[Objective] This study’s objective was to investigate the diversity of intestinal microorganisms in adult Vespa velutina (Asian hornet) killed by natural causes. This study investigates the composition of intestinal fungi and bacteria and predicts the pathogenic pathogen in adult Vespa velutina (Asian hornet). [Methods] We determined the ITS1 sequence of fungi and the V3–V4 variant region of 16S rRNA of bacteria using Illumina MiSeq technology. Operational taxonomic units (OTU) of gut symbiotic microorganisms were quantified, and the resulting data were subjected to analysis of species abundance, composition, and alpha diversity. OTU function was predicted using PICRUSt2/FUNGuild. In addition, cultured microorganisms from the gut microbiota of adult Vespa velutina were isolated and identified. A number of 3610 (fungi) and 8373 (bacteria) were identified via cluster analysis. A total of 13 strains, 51 classes, 126 orders, 285 families, and 586 genera were identified for fungi and 44 strains, 113 classes, 319 orders, 662 families, and 1394 genera were identified for bacteria. E. shigella, Herbaspirillum, and Aaaia were the most abundant classes of bacteria, and Fusarium, Mortierella, and Starmerella were the most abundant classes of fungi. In addition, 16 community genera of fungi and 11 of bacteria were outlined as core taxa. Species diversity and richness for the gut fungal and bacterial communities with VN were found to be higher than those with VA. Furthermore, bacterial species diversity and richness were found to be higher than those of fungi in VA and VN. Functional analysis revealed that Vespa velutina gut bacteria exhibited 20 functions, while fungi were classified into three types of nutrient modes. Cultivable bacteria were obtained from two phyla and two classes, but no fungi could be cultivated. [Conclusion] Variations in the species diversity and abundance of both fungi and bacteria in the gut were observed between the VA and the VN. The involvement of bacteria in the death of adult Vespa velutina was found to be significant. In addition, VA1 (the self-named strain) may be a pathogenic bacterium derived from the gut of the VA that exhibits virulence.

Eucalyptus citriodora is a wood and oil dual-purpose tree with strong growth adaptability and high ornamental value. Recent years, it has been widely planted in Guangxi in China. In Nov. 2021, branch blight was found to be widespread on E. citriodora in Qinzhou in China (21°57'57"N, 108°42'6"E). The occurrence area was over 7000 m2, and the disease incidence was 23% (23/100). Twigs were withered in most of infected plants, and only top branch died in few plants. The lesions started from branch tips, then expanded and caused 5-20 cm branches died in final. The lesions were tiny and brown at early stage, then turned dark brown or black. Ten diseased branches were sampled randomly in field and were cut into 1 cm pieces. After surface disinfecting with 75% ethanol for 3 min, 0.1% HgCl2 for 5 min, washing with sterile water three times, samples were placed onto Potato Dextrose Agar (PDA) medium. Hyphae appeared after incubating for 5 days at 28 ℃. The diameter of colonies reached 64-71 mm after 7 days incubation. The colonies were white and felt-like, and then turned yellowish gradually with flourish aerial hyphae. Two weeks later, pycnidia appeared, which were nearly spherical, initial pale yellow and later black. Sometimes secretions overflowed from the aperture on pycnidia. There were 2 types of conidia (α and β type), which were unicellular and hyaline. The α type was spindle to ellipse and had 1-2 oil globule, with 5.56±0.50 × 2.67±0.39 μm (n=100) in size. The β type was linear and one end bent in hook shape, with 17.10±2.54 × 1.55±0.32 μm (n=50) in size. Three isolates (LEQZ01, LEQZ02, LEQZ03) were selected for further study. The internal transcribed spacers (ITS) region of rDNA, translation elongation factor 1-α (tef1 α) and β-tubulin (tub2) genes were amplified using primer pairs ITS1/ITS4 (White et al. 1990), EF1-983F/EF1-1567R (Rehner et al. 2005) and Tub1/ Tub2 (Chauhan et al. 2007), respectively. BLASTn searches showed that the ITS (OM339849, ON075781, ON075782), tef1 α (ON093807-ON093809) and tub2 (ON093810-ON093812) sequences had the highest similarity with Diaporthe ueckerae strains, with 99% (543/549, 544/549, 544/549) identity for ITS (NR 147543.1), with 99% (350/351, 353/353, 349/350) identity for tef1 α (KY569388.1), with 99% (754/754, 753/754, 754/754) identity for tub2 (MW514128.1). A neighbor-joining tree constructed by combining 3 sequenced loci. Three isolates clustered in the D. ueckerae clade with 100% bootstrap support. Based on morphological (Yi et al. 2018) and molecular evidences, the pathogen was identified as D. ueckerae. In a pathogenicity test, 20 healthy E. citriodora seedlings were divided into 4 groups. Before inoculation, twigs were surface disinfected with 75% ethanol followed by washing 3 times using sterile water. Tiny artificial wounds at 5 cm below the seedling top were inoculated by hyphae taken from colonies incubated for 7 days at 25 ℃ in the dark, and covered with damp cotton in 1-3 groups (Yi et al. 2018). Yet the wounds were covered with damp cotton in control group. Two days later, wounds started to turn brown in test groups, and symptoms similar to field were obtained after 10 days. But no lesion emerged in control group. Then germs were re-isolated from symptomatic twigs and identified as D. ueckerae following the methods above. To our knowledge, this is the first report of branch blight caused by D. ueckerae on E. citriodora in China. Further researches on disease epidemiology would help to prevent spread to more locations.

