Raising of Horn Fly Haematobia irritans(L.)(Diptera:Muscidae)in Laboratory by Means of Egg and Larva Inoculation

Several studies have required Haematobia irritans (L.) raising in laboratory. The present study assessed two methods of inoculating immature forms of H. irritans to obtain adults. In 2007, 15 Nellore steers (Bos indicus) (L.) were used for the collection of feces free of anthelmintic treatment and flies to produce for eggs and larva. For method I, 30 eggs were incubated in square filter paper (5 × 5 cm) and deposited on bovine feces (500 g) where they were kept until hatching and spontaneous penetration of larvae (L1) into the fecal mass. After 24 h, eggs were analyzed under a stereoscope microscope (40×) for the number of larvae that instinctively penetrated the feces. In method II, larvae were obtained only by natural egg hatching. At birth, 30 larvae were collected and individually inoculated, directly onto the fecal plate by employing a moistened brush. The tests were carried out at controlled temperature (28°C ± 2°C) and saturated humidity (80%) until the emergence of flies with both methods. The number of emerged flies was considered in the result. Using method I, 276 (76.7%) flies emerged from 360 inoculated eggs, while using method II, 283 (78.6%) flies emerged from 360 inoculated larvae. There was no significant difference (P = 0.7821) between methods for the number of flies;however, the proportion between males and females by means of larva inoculation was different from 1:1 (P = 0.0146). Results indicated that both methods led to a satisfactory production of flies and egg inoculation provided an easier establishment.

Use of electroporation as an option to transform the horn fly, Haematobia irritans： a species recalcitrant to microinjection

The horn fly, Haematobia irritans, is a serious pest of cattle in North America. The control of horn flies has primarily relied on insecticides. However, the heavy use of insecticides has led to the development of insecticide resistance in horn flies. Novel methods to control horn flies are greatly needed. Transgenic technology is an effective tool to genetically modify insects and may lead to novel methods of pest control based on genomic approaches. Here we report apiggyBac-mediated transformation of the horn fly via electroporation. Transformation with a DsRed fluorescent marker protein coding region was verified by PCR analysis of individual fly bodies and pupal cases and sequencing of PCR products. However, Southern blot analysis failed to indicate the DsRed gene was integrated into the horn fly genome. Thus, the electroporation protocol may have caused the DsRed gene to be integrated into bacterial symbionts of the horn fly.

Dynamics and mechanisms of permethrin resistance in a field population of the horn fly, Haematobia irritans irritans

A study was conducted at the Pressler ranch, near Kerrville, Texas, USA between 2002 and 2006 to determine the dynamics and mechanisms of resistance to permethrin in a field population of the horn fly, Haematobia irritans irritans （L.）. Changes of resistance to pyrethroid insecticide associated with use of a pour-on formulation of cyfluthrin in 2002 and use of diazinon ear tags in subsequent years were studied using a filter paper bioassay technique and a polymerase chain reaction assay that detects two sodium channel mutations, kdr and super-kdr resistance alleles. A maximum of 294-fold resistance to permethrin was observed in the summer of 2002. A significant decrease in the resistance level was observed in spring 2003, and resistance continued to decline after animals were treated with diazinon ear tags. In response to pyrethroid treatments, the allelic kdr and super-kdr frequency increased from 56.3% to 93.8% and from 7.5% to 43.8%, respectively in 2002, and decreased significantly in 2003 when the pyrethroid insecticide was no longer used to treat animals. Females were found to have a higher allelic super-kdr frequency than males in 2002, while no difference was detected between males and females in the allelic kdr frequency. There was a significant positive correlation between frequencies of the sodium channel mutations and levels ofpermethrin resistance, suggesting that the sodium channel mutations, kdr and super-kdr, are the major mechanisms of resistance to pyrethroids in this horn fly population. Results of synergist bioassays also indicated possible contributions of two metabolic detoxification mechanisms, the mixed function oxidases （MFO） and glutathione S-trans- ferases （GST）. Compared to a horn fly infestation of an untreated herd, treatments with the pyrethroid pour-on formulation failed to control horn flies at the Pressler ranch in 2002. Sustained control of horn flies was achieved with the use of diazinon ear tags in 2003 and subsequent years.

角蝇各龄期幼虫体内斯氏副柔线虫的分子生物学鉴定

确定角蝇各龄期幼虫体内的斯氏副柔线虫(Parabronema skrjabini)幼虫。通过大量剖检角蝇各龄期幼虫,收集其体内的线虫幼虫,经扩增测序获得ITS基因序列,利用DNAStar 5.0软件,将其与斯氏副柔线虫成虫的ITS基因序列进行同源性比较。结果表明,角蝇Ⅰ、Ⅱ、Ⅲ期幼虫体内的线虫幼虫确为斯氏副柔线虫幼虫。该研究结果不但为鉴定角蝇各龄期幼虫体内的斯氏副柔线虫幼虫提供了简易准确的方法,而且也为弄清斯氏副柔线虫在其传播媒介角蝇体内的发育过程奠定了基础。

铁板砂、花岗岩免烧砖的研制

利用建筑垃圾铁板砂、花岗岩边角废料和粉煤灰等制备免烧砖,研究各原料对免烧砖强度的影响规律。确定了制备免烧砖各原料的最佳配合比:铁板砂45%、花岗岩15%、粉煤灰10%、生石灰26%、石膏3%、水泥1%,按此配比可以制备出28 d抗压、抗折强度分别为25、10 MPa的免烧砖。

角蝇及其防制

角蝇是一种广泛存在于欧洲、亚洲及南美北美地区且危害性严重的经济性害虫,可通过叮咬吸血对畜牧业造成重大经济损失,也可作为媒介生物在畜群间传播病原体。实际生产中,根据角蝇具有在牛粪中产卵的生活习性,粪便排泄物或直接被清除,或被掺入多拉菌素、伊维菌素等以杀死角蝇幼虫。而控制成蝇则多采用化学手段,其中耳标式杀虫剂由于其防制效率高、防制周期较长、用药量低等特点,近些年来得到广泛应用。本文结合近几年国内外相关文献,对角蝇的生物学特性、危害以及角蝇综合防制展开综述,为角蝇防制提供理论基础。