Showing papers in "Phytoparasitica in 2015"

DNA sequence-based identification of Fusarium : Current status and future directions

Abstract: Fusarium ranks as one of the world’s most economically destructive and species-rich groups of mycotoxigenic plant pathogens (Aoki et al. 2014). These ubiquitous molds produce a plethora of toxic secondary metabolites, such as trichothecenes, zearalenone, fumonisins, and enniatins, which pose a significant threat to agricultural biosecurity, food safety, and plant, human and animal health (Marasas et al.1984). Fusarial-induced diseases of virtually every economically important plant cost the global agricultural economy multi-billion euro losses annually. Moreover, phylogenetically diverse fusaria, including plant pathogens (Short et al. 2011), cause infections in humans, with those involving the cornea and nails being the most common (Chang et al.2006 and references therein). Because fusaria are broadly resistant to the spectrum of antifungals currently available, disseminated infections in patients who are artificially immunosuppressed or immunocompromised and severely neutropenic are typically fatal (Balajee et al.2009). The likely reservoir of nosocomial fusarioses is the plumbing system, which has been shown to harbor the most common human opportunistic fusaria (Kuchar 1996; Short et al.2011). Accurate identification of the etiological and/or toxigenic agent is central to disease management and infection control (Wingfield et al. 2012). Thus, the primary focus of this mini-review is to provide a contemporary guide to the following three web-accessible resources for DNA sequence-based identification of Fusarium: FUSARIUM-ID (http://isolate.fusariumdb.org/; Geiser et al.2004; Park et al. 2010), Fusarium MLST (http://www.cbs.knaw.nl/fusarium/; O’Donnell et al.2010), and NCBI GenBank (http://www.ncbi.nlm.nih.gov/). The following brief overview of Fusarium phylogenetic diversity is provided as background information for the sections on DNA sequence-based identification.

Tropical race 4 of Panama disease in the Middle East

Abstract: Panama disease (aka Fusarium wilt) of banana (Musa spp) has been a destructive problem for well over a century Race 1 of the pathogen, Fusarium oxysporum f sp cubense (Foc), was responsible for the demise of the first export trades of banana that were based on the cultivar ‘Gros Michel’ Currently, tropical race 4 (TR4) impacts the Cavendish cultivars, which are most important in both export and smallholder production TR4 was confirmed in Jordan in 2013, but has probably been present in the country since at least 2005 The outbreak in Jordan was apparently the first occurrence of Panama disease in the Middle East, but it also represented a considerable expansion of TR4’s distribution, which had previously been restricted to the Far East How TR4 arrived in Jordan is not known However, it is clear that TR4 has spread within Jordan, and is now also present elsewhere in the Middle East and Africa We review the history, epidemiology and management of Panama disease, and discuss the current distribution of TR4 and its potential impact on banana production in the Middle East

Comparison of Bradysia odoriphaga Yang and Zhang reared on artificial diet and different host plants based on an age-stage, two-sex life table

Abstract: An age-stage two-sex life table was constructed in order to investigate the differences in population characteristics between Bradysia odoriphaga Yang and Zhang individuals reared on artificial diet, Chinese chive [Allium tuberosum], Welsh onion [Allium cepa], cucumber [Cucumis sativus], lettuce [Lactuca sativa], and Chinese cabbage [Brassica rapa pekinensis]. A population projection was also used to determine the potential trend of populations. The intrinsic rates of increase (r) of B. odoriphaga reared on artificial diet, Chinese chive, Welsh onion, cucumber, lettuce, and Chinese cabbage were 0.1477, 0.1545, 0.1295, 0.1405, 0.1294, and 0.0732 d-1, respectively. The highest net reproductive rate was 61.26 offspring per individual reared on Chinese chive, followed by 53.19, 49.90, 38.15, 30.54, and 16.20 offspring per individual for populations reared on artificial diet, Welsh onion, cucumber, lettuce, and Chinese cabbage, respectively. The mean generation times of B. odoriphaga ranged from 25.88 days when reared on cucumber to 37.86 days when reared on Chinese cabbage. B. odoriphaga feeding on Chinese cabbage had the longest total preoviposition period of female insects from birth (TPOP), larval and pupal period, and the lowest fecundity, and this insect reared on Chinese chive had the highest survival rate and reproductive value. The population projection revealed B. odoriphaga had explosive population growth in a relatively short time when reared on Chinese chive. These findings demonstrated that B. odoriphaga can successfully survive on artificial diet and five host plants, and our results showed the superiority of mass rearing B. odoriphaga on Chinese chives and the laboratory-prepared diet. These findings obtained under laboratory conditions also lay the basis for further studies of the population development of B. odoriphaga in the different host plants fields.

