杂拟谷盗的热适应特性

为了解杂拟谷盗Tribolium confusum Jacquelin du Val的热适应特性,将杂拟谷盗分别于15,25和35℃下驯化2周后,用温度梯度仪测量在不同温度驯化下杂拟谷盗的最适温度、临界低温和临界高温。结果表明,驯化温度对杂拟谷盗最适温度、临界低温和临界高温的影响极显著(P<0.01),最适温度、临界低温、临界高温均随着驯化温度的升高而升高。最适温区的范围随着驯化温度的升高而扩大。驯化温度对杂拟谷盗最适温度的影响最大(0.317),对临界低温的影响(0.310)大于临界高温(0.255)。     

Avidin expressed in transgenic rice confers resistance to the stored-product insect pests Tribolium confusum and Sitotroga cerealella

Rice (Oryza sativa var. Nipponbare) was transformed with an artificial avidin gene. The features of this construct are as follows: (1) a signal peptide sequence derived from barley alpha amylase was added at the N-terminal region, (2) codon usage of the gene was optimized for rice, and (3) the gene was driven by rice glutelin GluB-1, an endosperm-specific promoter. Avidin was produced in the grain of the transgenic rice but not in the leaves. The concentration of avidin in the kernels was about 1,800 ppm. All larvae of the confused flour beetle (Tribolium confusum) and Angoumois grain moth (Sitotroga cerealella) died when fed transgenic avidin rice powder or kernels, respectively, whereas most of the test insects developed into adults when they were fed a nontransgenic rice control diet. Avidin extracted from the transgenic rice kernel lost most biotin-binding activity after 5 min heating at 95 degrees C.     

The Influence of Oxidizing Agents on Macromolecular Synthesis for Chitinous Material

Summary

The 5th instar larvae of the common flour beetle, Tribolium confusum, was utilized as an invertebrate model to test the larvicidal potential of oxidizing agents used as flour preservatives. Larvae were exposed to 10 ppm of either diflubenzuron or benzoyl peroxide. Results showed decreases in both total protein and glucose concentrations. Histological examination also indicated smaller deposition of chitinous material in the endocuticle. Both treatments had similar effects. Thus, these data indicate that oxidizing agents mixed in flour may be used for the control of development of flour beetle larvae.     

Use of ablated stalks to assess field rates of parasitism of Diatraea saccharalis (Lepidoptera: Crambidae) by Cotesia flavipes (Hymenoptera: Braconidae)

We evaluated a technique that used ablated sections of corn stalks infested with larvae of Diatraea saccharalis F. to assess parasitism by Cotesia flavipes (Cameron) in a corn field. Stalkborer larvae were retrieved successfully from the artificially infested, ablated stalks for at least 96 h after deployment in the field. Levels of parasitism in ablated stalks attached to corn plants were comparable to levels of parasitism measured using whole plants that were artificially infested. Olfactometer comparisons showed preference by female C. flavipes for both whole plants and ablated stalks containing larval D. saccharalis, over uninfested stalks and plants. This technique provides a means to estimate parasitism of stalkborer larvae by C. flavipes without destructive sampling of agronomic plants.     

Spatial and temporal population interactions between the parasitoids Cotesia flavipes and Tachinidae flies: considerations on the adverse effects of biological control practice

Biological control of Diatraea saccharalis is regarded as one of the best examples of successful classical biological control in Brazil. Since the introduction of the exotic parasitoid Cotesia flavipes, the decrease of D. saccharalis infestation in sugarcane fields has been attributed to the effectiveness of this agent. Recently, the native tachinid fly parasitoids (Lydella minense and Paratheresia claripalpis) have also been implicated in the success. Here, we investigated the spatial and temporal population interactions between C. flavipes and the tachinid flies, and provide a critical analysis of the biological control practice, focusing on the undesirable effects of introductions of exotic natural enemies. To investigate these questions, a large data set comprising information from two sugarcane mills located in the state of São Paulo, Brazil (Barra and São João Mills), was analysed. Analysis of the correlation between C. flavipes and tachinid fly population densities through time revealed that such populations were inversely correlated in the São João Mill and not correlated in the Barra Mill. Logistic regressions were computed to investigate the proportion of sites occupied by the parasitoid species at both mills as a function of time. An increasing trend in the proportion of sites occupied by C. flavipes was observed, with a concomitant decrease of the sites occupied by tachinid flies. This effect was more intense in the São João Mill. Thus, there is a convincing possibility that constant releases of C. flavipes decreased the tachinid fly populations, resulting in an undesirable effect of biological control practice.     

