Effect of Plant Type on the Persistence of Beauveria bassiana

Field evaluation of isolate MK 2001 of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin, revealed conidia persistence and infectivity up to 26 days on foliage of lettuce and celery, two crops with substantial plant differences. Plants were treated at a rate of 100 ml/cage at a concentration of 1×10⁸ conidia/ml. The number of colony-forming units (CFU) recovered immediately after treatments from discs sampled on lettuce and celery leaves were not significantly different, due to similar foliar coverage of conidia by application. Significant differences were observed between both host plants during the 26 days of the field trial. The number of CFUs recovered on lettuce was significantly higher than that on celery leaves. However, for each host plant, there were no significant differences either between lettuce external leaves and internal leaves or between celery canopy and bottom leaves. An in vitro pathogenicity test carried out on Lygus lineolaris adults fed with leaf discs harvested from treated cages resulted in a high pathogenicity of B. bassiana isolate MK 2001. The mortality immediately after treatment did not differ from the death counts taken every other day for 26 days. However, efficacy was significantly different between both plants. Mortality was 91% on lettuce and 78% on celery, 7 days post-treatment. This study highlighted that plant type must be taken into account in foliar application of B. bassiana.     

Efficacy of the Entomopathogenic Fungus, Culicinomyces clavisporus against Larvae of the Biting Midge, Culicoides nubeculosus (Diptera: Ceratopogonidae)

Culicinomyces clavisporus, a fungal pathogen of a wide range of mosquito species, was investigated in relation to potential pathogenicity against Culicoides nubeculosus biting midge larvae. Seven different C. clavisporus strains were assayed. Each showed some degree of activity against C. nubeculosus larvae with LC₅₀ values of between 3.2×10^-5 and 1.1×10^-6 spores/mL; these effects occurred in dose-dependent manners and tended to be delayed until 72-96 h post treatment. The results are discussed in relation to incorporation of C. clavisporus into biocontrol programmes for Culicoides spp.     

Laboratory investigations on the potential of entomopathogenic fungi for biocontrol of Helicoverpa armigera (Lepidoptera: Noctuidae) larvae and pupae

The susceptibility of third instar Helicoverpa armigera to seven strains of three entomopathogenic fungal species, i.e. Metarhizium anisopliae, Beauveria bassiana and Paecilomyces fumosoroseus, was tested under laboratory conditions using the larval immersion method. High efficacies ranging from 68 to 100% corrected mortality were recorded with more profound effects in treatments with B. bassiana and P. fumosoroseus strains. The median lethal concentration (LC₅₀) for L3 was 6.0×10⁵ in M. anisopliae 79, 1.5×10⁵ in B. bassiana 124 and 4.2×10⁴ in P. fumosoroseus 14. These three strains were further used to characterize the age-dependent mortality of different larval stages (L2-L5) and the effect against pupae of H. armigera. Larval stages did not differ in their mortality but differed i in median lethal time, with shorter values recorded in the second instar. Tested fungi also caused a high reduction between 74.4 and 100% in the emergence of pupae using the soil inoculation method and the pupal immersion technique. All three fungal species, especially P. fumosoroseus, have a high potential for biocontrol of H. armigera larvae and also as a soil treatment targeting the pupae.     