Seasonal phenology of Tuta absoluta (Lepidoptera: Gelechiidae) in protected and open-field crops under Mediterranean climatic conditions

Abstract: The population structure and dynamics of the tomato leafminer Tuta absoluta were investigated in a protected tomato crop and on potato and tomato crops and Solanum nigrum plants under open-field Mediterranean climatic conditions (Sardinia) by captures in pheromone-baited traps and visual inspection of host plants. In the greenhouse crop, male captures and leaf infestation were low in winter and increased steadily in spring up to 797.3 males/trap/week and 6.4 mines/leaf, respectively. Under open-field conditions, males were captured all year round with a peak in early September, concurrently with highest mean daily temperatures. Pest density in potato crops was very low (<0.3 mines/leaf), as well as on S. nigrum (0.16 mines/leaf). Conversely, high pest infestation was observed in tomato leaves (3.8 mines/leaf) and fruits (27% damaged fruits). Eggs, larvae and adults were detected over two consecutive winters, indicating that T. absoluta can develop continuously over the year under natural conditions. Parasitoids were recorded throughout the survey at low rates (≤16.1%). The most active beneficials were Necremnus tutae and Neochrysocharis formosa in protected and open-field crops, respectively. The tomato leafminer completed 6 generations in the greenhouse tomato crop during the winter-spring growing season, whereas in open-field crops the pest completed two generations on winter potato and 4-5 in spring-summer tomato. The degree-day model based on minimum and maximum temperatures reliably described the population dynamics in the protected crop, and estimated the completion of 7.4 generations per year under open-field Mediterranean conditions.

Characterization of Colletotrichum spp. causing anthracnose of bell pepper (Capsicum annuum L.) in Trinidad

Abstract: Anthracnose fruit rot of pepper (Capsicum spp.) is an economically important disease in many countries worldwide. This study was conducted to identify and characterize the pathogens responsible for anthracnose disease in bell peppers (C. annuum L.) in Trinidad. Seventy-two percent of all isolates were Colletotrichum truncatum and 28% were C. gloeosporioides. Growth rate and conidia dimensions were reliable morphological markers that allowed differentiation between C. gloeosporioides and C. truncatum isolates. Benomyl sensitivity testing also distinguished between isolates of C. gloeosporioides and C. truncatum. C. truncatum was resistant to benomyl at all concentrations tested while C. gloeosporioides sensu lato was sensitive to concentrations above 0.1 μg ml-1 . Pathogenicity tests demonstrated different levels of resistance to anthracnose in various Capsicum genotypes. C. gloeosporioides sensu lato isolates caused significantly greater damage than C. truncatum isolates regardless of pepper cultivar. PCR with taxon- and species-specific primers produced amplicons of expected band sizes for all Colletotrichum species and only for C. gloeosporioides, respectively. Molecular analysis of ITS and β-tubulin sequences positioned C. gloeosporioides sensu lato and C. truncatum isolates from bell pepper into separate species-specific clusters.

Soil solarization: the idea, the research and its development

Abstract: One effective method for the management of soilborne pathogens is soil disinfestation. The basic idea is to treat the soil by drastic means, before planting, in order to eliminate the pathogens surviving there, thereby ensuring the health of the subsequent crop. There are two basic approaches to soil disinfestation: chemical, using fumigants, and physical, by heating the soil (mainly by steam). These approaches were developed in 1870, in the early days of plant pathology, and the chemical approach has dominated ever since.

First record of two invasive eucalypt psyllids (Hemiptera: Psylloidea) in Israel

Abstract: Two eucalypt-feeding psyllids (Hemiptera: Psylloidea: Aphalaridae): the eucalypt shoot psyllid, Blastopsylla occidentalis Taylor and the red gum lerp psyllid, Glycaspis brimblecombei Moore are reported from Israel for the first time. Both species belong to Spondyliaspidinae, a subfamily of jumping plant lice that feed generally on Myrtaceae, mainly eucalypts. The psyllids were collected from Eucalyptus camaldulensis Dehnh., a dominant eucalypt species in Israel. A summary ofthe globaldistributionand the host trees of the two psyllids are provided and their potential threat to eucalypts in Israel is discussed. Diagnostic information to distinguish between the two psyllids is presented, with an identification key for the adults of six eucalypt-feeding psyllid species in the Western Palearc- tic region.

Integrating pesticides and predatory mites in soft fruit crops

Abstract: Incorporation of predatory mites (Phytoseiidae) as biological control agents in soft fruit integrated pest management (IPM) programmes requires understanding of the interactions between environment, other organisms and crop management practices. This knowledge is dispersed among commercial online databases and peer reviewed papers and can be contradictory or difficult to access and interpret. The review brings together findings from databases and peer reviewed laboratory, field and semi-field studies of pesticide toxicity and persistence to soft fruit phytoseiid mites and also considers resistance, spray programmes and how these interact with species sensitivity, alternative food availability and plant structure. Predictably, acaricides and insecticides are the most toxic pesticides to phytoseiid mites, but their toxicity varies. Few fungicides are harmful, but data for many is lacking; it is very scarce for herbicides. There is virtually no data on tank mixes of pesticides applied to many soft fruit crops. Persistence of pesticides varies so release times for predatory mites after application range from a few days to several weeks and some of the most toxic active ingredients are not always the most persistent. Phytoseiid species vary in susceptibility to pesticides and in some populations resistance has occurred. Interactions with the environment are more difficult to define, but fungicides, for example, may reduce alternative food items whilst plant architecture may offer phytoseiid mites protection from spray residues. This review provides a timely synopsis to inform future research needs and provides practical guidance to enable better management of predatory mites in soft fruit crops.

