西方蜜蜂群中大蜂螨,小蜂螨某些寄生分布特征的研究

本文就大蜂螨、小蜂螨在西方蜜蜂群中的某些寄生分布特征进行了研究,结果表明:在蜂群同时有雄蜂和工蜂封盖子可寄生时,大蜂螨趋于选择雄蜂封盖子寄生,差异显著(P<0.01),因此在春季繁殖期通过割封盖4～5天的雄蜂封盖子使幼螨死亡可达到减轻危害的目的。而小蜂螨对雄蜂和工蜂封盖子的寄生差异不显著(P>0.05)。大蜂螨对巢脾不同部位的雄蜂封盖子选择性不明显(P>0.05),而小蜂螨更喜于选择上缘的雄蜂封盖子寄生,差异显著(P<0.05)。     

不同种类杀螨剂对壁蜂蜂螨的防治及安全性

为探讨不同杀螨剂对壁蜂Osmia cornifrons蜂螨的防控作用,筛选了适合壁蜂定巢繁殖的巢管管口内径范围,并采用药液浸渍法比较了螺螨酯、炔螨特、联苯肼酯、四螨嗪、三唑锡5种杀螨剂对壁蜂蜂螨的防治效果及安全性。结果表明,壁蜂芦苇巢管管口内径在8.00~8.49 mm范围时最适合壁蜂定巢繁殖,巢室数量最多,为8.5个,显著高于其它管口内径范围下的巢室数。与空白对照相比,5种杀螨剂各剂量处理对芦苇巢管中壁蜂的巢室数均无显著影响,不同剂量的三唑锡和四螨嗪浸渍芦苇巢管均可有效控制芦苇巢管内蜂螨的为害,2种药剂各剂量处理对巢管中蜂螨的防治效果为97.22%~100.00%,对巢室蜂螨的防治效果为98.75%~100.00%,防治效果显著;而不同剂量的螺螨酯、炔螨特和联苯肼酯对芦苇巢管中蜂螨的防治效果较低,各剂量处理对巢管蜂螨的防治效果为39.81%~80.56%,对巢室蜂螨的防治效果为46.01%~83.82%。表明四螨嗪和三唑锡浸渍处理芦苇巢管可作为有效防治壁蜂蜂螨为害的安全施药手段。     

基于主成分分析的郑州市小蜂螨暴发风险等级评价

小蜂螨作为亚洲地区主要的蜜蜂害虫,严重阻碍了蜂产业的健康稳定发展。定量描述小蜂螨的暴发风险等级可以为该螨的早期防控提供一定的科学依据。本研究根据郑州市1991年至2010年的气象数据,利用主成分分析法将小蜂螨暴发地的6个相关气象指标转换成3个相互独立的综合指标,再对综合指标值进行加权相加得到各年小蜂螨暴发风险的综合评价值,并对其进行等级划分,分别得到各年小蜂螨的暴发风险等级。其中除2006年外,其余年份均与实际调查结果相符,其等级评价正确率达90%。根据不同的暴发风险等级,需要采取不同的防御手段,特别是对当年小蜂螨暴发风险等级较高的地区应加强监测,做好防治工作。     

蒲螨生物学习性及对椰心叶甲龄期选择性的初步研究

在室内温度(25±2)℃,光周期L∥D=12h∥12h,相对湿度(75±10)%条件下,对蒲螨的寄生行为、其对寄主龄期的选择性、膨腹体的发育过程以及世代生活史进行观察。结果表明:在室内蒲螨能很好地找寻寄主并寄生。平均每头雌螨一生产雌43.31头,产雄4.82头,产子期14.06d,寿命为21.21d。蒲螨对椰心叶甲各龄期的选择性达极显著差异,最喜欢寄生蛹,选择寄生率达到96.67%;其次是5龄幼虫,寄生率为60.00%;1龄幼虫的寄生率最低,只有10.00%。     