乙基多杀菌素和印楝素对西花蓟马生长发育及繁殖的亚致死效应

为探讨乙基多杀菌素和印楝素对西花蓟马的亚致死效应,采用浸叶法确定了它们对西花蓟马2龄若虫的亚致死浓度(LC₂₅),并研究了该浓度下两种生物源农药对西花蓟马生长发育和繁殖力的影响.结果表明: 两种生物源农药亚致死浓度处理对西花蓟马均有不同程度的影响.在两性生殖方式下,乙基多杀菌素对西花蓟马产卵前期、雌成虫寿命和产卵量均无显著影响,但雄成虫寿命显著缩短;印楝素处理后,西花蓟马产卵量显著降低,产卵前期明显延长.在孤雌生殖方式下,不论乙基多杀菌素和印楝素处理,西花蓟马产卵前期均明显延长,但只有印楝素使雌成虫寿命缩短和产卵量显著降低.两种生物源农药对西花蓟马次代各虫态的发育历期影响不同,无论在何种生殖方式下,乙基多杀菌素处理后西花蓟马的未成熟期均明显短于印楝素处理.乙基多杀菌素处理后西花蓟马的内禀增长率(r_m)和周限增长率(λ)均高于对照,而印楝素较对照低.以上结果说明,两种杀虫剂对西花蓟马生长发育和繁殖影响不同,乙基多杀菌素亚致死浓度对西花蓟马种群的增长有一定的刺激作用,而印楝素有明显的抑制作用.两种杀虫剂的影响程度还与西花蓟马的生殖方式有关.     

Whey for mass production of Beauveria bassiana and Metarhizium anisopliae

Spore production of Beauveria bassiana and Metarhizium anisopliae was studied in a novel whey-based culture media. Spore yield and viability were determined for two B. bassiana (GHA-726 and CA-603) and two M. anisopliae (CA-1 and IMI 330189) isolates following production in three whey-based systems: solid, liquid, and a diphasic production system. Our study indicated that whey permeate can be used effectively for production of spores of entomopathogenic fungi. However, spore yield and viability were significantly influenced by fungal isolate, whey concentration, and the type of production process used. Under the conditions defined in the present study, spore yields ranging from 1.3 × 10⁹–10 × 10¹¹ spores l⁻¹ of whey medium could be obtained depending on the strain and production process used. Our study revealed that spores produced by all strains in whey-based solid and liquid media showed between 73–99 % viability; germination rates were comparable with those obtained using the standard SDA medium. In the two-stage production process, the viabilities of conidia produced by GHA-726, CA-603, and CA-1 were 35–86, 32–98, and 6–29 %, respectively; viability was correlated with whey concentration and isolates. Whey permeate can be used as a growth substrate for mass production of biocontrol fungi. We hypothesize that spore yield and viability could be improved by careful selection of whey content in the medium, incorporation of critical additives and optimization of culture conditions.     

Taxonomic revision of Lepisorus (J. Sm.) Ching sect. Lepisorus (Polypodiaceae) from China

The taxonomy of Lepisorus (J. Sm.) Ching sect. Lepisorus in China was revised based on herbarium specimen examinations, field observations, and microscopic study of rhizome scales, soral paraphyses, leaf epidermis and spores. As a result nine species were recognized: Lepisorus macrosphaerus (Baker) Ching, L. asterolepis (Baker) Ching, L. marginatus Ching, L. kuchenensis (Y. C. Wu) Ching, L. megasorus(C. Chr.) Ching, L. kawakamii (Hayata) Tagawa, L. subsessilis Ching & Y. X. Lin, L. affinis Ching and L. nudus (Hook.) Ching. Lepisorus kawakamii (Hayata) Tagawa was reinstated; L. gyirongensis Ching & S. K. Wu and L. longus Ching were reduced to synonyms of L. nudus and L. affinis respectively. The subdivision of L. macrosphaerusis was not accepted. Rhizome scales and paraphyses are the most useful characters for species delimitation as well as for infrageneric classification. Characteristics of the leaf epidermis and spore ornamentation are usually stable and thus of great significance in understanding the relationships among groups within the genus.     

Native braconid parasitism of the Tarnished plant bug (Hemiptera: Miridae) in Southern Ontario