近年来,在我国桉树上发生了一种严重的外来入侵害虫——桉树叶瘿球角姬小蜂 Ophelimus maskelli(Ashmead)(膜翅目:姬小蜂科Eulophidae),其在桉树叶片上形成密密麻麻的小疱状虫瘿,造成桉树叶片大量脱落.为了利用天敌对该害虫进行生物防治,我们开展了该害虫的天敌调查.通过采集受害桉树叶片进行饲养,获得了一种寄生该害虫的寄生蜂——桉树扁角金绿姬小蜂 Closterocerus chamaeleon(Girault)(膜翅目:姬小蜂科Eulophidae).该寄生蜂为我国新纪录种,本文对其形态特征进行了详细描述,并提供了成虫鉴别特征的彩色照片.桉树扁角金绿姬小蜂原产地是澳大利亚,现在已被引进到世界上许多桉树栽培的国家和地区防治桉树叶瘿球角姬小蜂,防效十分显著.桉树扁角金绿姬小蜂是自然控制该害虫的优势天敌,我国现在发现了这种天敌,将在我国生物防治这种桉树外来入侵害虫上发挥重要作用.

Aniseed (Illicium verum) is a woody spice tree that has been grown in China for a long time. Anthracnose is an important disease of aniseed, which can cause severe leaf drop. In Sep. 2020, severe anthracnose was observed in Shanglin (23°35'5"N, 108°19'51"E), Nanning, Guangxi in China, and the incidence was 85%. The symptoms at the early stage were small, round and watery, then became larger and gradually turned brown. The acervuli would appear at the later stage, and contain many conidia. Leaves with disease were randomly sampled from 10 plants, and were cut into small rectangular pieces of 0.5×1 cm, and disinfected with 75% alcohol 1 min, with 0.1% HgCl2 3 min. After washing with sterile water 3 times, they were placed onto potato dextrose agar (PDA) medium and incubated at 25°C for 5 days. The average colony growth rate was 11.85 mm/d in 7 days. The colony was white or light gray in the initial stage, with dense aerial mycelium, and the central mycelium of the colony was dark grey in the later stage. Conidia were colorless, single spore, smooth, cylindrical, both ends obtuse, with an average size of 14.95 ± 0.97 μm × 5.46 ± 0.44 μm (n = 100). The conidial appressorium was oval or club-shaped, brown, margin intact, with an average size of 7.83 ± 1.21 μm × 5.82 ± 0.58μm (n = 50). Three strains GXNN02, GXNN03 and GXNN05 were selected for further study. Primer pairs T1/βt2b, ACT512/ACT783, GDF/GDR, CHS1-79F / CHS1-354R and ITS1/ITS4 (Weir et al. 2012) were used to amplify tubulin (TUB), actin (ACT), 3-phosphate glyceraldehyde dehydrogenase (GAPDH), chitinase (CHS1) and the internal transcribed spacers of rDNA (ITS) respectively. BLASTn searches showed that the TUB (ON619861-63 ), ACT (ON619852-54), GAPDH (ON619855-57), CHS1 (ON619858-60) and ITS (ON573028-30) sequences had the highest similarity to Colletotrichum siamense with up to 99% (699/702, 676/679, 699/702) identity for TUB (JX010404.1); 99% (281/282, 253/254, 249/250) identity for ACT (JX009518.1); 99% (275/277, 275/277, 239/241) identity for GAPDH (JX009924.1); 99% (296/299, 296/299, 259/262) identity for CHS1 (JX009865.1); up to 99% (527/530, 485/487, 527/530) identity for ITS (JX010171.1) of ex-type ICMP 18578. A ML tree was constructed by combining 5 sequenced loci, and three isolates clustered in the C. siamense clade with 94% bootstrap support. Therefore, combined with the morphological characteristics, the pathogens were identified as C. siamense. In a pathogenicity test, these three isolates were tested on 9 healthy aniseed seedlings with at least 10 leaves, and 3 seedlings as control. The leaves were surface disinfected with 75% alcohol, and then wiped with sterilized water three times. Holes were made near the edge of the leaves and were sprayed with conidial solution (6×106 spores/mL) in test groups, and use sterilized water as control. Then the leaves were sealed inside a plastic bag for 48 h to retain moisture. Brown spot and black acervuli, similar to the symptoms in the field, were observed on the leaves in test groups within 10-15 days. No symptoms were observed on the negative control leaves. The pathogens were reisolated from the treated infected leaves and were identified as C. siamense, thus fulfilling Koch's postulates. The pathogenicity test was confirmed by repeating in triplicate. The isolation frequency of C. siamense in our samples was 82.50%. To our knowledge, this is the first report of C. siamense in China. Further research on the occurrence of the disease will help prevent the spread of the disease.

