家蚕幼虫BmToll9基因对肽聚糖和金黄色葡萄球菌的响应表达

【目的】Toll信号通路是昆虫中重要的免疫信号通路,其中Toll受体在保持Toll通路的正常免疫应答、抵抗外源病原体中起到关键的作用。本研究旨在探究肽聚糖和金黄色葡萄球菌Staphylococcus aureus对家蚕Bombyx mori Toll受体基因BmToll9-1和BmToll9-2表达的影响。【方法】将革兰氏阳性菌细胞壁主要成分肽聚糖和革兰氏阳性菌金黄色葡萄球菌分别注射感染家蚕5龄第1天幼虫,诱导其发生免疫反应;采用实时荧光定量PCR分析注射后不同感染时间点BmToll9-2和BmToll9-1基因在家蚕幼虫中肠、表皮、脂肪体和丝腺中的相对表达水平。【结果】往家蚕5龄幼虫中注射肽聚糖或金黄色葡萄球菌后,BmToll9-2基因出现了时间和组织的差异性表达。注射肽聚糖和金黄色葡萄球菌均能诱导5龄幼虫中肠BmToll9-2基因的表达上调,注射肽聚糖和金黄色葡萄球菌分别在3和6 h时对基因表达的诱导效果最好,且注射金黄色葡萄球菌比注射肽聚糖对基因表达的诱导效果更好。注射金黄色葡萄球菌能引起5龄幼虫表皮、脂肪体和丝腺中BmToll9-2基因的表达上调,分别于注射后24, 6和24 h时诱导效果最好。注射金黄色葡萄球菌亦能诱导同源的BmToll9-1基因的上调表达。【结论】家蚕幼虫BmToll9基因在肽聚糖或金黄色葡萄球菌注射处理后均能在不同组织中发生上调表达,推测BmToll9基因参与了家蚕对肽聚糖和金黄色葡萄球菌的免疫反应。     

BmSUC1 is essential for glycometabolism modulation in the silkworm, Bombyx mori

Sucrose is the most commonly transported sugar in plants and is easily assimilated by insects to fulfill the requirement of physiological metabolism. BmSuc1 is a novel animal β-fructofuranosidase (β-FFase, EC 3.2.1.26)-encoding gene that was firstly cloned and identified in silkworm, Bombyx mori. BmSUC1 was presumed to play an important role in the silkworm-mulberry enzymatic adaptation system by effectively hydrolyzing sucrose absorbed from mulberry leaves. However, this has not been proved with direct evidence thus far. In this study, we investigated sucrose hydrolysis activity in the larval midgut of B. mori by inhibition tests and found that sucrase activity mainly stemmed from β-FFase, not α-glucosidase. Next, we performed shRNA-mediated transgenic RNAi to analyze the growth characteristics of silkworm larvae and variations in glycometabolism in vivo in transgenic silkworms. The results showed that in the RNAi-BmSuc1 transgenic line, larval development was delayed, and their body size was markedly reduced. Finally, the activity of several disaccharidases alone in the midgut and the sugar distribution, total sugar and glycogen in the midgut, hemolymph and fat body were then determined and compared. Our results demonstrated that silencing BmSuc1 significantly reduced glucose and apparently activated maltase and trehalase in the midgut. Together with a clear decrease in both glycogen and trehalose in the fat body, we conclude that BmSUC1 acts as an essential sucrase by directly modulating the degree of sucrose hydrolysis in the silkworm larval midgut, and insufficient sugar storage in the fat body may be responsible for larval malnutrition and abnormal petite phenotypes.     