Three agricultural regions in southern Ontario (London, Niagara and Guelph) were sampled weekly from May to September for Lygus spp. and their parasitoids in 1998, 1999 and only one region in 2000. Alfalfa was the primary crop sampled, including both “clean” and weedy alfalfa fields. Lygus lineolaris (Palisot de Beauvois) accounted for 99% of all Lygus spp. collected by sweepnet. Lygus lineolaris had two generations (mid-June and late July) on alfalfa with a partial third generation in early September which contributes to the over-wintering adults. In 1998 and 2000, an early first generation peak of Lygus nymphs was observed in mid-May on the weeds, chickweed and shepherd's purse. Overall rates of parasitism (from dissections) for native parasitoids were consistent from year to year and the means of the three regions in each growing season were below 11%. Both nymphs and adult Lygus were parasitized, with the highly mobile adults being a potential means of dispersing the parasitoids. In general weedy fields were more highly parasitized than fields of weed-free alfalfa. Six species of native braconid parasitoids were collected from L. lineolaris in southern Ontario (in decreasing order of occurrence): Peristenus pallipes (Curtis), Peristenus pseudopallipes (Loan), Leiophron lygivorus (Loan), L. solidaginis Loan, L. uniformis (Gahan), and Leiophron sp. near brevipetiolatus Loan. The large populations of Lygus and the low percent baseline parasitism in southern Ontario, particularly of second generation Lygus, support the need for introduction of a multivoltine parasitoid species in this region.     

Relationship between tomato fruit growth and fruit osmotic potential under salinity

To investigate the relationship between fruit growth and fruit osmotic potential (Ψ_s) in salty conditions, a sensitive tomato cultivar (Lycopersicon esculentum Mill.) and a tolerant accession of the wild species Lycopersicon pimpinellifolium Mill. were grown in a greenhouse with 0 and 70 mM NaCl, and the growth of the fruit studied from 15 to 70 days after anthesis (DAA). L. pimpinellifolium did not reduce significantly fruit weight in salty conditions throughout the growth period, whereas L. esculentum fruit weights decreased significantly with salinity from 45 DAA. L. esculentum fruit fresh weight reductions resulted from both less dry matter and water accumulation, although the fruit water content was affected by salinity before the fruit weight. In both species, fruit osmotic potential (Ψ_s) decreased significantly with salinity during the rapid fruit growth phase, although the changes were different. Thus, fruits from L. pimpinellifolium salt treated plants showed a Ψ_s reduction at the beginning (15 DAA) twice as high as that found in L. esculentum. As the advanced growth stage (from 15 to 55 DAA), the Ψ_s reduction percentages induced by salinity were quite similar in L. pimpinellifolium fruits, while increased in L. esculentum. Under saline conditions, the solutes contributing to reduce the fruit Ψ_s during the first 55 DAA were the inorganic solutes in both species, while in the ripe fruits they were hexoses. L. esculentum fruits accumulated K⁺ as the main osmoticum in salty conditions, while L. pimpinellifolium fruits were able to use not only K⁺ but also the Na⁺ provided by the salt.     

多花黑麦草对不同形态氮的吸收动力学特征研究

采用改进常规耗竭法,比较研究了多花黑麦草(Lolium multiflorum Lam.)对NH₄⁺和NO₃^-吸收动力学特征。结果表明多花黑麦草对NH₄⁺和NO₃^-吸收符合Miehaelis-Menten方程,它对NH₄⁺的亲和力显著大于对NO₃^-的亲和力,但对NH₄⁺和NO₃^-的最大吸收速率差异不显著,说明多花黑麦草偏爱吸收NH₄⁺,在实际污水净化过程中,多花黑麦草具有优先吸收NH₄⁺的趋势,若有足够的停留时间,其对NH₄⁺净化程度会更高些;当吸收系统微生物受抑制时,多花黑麦草对NO₃^-的吸收速率明显降低,亲和力明显提高,可见微生物对吸收体系中氮素的去除有一定促进作用。     

