应用苹果蠹蛾线虫防治荔枝龟背天牛幼虫的研究

荔枝龟背天牛Ａｒｉｓｔｏｂｉａ ｔｅｓｔｕｄｏ（Ｖｏｅｔ）是岭南重要经济果品荔枝的重要钻蛀害虫，现用的防治手段效果欠佳。１９８８－１９９３年间，作者利用苹果蠹蛾线虫Ｓｔｅｉｎｅｒｎｅｍａ ｃａｒｐｏｃａｐｓａｅ的Ａｇｒｉｏｔｅｓ品系注射于受害枝条末端排粪孔，试验面积约２０ｈａ，防治效果达７３．３％－１００％。研究证明，应用苹果蠹蛾线虫防治龟背天牛是一种有效的新途径。     

苹果蠹蛾线虫广州品系的研究

本文对广州桑园土壤分离的病原线虫进行了形态观察和杂交试验,鉴定此线虫为苹果蠹蛾线虫广州品系Steimsrnoma car pocapsoeGZ。通过与目前世界上广泛应用的苹果蠹蛾线虫苏联品系Agriotos比较,显示出广州品系无论是侵染寄主的能力、数量、还是在土壤中迁移的速度、深度和耐高温的能力,均优于Agriotos品系,预示了这个品系在害虫生物防治上具有较大的应用潜能。     

Development of a new application apparatus for entomopathogenic nematodes

This paper describes the assessment of nematode spray application methods and details the redesign of a spinning disc applicator for the improved application of the infective juveniles of entomopathogenic nematodes to foliage. The assessment highlighted fundamental design features that prevent efficient and accurate nematode application and these are dealt with in turn specifically to enable improved nematode application. The redesigned or prototype spinning disc was shown to improve nematode carriage in droplets, leading to greater deposition of nematodes per unit area. There is a trade-off between spray droplet coverage of the target surface and the production of a suitable droplet spectrum for nematode carriage.     

昆虫病原线虫侵染鳞翅目幼虫的血淋巴病理学

菜青虫经口感染斯氏线虫后,２０小时左右在其血淋巴中出现杆状的共生细菌,并开始大量增殖,４８小时的细菌数已达出现初期的１万倍以上。用３种不同品系线虫 结果显示：经分别感染不同线虫的大蜡螟幼虫,其血细胞数总的增减变化趋势是一致的,在感染初期血细胞数较健康虫体明显降低,４￣６小时达最低值;随后逐渐增加,１２小时后血细胞数达到高峰;随后不迅速下降。感染线虫的家蚕１２小时后其血淋巴的蛋白质含量较对照明显降低     

斯氏线虫S.carpocapsae BJ对森林革蜱饱血雌蜱产卵量的影响

研究了不同浓度的斯氏线虫S.carpocapsae BJ对森林革蜱饱血雌蜱产卵量的影响。用浓度为10003、000、5 000、7 0001、0000IJs/dish的线虫接种到培养皿中侵染森林革蜱饱血雌蜱,对照组用重蒸水代替。结果表明,随着线虫浓度的增加,雌蜱的死亡率不断提高(30%~95%);处理组饱血雌蜱的产卵量显著少于对照组,低浓度时随着线虫浓度的增加,产卵量呈显著下降的趋势,而浓度5 000IJs/dish以上的3个处理组之间,雌蜱的产卵量无显著差异;低浓度时线虫浓度的增加使线虫侵入率显著提高,浓度达到一定数值后,浓度的增加对线虫的侵入率和雌蜱的产卵量都无显著影响。     

Molecular detection of nematode predation and scavenging in oribatid mites: Laboratory and field experiments

Recent stable isotope analyses indicate that a number of putative detritivorous soil microarthropods is not typical detritivores but rather live as predators or scavengers. Using molecular gut content analyses the present study investigates if nematodes indeed form part of the diet of oribatid mites. First, in a no-choice laboratory feeding experiment two nematode species (Phasmarhabditis hermaphrodita and Steinernema feltiae) were offered to eight species of oribatid mites and one gamasid mite. Second, after feeding for 4 and 48 h on each nematode species the detection time of prey DNA in the oribatid mite species Steganacarus magnus was investigated. Third, in a field experiment nematode prey (P. hermaphrodita and S. feltiae) in the diet of microarthropods was investigated distinguishing between scavenging and predation. In the no-choice laboratory experiment not only the gamasid mite but also several of the studied oribatid mite species consumed nematodes. After feeding on nematodes for 4 h prey DNA was detectable in S. magnus for only 4 h, but after feeding for 48 h prey DNA was detectable for 128 h, indicating that the duration of feeding on prey is an important determinant for prey DNA detection. The field experiment confirmed that oribatid mite species including Liacarus subterraneus, Platynothrus peltifer and S. magnus intensively prey on nematodes. Interestingly, DNA of dead P. hermaphrodita was detectable to a similar degree as that of living individuals indicating that scavenging is of significant importance in decomposer food webs. Results of our study indicate that predation and scavenging on nematodes by “detritivorous” microarthropods in soil food webs need to be reconsidered.     

Progeny production of Steinernema abbasi in lepidopterous larvae

Progeny production of a new entomopathogenic nematode Steinernema abbasi in various lepidopterous prepupae was investigated. Most dauer juveniles (DJs) developed in the greater wax moth, Galleria mellonella (234 000) but the bollworms Helicoverpa virescens (220 000) and Spodoptera exigua (166 000) were also good hosts. Progeny production was independent of the number of nematodes invading the host between the doses of 40 and 230 DJs. The infectivity of DJs declined when they were stored for 3 months but at 30°C approximately 11% of the DJs were still infective. S. abbasi is a nematode of the semi-arid tropics and it would be possible to use the nematode to target pests in these areas if it can be produced satisfactorily locally.     

昆虫病原线虫Steinernema sp.(CB-2y)的生物学特性研究

Sfeinernema sp. (CB-2y)是1986年从河北省一苹果园土样中分离获得的昆虫病原线虫。室内试验表明,它在15-30℃下能侵染害虫,并在其体内繁殖,离体培养的最适温度为20-25℃。在含水量10-17.5％的沙壤中,线虫具有侵染力。含水最低于7.5％时,虽能存活,但不能侵染害虫。在2.5％含水量沙壤中,则不能存活。CB-2y线虫能在北京地区越冬,在25-30厘米深层土中,越冬存活率为47.8％。该线虫垂直扩散能力强,3天内在沙中57％的线虫已扩散到5厘米以远,最远距离可达30厘米。在23℃含水量14.5％的沙壤中,16周后CB-2y仍能保持侵染力,而S. feltiae Agriotos的侵染力只能保持4周。     

北京地区昆虫病原线虫的自然发生情况初步调查

用大蜡螟诱集法,对在北京地区采集的175个土样进行了线虫分离,得到斯氏属线虫5个,异小杆属线虫6个,小杆线虫2个。土样有线虫率为13.1％。土样有线虫率与植被、土壤质地有关。从4种植被下采集土样的有线虫率分别是:果园28.2％、菜地10.5％、大田作物7.7％、未耕地0。4种土壤质地中土样有线虫率为:松沙土20.8％、砂壤土15.1％、中壤土12.2％、轻壤土5.4％。本土线虫对桃小食心虫、韭菜蛆、小木蠹蛾、二化螟的侵染力均高于引进的线虫。