Andmebaasi logo

3. Doktoritööd

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/2490

Sirvi

Sirvi 3. Doktoritööd Autor "Arus, Liina" järgi

Nüüd näidatakse 1 - 1 1
  • Pisipilt
    Kirje
    The influence of cultivar and natural enemies on raspberry beetle (Byturus tomentosus De Geer)
    (Eesti Maaülikool, 2013) Arus, Liina; Luik, Anne (advisor)
    The raspberry beetle (Byturus tomentosus De Geer), which is the main raspberry pest, causes large yield losses and reduces fruit quality of raspberry. Control of the raspberry beetle relies on synthetic chemical insecticides, which pollute fruits and the environment and also kills the natural enemies of the pests. The present study focuses on the susceptibility of raspberry cultivars to raspberry beetle and on determining the pest’s natural enemies to maximise the biocontrol of the raspberry beetle by promoting the pest’s natural enemies with different cultivation technologies. The results of the study showed that by choice of cultivars and promoting natural enemies with cultivation technologies it is possible to regulate the raspberry beetle population. Phenological synchronisation between beginning of flowering of cultivars and raspberry beetle oviposition period plays a key role. Early flowering cultivars are phenologically better synchronized with the oviposition period of raspberry beetle. The early flowering cultivars ‘Novokitaivska’, ‘Aita’, and ‘Ivars’ were the most damaged, being more susceptible to raspberry beetle. Of the late flowering cultivars, ‘Glen Ample’ and ‘Glen Magna’ were less damaged than the others. In raspberry plantations the species’ composition and abundance of carabids, potential natural enemies of raspberry beetle larvae, was established during the falling time of the raspberry beetle larvae to soil for pupation. This is the first time that it has been shown that the abundance of dominant carabid species is related to phenology of raspberry beetle. Carabids: Pterostichus melanarius, Pterostichus niger, Carabus nemoralis and Harpalus rufipes – aggregate in the plantation during raspberry ripening time when raspberry beetle larvae as prey objects are available. Laboratory feeding tests confirmed that raspberry beetle larvae are preferred food objects for these carabids. These dominant carabid species are potential key predators of raspberry beetle larvae and their occurrence is enhanced by cultivation technologies, such as straw mulch and intercropping system with flowering plants. In this study the occurrence of parasitoids in the larvae of raspberry beetle is established first time. The level of parasitisation was enhanced in raspberry intercropping with flowering plants. Thus in addition to predators, parasitoids can also play a role in raspberry beetle population regulation. Results of the current study are very important for sustainable raspberry production practice. Growing late flowering cultivars that are less susceptible to raspberry beetle and combining them with cultivation technologies like mulching and intercropping which enhance the pests’ natural enemies - there is a possibility to regulate raspberry beetle populations without using pesticides and thereby minimizing the pollution of the environment.