Lysozyme for capture of microorganisms on protein biochips

Lysozyme placed on the SiO₂ surfaces that have previously been derivatized with C₁₈ coating will capture both Escherichia coli and Listeria monocytogenes cells from PBS buffer at pH 7.2. This phenomenon is of significance for the design and fabrication of protein biochips that are designed to capture bacteria from buffer or water so that these can be further interrogated with respect to possible pathogenicity. Fluorescent microscopy shows that two types of bacteria (gram-negative E. coli and gram-positive Listeria spp.) will be adsorbed by lysozyme placed on the surface of the biochip but that strong adsorption of the bacteria is reduced but not eliminated when Tween 20 is present (at 0.5%) in the PBS buffer in which the cells are suspended. In comparison, Tween 20 and Bovine Serum Albumin (BSA) almost completely block adsorption of these bacteria on C₁₈ coated surfaces. The combination of a lysozyme surface with Tween 20 gives a greater degree of adsorption of L. monocytogenes than E. coli, and hence suggests selectivity for the more hydrophobic E. coli may be reduced by the Tween 20. This paper presents protocols for preparing protein-coated, SiO₂ surfaces and the effect of buffer containing Tween 20 on adsorption of bacteria by SiO₂ surfaces coated with C₁₈ to which BSA, lysozyme or C11E9 antibody is immobilized at pH 7.2 and ambient temperature.     

Determination of the maximum and minimum lethal temperatures (LT50) for Loxosceles intermedia Mello-Leitão, 1934 and L. laeta (Nicolet, 1849) (Araneae, Sicariidae)

In this study, the maximum and minimum lethal temperatures (LT₅₀) of L. intermedia and L. laeta were determined in two treatments: gradual heating (25–50°C) and cooling (25°C to −5°C), and 1 h at a constant temperature. In gradual temperatures change, L. intermedia mortality started at 40°C and the LT₅₀ was 42°C; for L. laeta, mortality began at 35°C and the LT₅₀ was 40°C. At low temperatures, mortality was registered only at −5°C for both species. In the constant temperature L. intermedia showed a maximum LT₅₀ at 35°C and L. laeta at 32°C; the minimum LT for both species was −7°C.     

NaCl处理下两种引进红树的光合及抗氧化防御能力

在长期盐胁迫(28天, NaCl浓度从100 mmol·L^-1升至400 mmol·L^-1)下, 比较研究了引进的无瓣海桑(Sonneratia apetala)和拉关木(Laguncularia racemosa)幼苗叶片的气体交换、叶绿素含量、最大光化学效率(F_v/F_m)、O₂^-_· 产生速率以及抗氧化酶的活性, 探讨了两种红树幼苗光合、抗氧化防御能力的差异与耐盐性的关系。结果显示: NaCl处理没有明显地影响两种红树幼苗的生长, 表明盐生植物对盐环境的适应性, 但两种红树的生理反应对NaCl处理存在较大的差异。在实验的第28天(苗木的NaCl累计处理浓度递增到400 mmol·L^-1)时, 与对照相比, 无瓣海桑叶片的净光合速率、水分利用效率增加, 气孔导度、蒸腾速率和胞间CO₂浓度/大气CO₂浓度(C_i/C_a)相应降低; 然而, 拉关木叶的净光合速率、蒸腾速率和水分利用效率均回落到对照的水平, 而气孔导度和C_i/C_a均增加, 表明同样的NaCl浓度处理对拉关木叶的净光合速率影响大于无瓣海桑。在NaCl处理期间, 无瓣海桑F_v/F_m一直保持在0.8以上, 而拉关木的F_v/F_m为0.75以下, 说明无瓣海桑具有高于拉关木的潜在最大光合能力。在实验的第7天(NaCl浓度为100 mmol·L^-1)和14天(苗木的NaCl累计处理浓度递增到200 mmol·L^-1)时, 两种红树O₂^-_· 产生速率迅速增加, 在实验的第28天(苗木的NaCl累计处理浓度递增到400 mmol·L^-1)时, 无瓣海桑O₂^-_· 产生速率是对照的5.3倍, 差异极显著, 此时, 拉关木叶中O₂^-_· 产生速率已降低到低于对照的水平。盐处理诱导了两种红树叶中抗氧化酶(超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、过氧化物酶(POD))活性增加, 但拉关木增加的幅度大于无瓣海桑, 表明拉关木能响应盐胁迫并上调抗氧化酶活性, 降低盐诱导的膜脂过氧化, 提高耐盐的能力, 无瓣海桑通过提高水分利用效率来保持体内的水分, 同时, 保持PSII的最大光化学量子产量, 使得无瓣海桑在高盐处理时仍能保持高于对照水平的光合速率。     

