AbstractThe landing response of the large cabbage white butterfly Pieris brassicae was studied under controlled optical and gustatory stimulus conditions. Experience-based changes in landing behaviour were examined by offering cardboard circles of two different shades of green, treated with either an oviposition stimulant or a deterrent. We employed two training situations. In one situation the two shades of green, carrying either the stimulant or the deterrent, were offered simultaneously, in the other sequentially. During the 1 hour training periods, butterflies were either landing and drumming spontaneously or they were caught at the end of the period and placed on the artificial leaves until tarsal drumming ensued. Our experiments demonstrated that P. brassicae females can learn to associate visually detected substrate characteristics with contact-chemosensory information available only after landing. Furthermore, a learned preference for a substrate could be turned into a preference for the alternative substrate by exposing the insect to a deterrent on the previously preferred substrate. These results provide indications of aversion learning, thus far undocumented in oviposition behaviour of Lepidoptera. Bringing the butterflies into forced contact with the oviposition stimulant resulted in similar effects on landing preference compared to those of spontaneous landing, but spontaneous landing had a stronger effect on preference for associations involving the deterrent. The simultaneous training regime, which supposedly requires a less important role for short-term memory, was more effective in modifying landing preferences.
Comparison of Efficacy of Synthetic Pesticides with Botanical Extracts under Field Condition on Cabbage White Butterfly (<i>Pieris brassicae</i>)