Eucalypt species are among the most important for timber production worldwide. Eucalyptus cloeziana is increasingly culticated due to its desirable structural properties. Leaf blight is one of the most devastating diseases of E. cloeziana in China. In May 2019, leaf blight samples were collected from E. cloeziana in Chongzuo, Guangxi, China (22°20'37.70"N, 107°49'29.29"E). Lesions began at the leaf margin and extended to 1/4-3/4 of the total leaf surface area. Lesions (26.76±12.64 mm diameter) were round, yellow, and withered in appearance, and sometimes many black, round pycnidia were observed. Leaves with blight were collected randomly from 10 E. cloeziana plants. Tissue blocks (3 mm×3 mm) were sampled from diseased and healthy leaf portions, then surface disinfected with 75% ethanol for 20 s and 0.1% HgCl2 for 3 min. After washing with sterile water three times, dry tissue blocks were placed on potato dextrose agar (PDA) medium and incubated at 28°C for 5 days. Hyphae were milky white or whitish, and sparse. The colonies had petal-shaped edges and the conidiophores were clustered, branched and transparent. Spore-forming cells were solitary and smooth; conidia were smooth, fusiform or oblong, transparent, blunt-based, mostly erect, and 16.54±2.19 × 3.38±0.77 μm (n=100 in each isolate) in size. Three representative isolates (AB-6, AB-9, AB-16) were selected for further study. For molecular identification, the internal transcribed spacer (ITS) region of rDNA, translation elongation factor 1-α (TEF1), and large subunit ribosomal RNA (LSU) were amplified with primers ITS1/ITS4 (White et al. 1990), EF1-983F/EF1-1567R (Rehner and Buckleyet al. 2005), and LR0R/LR5 (Vilgalys and Hesteret al. 1990), respectively. BLASTn searches showed that the ITS (OM280456, ON026088-89), TEF1 (ON055278-80) and LSU (OM281346, ON026097-98) sequences had the highest similarity to Coniella quercicola strains with: 99% (600/605, 600/605, 600/604) identity for ITS (MH859478.1); 98% (326/333, 327/334, 325/332) identity for TEF1 (KX833698.1); 99% (870/872, 833/834, 830/831) identity for LSU (MH871258.1) of ex-type CBS 904.69. A Neighbor-Joining phylogenetic tree was constructed by combining 3 sequenced loci. Three isolates clustered in the C. quercicola clade with 100% bootstrap support. Thus, based on morphological (Maas et al. 1979; Wang and Lin et al. 2004) and molecular characteristics, the pathogen was identified as C. quercicola. In a pathogenicity test, 20 healthy E. cloeziana seedlings with at least 5 leaves were divided into 4 groups: groups 1-3 were used to inoculate three isolates respectively, and the fourth group acted as control. After surface disinfection with 75% ethanol and wiping with sterile water, tiny wounds were maked made by inoculation needle on each leaf. Fungal culture plugsblocks cut from 3 isolates were placed on wounds in groups 1-3 respectively,. withWarter- agar blockplugs served as control in group 4. The leaves were covered with wet cotton and sealed in airtight bags to retain moisture at room temperature with natural light. After 3 days, light brown lesions were observed in groups 1-3, with no symptoms present in the control group. The pathogenicity test was confirmed by repeating in triplicate and fungi re-isolated from symptomatic leaves were identified as C. quercicola. To our knowledge, this is the first report of leaf blight on E. cloeziana caused by C. quercicola in China. This study increases our understanding of E. cloeziana leaf blight and future research may allow the development of targeted prevention methods for more effective disease controls.

