Effect of Sinapis alba L. as an Insectary Plant on the Occurrence of Aphis fabae Scop., Coccinellidae and Syrphidae in Broad Bean

Abstract

Introducing insectary plants along with principal crops is an effective way to increase the biological diversity of beneficial insects and improve the stability of ecological equilibrium in agrocenoses and could be an alternative to chemical plant protection, particularly in organic farming. The goal of this study was to determine the effect of white mustard as a companion plant in broad bean cultivation on the occurrence of Aphis fabae Scop., Syrphidae, and Coccinellidae. The study also aimed at finding the optimum row separation of broad bean plants. It also evaluated the effectiveness of the thinning of mustard in a specific time to eliminate excessive competition with the main crop. The results showed that white mustard contributed to visible suppression of A. fabae abundance on broad bean (to the level similar as with the use of chemical protection). S. alba contributed to an increased abundance of hoverflies and lady beetles on broad bean despite the relatively low abundance of their prey, i.e., aphids. Mustard thinning positively affected abundance of larvae and adults of lady beetles as well as improved predator-prey ratio for hoverfly larvae and adult lady beetles. The most appropriate distance between broad bean rows when white mustard was introduced was 65 cm, with the concomitant conduct of mustard thinning when the broad bean plants reached flower bud formation. White mustard can be recommended as an element increasing the role of natural enemies of aphids in mixed crops, however, its strong growth should be taken into account and the plant density should be properly adjusted to avoid excessive competition with main plant.