The stimulation of immune defence accelerates development in the red flour beetle (Tribolium castaneum)

The timing of the transition between life stages is of key importance for an organism. Depending on the environmental conditions, maturing earlier at a smaller size or maturing later at a larger size can be advantageous for fitness. Exposure to parasites and subsequent immune activation may lead to alterations in development. Immune defence often comes at a cost, such as energy drain towards immune function, which is likely to delay development. On the other hand, animals may react to an anticipated risk of infection with a phenotypically plastic shift in life history, which may more likely lead to accelerated development and earlier maturation. We tested these alternatives in the red flour beetle, Tribolium castaneum. Young larvae were exposed to a non-infectious immune challenge with heat-killed bacteria (either Escherichia coli or Bacillus thuringiensis) and they were followed up for their development, survival, adult size and reproduction. We found that animals that had experienced a bacterial challenge developed into adults earlier than sham-treated beetles, while they did not differ significantly in survival or adult size. Beetles exposed to E. coli produced fewer offspring, while exposure to B. thuringiensis did not affect offspring number. Taken together, our results indicate that T. castaneum is able to speed up its development when facing a risk of infection.     

磷化氢对赤拟谷盗成虫体内CAT和SOD活性的影响

用赤拟谷盗Tribolium castaneum(Herbst)成虫,研究PH3对其体内超氧化物岐化酶(SOD)和过氧化氢酶(CAT)活性的影响。结果表明PH3熏蒸后,4种不同地理种群的成虫体内,CAT酶活性都有所降低。种群NGD1降低最多,接近57%,而NGD4则只降低了19%,NGD2和NGD3的降低都在40%左右。不同地理种群的成虫体内,SOD酶活性在熏蒸后都有所增加,种群NGD1增加幅度最大,NGD2增加幅度最小。SOD和CAT活性的变化幅度与成虫对PH3产生的抗性有关,抗性越大,酶活性变化越大。     

Analysis of polysaccharide hydrolases secreted by Aspergillus flavipes FP-500 on corn cobs and wheat bran as complex carbon sources

Abstract

Aspergillus flavipes FP-500 is a Mexican native strain that has been reported as a good producer of xylanases and pectinases; therefore, it promises a strong impact on biotechnology. To provide an overview of protein secretion by A. flavipes, we carried out a comparative proteome analysis of extracellular proteins in liquid cultures with two heterogeneous agro-industrial residues; corn cob (CC) and wheat bran (WB), as carbon sources. Extracellular proteins obtained from both cultures were identified using MS/MS spectrometry. We identified 134 proteins, which were classified into four groups: glycosyl hydrolases (GH), esterases/proteases, miscellaneous proteins, and unidentified proteins. Around 50% of the total proteins identified were GH such as xylanases, β-xylosidases, β-galactosidases, cellulolytic enzymes like β-glucosidase, endoglucanases, and cellobiohydrolases. From this family, a core of 22 (16%) of the proteins identified were found in both substrates, CC and WB, whereas 30% and 54% were unique for CC and WB, respectively. In the esterases/proteases group, proteases, lipases and esterases like feruloylesterases, and acetyl-xylanesterase were identified. Proteins with diverse functions such as monophosphate dehydrogenase or N-acetylglucosaminidase were present. Here, we present strong evidences indicating that the composition and heterogeneity of the used carbon source determine the specific set of protein secreted by the fungus.     