[目的]对我国桉树叶片上形成疱状虫瘿危害,造成桉树叶片大量脱落的外来入侵的一种害虫进行分类鉴定,确定害虫种类,为防治该外来入侵害虫提供参考.[方法]在广西北海市合浦县,采集雷林 1号桉树有虫瘿叶片120枚,置于 2个圆形透明塑料桶中饲养,每天收集从虫瘿中羽化出的小蜂,统计数量并鉴定种类.[结果]共养出形成虫瘿的小蜂 198头,经分类研究、鉴定,该害虫为桉树叶瘿球角姬小蜂[Ophelimus maskelli(Ashmead)](膜翅目Hymenoptera:姬小蜂科Eulophidae),是一种原产于新西兰和澳大利亚桉树上的害虫,这是该害虫在我国的首次发现.对该害虫的形态特征进行了详细描述,并附有形态特征照片,并列举了该小蜂与本属其他种的鉴别特征,以准确鉴定、区分该害虫.[结论]在广西发现的桉树叶瘿球角姬小蜂可在多种桉树叶片上形成虫瘿,造成大量叶片脱落,影响桉树生长.对该病虫需加强检疫,防止和阻止进一步在我国桉树栽培地区传播蔓延,同时要加强监测,及时发现和防治.特别是引进该害虫的重要天敌——桉树扁角金绿姬小蜂[Closterocerus chamaeleon(Girault)]开展生物防治.

Ascosphaera apis and some Aspergillus species are the main pathogenic fungi of honey bee, and A. apis is the pathogen of chalkbrood disease. However, the infection mechanism of them is incompletely known and it is still unclear whether other factors impact their pathogenesis. In this study, Aspergillus tubingensis were obtained from the chalkbrood bee samples for the first time. Our results showed that A. tubingensis could promote the accumulation of the spores of A. apis . Pathogenicity test found that inoculation of the spores of the two fungi alone or their combination could induce disease characterization of chalkbrood and stonebrood but the extent was less than those in field. To further identify other pathogens impacted the pathogenesis, we found several honey bee viruses presented in the pathogenic fungi A. apis and A. tubingensis , which were different from previous reported. Our results indicated that acute bee paralysis virus (ABPV) and chronic bee paralysis virus (CBPV) could replicate in these two fungi and increased in titer with the going of cultivation time. In addition, CBPV could not only transmit vertically to the next generation by spores, but also spread horizontally to different fungi through hyphal anastomosis. These results suggested that the honey bee chalkbrood contained the other pathogenic fungi besides A. apis , the interactions between different pathogens of chalkbrood microbial communities may influence the prevalence of chalkbrood. Moreover, the discovery of honey bee viruses and their transmission mode in these two fungi enhanced the potential of exploring fungi virus as valuable factors that cause fungal disease outbreak.

Antibiotics are omnipresent in the environment due to their widespread use, and they have wide-ranging negative impacts on organisms. Virus resistance differs substantially between domesticated Apis mellifera and wild Apis cerana, although both are commonly raised in China. Here, we investigated whether antibiotics can increase the sensitivity of honey bees to viral infection using the Israeli acute paralysis virus (IAPV) and tetra-cycline as representative virus and antibiotic. Although IAPV multiplied to lower levels in A. cerana than A. mellifera, resulting in decreased mortality (P < 0.01), there was no significant difference in immune responses to viral infection between the two species. Adult worker bees (A. cerana and A. mellifera) were treated with or without tetracycline to demonstrate the prominent role of gut microbiota against viral infection, and found Lactobacillus played a vital antiviral role in A. cerana. In A. cerana but not A. mellifera, tetracycline treatment reduced clearly bee survival and increased susceptibility to IAPV infection (P < 0.01). Our findings revealed that long-term antibiotic treatment in A. mellifera had altered the native gut microbiome and promoted the sensitivity to viral infection. We highlight the effects of antibiotics exposure on resistance to microbial and viral infection.