Selective transport of the mulberry leaf urease from the midgut into the larval hemolymph of the silkworm,Bombyx mori

Just before spinning, larvae of the silkworm, Bombyx mori, absorb intact urease of the host plant (mulberry leaf) from the midgut lumen into the hemolymph. In order to investigate whether the transport of the mulberry leaf urease is selective, crude proteins extracted from the mulberry leaves were labeled with biotin and orally administered to the fifth instar larvae. The biotinylated proteins transported into the hemolymph were detected by ligand blotting using streptavidin. When the biotinylated proteins were administered to 5-day-old fifth instar larvae, a strong signal of a biotinylated protein was detected in the hemolymph 2 days after the administration. In contrast, when the biotinylated mulberry leaf proteins were administered to 3-day-old fifth instar larvae, no signal derived from the biotinylated proteins was detected in the hemolymph. The signal weakened when the biotinylated proteins had been immunoprecipitated before administering to the larvae, indicating that the signal came from the mulberry leaf urease. These results show that the transport of the mulberry leaf urease from the midgut into the hemolymph is selective and larval-stage specific. Subsequently, binding assays were carried out to test the binding ability of the mulberry leaf urease to the brush border membrane in the epithelial cells of larval midgut. The urease was not bound to the brush border membrane vesicles (BBMV) from the midgut of 3-day-old fifth instar larvae, while more than 60% of the total amount of incubated urease was bound to the BBMV from the midgut of 6-day-old fifth instar larvae. The urease binding ability of BBMV correlated with the uptake of the mulberry leaf urease. This suggests that a urease binding molecule(s) exists in the BBM of the midgut epithelium, which is involved in the uptake of the mulberry leaf urease. In addition, the uptake of the mulberry leaf urease into the hemolymph was induced by 20-hydroxyecdysone.     

Baculovirus-mediated Expression of a Gene for Trehalase of the Mealworm Beetle, Tenebrio molitor, in Insect Cells, SF-9, and Larvae of the Cabbage Armyworm, Mamestra brassicae

It is of interest to understand what kinds of physiological and biochemical changes occur in insects if the homeostasis of trehalose in the hemolymph is disrupted by the infection with a recombinant baculovirus containing a secretory-trehalase gene. For this purpose, two recombinant non-occluded Autographa california multicapsid nucleopolyhedroviruses (AcMNPVs), vTREVL and vERTVL, containing a trehalase cDNA of the mealworm beetle, Tenebrio molitor, were constructed. The trehalase cDNA was inserted in the sense orientation downstream of the polyhedrin promoter for vTREVL, and in the anitsense orientation for vERTVL. The active trehelase of T. molitor was found outside of cells when SF-9 cells or larvae of the cabbage armyworm, Mamestra brassicae, were infected with vTREVL. In the hemolymph of vTREVL-infected larvae, expression of the active trehelase was followed by disappearance of trehalose and appearance of glucose. However, the mortality time of virus-infected 5th instar larvae increased in the following order: AcMNPV C6 (wild-type virus) ≤ vERTVL < vTREVL. The symptoms (the browning and liquefying of the host body) of NPV infection were moderated considerably in vTREVL-infected larvae.     

Lipid transfer particle catalyzes transfer of carotenoids between lipophorins of Bombyx mori

