Interactions between two biological control agents and their target weed: a beetle,a bug and a cactus weed

ABSTRACT

Pereskia aculeata Miller (Cactaceae) is an invasive alien shrub introduced into South Africa from Brazil. The leaf-feeding beetle, Phenrica guerini Bechyne (Chrysomelidae), was released as a biological control agent in South Africa in 1991 followed by the stem-wilting bug, Catorhintha schaffneri Brailovsky & Garcia (Coreidae), in 2014. This study investigated the interactions between the two agents under laboratory conditions. Potted plants were exposed to one of four treatments: control (no agents), P. guerini only, C. schaffneri only and both species together. Four densities, ranging from 2 to 12 insects per plant were used. Cathorhitha schaffneri alone at low to moderate densities resulted in the same reduction in number of leaves and shoot length as when combine with P. guerini. At the highest density, C. schaffneri reduced the number of leaves significantly more than any treatment. Mortality of P. guerini was significantly higher than C. schaffneri at the highest density when in combination. The antagonistic interaction between P. guerini and C. schaffneri suggests that these agents should not be released together because this would impact negatively on the overall biocontrol programme against P. aculeata. It is recommended that C. schaffneri should be released at sites where P. guerini is not present. Extrapolation of laboratory-based studies into the field is often challenging, so mass-rearing and releases of P. guerini should continue until there is convincing proof that C. schaffneri alone is more effective than P. guerini in the field.     

A promising biological control agent for the invasive alien plant,Pereskia aculeata Miller (Cactaceae), in South Africa

Pereskia aculeata Miller (Cactaceae) is an invasive alien plant from Central and South America that has become a problematic environmental weed in South Africa. A potential biological control agent, the stem-wilter, Catorhintha schaffneri Brailovsky & Garcia (Coreidae), was collected in southern Brazil and imported into quarantine in South Africa. Field host range data suggested that C. schaffneri has a host range restricted to P. aculeata. No-choice nymph survival tests were then conducted on 27 test plant species in 9 families. Survival to the adult stage was only recorded on P. aculeata and the closely related Pereskia grandifolia Haw. (Cactaceae). Mortality was significantly higher on P. grandifolia with only 3% of the nymphs reaching the adult stage compared with 74% on P. aculeata indicating that P. aculeata is the primary host plant. P. grandifolia is native in South America and is of no agricultural importance in South Africa so any feeding on P. grandifolia in South Africa would have no negative environmental or economic consequences. In other tests, adult survival on P. aculeata [25.8 days (SE ± 3.74)] was significantly longer than on other test plant species [4.3 days (SE ± 0.36)] further confirming the host specificity of the species. Impact studies conducted in quarantine indicated that C. schaffneri is damaging to P. aculeata, significantly reducing the number of leaves and the shoot lengths of plants, even at relatively low insect densities. C. schaffneri is safe for release in South Africa and is likely to be a damaging and effective agent.     

Somatic embryogenesis and plant regeneration in Acacia farnesiana and A. schaffneri

Summary Efficient plant regeneration systems via somatic embryogenesis have been developed for Acacia farnesiana and Acacia schaffneri [Leguminosae (Mimosoideae)]. The protocol used in this study consisted of placing immature, zygotic embryos of these species in Murashige and Skoog semi-solid basal medium supplemented with 9.05 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 4.65 μM kinetin to induce callus. Some parts of the callus were used for direct embryo differentiation and others for establishment of cell suspension cultures. In the first case, somatic embryos were produced on semi-solid differentiation media without growth regulators or with abscisic acid (ABA). The higher number of somatic embryos, 345 and 198 embryos per g callus in A. farnesiana and A. schaffneri, respectively was obtained in media without growth regulators, but adding ABA increased the percentage of embryos that reached more advanced differentiation stages. The production of somatic embryos was achieved starting from cell suspensions only when these suspensions were plated into the semi-solid differentiation medium. Somatic embryos germinated on medium containing 217 μM adenine sulfate with efficiencies of 69% in A. farnesiana and 47% in A. schaffneri. Some somatic embryos that developed into plantlets were acclimatized in the greenhouse, and they grew into normal plants.     