寄主抗药性对菜蛾绒茧蜂寄生能力的影响

考察了在使用氰戊菊酯的条件下 ,小菜蛾抗药性对菜蛾绒茧蜂寄生能力的影响。在杀虫剂作用下 ,用抗性寄主饲养的菜蛾绒茧蜂RRC品系对抗性寄主RRP品系幼虫的寄生率达89% ,寄主幼虫死亡率仅 5% ,比RRC对小菜蛾敏感品系SSP幼虫寄生时、或用SSP饲养的菜蛾绒茧蜂SSC品系对SSP寄生时的寄生率显著要高 ,寄主死亡率显著要低。表明杀虫剂存在时 ,寄主抗药性使其具较高存活率而给寄生蜂提供更多的寄主 ,有利于寄生蜂的繁衍。方差分析结果显示 ,小菜蛾品系及蛾×蜂互作对供试小菜蛾幼虫的被寄生率及死亡率均有显著影响 ,表明小菜蛾抗性改变了其对菜蛾绒茧蜂的适合性     

卷叶螟绒茧蜂寄生棉大卷叶螟的行为及其与寄主密度的关系

卷叶螟绒茧蜂Apanteles derogatae Watanabe是棉大卷叶螟Sylepta derogata Fabricius幼虫期的一种重要内寄生蜂,对棉大卷叶螟种群有较好的控制作用。在实验室条件下,运用人工接虫观察法研究卷叶螟绒茧蜂对棉大卷叶螟幼虫的寄生行为。结果表明,该蜂搜寻寄主的时间平均为2．38 min,处理寄主的时间仅需0．86 min;寄生寄主的最适龄期为寄主2龄幼虫;对1龄幼虫的致死率达32%,但其寄生率仅为16%,其余16%的个体为穿刺致死。饲喂蜂蜜水能显著增加该蜂的产卵量,延长其产卵历期和增强其穿刺能力。寄生蜂的寄生能力与寄主密度的关系呈抛物线型:在寄生蜂均为16头/m~3雌蜂条件下,当寄主密度从80头/m~3增加到320头/m~3时,寄主的被寄生个体数随之增加,但当寄主密度超过320头/m~3后,寄主的被寄生个体数反而随寄主密度的上升呈下降趋势。     

空间场所对斑痣悬茧蜂选择不同龄期甜菜夜蛾幼虫行为的影响

实验室条件下以甜菜夜蛾各龄期幼虫为寄主,在大观察罩内的盆栽植物上模拟低龄（1～2龄）和高龄幼虫（3～5龄）在田间的分布特点接虫,在小观察罩内同质空间内混合各龄幼虫,分别观察斑痣悬茧蜂的寄主选择行为。研究结果表明,空间大小对斑痣悬茧蜂选择寄主龄期的行为具有很大影响。在大观察罩中,斑痣悬茧蜂对甜菜夜蛾低龄幼虫（1～2龄）的遭遇和放弃行为比例均大于高龄（3～5龄）幼虫,而在小观察罩内的表现则相反。虽然斑痣悬茧蜂的寄主处理时间随寄主龄期的增大而延长,但在大观察罩内斑痣悬茧蜂花费的寄主处理时间比在小观察罩内长。在小观察罩内,寄生蜂对低龄幼虫的再次攻击间隔时间（653.17s）长于高龄幼虫（171.32s）,但在大观察罩内则相反。在大观察罩内低龄幼虫的被寄生率（23.24%～38.54%）高于小观察罩内（7.88%～21.43%）,但是小观察罩内高龄幼虫（4龄）的被寄生率（34.65%）大于大观察罩（16.86%）。最后,就空间大小影响斑痣悬茧蜂寄主选择行为的机理进行了探讨。     

烟蚜茧蜂种内寄主识别与内部竞争

为明确寄生桃蚜Myzus persicae(Sulzer)的单性内寄生蜂烟蚜茧蜂Aphidius gifuensis Ashmead的种内识别与内部竞争,研究测定不同寄主密度对烟蚜茧蜂雌蜂卵的分布影响,以及不同产卵时间间隔对自身和同种寄主识别、种内内部竞争的影响。结果显示,烟蚜茧蜂在寄主密度为30头以下时,过寄生率高于31.16%;而寄主密度为50头以上时,过寄生率低于6.64%。在24 h以上的产卵时间间隔下,烟蚜茧蜂的自身过寄生率高于37.04%,而同种过寄生率在22.45%~25.93%之间;而且龄期较高的幼虫在种内内部竞争中获胜的概率高于72.00%。表明烟蚜茧蜂在低寄主密度下倾向于过寄生,在高寄主密度下有避免过寄生的趋势;烟蚜茧蜂倾向于自身过寄生,而对同种过寄生表现出一种产卵限制;在烟蚜茧蜂的种内内部竞争中,龄期较高的幼虫一般具有优势。     