The yellow color of Bombyx mori hemolymph is due to the presence of carotenoids, which are primarily associated with lipophorin particles. Carotenoids were extracted from high density lipophorin (HDLp) of B. mori and analyzed by HPLC. HDLp contained 33 μg of carotenoids per mg protein. Over 90% of carotenoids were lutein while -carotene and β-carotene were minor components. When larval hemolymph was subjected to density gradient ultracentrifugation, a second minor yellow band was present, which was identified as B. mori lipid transfer particle (LTP). During other life stages examined however, this second band was not visible. To determine if coloration of LTP may fluctuate during development, we determined its concentration in hemolymph and compared it to that of lipophorin. Both proteins were present during all life stages and their concentrations gradually increased. The ratio of lipophorin: LTP was 1015:1 during the fourth and fifth instar larval stages, and 2030:1 during the pupal and adult stages. Thus, there was no correlation between the yellow color attributed to LTP and its hemolymph concentration. It is possible that yellow coloration of the LTP fraction corresponds to developmental stages when the particle is active in carotene transport. To determine if LTP is capable of facilitating carotene transfer, we took advantage of a white hemolymph B. mori strain which, when fed artificial diet containing a low carotene content, gives rise to a lipophorin that is nearly colorless. A spectrophotometric, carotene specific, transfer assay was developed which employed wild type, carotene-rich HDLp as donor particle and colorless low density lipophorin, derived from the white hemolymph strain animals, as acceptor particle. In incubations lacking LTP carotenes remained associated with HDLp while inclusion of LTP induced a redistribution of carotenes between the donor and acceptor in a time and concentration dependent manner. Time course studies suggested the rate of LTP-mediated carotene transfer was relatively slow, requiring up to 4 h to reach equilibrium. By contrast, studies employing ³H-diacylglycerol labeled HDLp as donor particle in lipid transfer assays revealed a rapid equilibration of label between the particles. Thus, it is plausible that the slower rate of LTP-mediated carotene transfer is due to its probable sequestration in the core of HDLp.     

Comparative proteomic analysis between the domesticated silkworm (Bombyx mori) reared on fresh mulberry leaves and on artificial diet

To gain an insight into the effects of different diets on growth and development of the domesticated silkworm at protein level, we employed comparative proteomic approach to investigate the proteomic differences of midgut, hemolymph, fat body and posterior silk gland of the silkworms reared on fresh mulberry leaves and on artificial diet. Seventy-six differentially expressed proteins were identified by MALDI TOF/TOF MS, and among them, 41 proteins were up-regulated, and 35 proteins were downregulated. Database searches, combined with GO analysis and KEGG pathway analysis revealed that some hemolymph proteins such as Nuecin, Gloverin-like proteins, PGRP, P50 and beta/-N-acetylglucosamidase were related to innate immunity of the silkworm, and some proteins identified in silkworm midgut including Myosin 1 light chain, Tropomyosin 1, Profilin, Serpin-2 and GSH-Px were involved in digestion and nutrition absorption. Moreover, two up-regulated enzymes in fat body of larvae reared on artificial diet were identified as V-ATPase subunit B and Arginine kinase which participate in energy metabolism. Furthermore, 6 down-regulated proteins identified in posterior silk gland of silkworm larvae reared on artificial diet including Ribosomal protein SA, EF-2, EF-1gamma, AspAT, ERp57 and PHB were related to silk synthesis. Our results suggested that the different diets could alter the expression of proteins related to immune system, digestion and absorption of nutrient, energy metabolism and silk synthesis poor nutrition and absorption of nutrition in silkworm. The results also confirmed that the poor nutrient absorption, weakened innate immunity, decreased energy metabolism and reduced silk synthesis are the main reasons for low cocoons yield, inferior filament quality, low survival rate of young larvae and insufficient resistance against specific pathogens in the silkworms fed on artificial diet.     

