BEHAVIORAL AND CHEMOSENSORY RESPONSES OF THE TURNIP ROOT FLY (DELIA-FLORALIS) TO GLUCOSINOLATES

This study investigates the behavioural and neural mechanisms involved in the oviposition behaviour of the turnip root fly, Delia floralis ( Fallen). Behavioural studies showed that glucosinolates modulated the oviposition behaviour of the flies on artificial leaves as well as the number of eggs laid in the soil at the base of these leaves. Electrop hysiological responses to glucosinolates were obtained from type A and type D sensilla on the prothoracic and mesothoracic tarsi, as well as from the long contact sensilla on the labellum. The neural responses from these sensilla were positively correlated with the oviposition be haviour of the flies and with the number of eggs laid. Of the eleven g lucosinolates tested in the behavioural and electrophysiological tests , the flies were most responsive to glucobrassicanapin, gluconapin and glucobrassicin. The type D tarsal sensilla were more responsive to th e glucosinolates than either the type A tarsal sensilla or the labella r sensilla. The structure-activity investigations showed that slight m odifications to the chemical composition of the glucosinolates resulte d in changes in neural activity.