Searching Speed of Trichogramma minutum and Its Potential as a Measure of Parasitoid Quality

Searching speed has been proposed as a quality criterion for the prediction of field efficacy of mass-reared Trichogramma spp. The searching speed, walking speed, and activity of female T. minutum Riley were measured using an automated video tracking system. Two- and 3-day-old thelytokous females searched twice as fast as 1-day-old females, whereas the searching speed of a strain of arrhenotokous females was similar at all ages. When reared on Actebia fennica Tauscher, the resulting wide variation in wasp size was not related to searching speed or walking speed. Both strains of T. minutum searched faster later in the day. In a second laboratory experiment, the proportion of hosts parasitized, the proportion of hosts accepted, and searching speeds of parasitoids were measured simultaneously for groups of females of both strains. Percentage parasitism was related to host acceptance but not searching speed. Searching speed was unrelated to the estimated number of host contacts. These results suggest that searching speed is not a useful measure of parasitoid efficacy for T. minutum.