高温对家蚕三品系血淋巴中糖水平的影响（英文）

家蚕Bombyx mori的两个二化性品系热耐受型NB4D2和热敏感型CSR2均适合于温带气候,而多化性的PM（Pure Mysore) 品系适合于热带气候,将这3种品系5龄幼虫分别置于32℃和36℃的高温下,观察高温对其5龄幼虫至蛹期血淋巴中糖含量及海藻糖酶活性的影响。结果表明： PM幼虫和蛹的死亡率均小于NB4D2和CSR2。在蜕皮期间血淋巴海藻糖水平较高,而葡萄糖水平及海藻糖酶活性较低。32℃和36℃的高温下,幼虫蜕皮期间血淋巴中糖含量及海藻糖酶活性仅在其各自的水平上表现为小幅度的增加。蜕皮后幼虫血淋巴中海藻糖含量显著下降,而葡萄糖含量和海藻糖酶活性显著上升。在较高温度下,蜕皮后幼虫血淋巴中海藻糖含量下降幅度更大,而葡萄糖含量及海藻糖酶活性上升水平也更加显著。25±1℃下取食幼虫血淋巴中葡萄糖含量显著下降,海藻糖含量显著上升;3℃和36℃下PM 和NB4D2取食幼虫血淋巴葡萄糖和海藻糖含量以及海藻糖酶活性增加,而CSR2均减少或降低。吐丝幼虫血淋巴中葡萄糖含量及海藻糖酶活性显著下降,海藻糖小幅度下降。而在较高温度下,耐热型PM 和NB4D2吐丝家蚕血淋巴糖含量含量和海藻糖酶活性明显增加,而热敏感型CSR2的则明显下降。这3种品系蛹发育期的血淋巴糖含量及海藻糖酶活性均下降。在两较高温度下,PM蛹期血淋巴糖和海藻糖酶活性增加,而NB4D2 36℃时增加幅度小于32℃时。对于CSR2,32℃时观察到其血淋巴葡萄糖含量增加,但当环境温度增加到36℃时其血淋巴葡萄糖含量降至正常水平下。然而,当CSR2的蛹置于32℃和36℃时血淋巴海藻糖含量及其酶活性下降,且36℃时下降幅度更大。因此,桑蚕对高温的适应取决于家蚕的品系及发育阶段,并可通过其血淋巴糖及海藻糖酶活性水平进行验证。     

Absorption of mulberry root urease to the hemolymph of the silkworm, Bombyx mori

Mulberry leaves are the sole diet of the silkworm, Bombyx mori. The host urease is incorporated into the larval hemolymph and involved in nitrogen metabolism in the insect. To investigate the selective absorption of the host urease to the larvae, crude urease was prepared from mulberry leaves and roots. Root urease was identical to leaf urease on the basis of electrophoretic analyses: (1) the urease activity appeared in the same migration position in a native gel; (2) There was no difference in molecular mass of the subunit. The root urease was orally injected to the fifth instar larvae of the silkworm. Just before spinning, the larvae absorbed intact urease from the midgut lumen to the hemolymph without the loss of activity. The capacity to absorb urease occurred only at the specific stage. Localization of host urease in midgut tissue was observed using confocal laser scanning microscopy and transmission electron microscopy. Based on spatial distribution of immunofluorescent signals and immunogold particles, host urease specifically attached to the surfaces of microvilli existing in the apical side of columnar cells and appeared in the cytoplasm of the cells for transport to the hemolymph. The incorporation efficiency of root urease into the hemolymph was significantly higher than for ureases from jack bean seeds and Bacillus pasteurii. The urease that was transported to the hemolymph was electrophoretically altered, compared with the host urease extracted.     

A genetic diversity study of silkworm using cleaved amplified polymorphic sequence (CAPS) markers

The silkworm, Bombyx mori is a beneficial insect of great economic importance in China for its silk production. In this study, we obtained 11 cleaved amplified polymorphic sequence (CAPS) markers and one PCR polymorphism marker from the genes of the silkworm, B. mori. A backcross progeny analysis showed that all these molecular markers were segregated in a Mendelian fashion and that polymorphisms were co-dominant. These markers were used to investigate the genetic diversity among 29 strains of B. mori from China, Japan and Europe. Cluster analysis, based on the genetic similarities calculated from CAPS data, grouped these strains roughly according to their geographical origin. One group contained silkworm strains from Europe and some of the Japanese strains were interspersed into the Chinese groups, whereas other Japanese strains clustered together.     

