About Previous Investigations Regarding the Role of Glucosinolates in Controlling Brassica Insect Pests in Slovenia

The chapter presents previous field and laboratory investigations of cabbage flea beetles (Phyllotreta spp.) and cabbage stink bugs (Eurydema spp.) interactions with different Bras‐ sica crops in Slovenia. The special emphasis is given to an influence of different glucosi‐ nolates on injuries caused by mentioned economically important two genera of insect pests. In the study, we found out that the content of glucosinolates differs between differ‐ ent Brassica species, as well as between individual plant organs of the same species. The content of glucosinolates is conditioned also by environmental influences. Among the an‐ alysed glucosinolates, glucobrassicin was presented in all plant species. In almost all plant species, it inhibited the feeding of cabbage flea beetles, except in oil rape, where it had stimulative effects. We have established that the influence of individual glucosinolate on Phyllotreta spp. and Eurydema spp. is not identical as it differs between individual plant species. Because of the variability of glucosinolates as well as different preferences of the studied groups of harmful pests in regard to the plant species, one of the options for diminishing the damage caused by cabbage stink bugs and cabbage flea beetles is the use of mixed Brassica crops for trapping the pests in the growing season. In the future, glucosinolates should be employed to a greater extent in environmentally acceptable ways of food production, one of which is also the use of trap crops in order to reduce harmful effects of cabbage stink bugs.