Effect of a nuclepolyhedrovirus of Autographa californica expressing the enhancin gene of Trichoplusia ni granulovirus on T. ni larvae

A recombinant Autographa californica nucleopolyhedrovirus (AcMNPV) strain showing higher virulence against Trichoplusia ni larvae than the wild-type virus was developed. The 'enhancin' (VEF) gene of T. ni granulovirus (TnGV) and the AcMNPV polyhedrin gene were cloned into the baculovirus transfer vector pAcUW31. This plasmid and AcMNPV BacPAK6 DNA were co-transfected into the BTI-Tn5B1-4 cell line. A recombinant AcMNPV strain (BacVEFPol) was purified, amplified, and bioassayed against T. ni first instar larvae. Its estimated LC₅₀ (0.184 OB/mm²) was 2.18 times lower than the LC₅₀ estimated for the wild-type AcMNPV (0.402 OB/mm²). Likewise, an LT₅₀ of 67.7 h was estimated for the recombinant AcMNPV strain while the LT₅₀ of wild-type AcMNPV was estimated at 81.9 h. This indicates a 17.4% reduction of the time required to kill the larvae. The higher virulence of the recombinant strain, evidenced by its LC₅₀ and LT₅₀ values being lower than those of the wild-type strain, indicates that the VEF protein is expressed properly and may be occluded in the OBs.     

Sequence analysis of mouse cDNAs encoding ribosomal proteins L12 and L18

Mouse cDNAs encoding ribosomal proteins (r-proteins), L12 and L18, were isolated and their sequences determined. The L12 cDNA was found to contain 639 bp, including a coding sequence of 498 nucleotides (nt), 5' (78 nt) and 3' (45 nt) untranslated regions (UTRs), and a poly(A) tail of 18 nt. The L18 cDNA was shown to consist of 648 bp, including a coding sequence of 567 nt, 5' (26 nt) and 3' (39 nt) UTRs, and a poly(A) tail of 16 nt. The nt sequences of the protein-coding region from the mouse L12 and L18 cDNAs were found to exhibit 96% and 92% identity, respectively, with those of the rat. With the use of mouse L12 and L18 cDNA probes, multiple (at least 10) copies of the L12 and L18 gene families were shown to be present in the mouse and rat genomes. However, there was no sequence heterogeneity detected among seven L18 cDNA clones, indicating that only one copy of the L18 gene-related sequences is functional, and the other copies are presumably nonfunctional pseudogenes. The complete amino acid (aa) sequences of the mouse r-proteins, L12 and L18, were deduced from the nt sequences of their cDNA clones. L12 has 165 aa and a M_r, of 17 790, while L18 has 188 aa and a M_r of 21 570. The aa sequences of the mouse r-proteins, L12 and L18, exhibit 98% and 94% identity, respectively, to those of rat.     

Supercritical carbon dioxide and hydrogen peroxide cause mild changes in spore structures associated with high killing rate of Bacillus anthracis

The present work examines chemical and structural response in B. anthracis spores killed by a mixture of supercritical carbon dioxide (SCCO₂) and hydrogen peroxide (H₂O₂). Deactivation of 6-log of B. anthracis spores by SCCO₂ + H₂O₂ was demonstrated, but changes in structure were observed in only a small portion of spores. Results from phase contrast microscopy proved that this treatment is mild and does not trigger germination-like changes. TEM imaging revealed mild damage in a portion of spores while the majority remained intact. Dipicolinic acid (DPA) analysis showed that < 10% of the DPA was released from the spore core into the external milieu, further demonstrating only modest damage to the spores. Confocal fluorescent microscopy, assessing uptake of DNA-binding dyes, directly demonstrated compromise of the permeability barrier. However, the magnitude of uptake was small compared to spores that had been autoclaved. This work suggests that SCCO₂ + H₂O₂ is quite mild compared to other sterilization methods, which has major implications in its application. These results provide some insight on the possible interactions between spores and the SCCO₂ + H₂O₂ sterilization process.     