Analysis of importations for biological control of insect pests and weeds in New Zealand

Importations of biological control agents for insect pests and weeds in New Zealand are summarized and factors contributing to the relative success of the programmes are examined. The establishment rate of 30.9% is similar to that achieved worldwide, but is significantly lower than the rate achieved in the island habitat of Hawaii. The pioneering role of New Zealand in biological control is shown by the high proportion of programmes first attempted in this country. Although this novelty has not reduced the establishment rate, introductions against endemic species have not succeeded. Size of release was not a dominant feature in the establishment of agents. Complete or substantial success is recorded for 17 of the 70 target pests, with a relatively high success rate in forestry programmes. Examples of the influence of climate matching and competitive exclusion are also discussed. Changing practices and attitudes to the introduction of biological control agents are documented to show the increasing emphasis on specialists. No adverse effects of introductions are reported. The challenge to practitioners and regulators is to develop systems to evaluate conflicts of interest and develop workable mechanisms to determine which biological control agents are suitable for release.     

Evolutionary flexibility of pair-rule patterning revealed by functional analysis of secondary pair-rule genes, paired and sloppy-paired in the short-germ insect, Tribolium castaneum

In the Drosophila segmentation hierarchy, periodic expression of pair-rule genes translates gradients of regional information from maternal and gap genes into the segmental expression of segment polarity genes. In Tribolium, homologs of almost all the eight canonical Drosophila pair-rule genes are expressed in pair-rule domains, but only five have pair-rule functions. even-skipped, runt and odd-skipped act as primary pair-rule genes, while the functions of paired (prd) and sloppy-paired (slp) are secondary. Since secondary pair-rule genes directly regulate segment polarity genes in Drosophila, we analyzed Tc-prd and Tc-slp to determine the extent to which this paradigm is conserved in Tribolium. We found that the role of prd is conserved between Drosophila and Tribolium; it is required in both insects to activate engrailed in odd-numbered parasegments and wingless (wg) in even-numbered parasegments. Similarly, slp is required to activate wg in alternate parasegments and to maintain the remaining wg stripes in both insects. However, the parasegmental register for Tc-slp is opposite that of Drosophila slp1. Thus, while prd is functionally conserved, the fact that the register of slp function has evolved differently in the lineages leading to Drosophila and Tribolium reveals an unprecedented flexibility in pair-rule patterning.     

Responses of the stem borer larval endoparasitoid Cotesia flavipes (Hymenoptera: Braconidae) to plant derived synomones: Laboratory and field cage experiments

Laboratory and field cage experiments investigated the response of females of the stem borer larval endoparasitoid Cotesia flavipes to two synthetic synomone components, the terpenoid (E)-β-farnesene and the green leaf volatile, (Z)-3-hexenyl acetate, both compounds identified previously in headspace volatiles of maize plants damaged by stem borer (Chilo partellus). In dose response tests performed in a Y-tube olfactometer, parasitoids were significantly more attracted to the arms bearing 10 or 15 µg of (Z)-3-hexenyl acetate and (E)-β-farnesene than to the control arm. (E)-β-Farnesene was as attractive as the essential oil from the plant Hemizygia petiolata (Lamiaceae) rich in the same compound (80% relative amount). The plant essential oil elicited responses from females of the parasitoid comparable to those elicited by two positive controls, stem borer larval frass and adult parasitoid diet (20% honey solution), tested in the laboratory assays. In field cage trapping experiments, captures in traps baited with the terpenoid, the plant essential oil, (Z)-3-hexenyl acetate and the control of 20% honey solution, were not significantly different relative to captures in unbaited traps. Addition of the green leaf volatile (Z)-3-hexenyl acetate to the plant essential oil to yield a 1:1 two-component blend captured significantly more female parasitoids than traps baited with either of the two components alone. The results show that blends of green leaf volatiles and sesquiterpenoids may have potential in monitoring C. flavipes populations in the field.     

Germ-cell cluster formation in the telotrophic meroistic ovary of <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Coleoptera,Polyphaga, Tenebrionidae) and its implication on insect phylogeny