为明确香花油茶(Camellia osmantha)不同无性系苗期炭疽病发生情况及其病菌致病力分化状况,为香花油茶苗期炭疽病的综合防治和抗病育种提供理论依据,采用平行线取样法,对27个香花油茶无性系苗期炭疽病进行调查与统计,通过形态特征和分子系统学分析对炭疽病病菌进行鉴定,并采用离体叶片接种法对所获菌株进行致病性及致病力测定,明确各菌株的致病力等级.结果表明,2019—2021年,不同无性系炭疽病发病率及病情指数均呈上升趋势,均在2019—2020年增长较快;27个菌株的培养性状及形态特征均相似,鉴定为Colletotrichum fructicola;来自6和12号无性系的炭疽病菌株为强致病力菌株,其他25个无性系的炭疽病菌株均为中等致病力菌株.香花油茶无性系苗期炭疽病菌C.fructicola致病力分化明显,以中等致病力菌株为优势群体.

[目的]轮斑病是桉树的常见叶部真菌病害.本研究探讨健康和轮斑病害桉树叶内生真菌群落的结构差异,并筛选对轮班病菌具有拮抗作用的菌株.[方法]采用Illumina Miseq技术对健康和轮斑病害桉树叶内生真菌ITS rDNA进行测序,分析两组样品内生真菌的多样性和丰度.采用平板对峙法检测本实验室保存菌株对轮斑病菌生长的影响,并用PCR法验证抗病菌株是否存在于健康和病害叶片中.[结果]生物信息学分析结果表明健康桉树叶的内生真菌共注释到2门、15纲、55目、139科、238属、300种;轮斑病害桉树叶共注释到2门、12纲、55目、88科、130属、183种.轮斑病害桉树叶内生真菌群落多样性和优势菌种的集中程度均较健康叶片无显著改变,处于相对稳定的状态.而轮斑病害桉树叶内生真菌群落丰度较健康叶显著降低,两组叶片中真菌群落结构和组成存在较大差异.病害和健康桉树叶内均存在轮斑病菌Coniella eucalyptorum、花斑病菌Aureo-basidium pullulans和枝枯病菌Lasiodiplodia theobromae,其中轮斑病菌为病害叶内的优势真菌.平板对峙试验结果发现,本实验室保存的菌种中,仅有贝莱斯芽孢杆菌Bacillus velezensis对轮班病菌具有较强的拮抗作用.用PCR分别扩增轮斑病害和健康桉树叶基因组DNA中的GyrA基因片段,PCR产物的琼脂糖凝胶电泳结果表明B.velezensis仅存在于健康桉树叶内,而在轮斑病害桉树叶中未能检测到.[结论]桉树叶部内生真菌的群落结构可能受轮斑病菌侵染的影响,导致染病叶内生真菌群落的丰度下降;而贝莱斯芽孢杆菌对桉树轮斑病菌的生长具有一定的拮抗作用,有望成为一种新的针对桉树轮斑病的生物防治方法.本研究为明确桉树轮斑病的成因和开发轮斑病生防制剂提供了一定的理论和实验依据.