Susceptibility of Eldana saccharina (Lepidoptera: Pyralidae), Busseola fusca and Sesamia calamistis (Lepidoptera: Noctuidae) to Bacillus thuringiensis Cry toxins and potential side effects on the larval parasitoid Cotesia sesamiae (Hymenoptera: Braconidae)

Laboratory trials were conducted to determine the efficacy of four Bacillus thuringiensis (Bt) Cry toxins at five different concentrations (0.016, 0.08, 0.4, 2, 10 μg/mL) for controlling three lepidopteran stem-borer species (i.e., the pyralid Eldana saccharina and the noctuids Busseola fusca and Sesamia calamistis) as well as to evaluate their indirect effect on the braconid larval parasitoid Cotesia sesamiae. In addition, larvae from the treatments above, after having been parasitized, were either fed a contaminated (group 1) or a toxin-free (group 2) diet and compared with a control (i.e., parasitized larvae which have never fed on Bt-toxin). All Bt Cry toxins induced larval feeding inhibition. Compared with the control, significant mortality resulted at all concentrations and for all species of Lepidoptera. Cry1Ab was the most toxic with 10 days post treatment mortalities ranging from 81% in B. fusca and S. calamistis to 100% in E. saccharina. In contrast, Cry1Ac had comparatively low toxicity particularly for B. fusca and S. calamistis (e.g., respectively, 54 and 74% mortality at 10 days at the highest concentration). In the toxin-treated group 1, percentages of C. sesamiae cocoon-producing moth larvae were higher compared to group 2 and the control, whereas clutch size was higher than in group 2 but similar to the control. In both groups, 0.016, 0.08 μg/mL CrylAc yielded lower female-biased sex ratios than the control. It was suggested that paralyses of the moth larvae caused by the toxin may have facilitated parasitization leading to higher parasitism and clutch size.     

Host plant urease in the hemolymph of the silkworm, Bombyx mori

Urease activity was detected in the hemolymph of the silkworm, Bombyx mori from the beginning of spinning to the pharate adult stage if the larvae were reared on mulberry leaves throughout the 5th-instar (the last larval instar). In contrast, no urease activity was detected in the hemolymph of insects fed artificial diets, resulting in accumulation of urea during the spinning stage. To identify the hemolymph urease, the enzyme was highly purified from the hemolymph of the spinning larvae that had been reared on mulberry leaves and the properties of the purified enzyme were compared with those of the mulberry leaf urease. Four out of six monoclonal antibodies raised against jack bean seed urease cross-reacted equally with the silkworm hemolymph urease and the mulberry leaf urease. Under reducing conditions, the hemolymph urease and the mulberry leaf urease migrated at 90.5 kDa on SDS-PAGE gels. The first 20 N-terminal sequence of the hemolymph urease revealed complete identity with that of the leaf urease. The optimum pH for activity and Km value for urea were almost the same for the two enzymes. In conclusion, these two ureases are very likely identical, strongly suggesting that the mulberry leaf urease passes through the larval gut wall into the hemolymph without being digested. In addition, oral administration of mulberry leaf urease just before spinning induced considerable urease activity in the hemolymph of the larvae, but the same treatment did not induce enzyme activity in the hemolymph of the larvae three days before the onset of spinning. These results suggest that the silkworm larvae acquire the host plant urease specifically at the end of the feeding stage in order to degrade urea accumulated in the hemolymph.     

A novel sucrose hydrolase from the bombycoid silkworms Bombyx mori,Trilocha varians,and Samia cynthia ricini with a substrate specificity for sucrose

Although membrane-associated sucrase activity has been detected in the midgut of various lepidopteran species, it has not yet been identified and characterized at the molecular level. In the present study, we identified a novel sucrose hydrolase (SUH) gene from the following three bombycoid silkworms: Bombyx mori, Trilocha varians, and Samia cynthia ricini and named them BmSuh, TvSuh, and ScSuh, respectively. The EST dataset showed that BmSuh is one of the major glycoside hydrolase genes in the larval midgut of B. mori. These genes were almost exclusively expressed in the larval midgut in all three species, mainly at the feeding stage. SUHs are classified into the glycoside hydrolase family 13 and show significant homology to insect maltases. Enzymatic assays revealed that recombinant SUHs were distinct from conventional maltases and exhibited substrate specificity for sucrose. The recombinant BmSUH was less sensitive to sugar-mimic alkaloids than TvSUH and ScSUH, which may explain the reason why the sucrase activity in the B. mori midgut was less affected by the sugar-mimic alkaloids derived from mulberry.     