禾螟赤眼蜂的功能反应研究

在实验室条件下,以玉米禾螟卵和麦蛾卵为寄主,观察了禾螟赤眼蜂的功能反应。初步结果表明,在寄主卵密度为5,10,20,40粒的条件下,赤眼蜂对寄主的寄生率随卵的密度增加而增加,但密度由40粒增加到80粒时,寄生率的变化较为平缓。每只雌蜂寄生的卵粒数随着赤眼蜂密度的增加而减少。寄主密度的变化对赤眼蜂子一代的雌蜂比率无明显影响。     

巢房容积对工蜂几种主要形态特征的影响

巢房是蜜蜂哺育、繁殖后代的场所,蜂群的所有成员个体从卵期到成蜂羽化出房都是在巢房中进行生长发育的(王台不过是一种比较特殊的巢房而已),因此,巢房与蜂群的繁殖及个体发育有着紧密的联系。日常的蜂群管理过程中常常可以看到:同一蜂群刚刚羽化出房的个体中,有的细小体质纤弱,有的个体个体硕大体质健壮,这是否由于各巢房容积之间存在的差异所造成的呢?我们知道:新巢脾的巢房容积较大,而且大小比较一致,而旧巢脾上的巢房由于幼虫茧衣等物的不断沉积,容积不断缩小,巢房之间大小     

Resistance to carmine spider mite in watermelon

Resistance of 37Citrullus lanatus L. lines to the carmine spider mite,Tetranychus cinnabarinus (Boisduval), was evaluated in three laboratory experiments, each including seven plants per line. Infestation with ten adult female mites per leaf, of each plant, was done at the three-leaf stage. In experiment A, average counts 10 days after infestation of three leaves ranged from 42 to 144 mites per leaf. In experiment B, average counts 8 days after infestation of two leaves ranged from 40 to 286 mites per leaf. In experiment C, average counts 8 days after infestation of two leaves ranged from 15 to 196 mites per leaf. The results suggest that a definite variation in resistance against mite infestation exists among watermelon lines. Contribution from the Agricultural Research Organization. No. 1082-E, 1993 series.     

Previous infestation affects recolonization of cotton byAphis gossypii: induced resistance or plant damage?

The effect of previous infestation by the cotton aphid (Aphis gossypii Glover) on resistance of cotton seedlings to further infestation by the same insect, was examined in the laboratory. Seedlings which survived a heavy infestation and produced new leaves, were recolonized artificially and the fate of the colonizers was monitored. The two cotton varieties used in the experiments differed in resistance to aphid colonization, and a few seedlings were initially unsuitable for aphid colonization. Aphids transferred to new leaves on previously infested plants were not so successful as on uninfested seedlings and repeated attempts over a few weeks were sometimes required until a colony became established. Reinfested plants often showed no visible signs of stress, but the aphid colonies were frequently of the ‘yellow dwarf’ morph, indicating that the plants had been stressed after the first infestation. We suggest that damage caused by the first infestation — and not the production of some excess metabolites — is the reason for the lower success on previously infested plants.     

Changes in the incidence of ragwort (Senecio jacobaea L.) infestation of grassland over a 4-year period in NE Scotland

