| Abstract [eng] |
Persistence of Bacillus thuringiensis Subspecies israelensis After Application of Biological Preparation VectoBac 12AS Bacillus thuringiensis subspecies israelensis (Bti) is a group of bacteria which produces endotoxins that specifically effect particular groups of Diptera insects larvae. The biological preparation VectoBac 12AS is based on Bti and it is used globally, including Lithuania. Objective of our thesis is to investigate the persistence of Bacillus thuringiensis israelensis after application of biological preparation VectoBac 12AS. Bacillus thuringiensis israelensis detection included optimization of PCR conditions for chosen CRY11F and CRY11R, CRY4F and CRY4R primers, that amplifies insecticidal crystal protein Cry11Aa and insecticidal crystal protein Cry4Ba genes fragments sequences. VectoBac 12AS preperation efficiency, after 1 month of freezing in –20 ºC, after unfreezing and using against Culex pipiens mosquito larvae has not changed: after 24 hours after application of preparation all used larvae were dead. Bti persisted active and were able to form colonies. Samples of these colonies where investigated using PCR and it confirmed that there were colonies of Bti. Bti bacteria after application of VectoBac 12AS in Nemunas river can be detected in blackfly larvae and pupae (Simuliidae) and in chironomid (Chironomidae) larvae 314 days in the 21 km and 3-8 days in the 56 km of Nemunas river below VectoBac 12AS application location. After VectoBac 12A application in laboratory Bti persist in bloodsucking mosquitoes Culex pipiens larvae 3-21 days. Bti bacteria, that persisted in bloodsucking mosquitoes after application of preparation in laboratory, were viable and were able to form colonies. The results of this research are usefull for effective application of biological preparation VectoBac 12AS in order to decrease abundance of bloodsucking insects. |
