The family of owlet moths (Noctuiade) is comprised of numerous species, many of which are known as pests. To prevent as much damage as possible, it is crucial to distinguish between them while still in their larval state. Since many owlet moth larvae of different species look very much alike, it is almost impossible to tell them apart morphologically. Molecular methods have thus been implemented to aid in this problem, among them DNA barcoding. DNA barcoding is based on the idea that every living being contains a short universal segment in their DNA which can be used to discriminate them to the species level. However, the requirements for a region to be considered a barcode are very strict, which is why we still haven't found a truly universal segment of DNA. Therefore, different regions of DNA are used as barcodes for different groups of organisms. While DNA barcoding may have a very high success rate and can be used in many fields of science, it is insufficient when used alone. It yields the best results when combined with traditional methods.
The purpose of this thesis was to test the effectivenes of DNA barcoding for distinguishing between different species of noctuid larvae. Since we were unable to complete the experiments due to COVID 19 epidemic measures, we focused on a bioinformatic analysis, in which we compared barcode sequences from four noctuid species and one from the family Lycaenidae, the latter used as negative control. We noticed that both databases used in the analysis (GenBank and BOLD) contained sequences that had been annotated to a wrong species, so caution is advised when using downloaded sequences. We found DNA barcoding to be an effective method for distinguishing between noctuid species, with the exception of the sister species Chrysodeixis chalcites and Chrysodeixis eriosoma, as their sequences differ too little to be delineated by barcoding alone. On the other hand, we noticed that in the case of Trichoplusia ni sequences from samples caught in North America differ significantly from the ones caught in Eurasia. We concluded the research by a meteorological analysis where we analyzed the past five winters in the Upper Vipava valley. We found out that eventhough winters have become warmer in the last five years, they do not yet allow Chrysodeixis chalcites a successful overwintering and thus its spread to the inner area of Primorska, except in sheltered microlocations.
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