonidae: Diplazontinae), and Phytodietus ornatus (Desvignes) (Hymenoptera: Ichneumonidae: Tryphoninae).

Abstract

The paper presents 10 species of ichneumon wasps, one of them being reported for the first time in the Danube Delta Biosphere Reserve, Romania. Research has been carried out in some invasive plants areas of the Danube Delta Biosphere Reserve. There are being reported representatives of arthropod fauna (Insecta and Araneida) from four stations containing invasive plants: Pătlăgeanca, Beștepe, Plauru and Sabangia. One particular interest was the identification of the ichneumon wasps species in these areas

Abstract

Abstract

The paper presents 14 species of ichneumon wasps, three of them being reported for the first time from the Danube Delta Biosphere Reserve. Research has been carried out in some agricultural areas of the Danube Delta Biosphere Reserve. There are being reported representatives of arthropod fauna (Insecta and Araneida) from four stations: Murighiol (barley culture), Sarinasuf (alfalfa culture, the shores of Lake Razelm), Beștepe (sunflower culture) and Beștepe (colza culture). One particular interest was the identification of the ichneumon wasps species in these areas.

Abstract

Frequently, in polytunnels are found some nonparasitic or physiological disorders on vegetable plants such as tomatoes, peppers, eggplants, and some melons. The growing stagnation of tomato plants cultivated in polytunnels is evidenced by some symptoms that appear during the vegetation season. These symptoms may be due to biotic (e.g., diseases, pests) and environmental factors such as high fluctuations in soil moisture, low or high values of relative humidity of air, atmospheric drought, high temperatures, soil characteristics, etc. One of the soil attributes that favours physiological disorders, are also the substrate reaction, characterized by pH values lower than 5 or higher than 8. High content of some nutrients such as N, K, Mg, Na, Mn, antagonists to Ca, can also induce physiological disorders. The physiological disorders symptoms are manifested especially on the leaves and fruits. Some physiological disorders can often be misidentified as caused by pathogens, for example Blossom End Rot, can often be misidentified as gray rot caused by pathogen Botrytis cinerea Pers., which is a fungus (Ascomycota). Both disorders manifests by brown spots on fruit skin surface, both are favoured by high humidity and weak airing in polytunnels. One of the objectives of the paper is the environmental factors characterization which influence tomato plants affected by nonparasitic disorders such Blossom-end rot or leaf curling and leaf distorting. Following our investigations, it was found that frequently, some symptoms on tomatoes were not due to a parasite action. The correct identification and differentiation of parasitic disorders caused by the environmental factors, presents a particular practical importance in order to establish prevention measures and cultural recommendations.

Abstract

The aim of our proposals for soil sampling regarding mesofauna study in soils from greenhouses or polytunnels is motivated by the high soil heterogeneity and large variability of easy exchangeable soil properties such as water content, soluble salts distribution especially under drip irrigation and local fertilization. The intensive technology for growing vegetables or flowers, high irrigation requirements and the high soil moisture favors, in short time the degradation of morphological, physical, chemical properties and especially biological activity of the greenhouses soils. The large variability of the mesofauna species with different requirements to environmental conditions (e. g., hygrophilous to xerophilous species as regards soil humidity, salt tolerant or sensitive species to soil salinity etc.) has lead us to adapt soil sampling methods to particular conditions of every location. One of particular situation was in greenhouse where practice drip irrigation and local fertilizations of tomato plants. Using the adapted sampling methods, the identified mesofauna species confirmed the large variability of soil properties from plant rows, on the border of wetting strip, at middle distances of the plant rows and on the horticultural substrata used for seedling obtaining. After processing of field and laboratory obtained data we consider that proposed diagram for design location is useful for practical application in order to detect initiation processes of soil degradation and establish the proper measures to prevent decreasing soil quality. © SGEM 2018.

Abstract

Our investigation has been focused on establishing the slowing down plant growth at the border of polytunnels. In order to determine the limiting factors of plant growth, we have conducted studies on soil properties, entomofauna and soil mesofauna. The research has been carried out in several polytunnels located in North Eastern Romania (Bacău, Iaşi, Bârlad, Fălticeni, Hârlău, Târgu Frumos, Matca-Tecuci) In the field were developed and characterized soil profiles and samples were taken to determine the states of compactness and humidity. The results of researches revealed a strong growth stagnation of tomatoes, cucumbers, eggplants and peppers. The areas where plants have recorded the lowest growth are found in the lateral parts and at the entrance to the polytunnels, as a result of the larger amounts of rainfall, recorded during the vegetation season. Following the analysis, we found that there is a direct correlation between the width of the over wetted soil strip in the lateral parts of the polytunnel and its constructive parameters (width, height, plastic or glass walls), the distance between the polytunnels and the characteristics of the ploughed and under ploughed soil layers. As a result of a pluvial front, the amount of water fallen on the soil unit between the polytunnels, is 6 to 20 times higher than the land in the vicinity of the polytunnels, due to the water flowing from both sides of the solarium. Compaction of the plough layer between the polytunnels, the presence of the hardpan layer, are the additional factors on which the water infiltration rate depends. In addition to the growing stagnation of cultivated plants, a more pronounced incidence of diseases and a more intense attack of the pests, represented by Thysanoptera (Thrips tabaci) and Homoptera, especially aphids – Myzus persicae and Hemiptera – greenhouse whitefly (Trialeurodes vaporariorum). Mesofauna is known as indicator of edaphic conditions, such as water excess. Our investigation revealed very large differences, both quantitative and qualitative, between samples with excess moisture and dry soil between rows. Thus, the average global density was about 35 times higher in the excessively wet soil, and some groups missing in the dry soil are present here (Astigmata and Trombidiformes among mites), whereas. © SGEM 2018.

Abstract

Abstract