ELECTROPHYSIOLOGICAL AND BEHAVIORAL-RESPONSES OF CHESTNUT MOTHS, CYDIA-FAGIGLANDANA AND CYDIA-SPLENDANA (LEP, TORTRICIDAE), TO SEX ATTRACTANTS AND ODORS OF HOST PLANTS

EAG recordings were made from both males and females of Cydia fagiglan dana (Zell.) and C. splendana (Hb.) on stimulation with the tortricid sex attractants (E,E)-8,10-dodecadien-1-yl acetate (E8E10-12:Ac), (E,E )-8,10-dodecadien-1-ol (E8E10-12:OH) and (Z)-8-dodecen-1-yl acetate (Z 8-12:Ac). The dose-response curves of the various attractants were alm ost identical for males of both species. The order of increasing EAG s ensitivity was E8E10-12:OH < Z8-12:Ac < E8E10-12:Ac. In females, EAGs increased in the order E8E10-12OH < E8E10-12:Ac < Z8-12:Ac. They were much less sensitive to the sex attractants; the EAG amplitudes to E8E1 0-12:Ac were 20-50 times smaller than those of males. The antennae of C. fagiglandana females were about twice more responsive to the sex at tractants than those of females of C. splendana. Recordings from singl e antennal olfactory cells of C. fagiglandana males showed responses o f 1 or 2 cells on stimulation with the sex attractants and with volati les from chestnut leaves. The diel spontaneous locomotor activities of both species as measured in actographs ran almost concurrently. Most moths were active during the first 4-6 h and the last 2.5 h of the nig ht. During the day the moths were inactive, except females of C. splen dana which already showed some activity at the end of the afternoon. A correlation appeared to exist between the locomotor activities and be havioural responsiveness to attractive odours. Behavioural responses o f males and females were studied in a wind-tube in the presence and th e absence of an airstream. Female calling behaviour was observed. Resu lts suggested that E8E10-12:Ac is a main component of the female sex p heromone of both Cydia species. A stream of air, whether or not loaded with attractants, always induced antennal elevation and grooming of t he antennae and palps in both males and females. Responses to upwind a ttractants only occurred after switching off the airstream. It is prop osed that either (1) attractive odours in combination with an airstrea m may evoke an 'internal excitatory state' that finds active expressio n in standing air or that (2) intermittent stimulation with odours, wh ich may occur in the unsteady air shortly after switching off the airf low, is indispensable for inducing upwind displacement. Branches of ch estnut attracted both sexes and functioned as arrestants. Contrary to what was found in several other moth species, signals from the host pl ant did not appear to induce pheromone production. Males as well as fe males were attracted to E8E10-12:Ac, to calling conspecific females an d to the smear of abdomen tips cut off from calling conspecific female s. With a paper loaded with E8E10-12:Ac and three conspecific females present in the tube, the females lined up about 20 cm from each other and started to call. These results suggested that sensitivity of the f emales to their own sex attractants may permit them to detect the pres ence of other calling females, leading to settling and synchronization of pheromone production, and avoidance of pheromone-releasing females . As a result, calling females may evenly distribute over the environm ent.