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journal1 ›› 2016, Vol. 32 ›› Issue (4): 421-427.DOI: 10.16409/j.cnki.2095-039x.2016.04.001

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Developmental and Reproductive Aspects of Parasitoid Wasp, Orgilus ischnus and Its Bio-control Potentials to Loxostege sticticalis

DU Qin1,2, CHENG Yunxia1, LUO Lizhi1, LEI Chaoliang2, JIANG Xingfu1, ZHANG Lei1   

  1. 1. State Key Laboratory for Biology of Plant Diseases and Insect Pests/Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
    2. College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
  • Received:2015-12-17 Online:2016-08-08 Published:2016-07-29

Abstract: Orgilus ischnus Marshall (Hymenoptera: Brachonidae) is a parasitoid of early instar larval of beet webworm, Loxostege sticticalis L.. To explore the biological characteristics and bio-control potentials of O. ischnus, the developmental duration, cocoon weight, reproductive behavior and potential, and longevity of O. ischnus were investigated using the 1st instar larval L. sticticalis as host under laboratory conditions (23 ℃, 16L: 8D). The functional response and parasitism rate of the O. ischnus were analyzed at 8 densities from 5 to 40 host larvae per 650 mL/jar. The weight of the food consumed by the host larvae, the body weight and the size of the host larvae were compared with the un-parasitized ones. The results showed that the developmental period of egg and larvae, pre-pupae and pupae, and whole generation of the wasp was 12.8, 10.5 and 23.2 days, respectively. The cocoon average weight of the wasp was 4.1 mg. The wasp was a kind of synovigeny parasitoid, could mate immediately after emergence and oviposite soon after mating. The mating time was 49 s in average. The ovipositing peak happened at the first 4 days and the eighth day in the wasp life. The egg laying number per female in whole lifetime was about 100.5 in average. The longevity of female and male wasps was 11 and 14 days, respectively. The number of the host parasitized by O. ischnus increased as the host density increased while the actual parasitic rate decreased with the increase of host density, which fitted with Holling type Ⅱ. The weight of the food consumed by the parasitized larva was 106.7 mg, only accounting for 21.3% of the normal larvae. The body weight and size of the parasitized larva were significantly less than that of the normal larva at the 6th and 12th day after parasitizing. This review makes clear the biological characteristics of O. ischnus, and demonstrates the wasp is an effective parasitoid of early stages of larval L. sticticalis, provides technical support to improve the sustainable controlling of L. sticticalis.

Key words: Orgilus ischnus, Loxostege sticticalis, biological characteristics, parasitism, functional responses

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