Thermophilic and thermotolerant fungi in the desert soils of Saudi Arabia

Forty-eight thermophilic and thermotolerant species in addition to 5 varieties which belong to 24 genera were collected from desert soils in Saudi Arabia on glucose-(22 genera and 38 species + 5 varieties), cellulose-(15 genera and 27 species + 4 varieties) and 40% sucrose-Czapek's agar plates (13 genera and 26 species + 4 varieties) at 45 °C. The most frequent species were as follows: Aspergillus fumigatus, A. terreus, Humicola grisea var. thermoidae and Chaetomium thermophile var. copropile on glucose-; A. fumigatus, C. thermophile var. copropile, A. terreus, A. nidulans and C. thermophile var. dissitum on cellulose-; and A. fumigatus and A. terreus on 40% sucrose-Czapek's agar plates. Sixteen species and 4 varieties were particularly thermophilic and these were A. fumigatus, H. grisea var. thermoidae, H. insolens, H. lanuginosa, C. thermophile var. copropile, C. thermophile var. dissitum, C. virginicum, M. pusillus, S. thermophila, S.? pulverulentum, T. thermophilus, T.? emersoni, T. aurantiacus, T. thermophila, M. pulchella var. sulfurea, M. albomyces, ?A. terrestris, C. pruinosum, T. thermophila and P. thermophila. The remaining species showed different degrees of thermotolerant (32 species + 1 variety).     

Morphologic variation and classification of the North American Aristida purpurea complex (Gramineae)

The morphology of the Purpureae Group of North AmericanAristida is assessed by principal components and statistical analyses. Long considered a complex of about eight species, a mosaic of intergrading phenetic forms is revealed and the complex is reduced to one species with seven varieties. The taxa that are recognized areAristida purpurea var.purpurea, var.nealleyi (comb. nov.), var.curvifolia (comb. nov.), var.parishii (comb. nov.), var.wrightii (comb. nov.), var.fendleriana, and var.longiseta. A key and synopses for the varieties are provided.     

基于28S, COI和Cytb基因序列的薜荔和爱玉子传粉小蜂分子遗传关系研究

薜荔和爱玉子均属于桑科榕属植物,二者为同一物种的原变种与变种的关系,早期研究认为这两种榕树与同一种传粉榕小蜂(Wiebesia pumilae (Hill))建立了稳定的互利共生关系,但近期在形态学、生态学、传粉生物学等方面对二者的研究结果表明,薜荔传粉小蜂和爱玉子传粉小蜂之间可能发生了遗传分化。实验用核糖体28SrDNAD1-D3区、线粒体Cytb及COI基因部分序列,对采自福建3个不同样地的薜荔传粉小蜂和3个不同品系的栽培爱玉子的传粉小蜂进行分析,结果表明:(1)薜荔传粉小蜂和爱玉子传粉小蜂的核糖体28S序列的碱基组成中A,T,G,C 4种含量较平均,C+G的平均含量(56%)稍高于A+T的含量(44%)。线粒体Cytb序列中A+T的含量(76.1%)明显高于C+G的含量(23.9%),COI序列中A+T的含量(71.9%)也明显高于G+C的含量(28.1%),这是膜翅目昆虫线粒体基因的普遍特征。在薜荔和爱玉子传粉小蜂的线粒体Cytb及COI基因中,密码子第三位点A+T的含量最高。(2)比较薜荔和爱玉子传粉小蜂的3种分子标记的变异范围显示,28S进化速度较Cytb及COI序列慢,比较保守,更适合科、亚科等较高分类单元的研究。薜荔传粉小蜂与爱玉子传粉小蜂之间的亲缘关系较近,采用Cytb与COI序列进行分析更为精确。(3)用Cytb及COI序列对薜荔传粉小蜂与爱玉子传粉小蜂之间的遗传距离进行分析显示,薜荔传粉榕小蜂个体间Cytb序列平均遗传距离为0.0054,爱玉子传粉小蜂个体间的Cytb遗传距离为0.0164;薜荔传粉小蜂与爱玉子传粉小蜂群体之间的Cytb序列平均遗传距离为0.1385;COI序列的薜荔传粉榕小蜂个体间遗传距离为0.0048,爱玉子传粉小蜂各样本间平均遗传距离为0.0102;薜荔传粉小蜂与爱玉子传粉小蜂群体间COI序列平均遗传距离为0.1896,两群体间的遗传距离(差异大于10%以上)明显大于群体内各样本之间的遗传距离,表明薜荔传粉小蜂与爱玉子传粉小蜂之间已经发生了很大的遗传分化,其变异水平达到了种间分化水平,即薜荔传粉小蜂与爱玉子传粉小蜂为两个不同的种。     

Plants as a green alternative for alcohol preparation from aromatic aldehydes

A general methodology for the efficient reduction of aromatic aldehydes and three ketones to their corresponding alcohols (interesting as cosmetic fragrances in their majority) with moderate to excellent chemical yield was achieved by using homogenates of broccoli (B. oleracea var. italic), cauliflower (B. oleracea var. botrytis), beet (B. vulgaris var. cicla), and spinach (S. oleraceae) in aqueous suspension and mild reaction conditions. B. oleracea var. italic and B. oleracea var. botrytis gave the maximum bioconversion yields within short reaction times. Vegetables assayed exhibited an excellent yield (≥ 99%) after 24 hours for aromatic aldehydes.     