感染布氏白僵菌后油松毛虫血淋巴中海藻糖酶活性、海藻糖和葡萄糖含量的变化

为了揭示病原真菌白僵菌Beauveria侵染昆虫过程中如何利用虫体内糖类物质作为自身营养, 本研究测定了布氏白僵菌Beauveria brongniartii (Sacc.) Petch （2382菌株）感染油松毛虫Dendrolimus tabulaeformis Tsai et Liu幼虫后, 虫体血淋巴中酸性海藻糖降解酶活性及海藻糖和葡萄糖含量的变化。油松毛虫4龄幼虫感染菌株孢子悬浮液后, 血淋巴中酸性海藻糖降解酶的活性明显高于对照组, 感染后第3天酶活性达到最大值（0.2786 U/mg）, 此后第4-6 天酶活性逐渐降低; 染菌后的6 d中, 血淋巴中海藻糖含量显著低于对照组, 同样在感染后第4天其含量逐渐降低, 第6天时降到最低值。相比之下, 处理组血淋巴中的葡萄糖含量显著高于对照组; 处理组其含量在第1-3天内呈现快速升高趋势, 在第3天达到最大值（7.7615 mmol/L）, 然后逐渐降低。结果说明, 白僵菌侵入昆虫血淋巴后, 菌株代谢产生酸性海藻糖降解酶, 将血淋巴中的海藻糖水解成为葡萄糖, 然后为真菌利用, 破坏了虫体内的血糖平衡, 这是一个相互连接的生理代谢和生化反应过程。     

蜕皮激素诱导下家蚕CYP3基因家族的表达变化

为了研究家蚕Bombyx mori CYP3家族基因经蜕皮激素诱导后的表达变化, 用蜕皮激素溶液（2×10^-3 μg/μL）浸泡的桑叶喂食家蚕B. mori 5龄幼虫, 以不用蜕皮激素处理的桑叶喂食家蚕为对照, 采用双跟踪标定定量PCR（dual-spike-in qPCR）方法, 检测在蜕皮激素诱导下家蚕中肠和脂肪体内CYP3基因家族的转录水平。结果表明: 与对照相比, 在蜕皮激素诱导下家蚕幼虫体内脂肪体中CYP302, CYP306和CYP339的转录水平分别上升了191.4, 7.4和421倍, 在中肠中变化不显著; 其余基因转录水平变化不明显或检测不到转录活性。结果说明CYP339基因有可能参与家蚕蜕皮激素的代谢, 这为进一步研究P450基因与内源物质的关系提供理论基础。     

The secretion and action of the digestive enzymes of the salivary glands of the blowfly, Calliphora

The salivary glands of adult Calliphora contain enzymes which hydrolyze starch, sucrose and trehalose. Amylase and sucrase are shown to be secretory enzymes, while trehalase remains in the gland. Results of electrophoretic and ultrastructural studies suggest that protein secretion is confined to the abdominal region of the gland. Secretion of both fluid and protein occurs from a single type of cell. While a fly is feeding on solid sugar, amylase and sucrase are lost from the gland and appear in saliva, while the level of trehalase in the gland increases slightly. The mixture of food and saliva passes mainly to the crop where carbohydrate is digested by the salivary enzymes.     

