BEHAVIORAL-RESPONSES OF THE GYPSY-MOTH LEPIDOPTERA, LYMANTRIDAE IN A WIND-TUNNEL TO AIR-BORNE ENANTIOMERS OF DISPARLURE

Male gypsy moths (Lymantria dispar L.) in a wind tunnel fitted with a moving floor pattern to provide optomotor feedback to flying moths respond to (+)-cis-7,8-epoxy-2-meth-yloctadecane [(+)-disparlure] by flight with apparent positive optomotor anemotaxis and reversing anemomenotaxis (an upwind, zigzag flight). From quiesence, the latency to pre-flight wing fanning decreases with an increasing (+)-disparlure dispenser dosage. Ground speed of flight (the rate of floor movement required to maintain flight in the center of the wind tunnel) decreases with increasing (+)-disparlure concentration suggesting that the at-tractant concentration can provide an orthokinetic modulation of ground speed. The lowest dispenser dosages of (+)-disparlure tested (1 ng) resulted in greater lateral displacement in the zigzag than 10-1000 ng dosages. At wind velocities of 0.7 and 2.5 m/sec males maintained virtually identical ground speeds by adjusting their airspeed. The (-) enantiomer of disparlure when admixed to (+)-disparlure acts antagonistically to decrease the distance flown, the ground speed and the distance of flight, but the (-) enantiomer does not appear to affect preflight wing fanning latency. Considerable variation occurs in the mean ground speed of individuals, possibly optimum strategies related to orientation in well-defined aerial plumes (rapid flight) and meandering plumes (slow flight). © 1979 Entomological Society of America.