A roadside survey of 4749 fields in eight areas of NE Scotland was conducted annually from 1979 to 1982. The proportion of grass fields infested with ragwort remained steady at 18–19% from 1979 to 1981 but fell to 13·5% in 1982. This fall resulted from fewer fields becoming newly infested and from more fields that had remained in grass ceasing to be infested. The proportion of infested fields remaining in grass that showed a reduction of two or more points on a 0–5 logarithmic scale of ragwort density (a possible indication of the frequency of control measures) was 24·0% in 1979–1980, 21·7% in 1980–1981 and 36·3% in 1981–1982. The incidence of ragwort infestation was consistently higher in some areas than in others and was not related to the proportion of arable crops. The change in incidence of infestation varied greatly between different areas, as did the proportion of infested fields whose score on the 0–5 scale fell by two or more points. In 1979–1980 and 1980–1981 this proportion had to exceed 22% to effect a net decrease in the incidence of infestation in an area, but in 1981–1982 no relationship was evident between these two measures of change. The incidence of infestation in all areas increased with increasing sward age but one area (Moray and Nairn) had a much higher proportion of young grass infested than any of the others. Over 99% of ragwort infestations consisted of Senecio jacobaea, infestations of S. aquatints Huds. being rare.     

De Levenswijze en de Bestrijding van de Rondknopmijt van Zwarte Bes,Cecidophyopsis ribis

The biology, ecology and control of the black currant gall mite,Cecidophyopsis ribis, formerly calledPhytoptus ribis, Eriophyes ribis orCecidophyes ribis, was studied in the field. These observations rendered the following results. The number of mites in the infested buds varied greatly according to the season; low numbers were present during May, June and July, high numbers during November until April. The number of generations is unknown. The migration period is closely related to the development of the host plant; mites migrate during the blossom period in spring. Newly formed axillary buds are infested while a larger proportion of the mites congregate in the tips of the shoots; these mites infest the axillary buds after the end of the migration period. Dissemination of the mites can take place by wind transportation, leaping, insect transportation, and transportation by man. Buds on the basal parts and on the terminal parts of newly formed shoots appeared to be more heavily infested than buds on the middle parts of the shoots. This preference can be explained by the behaviour of the mites; the basal buds are infested during the migration period, the terminal buds are infested by the mites from the growing tips. Damage consists of deformation of the buds which do not give flowers, and the transmission of reversion virus which causes sterility of the host plant. Control can be achieved by frequent applications of endosulfan. In nurseries endrin can be applied to prevent infestation.Samenvatting De levenswijze van de rondknopmijtCecidophyopsis ribis werd onder veldomstandigheden bestudeerd. Daarbij bleek dat gedurende de periode van oktober tot april grote aantallen mijten in de aangetaste knoppen aanwezig kunnen zijn. Infectie van de nieuwe knoppen vindt plaats vanaf half april tot half mei; er is een duidelijk verband tussen het ontwikkeljngsstadium van de waardplant en het tot stand komen van de infectie. De mijten vertonen een voorkeur voor de knoppen aan de basis en aan de einden der scheuten. Verplaatsing vindt plaats door het lopen langs de takken; de mijten kunnen ook meegedragen worden door insekten of verplaatst worden door de wind. Schade ontstaat doordat de aangetaste knoppen niet uitlopen en de rondknopmijten het brandnetelbladvirus overbrengen. Als ziektebeeld ontstaat dan het zgn. brandnetelblad; door dit virus wordt onvruchtbaarheid van de struiken veroorzaakt. Bestrijding van de mijten is mogelijk door toepassing van endosulfan en endrin gedurende de migratieperiode. Op vruchtdragende struiken kan endrin niet toegepast worden in verband met het tijdens de oogst aanwezige residu van dit rniddel.Gedetacheerd bij het Proefstation voor de Fruitteelt in volle grond, Wilhelminadorp.     

Spread of proso millet (Panicum miliaceum L.) in Ontario, Canada. I. Rate of spread and crop susceptibility

The infestations of two biotypes of Panicum miliaceum L. were monitored over a 5-year period (1981–1985) as they occurred in two townships in southwestern Ontario, Canada. On average, 16·5% of the cultivated fields in Hullett township were infested with the black-seeded biotype while 12·9% of the fields in North Norwich township were infested with the golden-seeded biotype. Neither population showed clear signs of increasing. The two biotypes were similar in their ability to persist as adult infestations. The black-seeded biotype showed a greater potential for colonizing uninfested fields. The crops grown in this region showed different susceptibilities to infestation by P. miliaceum. Corn (maize) fields were susceptible while most grain fields were resistant to infestation. White beans were susceptible to infestation by the black-seeded biotype. Wheat and oat crops were more resistant to infestation by the golden-seeded biotype than to those of the black-seeded biotype.     

