EFFECTS OF THE FEEDING PROCESS OF IXODES-SCAPULARIS (ACARI, IXODIDAE)ON EMBRYONIC-DEVELOPMENT OF ITS PARASITOID, IXODIPHAGUS-HOOKERI (HYMENOPTERA, ENCYRTIDAE)

The chalcid wasp Ixodiphagus hookeri (Howard) is a parasitoid of sever al ixodid ticks including the blacklegged tick, Ixodes scapularis Say. We evaluated effects of the feeding process of nymphal I. scapularis on the embryonic development of I. hookeri. Potentially wasp-parasitiz ed nymphal I. scapularis were collected on Prudence Island, RI. Subsam ples of the questing nymph cohort were allowed to feed on laboratory w hite mice. Both the body length and the scutal length of ticks were me asured individually for questing nymphs and for feeding nymphs that we re removed from hosts at time intervals of 12, 24, 36, 18, and 72 h af ter attachment. The diameters of wasp eggs they contained were also me asured for each designated time interval. There was a positive relatio nship between the mean scutal index (ratio between body length and scu tal length) of ticks and the mean diameter of wasp eggs during 72 h of tick feeding (P < 0.05). Moreover, it appeared that within 24 h of ti ck attachment, the scutal index of ticks remained unchanged. However, after that period, the scutal index increased significantly (P < 0.05) . Diameters of wasp eggs increased continuously during tick feeding an d at 72 h after attachment, eclosed eggs and completely formed larvae were found in several ticks. We conclude that factors related to the f eeding process of nymphal I. scapularis are necessary to initiate the embryonic development of wasps.