Tribolium castaneum has telotrophic meroistic ovarioles of the Polyphaga type. During larval stages, germ cells multiply in a first mitotic cycle forming many small, irregularly branched germ-cell clusters which colonize between the anterior and posterior somatic tissues in each ovariole. Because germ-cell multiplication is accompanied by cluster splitting, we assume a very low number of germ cells per ovariole at the beginning of ovariole development. In the late larval and early pupal stages, we found programmed cell death of germ-cell clusters that are located in anterior and middle regions of the ovarioles. Only those clusters survive that rest on posterior somatic tissue. The germ cells that are in direct contact with posterior somatic cells transform into morphologically distinct pro-oocytes. Intercellular bridges interconnecting pro-oocytes are located posteriorly and are filled with fusomes that regularly fuse to form polyfusomes. Intercellular bridges connecting pro-oocytes to pro-nurse cells are always positioned anteriorly and contain small fusomal plugs. During pupal stages, a second wave of metasynchronous mitoses is initiated by the pro-oocytes, leading to linear subclusters with few bifurcations. We assume that the pro-oocytes together with posterior somatic cells build the center of determination and differentiation of germ cells throughout the larval, pupal, and adult stages. The early developmental pattern of germ-cell multiplication is highly similar to the events known from the telotrophic ovary of the Sialis type. We conclude that among the common ancestors of Neuropterida and Coleoptera, a telotrophic meroistic ovary of the Sialis type evolved, which still exists in Sialidae, Raphidioptera, and a myxophagan Coleoptera family, the Hydroscaphidae. Consequently, the telotrophic ovary of the Polyphaga type evolved from the Sialis type. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

21世纪我国害虫生物防治研究的进展、问题与展望

害虫生物防治是昆虫学的重要分支学科,进入21世纪以来,随着生命科学和生物技术的发展以及新原理、新方法的不断渗透、交叉与融合,使该分支学科在我国得到了快速发展。本文就近年来我国在天敌昆虫及其利用、昆虫病原微生物及其利用、昆虫信息素及其应用、生物农药及其推广应用、新兴生物技术在害虫生物防治中的应用等方面所取得的主要进展作了简要的回顾与总结;并在分析我国本领域学科发展水平与国际差距的基础上,指出了我国生物防治领域存在的主要问题及几个亟待加强的优先发展领域。     

昆虫蜕皮的分子机理及应用

昆虫蜕皮是一个由PTTH启始的、激素介导的基因序列表达和相互作用的级联反应过程。阐明昆虫蜕皮的分子机理,不仅可以解释发育生物学的科学问题,为害虫控制提供新的思路,还可以从中发现新的可资生产应用的分子。作者通过蛋白质组学方法从棉铃虫Helicoverpa armigera Hubner蜕皮幼虫鉴定到30个差异表达的蛋白质。通过抑制性消减杂交技术,从棉铃虫蜕皮幼虫、变态决定幼虫和5龄取食幼虫鉴定到100个表达序列标签(EST)。证明其中的11个EST在蜕皮或变态时差异表达。通过RT-PCR方法克隆棉铃虫激素接受子3基因,研究该基因在发育中的表达模式。用该基因构建具有绿色荧光蛋白标记和多角体蛋白的基因重组病毒(AcMNPV-GFP-HHR3-Polh)。实验结果表明,AcMNPV-GFPHHR3-Polh病毒可以通过注射或口服感染棉铃虫,导致棉铃虫幼虫非正常蜕皮、生长延缓、半数存活时间下降。该研究显示昆虫蜕皮功能基因在害虫控制中有很好的应用前景。蜕皮功能基因的表达与调控、蜕皮激素介导的信号转导通路、变态过程中组织解体和重建的分子机理、激素调控基因顺序表达的分子机理、变态起始因子、JH受体等是本领域今后的主要研究方向。     

Vision is Important for Plant Location by the Phytophagous Aquatic Specialist Euhrychiopsis lecontei Dietz (Coleoptera: Curculionidae)

The aquatic milfoil weevil Euhrychiopsis lecontei Dietz (Coleoptera: Curculionidae) is a specialist on Myriophyllum spp. and is used as a biological control agent for Eurasian watermilfoil (Myriophyllum spicatum L.), an invasive aquatic macrophyte. We show evidence that visual cues are important for plant detection by these weevils. Weevils had difficulty locating plants in dark conditions and were highly attracted to plant stems in the light, even when the plant sample was sealed in a vial. However, weevils were equally attracted to both M. spicatum and another aquatic macrophyte, coontail (Ceratophyllum demersum L.) in vials. Turbidity (0–100 NTU) did not significantly influence visual plant detection by the weevils. This work fills a void in the literature regarding visual plant location by aquatic specialists and may help lead to a better understanding of when and where these weevils will find, accept, and damage their target host-plants.     