Infectivity of Steinernema spp. (Nematoda: Steinernematidae) to Adult Litter Beetles, Alphitobius diaperinus (Coleoptera: Tenebrionidae) in the Laboratory

Three species of Steinernema, S. carpocapsae, S. feltiae, and S. scapterisci consisting of 12 different strains, were tested for their infectivity towards adults of the litter beetle Alphitobius diaperinus. Of the five most promising nematode strains, LC₅₀ values ranged from 1.5 to 77.0 nematodes per host in the filter paper assays. Assays in poultry litter material revealed LC₅₀ values to be 5.8 and 14.6 nematodes per host for the Mexican S. carpocapsae strain and Pye S. feltiae strain.     

大兴安岭重度火烧迹地恢复后土壤磷形态与解磷细菌分布特征

为了探讨大兴安岭重度火烧迹地恢复后土壤不同磷形态含量、解磷细菌群落结构的差异及两者之间的关系,以人工恢复(樟子松人工林、落叶松人工林)、人工促进天然恢复(次生林)以及天然恢复(天然次生林)的林地土壤为研究对象,采用Sui等修正的Hedley磷素分级法对根际土壤和0～10、10～20 cm非根际土壤进行磷素分级测定,并用高通量测序法得到土壤解磷细菌种群丰度。结果表明: 0～10 cm非根际土壤水溶性磷(H₂O-P_i)、碳酸氢钠无机磷(NaHCO₃-P_i)、碳酸氢钠有机磷(NaHCO₃-P_o)及根际土壤NaHCO₃-P_o含量表现为落叶松人工林>樟子松人工林>天然次生林>次生林。10～20 cm非根际土壤H₂O-P_i、NaHCO₃-P_i、NaHCO₃-P_o及根际土壤H₂O-P_i、NaHCO₃-P_i含量表现为落叶松人工林>樟子松人工林>次生林>天然次生林。不同林分根际与非根际土壤H₂O-P_i、NaHCO₃-P_i和NaHCO₃-P_o含量的比值(R/S)均大于1。中等活性氢氧化钠磷(NaOH-P)包括氢氧化钠无机磷(NaOH-P_i)和氢氧化钠有机磷(NaOH-P_o)。在0～10 cm非根际土壤及根际土壤中NaOH-P含量表现为落叶松人工林>天然次生林>次生林>樟子松人工林,在10～20 cm非根际土壤中表现为落叶松人工林>樟子松人工林>次生林>天然次生林。土壤NaOH-P存在明显的根际效应。酸溶性磷(HCl-P)包括酸溶性无机磷(HCl-P_i)和酸溶性有机磷(HCl-P_o)。在0～10 cm非根际土壤中HCl-P含量表现为落叶松人工林>天然次生林>樟子松人工林>次生林,在10～20 cm非根际及根际土壤中表现为落叶松人工林>樟子松人工林>天然次生林>次生林。土壤残留磷(residual-P)含量对林地恢复方式不敏感。各林分土壤主要解磷细菌均为慢生根瘤菌属、链霉菌属、伯克霍尔德菌属和芽孢杆菌属。樟子松人工林和落叶松人工林土壤解磷细菌丰度显著高于次生林和天然次生林。冗余分析表明,解磷细菌与不同磷形态之间相关性各异。在现阶段来看,人工恢复更有利于提高土壤磷的有效性和增加解磷细菌的丰度。     

