苍耳螟寄生蜂种类调查及黄眶离缘姬蜂生物学特性研究

INVESTIGATION ON THE PARASITOIDS WASP OF SIBERIAN COCKLEBUR STEM BORER AND STUDY ON THE ICHNEUMON WASP TRATHAL A FLAVO-ORBITALIS

苍耳Xanthium sibirium属菊科,为一年生草本,是稻田周围常见杂草类寄主植物,在我国广有分布.作者从1992—1997年查明湖南省部分地区苍耳蛀虫种类和苍耳螟寄生蜂种类,考查五千多头幼虫,鉴定出四种蛀虫,17种寄生蜂,其中姬蜂7种,茧蜂7种,小蜂3种.黄眶离缘姬蜂数量较多,寄生率较高,可达19%.该蜂是苍耳螟幼虫的一种主要寄生蜂,并可寄生二化螟、三化螟、稻纵卷叶螟.进行了黄眶离缘姬蜂的生物学特性研究.

1. In Hunan Siberian cocklebur Xanthium sibirium occupies major area,which is beside or surround the rice paddy field. It is an essential weed of nwarm,humid environment. 4 species are recorded as stem borers of Lepidoptera, the Siberian cocklebur stem borer are Ostrinia orientalis (Mutuura & Munroe) ,Ostrinia scapulalis (Walker) ,Ostrinia zealis (Guenee) and Chilo suppressalis which are widely distributed.2. The species of parasitoids wasp in Siberian cocklebur stem borer has been proved in part of region in Hunan province from 1992 to 1997. Larve over 5000 and four species of stem borerare examined. As morphology of three species in Ostrinia genus is very similar, identification is reliable on male genitalia.3. After investigation on parasitods wasp of Ostrinia orientalis (Mutuura& Munroe) , 7 species parasitoides including 7 species of ichneumon wasp , 7 species of braconid wasp and 3 species of chalcidid wasp were collected and were found in Hunan province. The number of Trathala flavo-orbitalis is more than that of other parasitoids wasps and its parasitic rate is higher than one of other parasitoids wasp during all cropping seaaon.4. Most of the ichneumon wasp and braconid wasp of Ostrinia orientalis are parasitoids wasp of striped rice borer Chilo suppressalis, yellow rice borer Tryporyza incertulas, and rice leaf roller Cnaphlocrosis medinalis. Authors recognize that parasitoids wasp existing in weeds beside paddy field begin to fly to ricefield from Siberian cocklebur durng the period of May after winter.5. Study shows that Siberian cocklebur is a valuable weeds source, undoubtedly this weed beside paddy field is a reproduction factory of parasitoids wasp and has effect on transitional host for parasitoids wasp. The traditional agricultural viewpoint of use it as fuel could be given up.6. Ichneumon wasp Trathala flavo -orbitalis is an essential natural enemy of the Ostrinia orientalis. It has 7 generations in Changsha in Hunan each year, At hibernation generation the average developing periods of pupa and adult are 10. 49±0. 88,9. 14±0. 85 days,respectively. At the 1st, 2nd, 3rd, 4thand 5th generation, the average developing periods of the egg-lavae, pupa and adult are 13. 2±0. 44, 9.24±0.91, 8.94±0.74, 8.16±0.85, 9. 01±0.79, 7.88±0. 93, 7. 38 ± 0. 71, 8. 14±0. 89, 4. 95±0. 79, 9. 69±0. 58, 8. 48 ± 0. 69, 6. 19 ± 0. 83, 11. 15 ± 0. 62, 10. 83 ± 0. 69, 8. 38 ± 0. 87 days, respectively. At about 25. 5℃ ,27. 5℃ ,33. 4℃ ,32. 6℃ ,30. 6℃ and 23. 4℃ ,the mean longevity of the adult that fed on honey water,honey water (one day), water (one day) and untreatment are 12. 10 ±0. 80, 8. 96±0. 69, 4. 75±0. 79, 4. 00±0. 65, 9. 37±0. 76, 6.94±0.91, 4.06± 0.82, 3.08±0.86, 6.31±0.89, 4.72±0.81, 3. 63±0.91, 2.00± 0.79, 6.03±0.76, 4.41±0.88, 3.01±0.86, 2.00±0.81, 7.69±0. 92, 5.61±0.88,4.00±0.69, 3.10 ± 0.83, 12.38± 0.83, 8.35±0.85, 5.11±0.69, 4.15±0. 86 days, respectively. Most of the emergences occurred at 8-9 a. m.. Female lays eggs in the 1st to 3rd instar larvae of the host, and prefer to oviposit in second instar larvae.