Co-occurrence between 2 egg parasitoids of <i> <u>Dalbulus maidis</u> </i> (Hemiptera: Cicadellidae) under field conditions: host-finding efficiency and observed parasitism

Little is known about the interaction between different egg parasitoid species parasitizing a single host species, under field conditions. In a 2-yr study, we investigated the efficiency of finding and parasitism of eggs of Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) by the egg parasitoids Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) and Paracentrobia subflava (Girault) (Hymenoptera: Trichogrammatidae) in maize fields. Host-finding efficiency was compared in fields of plants that differed in age, and on maize edges versus within the maize fields. Then, host-finding and parasitism during short (1 d) versus long (5 d) exposure periods were compared. Anagrus virlai and P. subflava showed similar, highly efficient host searching of maize leaves baited with D. maidis eggs, with similar efficiency in maize crops of different ages. Host-finding was higher, however, in the maize edges than within the maize field. With regard to speed of finding, whereas both parasitoid species were able to search and parasitize D. maidis eggs (at similar levels) when given 5 d of exposure, only P. subflava was able to find and parasitize D. maidis eggs within 24 h. Host-finding of D. maidis eggs was independent between A. virlai and P. subflava when both species parasitized on a single maize leaf. These results suggest that co-occurrence of both parasitoid species is facilitated because each species finds host eggs at different times, parasitoids adults emerge at different times, and a high quantity of host eggs is available.