Dispersal in patchy environments: effect on the prevalence of small mammal ectoparasites

Part-time ectoparasites on small mammals disperse via the habitat, while full-time parasites spread throughout the host population by direct contacts between host animals. It is therefore supposed that the effect of the natural environment is different for the two groups. This was studied as differences between observed and expected prevalence, the percentage of the infested host population, during different environmental conditions. Two possible mechanisms of such an effect were analysed, i.e. a) host selection and its change with host frequency and b) parasite migration and reproduction rates as reflected by the frequency distribution patterns on the hosts. As expected the prevalence of full-time ectoparasites (Anoplura and subfamily Laelapinae) could be predicted on the basis of host species frequencies during different environmental conditions, with the exception of one louse species (Hoplopleura acanthopus), because of its restricted distribution. Prediction was not possible for part-time ectoparasites (subfamily Hameogamasinae). Species of the subfamily Haemogamasinae were more catholic in host selection than species of Anoplura and subfamily Laelapinae. The haemogamasin mites changed host species to a greater extent than did Anoplura and Laelapinae. All haemogamasin mites had short-tailed frequency distribution patterns and all Anoplura and Laelapinae, except Hyperlaelaps microti, had long-tailed frequency distributions.     

Effect of <Emphasis Type="Italic">Meloidogyne ethiopica</Emphasis> parasitism on water management and physiological stress in tomato

Root-knot nematodes (RKN) are obligate endoparasites that severely damage the host root system. Nutrient and water uptake are substantially reduced in infested plants, resulting into altered physiological processes and reduced plant growth. The effect of nematode infestation on the morphological changes of roots and subsequent physiological plant responses of infested tomatoes with the RKN Meloidogyne ethiopica was studied in a pot experiment. Plants were infested with two inoculum densities (10 or 50 eggs per cm³ substrate) and its effect was evaluated 74 and 102 days post inoculation (DPI). Morphological changes and root growth was determined by analysing scanned images of the whole root system. Nematode infestation reduced the portion of fine roots and increased that of coarse roots due to gall formation. Fine roots of non-infested control plants represented around 51% of the area of the whole root system at 74 and 102 DPI. In comparison to controls, plants inoculated with low and high nematode density had 2.1 and 3.2-times lower surface area of fine roots at 102 DPI. Root analyses revealed that plants had a very limited ability to mitigate the effects of the root-knot nematodes infestation by altering root growth. Root galls had a major influence on the hydraulic conductivity of the root system, which was significantly reduced. The low leaf water potential of infested plants coincided with decreased stomatal conductivity, transpiration and photosynthesis. The latter two were reduced by 60–70% when compared to non-infested control plants.     

Surveys of beet cyst nematode in England 1977–80

Surveys of sugar beet crops for beet cyst nematode ( Heterodera schachtii Schmidt) in seven selected areas of England have provided data on distribution of the pest and on some factors affecting its occurrence. These data were mapped by CAMGRID computer program.
Infestations occurred mostly on the East Anglian fenland (14% of fields infested) and in this area were more frequent nearer the sugar beet processing factory. In the remaining areas the few infested fields (5% or less) were generally scattered but a small concentration of infestation occurred in the West Midlands in an area of intensive horticulture with frequent brassica crops. The survey data did not support the view that beet cyst nematode infestations occur more frequently near access points to the crop. In the surveyed areas frequency of host crops appears to be more important than soil type in determining the likelihood of infestation.     

Immunization of rabbits with antigens from Psoroptes cuniculi, the rabbit scab mite.

Rabbits immunized with the whole body extract of Psoroptes cuniculi (Delafond, 1859) developed partial immunity to the infestation with this mite. These rabbits manifested P. cuniculi antigen-induced cell response and a high level of specific serum antibody after the immunization. Electrophoretic separation of the mite extract followed by immunostaining with various sera revealed differences between artificially immunized and naturally infested rabbits to most of the P. cuniculi antigens. However, the specific antibody pattern, that was developed by the immunized rabbits, was not changed after these rabbits were infested with the mites.