Dual control of midgut trehalase activity by 20-hydroxyecdysone and an inhibitory factor in the bamboo borer Omphisa fuscidentalis Hampson

During larval diapause lasting 9 months from September to May, trehalase activity in the midgut of the bamboo borer Omphisa fuscidentalis Hampson (Lepidoptera: Crambidae) was low from December to April, followed by a fourfold increase in May that remained high during the pupal stage in July. An application of juvenile hormone analog (JHA) produced increases in the ecdysteroid titer, while trehalase activity was increased by both JHA and 20-hydroxyecdysone (20E) injection. The trehalase activity in the midgut of diapausing larvae was doubled by incubating the midgut with 20E for 48h. During diapause as well as after JHA application, expression of two ecdysone receptor isoform genes (EcR-A and EcR-B1) in the midgut increased simultaneously with the increase in hemolymph ecdysteroid titer, followed by an increase in trehalase activity. The hemolymph of diapausing larvae contained a trehalase inhibitor and inhibitory activity was high during diapause. After 20E injection, trehalase inhibition decreased as midgut trehalase activity increased. Taken together, at least two factors may participate in the change in midgut trehalase activity: increase in trehalase activity and decrease in trehalase inhibitor activity, both of which may be induced by 20E.     

Characterization and purification of the biologically active v-sis protein generated in silkworm larvae with the Bombyx mori nuclear polyhedrosis virus vector system

The v-sis oncogene of simian sarcoma virus encodes a protein which is homologous to the human platelet-derived growth factor B-chain. The biologically active v-sis protein was expressed in silkworm larvae using the Bombyx mori nuclear polyhedrosis virus vector system. The v-sis protein purified from infected silkworm larvae is a 30 kDa disulfide-linked homodimer. Mitogenic activity of the v-sis protein was comparable to that of PDGF and inhibited by the pretreatment with anti-PDGF antibody. These results show that the recombinant v-sis protein is biologically and antigenically related to PDGF.     

Feeding glucose or sucrose, but not trehalose, suppresses the starvation-induced premature pupation in the yellow-spotted longicorn beetle, Psacothea hilaris

Under 25 degrees C and a long-day photoperiod, starvation induces premature pupation in 4th instar Psacothea hilaris larvae exceeding a threshold weight of 180 mg, resulting in the formation of small but morphologically normal adults. To investigate possible mechanisms underlying this phenomenon, we first measured the hemolymph trehalose and glucose levels of starved larvae. When larvae were starved after 4 days of feeding (attaining the threshold weight), glucose levels decreased 4-fold within the next 24 h, while trehalose levels, after a temporary slight decrease, increased remarkably to reach a peak just before the prepupa stage. The effects of ingesting various nutrients on the developmental fate and the hemolymph sugar titers of starving larvae were then examined. Feeding on agar blocks containing sucrose or glucose totally suppressed the occurrence of premature pupation, while trehalose, fructose, casein and starch were ineffective. Feeding on glucose or trehalose resulted in a 6-fold decrease in hemolymph glucose levels and remarkably elevated trehalose levels. Since feeding on glucose and trehalose induced similar changes in hemolymph sugar titers but trehalose was not effective in suppressing premature pupation, glucose may have exhibited its effects via gustatory mechanisms.     

Effects of toxic β‐glucosides on carbohydrate metabolism in cotton bollworm,Helicoverpa armigera (Hübner)

The purpose of this study was to evaluate the effects of three toxic β‐glucosides, phlorizin, santonin, and amygdalin, on carbohydrate metabolism in the cotton bollworm, Helicoverpa armigera (Hübner), when diets mixed with β‐glucosides were fed to third‐instar larvae. The growth of the larvae was significantly inhibited by exposure to santonin after 96 hr but not obviously affected by phlorizin and amygdalin. The midgut trehalase activities were only 51.7%, 32%, and 42.5% of that of the control after treatment with phlorizin, santonin and amygdalin at 2 mg/ml, respectively. In the hemolymph and fat body, the amount of trehalose decreased in all cases. However, the effects of santonin on the alteration of the glycogen and glucose levels as well as the activities of glycogen phosphorylase, were different than those of the other two β‐glucosides. It appears that the three β‐glucosides have different influences on the carbohydrate metabolism of cotton bollworm.