Meiotic chromosome pairing in Actinidia chinensis var. deliciosa

Polyploids are defined as either autopolyploids or allopolyploids, depending on their mode of origin and/or chromosome pairing behaviour. Autopolyploids have chromosome sets that are the result of the duplication or combination of related genomes (e.g., AAAA), while allopolyploids result from the combination of sets of chromosomes from two or more different taxa (e.g., AABB, AABBCC). Allopolyploids are expected to show preferential pairing of homologous chromosomes from within each parental sub-genome, leading to disomic inheritance. In contrast, autopolyploids are expected to show random pairing of chromosomes (non-preferential pairing), potentially leading to polysomic inheritance. The two main cultivated taxa of Actinidia (kiwifruit) are A. chinensis (2x and 4x) and A. chinensis var. deliciosa (6x). There is debate whether A. chinensis var. deliciosa is an autopolyploid derived solely from A. chinensis or whether it is an allopolyploid derived from A. chinensis and one or two other Actinidia taxa. To investigate whether preferential or non-preferential chromosome pairing occurs in A. chinensis var. deliciosa, the inheritance of microsatellite alleles was analysed in the tetraploid progeny of a cross between A. chinensis var. deliciosa and the distantly related Actinidia eriantha Benth. (2x). The frequencies of inherited microsatellite allelic combinations in the hybrids suggested that non-preferential chromosome pairing had occurred in the A. chinensis var. deliciosa parent. Meiotic chromosome analysis showed predominantly bivalent formation in A. chinensis var. deliciosa, but a low frequency of quadrivalent chromosome formations was observed (1 observed in 20 pollen mother cells).     

Taxonomy of Gundlachia (Compositae: Astereae)

Gundlachia, a genus of shrubs occurring in the Caribbean islands, is treated as comprising two species, one of which has six varieties. Five new combinations are made: Gundlachia corymbosa var. apiculata (Britton & S. F. Blake) M. A. Lane, G. corymbosa var. compacta (Urb. & Ekman) M. A. Lane, G. corymbosa var. cubana (Britton & S. F. Blake) M. A. Lane, G. corymbosa var. foliosa (Britton & S. F. Blake) M. A. Lane, and G. corymbosa var. ocoana (Urb. & Ekman) M. A. Lane. Gundlachia is probably most closely related to Gymnosperma.     

Karyotype analysis of some Minuartia L. (Caryophyllaceae) taxa

Karyotypic characters, mitotic metaphase chromosomes, monoploid idiograms and karyograms of Minuartia anatolica (Boiss.) Woronow var. phrygia (Bornm.) McNeill, Minuartia anatolica (Boiss.) Woronow var. scleranthoides (Boiss. & Noe) McNeill, Minuartia corymbulosa (Boiss. & Balansa) McNeill var. gypsophilloides McNeill and Minuartia aksoyi M.Koç & Hamzao?lu were investigated for the first time. Analysis of somatic metaphases showed that the chromosome numbers and the formulas of these taxa were 2n = 24 = 14m + 6sm + 4st for Minuartia anatolica var. phrygia, 2n = 14 = 6m + 8sm for Minuartia anatolica var. scleranthoides, 2n = 14 = 6m + 4sm + 4st for Minuartia corymbulosa var. gypsophilloides and 2n = 30 = 14m + 10sm + 6st for Minuartia aksoyi. No satellites were observed in the karyotypes of these taxa. Karyotype asymmetry was estimated by many different methods, namely the Stebbins classification, the karyotype asymmetry index (As K %), the total form percent (TF %), the Rec and Syi indices, the intrachromosomal asymmetry index (A1) and interchromosomal asymmetry index (A2), the dispersion index (DI), the degree of asymmetry of karyotype (A index) and the asymmetry index (AI).     

New taxa in Pectis (Compositae: Pectidinae) from Mexico and the southwestern United States

Pectis minutiflora,P. papposa var.grandis, andP. purpurea var.sonorae are described as new. A new combination,P. purpurea var.lancifolia also is included. Chromosome counts (n = 12) are reported forP. papposa var.grandis andP. purpurea var.sonorae.     

PCR-RFLP analysis of chitinase genes enables efficient genotyping of Metarhizium anisopliae var. anisopliae

A new genotyping tool has been developed and evaluated for Metarhizium anisopliae var. anisopliae. The tool is based on Restriction Fragment Length Polymorphism (RFLP) analysis of three chitinase genes that are functionally linked to insect-pathogenicity of this fungus. It allowed for discrimination of 14 genotypes among 22 M. anisopliae var. anisopliae strains of a world wide collection. Analyses revealed that the approach may also be applicable to other Metarhizium varieties. The new tool will be useful for genetic characterization of M. anisopliae var. anisopliae strains, and it is applicable for laboratories with limited access to molecular diagnostic equipment.     

