Biological characteristics of Platygaster oryzae Cameron and P foersteri Gahan Hymenoptera, Platygastridae, parasitoids of the rice gall midge, Orseolia oryzae Wood-Mason in Thailand
Kobayashi, M.; Kadkao, S.
Kontyu 521: 128-136
1984
Accession: 037971550
Biological characteristics of P. oryzae and P. foersteri, the predominant parasitoids of the rice gall midge O. oryzae in Thailand, were investigated. In the laboratory, P. oryzae developed a mean total of 1840 matured ovarian eggs, of which about 900 were deposited in about 30 host eggs over a life span of 1-2 days. In host eggs collected in the paddy field .apprx. 60 eggs per host were observed, suggesting that a host egg could be attacked more than once by the parasitoids. Almost all eggs that were deposited could develop to adult stage. The proportion of females to males was 98%. The ovary of P. foersteri contained an average of 760 eggs. Of these, 220 eggs were singly deposited in host eggs. In spite of the fact that only 1 individual can develop to adult stage in a host, host eggs collected in the paddy field contained about 4 eggs each, also suggesting that a host egg may be attacked more than once. The longevity of P. foersteri was 3-4 days. The proportion of females to males was about 80%. Comparison of these 2 spp. suggested that P. oryzae may be an r-strategist and P. foersteri a K-strategist.