Plants influencing the behaviour of Large White Butterfly (Pieris brassicae L.)
Large White Butterfly, Pieris brassicae L. (LWB) is one of the greatest pests of cruciferous cultures in Estonia, and, in the years of its biggest abundance, it can destroy a significant part of a crop. Many plants contain natural compounds that can repel and/or attract insects and protect neighbouring plants. This principle is used in a method known as companion planting. The aim of this paper was to establish to what extent it was possible to influence, by using companion plants, the oviposition intensity of adults of LWB on Brassica oleracea var. capitata f. alba. Cabbage plots were surrounded, as a border around garden beds, by the following plant species: Salvia horminum L. (syn. viridis L), Chrysanthemum carinatum Schousboe, Tagetes patula L., Allium cepa L. or Calendula officinalis L. Companion plants were replanted on the experimental plots in two rows. On control plots only cabbage was growing.
French marigold, T. patula and painted daisy, C. carinatum were oviposition repellent to P. brassicae – compared with the control variant; butterflies laid fewer eggs on cabbage of these variants. At the same time, flowers of T. patula were attractive to adults of P. brassicae as the butterfly fed intensively on the flowers. There were no butterflies on flowers of C. carinatum, allowing us to conclude that this plant was a repellent to adults of P. brassicae. Certain repellent effects of painted sage, S. horminum, appeared towards the end of the summer, when the plants were in full flower. Butterflies laid eagerly eggs on cabbage plants surrounded by calendula, C. officinalis and onion, A. cepa. Our experiments showed how important it is to reckon with a certain pest, the control of which is intended, in choosing plants for founding a garden with diverse vegetation.