Comparison of host searching behavior of Ooencyrtus nezarae Ishii and Gryon japonicum (Ashmead), egg parasitoids of Riptortus pedestris (Fabricius)
Dongmok Kim and Un Taek Lim
Department of Bioresource Science, Andong National University, 760-749 Andong, Republic of Korea
Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Platygastridae) are sympatric egg parasitoids of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) in Korea and Japan. We compared host foraging efficiency of the two parasitoids in the context of different spatial and temporal variability. A single egg of R. pedestris was attached on potted bean plant containing either two or six leaves, and a 4-10 days old parasitoid of each species was released for five to six different time periods inside the nylon pouch covering the bean plant. Additionally, to assess host egg handling time, single female O. nezarae was released in a plastic styrene vials containing a host egg for the periods of 10, 30, 60, and 120 min. In both two and six leaves assays, progenies of G. japonicum and O. nezarae started to emerge from the host eggs exposed to the parasitoids for 10 and 120 min, respectively. Gryon japonicum might find host egg faster than O. nezarae. But, in the experiment of host egg handling time, O. nezarae needed oviposition time of 90-120 min for the successful development and emergence of their progeny. Thus, there would not be difference in host searching time between G. japonicum and O. nezarae.
Keyword: Ooencyrtus nezarae, Gryon japonicum, egg parasitoid, host search, Riptortus pedestris, host egg handling time
