Biological control of cabbage pests

Cabbage is an important vegetable crop in Serbia. Selective and non-persistent insecticides are used for pest control. Due to pesticide residues in food and the occurrence of resistance, we investigated the possibility of applying several methods of biological control against a wide range of pests in our conditions: the application of preparations on the basis of Bacillus thuringiensis var. kurstaki Berliner, Baculoviruses and Trichogramma evanescens Westwood. Biological preparations based upon B. thuringiensis var, kurstaki Berliner, registered in Yugoslavia, can be used successfully for the control of Pieris brassicae L., Pieris rapae L., Plutella xylostella L., and Autographa gamma Hbn. However, these preparations are ineffective on Mamestra brassicae L. that regularly causes damage greater than the economic damage threshold of 2% of damaged heads. 75.000 wasps (T. evanescens) were released in three repetitions in a 1,5 ha cabbage plot. They decreased the attack of M. brassicae by 47%, P. rapae by 42% and P. xylostella by 60% in relation to the control. These results prove that in the conditions of our country (regular severe pest attack) T. evanescens alone cannot protect cabbage, but that it should be used in combination with biological preparations based upon Baculoviruses and B. thuringiensis var. kurstaki.