Eucalypt GL-9 (Eucalyptus grandis × Eucalyptus urophylla) is one of the most widely grown genotypes of Eucalyptus in China. Each year, leaf blight causes serious economic losses in the eucalyptus industry in the south of China. In December 2019, a leaf blight disease was found to be widespread on eucalyptus GL-9 in Hechi in Guangxi, China (25°22'17"N, 108°15'32"E). Symptomatic lesions were usually brown at the early stage of infection and then turned off-white at the late stage. They had a large number of black round pycnidia randomly dispersed on the surface. Most of the lesions initially started from the leaf tip and then gradually expanded to the base of the leaf. Three randomly sampled leaves were washed using sterile water. Next, small pieces of tissue (5×10 mm) were removed from the margins of the lesions, surface disinfected with 75% ethanol for 1 min and 0.1% HgCl2 for 3 min, and then washed three times with sterile water. The tissues were placed on potato dextrose agar (PDA) and incubated at 28°C for 5 days to observe the fungus morphological characteristics. The hyphae on the PDA were milky yellow, and the PDA was light yellow when viewed from the bottom, with few aerial hyphae. The colonies had petal-like edges. In the later stage, hyphae in the center of the colonies turned brown. Three representative isolate (EC7, EC8, EC10) were selected for further study. Their conidia were olive-shaped, spindle-shaped, or obliquely globose, 8.80-11.93 μm in length (10.35 μm in average), 4.69-7.33 μm in width (6.06 μm in average) (n=100 in each isolate), with a conical apiculus and a hyaline basal appendage that was tubular, smooth, and thin-walled. For molecular identification, their genomic DNA was extracted using a Genomic DNA Kit (Tiangen, China). The internal transcribed spacer (ITS) region of rDNA and β-tubulin (TUB) genes were amplified using ITS5/ITS4 and βt2a/βt2b primer sets, respectively (White et al. 1990). BLASTn searches showed that the ITS and TUB sequences had the highest identity with Apoharknessia eucalyptorum strains, with 100% (586/586 in EC7 and EC8, 590/590 in EC10) identity for ITS (KY979752.1) and 99% (502/505 in EC7, 506/508 in EC8 and 504/507 in EC10) identity for TUB (KY979919.1) of ex-type CBS 142519. The ITS and TUB sequences of three isolates were submitted to GenBank (EC7: OM060439 and OM103586, EC8: OM679378 and OM715153, EC10: OM679377 and OM715152). A maximum likelihood phylogenetic tree was constructed by combining the two sequenced loci in MEGA7. Three isolates clustered in the A. eucalyptorum clade with 92% bootstrap support. Thus, based on morphological (Crous et al. 2017; Garrett et al. 2018) and molecular characteristics, the pathogen was identified as A. eucalyptorum. In a pathogenicity test, twenty healthy GL-9 seedlings were collected, and were divided into four groups. Seedlings from groups 1-3 were used to inoculate three isolates respectively, and seedlings from another group were sprayed distilled water as control. Before test, leaves were washed with sterile water, surface disinfected with 75% ethanol, and then rinsed with sterile water. After drying, an inoculation needle was used to make tiny wounds near the leaf margin on each leaf. Next, conidia solution (1×107 conidia/ml) and sterile water were sprayed to leaves in different groups and moistened with airtight bags. After 3 days, airtight bags were moved. Lesions appeared on all the pathogen-inoculated leaves, whereas only the inoculation point turned brown on the control leaves. The pathogenicity test was repeated three times and the same results were obtained. Fungi were re-isolated from symptomatic leaves and identified as A. eucalyptorum following the same methodologies used for the initial identification. To our knowledge, this is the first report of A. eucalyptorum causing leaf blight on E. grandis × E. urophylla in China. This study expands the understanding of the pathogen of leaf blight on E. grandis × E. urophylla. More research is needed to develop effective strategies to manage this disease.

[目的]鉴定广西香花油茶炭疽病病原菌,掌握其生物学特性,为抗病油茶品种选育提供参考依据.[方法]采集广西南宁市、来宾市和崇左市香花油茶林地典型炭疽病样品,以组织分离法和柯赫氏法获得致病菌株,依据病原菌形态特征描述和病原菌核糖体内转录间隔区(ITS)、肌动蛋白(ACT)、几丁质合成酶(CHS1)和3-磷酸甘油醛脱氢酶(GPDH)多基因分子系统学分析结果进行鉴定,并采用平板法测定病原菌的生物学特性.[结果]从广西南宁市、来宾市和崇左市3个地区香花油茶林地采集典型炭疽病样品中分离获得的76株炭疽菌属真菌,对健康香花油茶叶片均具有致病性,但致病力略有差异;代表菌株CXNN02、CXLB08和CXCZ09的离体接种病斑平均直径分别为6.48、6.39和5.20 mm,活体接种病斑比前者略小,分别为5.53、5.33和4.97 mm,以CX-NN02菌株的致病力略强.菌株CXNN02在PDA培养基上菌落呈圆形,菌丝灰色至深灰色,气生菌丝茂盛,绒毛状,背面产生黑色色素;菌丝生长较快,平均生长速率为11.75 mm/d;分生孢子光滑,无色,单胞,圆柱状,顶端钝圆或略尖,大小为(13.30～20.67)μm×(3.39～7.48)μm;分生孢子附着胞浅褐色至褐色,单个或多个,圆形或近圆形,边缘完整,大小为(6.50～10.69)μm×(5.17～9.50)μm.对菌株CXNN02、CXLB08和CXCZ09进行形态学结合病原菌多位点基因系统发育进化树分析,确定核果炭疽菌(Colle-totrichum fructicola)是广西香花油茶炭疽病病原菌.生物学特性测定结果显示,香花油茶炭疽病病原菌菌丝生长和产孢的最佳温度均为28℃,最适菌丝生长pH为4～5,最适产孢pH为6,菌丝生长的较佳碳源为D-麦芽糖、D-葡萄糖、D-果糖和D-木糖,最佳产孢碳源为乳糖,较佳氮源为牛肉膏、蛋白胨和酵母粉3种有机氮源,最佳产孢氮源为酵母粉;完全黑暗有利于香花油茶炭疽病病原菌菌丝生长和产孢.[结论]广西香花油茶炭疽病病原菌为核果炭疽菌,其菌丝生长和产孢受温度、pH、碳氮源和光照条件影响明显.香花油茶是核果炭疽菌的新寄主,进行香花油茶抗病品种选育及制定炭疽病防治措施时需充分了解该菌的生物学特性.

