ISHS Acta Horticulturae 293: IX International Symposium on Apricot Culture
FAUNAL INVESTIGATIONS IN THE APRICOT ORCHARDS IN BULGARIA |
| Author: | L. Ivanova |
| Abstract:
The main horticultural species in the Silistra region is the apricot and 53% of the apricot plantations in Bulgaria are situated here. The increase of the apricot acreage and its concentration in big massifs led to the increase of the negative influence of the pests. Those of economical importance gained the opportunity of multiplying on a large scale. The long life of the apricot culture allows the formation of entomofauna for a long period of time in the plantations, its keeping in a relative balance and its slow enrichment on a given place. The purpose of this investigation was to establish the species and the quantity of the fauna in the industrial apricot orchards in Bulgaria; to study the relationships between the host, the pests and the useful insects in order to restore the biological balance in favour of man, to clarify the reasons for the alteration of the pest populations and the reliable parasites and predatory insects, using the ecological approach. To investigate the species and the numerical dynamics of the harmful, useful and neutral entomofauna, trials have been carried out in the period of 1979–1985 in a fructiferous apricot plantation of 150 dka with the main cultivars: Hungarian apricot, Early Kishinevska, Early Silistrenska, Festival, Silistrenska kompotna, Mirculesti etc. The following methods have been used: route inquiries, visual method, method of baits (food, colour, sexual, light baits,) shaking, mowing, soil excavations. Every 7–10 days during the vegetation period observations and countings of the populations of the harmful, useful and neutral insects and acari were made. The trial area was divided into 3 variants: I variant-control, in which no chemical treatment was done - 20 dka; II variant-integrated, sprayed in accordance with the density of the main pests with less toxic chemicals - 65 dka and III variant-chemical, sprayed in the traditional way, adopted in the practice - 65 dka. As a result of this investigation 90 harmful, 79 useful and 91 neutral species have been established, belonging to 3 classes: Insecta, Nematoda and Arachnida. The established harmful species are the main determining element in the entire fauna of the apricot culture (table 1). The separate harmful phytophagi from different classes and orders are not equally adapted to the apricot tree. According to the degree of connection with the host and the way of regarding it we classify them provisorily in three groups; persistent, non-persistent and occasional (table 2). Apricot trees are among the main hosts for the persistent pests. Here we relate the species: Anarsia lineatella Zell., Grapholitha molesta Busck., Lymantria dispar L., Euproctis chrysorrhoea L., Orgyia gonostigma L., Orgyia antiqua L., Sphaerolecanium prunastri F., Tmetocera ocellana F., Hedia nubiferana How. and others. The non-persistent pests do not infest the apricot trees | |
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