Abstract:

Telenomus remus (Nixon) is an important egg parasitoid of Spodoptera frugiperda (J. E. Smith), a major invasive pest. In order to clarify the intraspecific host discrimination and the superparasitism of T. remus, the self-recognition (same individual) and conspecific-recognition (different individual) ability to recognize the hosts eggs parasitized at different time intervals were determined, and the superparasitism rate of single and multi-female T. remus under different host density were also investigated. The results showed no superparasitism in T. remus , either self-recognition or conspecific-recognition. After a single female T. remus parasitizing for 24 h at different parasitoid-egg ratios, the percentage of 1^st instar larvae of T. remus in S. frugiperda eggs was less than 100%, and only one was found in each host egg. With multi-female T. remus and sufficient hosts, and when parasitoid-egg ratios were 1:100, 2:200, 4:400, 6:600 and 8:800, the percentage of unparasitized host eggs were 52.8%, 67.2%, 63.2%, 53.6% and 51.2%, respectively, and the percentage of host eggs with one 1^st instar larva were 47.2%, 32.8%, 36.8%,46.4% and 48.8%, respectively. With multi-female T. remus and insufficient hosts, and when parasitoid-egg ratios were 2:20, 3:21, 4:20, 7:21 and 20:20, the parasitism rates of T. remus were 60.0%, 83.0%, 95.0%, 94.0% and 96.0%, respectively, and the superparasitism rates were 11.0%, 38.0%, 64.0%, 73.0% and 92.0%, respectively, the average number of 1^st instar larva of T. remus in a single host egg were 0.4, 0.6, 1.1, 1.3 and 2.1, respectively, and the maximum number were 3.0, 4.0, 5.0, 6.0 and 12.0, respectively. The results show that T. remus has the ability of self and conspecific-recognition, the superparasitism of a single female T. remus does not depend on host density. When the host is sufficient, the superparasitism of multi-female T. remus does not occur, but when the host is insufficient, the parasitism and superparasitism rate, the average and maximum number of 1^st instar larvae in a single host egg increase with the increase of parasitoid-egg ratios. The parasitoid-egg ratio of 4:20 is suitable for propagation of the wasp because it produces high parasitism rate, low superparasitism rate, and low internal competition.

Key words:

Telenomus remus, Spodoptera frugiperda, intraspecific host discrimination, superparasitism