The dynamics of infection of Tribolium confusum by Hymenolepis diminuta: the influence of infective-stage density and spatial distribution

The mean parasite burden of a population of Tribolium confusum is shown to rise to a plateau as the exposure density of infective eggs of Hymenolepis diminuta increases. The level of this plateau is shown to be dependent on the nutritional status of the host population, being depressed from approximately 18 cysticeroids/beetle in hosts which have been starved prior to experimentation, to approximately 2 cysticercoids/beetle in satiated hosts. A simple model is used to describe the shape of this infection functional response in terms of the predator-prey interaction between hosts (T. confusum) and parasite infective stages (H. diminuta eggs). The distribution of successful infections/host is shown to be over-dispersed, even when hosts are exposed to infective stages arranged in a uniform spatial pattern. The over-dispersion of parasite numbers/host is shown to become more severe as the spatial pattern of infective stages changes from under-dispersed, through random, to over-dispersed. Experimental results are discussed in relation to the dynamics of parasite-host interactions, in which infection takes place by host ingestion of a free-living infective stage.     

Physiological differences between strains of Tribolium castaneum selected for resistance to hypoxia and hypercarbia, and the unselected strain

Abstract. The metabolic rates, as expressed by oxygen (O₂) consumption, carbon dioxide (CO₂) production, and losses in wet and dry weights, were examined for adults of three strains of the red flour beetle Tribolium castaneum (Herbst), during exposure to two modified atmospheres (MAs). Exposure of a strain selected for resistance over twenty-one generations to an atmosphere of 65% CO₂, 20% O₂ and the balance nitrogen (N₂), termed a high carbon dioxide concentration atmosphere (HCC) and exposure of an unselected strain to HCC, showed considerable levels of aerobic metabolism during exposure. For the unselected strain water loss and mobilization of energy reserves were rapid and mortality was followed by rapid desiccation. For the HCC-resistant strain water balance was maintained and energy reserves were utilized more slowly over a prolonged period. Exposure of a strain selected for resistance over twenty-one generations to a low oxygen concentration atmosphere (LOC) of 0.5% O₂ in N₂, and an unselected strain to LOC, revealed that even at 0.5% O₂, metabolism was largely aerobic in both strains. Maintenance of water balance was not a major factor causing mortality of either strain during exposure to LOC. In air, metabolic rates of both the resistant strains were lower than that of the unselected strain.     

Characterization of esterases in malathion-resistant and susceptible strains of the pteromalid parasitoid Anisopteromalus calandrae

General esterase, malathion-specific carboxylesterase, phosphotriesterase, glutathione S-transferase, cytochrome P-450-dependent monooxygenase activity, and target site sensitivity were compared in malathion-resistant (R) and malathion-susceptible (S) strains of the parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae). Activity against -naphthyl acetate was not significantly different in male and female wasps for either strain. General esterase activity ranged from 1.2-fold to 2.5-fold higher in the R strain compared with the S strain, but these differences between strains were not consistent. Based on V_max/K_m ratios estimated for a number of analogs of four substrates (-naphthyl acetate, β-naphthyl acetate, 4-methylumbelliferyl acetate, and p-nitrophenyl acetate) there was no evidence that general esterase activity was elevated or reduced in the R strain. Malathion-specific carboxylesterase (MCE) activity, determined by using 2,3-¹⁴C-malathion as substrate, was 10- to 30-fold higher in the R strain compared with that in the S strain. The MCE has a pH optima at about pH 7, is cytosolic, and is labile upon storage at −80°C. MCE activity could be recovered from native 10% PAGE gels and IEF–PAGE gels (pI=5.2), but the peak of MCE activity also contained the major peak of activity against -naphthyl acetate. There was no evidence for major involvement of phosphotriesterase, glutathione S-transferase, monooxygenase, or altered acetylcholinesterase in the resistance. These data suggest that an increased activity of a MCE in the R strain is the probable major mechanism conferring resistance to malathion in A. calandrae. This study provides the first characterization of a biochemical resistance mechanism in a parasitoid with a high level of resistance to an organophosphate insecticide.