Although honey bee responses to pathogens have been systematically described in the past decades, antiviral signalling pathways mechanisms are not thoroughly characterized. To decipher direct antiviral roles of an immune pathway, we firstly used the infectious clone of Israeli acute paralysis virus (IAPV) to screen 42 immune genes involved in mTOR, MAPK, Toll, Endocytosis, Jak-STAT pathway and homeobox protein, heat shock protein, as well as antimicrobial peptides (AMPs), and found that Toll pathway was a potential predominant immune pathway in Apis mellifera . Consistent with this, only dsRNA-PGRP-S2 treated A. mellifera significantly exhibited impaired activation of Toll pathway, promoting susceptibility to the IAPV infection. Finally, immunofluorescence results confirmed that the Toll pathway was initiated by peptidoglycan recognition protein S2 (PGRP-S2) interacting with Toll protein. Co-immunoprecipitation findings also further preliminarily confirmed PGRP-S2 directly interacting with viral capsid protein IAPV-VP3 to induce the activation of the Toll pathway in A. mellifera . These findings highlight that the Toll pathway is demanded efficient inhibitions of IAPV replication as a specific antiviral pathway in A. mellifera , and PGRP-S2, acting as a pattern recognition receptor, could be a new approach for control of the viral disease. Author summary Honey bee viruses, particularly IAPV, had been implicated in the colony decline with a global distribution resulting in insufficient pollination services. However, little is known about the antiviral mechanism of honey bee. In this study, we found that the Toll pathway was required for A. mellifera against IAPV infection and initiated by PGRP-S2. We also confirmed that dsRNA-PGRP-S2 treated A. mellifera exhibited impaired Toll pathway activation and promoted susceptibility to the IAPV infection. As a result, we employed co-immunoprecipitation technique to identify the interaction between the PGRP-S2 with Toll. Moreover, it was found the PGRP-S2 directly recognized IAPV-VP3 to activate the immune pathway against IAPV infection. Our work provides novel evidence that honey bees own a specific antiviral immune pathway and suggests that targeting PGRP-S2 could be a new approach for controlling the viral disease.

[目的]明确广西杉木炭疽病的病原种类及生物学特性,为杉木抗病育种及杉木炭疽病的防治技术研究提供科学依据.[方法]采集广西河池、百色、桂林、柳州、贺州和南宁市杉木种子园及林地炭疽病样品,采用常规组织和单孢分离法获得杉木炭疽病病原菌菌株,通过形态特征结合病原菌核糖体内转录间隔区(ITS)、几丁质合成酶(CHS1)、3-磷酸甘油醛脱氢酶(GPDH)、微管蛋白(TUB2)和肌动蛋白(ACT)多基因分子系统学分析,对获得的炭疽病菌菌株进行鉴定;采用平板培养法测定病原菌生物学特性.[结果]从杉木炭疽病样品中共分离获得60株炭疽菌属真菌,均具有致病性,但致病力存在差异.通过形态学结合病原菌多位点基因系统发育分析,确定广西杉木炭疽病病原菌种类为核果炭疽菌(Colletotrichum fructicola)和山茶炭疽菌(C.camelliae).生物学特性测定结果显示,C.fruc-ticola和C.camelliae菌丝生长及产孢最适温度分别为28和25℃;光照对C.fructicola菌丝生长无明显影响,但有利于C.camealliae菌丝生长,黑暗有利于2种病原菌产孢;pH 4时最适宜2种病原菌菌丝生长,pH 4最适宜C.fructicola产孢,pH 5最适宜C.camealliae产孢;2种病原菌对D-麦芽糖利用最好,乳糖和D-山梨醇最有利于C.fructicola产孢,可溶性淀粉和阿拉伯糖最有利于C.camelliae产孢;蛋白胨和酵母粉均有利于2种病原菌菌丝生长,酵母粉有利于C.fructi-colaz产孢,酵母粉和牛肉膏有利于C.camelliae产孢.[结论]广西杉木炭疽病病原为核果炭疽菌(C.fructicola)和山茶炭疽菌(C.camelliae).温度、pH和碳氮源对2种病原菌菌丝生长及产孢影响明显,光照对2种病原的影响略有不同.