绿僵菌MaFZ-13对橙带蓝尺蛾幼虫致病力及林间防治效果

【目的】橙带蓝尺蛾Milionia basalis近年来在我国南方地区严重危害罗汉松Podocarpusmacrophyllus和竹柏Podocarpus nagi,扩散蔓延速度快,造成了很大的损失。本研究旨在评估金龟子绿僵菌Metarhizium anisopliae MaFZ-13菌株对橙带蓝尺蛾幼虫的致病力,探寻橙带蓝尺蛾生物防治新资源。【方法】通过绿僵菌MaFZ-13不同浓度(1.0×10⁵~1.0×10⁹孢子/mL)孢子悬浮液接种橙带蓝尺蛾幼虫,运用时间-剂量-死亡率(TDM)模型对生物测定结果进行分析,同时通过林间喷施1.0×10⁸孢子/mL绿僵菌孢子悬浮液进行林间防治效果试验。【结果】橙带蓝尺蛾幼虫累计死亡率随着绿僵菌MaFZ-13孢子悬浮液孢子浓度的增加和接种时间的延长而增大。接种1.0×10⁹孢子/mL孢子悬浮液8 d后以及接种1.0×10⁸孢子/mL孢子悬浮液10 d后,幼虫死亡率均达到100%;接种1.0×10⁷孢子/mL孢子悬浮液15 d后幼虫死亡率为95.6%。应用TDM模型对生测数据进行分析,结果表明所建模型通过Hosmer-Lemeshow拟合异质性检验,并由模型估算出了该菌株对橙带蓝尺蛾幼虫的致死剂量和致死时间。绿僵菌MaFZ-13菌株接种4, 5, 6和7 d后的半致死剂量(LC₅₀)对数估计值分别为7.99, 7.12, 6.46和5.83。以1.0×10⁷, 1.0×10⁸和1.0×10⁹孢子/mL的孢子浓度接种时,绿僵菌MaFZ-13菌株对橙带蓝尺蛾幼虫的LT₅₀值分别为5.19,3.99和2.81 d。林间用1.0×10⁸孢子/mL绿僵菌孢子悬浮液喷洒9 d后橙带蓝尺蛾幼虫死亡率可达到85.8%,防治效果为85.05%。【结论】绿僵菌MaFZ-13对橙带蓝尺蛾幼虫具有较强的致病力,林间防治效果良好,具有较好的应用潜力。     

4种蚜虫对异色瓢虫生长发育和繁殖的影响

为明确桃蚜、萝卜蚜、胡萝卜微管蚜、瓜蚜对异色瓢虫种群扩繁的适宜性,在实验室条件下,以4种蚜为食料构建异色瓢虫两性生命表,研究不同蚜虫对异色瓢虫生长发育和繁殖的影响。结果表明: 取食不同蚜虫,异色瓢虫未成熟期由长到短依次为萝卜蚜(18.18 d)、瓜蚜(17.48 d)、胡萝卜微管蚜(16.23 d)、桃蚜(15.77 d);成虫前期存活率由高到低依次为胡萝卜微管蚜(88.3%)、桃蚜(86.7%)、萝卜蚜(55.0%)、瓜蚜(55.0%);成虫繁殖力由高到低依次为胡萝卜微管蚜(1750.5粒)、桃蚜(1441.5粒)、瓜蚜(1006.3粒)、萝卜蚜(965.2粒);成虫寿命由长到短依次为胡萝卜微管蚜(78.8 d)、桃蚜(63.1 d)、瓜蚜(54.3 d)、萝卜蚜(48.4 d);异色瓢虫种群内禀增长率r_m由高到低依次为桃蚜(0.19)、胡萝卜微管蚜(0.18)、萝卜蚜(0.14)、棉蚜(0.14);净增值率R₀由高到低依次为胡萝卜微管蚜(895.83)、桃蚜(600.62)、萝卜蚜(273.47)、棉蚜(268.33)。4种蚜虫中,胡萝卜微管蚜和桃蚜更有利于异色瓢虫种群扩繁。     

Polar bear thermoregulation: Effect of oil on the insulative properties of fur

1. 1.|Oil caused a substantial decrease in the insulative value of polar bear (Ursus maritimus) pelts measured in vitro.

2. 2.|Following oil contamination the calm air heat transfer coefficient increased by a factor of 2 to 5: the wind coefficient averaged 290% greater and the solar utilization increased by 55%.

3. 3.|Conductance through oil-covered furs remained high at winter temperatures (T_a = 0.6°C) but decreased with time at summer temperatures (T_a = 24.7°C).

4. 4.|The most viscous of the three oils tested had a more consistently negative effect on insulation.