Identification of genetic variations of cultivated and weedy types of Perilla species in Korea and Japan using morphological and SSR markers

To better understand the genetic diversity and relationships of the two cultivated types of Perilla crop and their weedy types in Korea and Japan, we evaluated the genetic variations of 56 accessions by assessing five morphological characteristics and 18 SSR markers. The two cultivated types of var. frutescens and var. crispa were clearly distinguished by seed size, whereas most accessions of cultivated and weedy types of var. crispa cannot be distinguished strictly by seed characteristics. A total of 165 alleles with the SSR analysis were detected with an average number of 9.2 alleles per locus among the 56 Perilla accessions. The number of alleles per locus ranged from two for KWPE-56 and KWPE-39 to 21 for GBPFM-204. Additionally, the genetic diversity of each locus ranged from 0.497 at KWPE-56 and KWPE-39 to 0.959 at GBPFM-204, with an average of 0.692. The average genetic diversity values were 0.549, 0.685, 0.451 and 0.557 for cultivated and weedy types of var. frutescens and for cultivated and weedy types of var. crispa, respectively. The weedy type accessions of var. frutescens and var. crispa evidenced greater variation than the corresponding cultivated type accessions. The accessions of the cultivated and weedy types of var. frutescens and var. crispa from Korea exhibited greater SSR diversity than those of Japan. An UPGMA phylogenetic tree revealed three major groups, which was congruent with their morphological characteristics except for a few odd accessions. SSR markers clarified the genetic relationships between var. frutescens and var. crispa and helped improve our understanding of the genetic diversity of the two cultivated types of P. frutescens and their weedy types in Korea and Japan.     

Callus formation and plantlet development from axillary buds of taro

Excised lateral buds of taro [Colocasia esculenta var. esculenta (L.) A.F. Hill] developed into plantlets and formed callus if cultured on media containing taro extract. α-Naphthaleneacetic acid enhanced the process but only if taro extract was also present. The tissue requirements for this variety of taro are different from those of Colocasia esculenta var. antiquorum (L.) A.F. Hill.     

膜荚黄芪SCAR标记的建立

用RAPD方法对膜荚黄芪和蒙古黄芪进行指纹图谱的研究。采用BSA法从120个10碱基随机引物筛选出7个在膜荚黄芪基因池和蒙古黄芪基因池中表现多态性的引物。单株检测表明,引物OPD14具有膜荚黄芪特异性,在检测的膜荚黄芪个体中均能各自扩增出一条300 bp左右的特异带,而在蒙古黄芪的单株中则未见,将该膜荚黄芪特异性片断命名为OPD14_-300。获得的RAPD标记OPD14_-300经克隆、测序、重新设计一对特异性引物转化成更稳定的SCAR标记;该SCAR标记只在膜荚黄芪个体中出现,达到了在分子水平上快速、准确地鉴定膜荚黄芪和蒙古黄芪的目的。     

Some Observations on Bacterial Thermal Death Time Curves

Thermal death rate data were obtained for spores of Clostridium sporogenes P.A. 3679 and Bacillus subtilis var. niger, and for cells of Salmonella senftenberg 775W. The survival curves for P.A. 3679 were approximately linear, but for B. subtilis var. niger or S. senftenberg 775W they were sigmoidal. Decimal reduction times were derived from the regression slopes of the apparent linear portion of the survival curves, and from these a phantom thermal death time (TDT) curve was constructed. In general, the phantom TDT curves were linear for B. subtilis var. niger and S. senftenberg 775W and nonlinear for P.A. 3679.     

Biostratigraphic significance of sequential size variations of the calcareous nannofossil genus Reticulofenestra in the Upper Pliocene of the North Atlantic

We demonstrate size fluctuations of the calcareous nannofossil genus Reticulofenestra in Upper Pliocene sediments from the North Atlantic Ocean and clarify a characteristic evolutionary trend of this genus. Four bioevents, which are based on abrupt decreases in maximum size and on changes of morphologic features of Reticulofenestra specimens, are detected in the sediments. They are the disappearance of R. minutula var. A, the termination of Acme Zone II of R. minutula var. C, the disappearance of R. minutula var. B, and the termination of Acme Zone I of R. minutula var. C, in ascending order. These are nearly synchronous and traceable events.     

Nomenclatural notes on Aster (Asteraceae)—III. The status of a. Sandwicensis

Plants ofAster sandwicensis (A. Gray in H. Mann) Hieron. belong inA. subulatus Michaux but are recognized as taxonomically distinct from those of var.subulatus. A new combination is needed:A. subulatus var.sandwicensis (A. Gray in H. Mann) A. G. Jones, comb. nov.Chamisso s.n. (G-DC!) is chosen as the lectotype.