采用菌丝生长速率法测定9种杀菌剂对桉树轮斑病原菌(Pilidiella eucalyptorum、P.diplodiella)的室内毒力.结果表明,供试的杀菌剂对病原菌具有不同程度的抑制作用.对P.eucalyptorum毒力最强的杀菌剂是10％苯醚甲环唑ME,EC50值为0.0116 mg/L;其次是25％吡唑醚菌酯SC,EC50值为0.0453 mg/L;毒力最弱的是80％乙蒜素EC,EC50值为6.8393 mg/L.对P.diplodiella毒力最强的杀菌剂是43％戊唑醇SC,EC50值为0.0473 mg/L;其次是20％丙环唑ME,EC50值为0.0857 mg/L;毒力最弱的是80％乙蒜素EC,EC50值为2.8099 mg/L.

采用平板培养法和液体培养法研究桉树轮斑病原菌(Pilidiella eucalyptorum)的生物学特性,为桉树轮斑病的监测及防治技术提供理论基础.结果表明,该菌菌丝在10～35℃及pH 2～12的环境里均能生长,最适温度为28℃,最适pH值为6;6 h/18 h紫外光光暗交替与12 h日光灯光暗交替有利于菌丝生长;乳糖和蔗糖是菌丝生长最佳碳源;蛋白胨和酵母粉是菌丝生长最佳氮源;分生孢子在20～30℃均可萌发,以28℃萌发率最高;在饱和湿度且有水滴条件下分生孢子萌发率最高;病原菌菌丝和分生孢子的致死温度分别为48和50℃.

为土沉香黄野螟的有效防治提供技术支持,在钦州市国有钦廉林场土沉香示范基地实地观察黄野螟的生物学特性,并开展暗黑赤眼蜂、玉米螟赤眼蜂、螟黄赤眼蜂、松毛虫赤眼蜂对土沉香黄野螟的防治效果试验.结果表明:螟黄赤眼蜂对土沉香黄野螟卵块寄生率最高,达85.34％;通过3次释放(2019年3月30日、4月29日、5月9日)螟黄赤眼蜂(10卡/667m2,1卡约1500头赤眼蜂),黄野螟发生率明显降低,在7月中旬降低到5％以下并趋于稳定,最终防治率为43％.土沉香种植林释放螟黄赤眼蜂可控制黄野螟的危害.

南宁市老虎岭水库是南宁市重要水源地,选取老虎岭水库周边的竹林、阔叶林、针叶林3类生境9个样地,以巴氏罐诱法采集该地区土壤节肢动物,对其进行多样性研究.结果表明:共获得标本2 497头,分属14目46科,蚁科为最大的优势种类,其次为长蠹科.3类生境中竹林中采集到的节肢动物最多(867头),针叶林中最少(778头).竹林和针叶林中蚁科为优势类群,分别占68.97％和63.40％;阔叶林中长蠹科为优势种群,占55.05％.3类生境中物种多样性指数和优势度指数总体上差异不显著,均匀度指数和丰富度指数在竹林与阔叶林间差异显著,不同样地间各指数均有所差异.3类生境土壤节肢动物与其他地区相比,多样性较高,说明老虎岭水库周边环境保护较好.

为筛选对黄脚胡蜂职蜂具有趋避活性的植物提取物,利用触角电位(EAG)检测和四臂嗅觉仪研究黄脚胡蜂职蜂对6种具有不同特征气味的植物提取物(2-苯乙醇、苯甲醇、乙酸苄酯、香草醛、肉桂醛和邻氨基苯甲酸甲酯)的趋避反应.结果表明:黄脚胡蜂职蜂对6种植物提取物均有不同程度的电生理反应,其中,对体积浓度为1.0％的肉桂醛反应值最大,对体积浓度为1.0％的2-苯乙醇EAG反应值最小,仅为前者的6.8％.单一植物提取物趋避行为测定结果表明,6种植物提取物对黄脚胡蜂职蜂的首次选择均具有显著的趋避作用(P<0.05),其中苯甲醇的趋避效果最好.