Characterization and complete nucleotide sequencing of Pepper Mild Mottle Virus infecting Bell Pepper in India

Abstract: Capsicum (Capsicum annuum L var. grossum Sendt) commonly known as bell pepper or sweet pepper, is one of the most economical agricultural crop grown under both open and polyhouse conditions. The presence of Pepper mild mottle virus (PMMoV) from different districts of Himachal Pradesh was confirmed by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and RT-PCR using coat protein (CP) gene amplification. The first complete genome sequence of Indian isolate of PMMoV (HP-1) was elucidated and compared with other members of Virgaviridae family and PMMoV isolates. Sequence homology, multiple alignment and phylogenetic analysis on the basis of nucleotide and amino acid sequences showed that PMMoV-HP1 isolate is more closely related to the PMMoV-J, the Japanese isolate. Based on CP gene amino acid sequence analysis, the PMMoV-HP1 isolate showed 100 per cent identity with P12 pathotypes (capable of breaking L 2 gene mediated resistance in capsicum). This is the first report of the PMMoV complete genome organization intercepted in India.

Stress avoidance: vertical movement of entomopathogenic nematodes in response to soil moisture gradient

Abstract: Survival of entomopathogenic nematodes (EPNs) in soils is attributed to their entering a dormant state—anhydrobiosis—as soil moisture decreases, but EPNs with poor desiccation tolerance and low anhydrobiotic capabilities may practice desiccation avoidance. We compared the effect of soil moisture gradient on downward movement of the highly desiccation-tolerant Steinernema carpocapsae and the poorly desiccation-tolerant Heterorhabditis bacteriophora. Infective juveniles (IJs) were applied to the surface of moist (11–13% w/w moisture) sandy soil in buckets. Nematode distribution was monitored at different depths 3, 14 and 28 days after application. In uncovered buckets, soil moisture decreased to 1% in the upper 5-cm layer after 28 days. H. bacteriophora IJs abandoned the upper soil layers as dryness intensified with >80% found in the bottom (20–25 cm) layer. In contrast, >70% S. carpocapsae IJs remained in the upper layer. In covered buckets, with 10% moisture throughout the experiment, heterorhabditid IJs were equally distributed between the 10–15 cm and 20–25 cm layers; only 7% remained in the upper layer. Again, >70% S. carpocapsae IJs remained in the upper layer throughout. Soil type influenced H. bacteriophora IJs' downward migration. In sandy and sandy loam soils, with rapid evaporation, >80% IJs were in the bottom layer 14 and 28 days after application. In the loam soil, with higher moisture retention, >75% IJs remained in the 10–15 cm layer and <20% migrated to the bottom. Results provide initial evidence of a possible stress-avoidance strategy in H. bacteriophora under natural conditions.

Resistance inducers in the control of root lesion nematodes in resistant and susceptible cultivars of maize

Abstract: Pratylenchus brachyurus stands out among the major importance nematodes for the national agriculture, due your difficulty of control. Thus, the study aimed to evaluate the efficiency of resistance inductors in the nematode management in resistant and susceptible maize. It was studied the inductors acibenzolar-S-metil, Ecolife™ and manganese phosphite. The experiment was conducted in a factorial arrangement (2 × 4) composed for two maize genotypes (resistant and susceptible to nematode). Each inductor was applied, singly, seven days and one day before inoculation and seven days after inoculation to nematode. Untreated plants were used as control. The inductor Acibenzolar-S-metil was efficient to reduce the nematode population in both genotypes. Ecolife™ promoted the nematode reduction in susceptible genotype while the results were variable for manganese phosphite. In general, the inductors showed no significant effect on plant development and the same factor mainly affected by genotype.

Integrating resistance and tolerance for improved evaluation of sorghum lines against Fusarium stalk rot and charcoal rot

Abstract: Stalk rots are major fungal diseases of sorghum [Sorghum bicolor (L.) Moench] worldwide and cause significant economic loss. Conventionally, the length of stem lesions, produced by Fusarium thapsinum (FT; Fusarium stalk rot) and Macrophomina phaseolina (MP; charcoal rot), are measured to assess the degree of plant resistance. Genotypes with shorter lesion length (LL) are more resistant and expected to exhibit improved yield compared to susceptible genotypes. However, recent reports reveal inconsistent correlations between yield and LL, demonstrating the inadequacy of LL to predict yield under disease pressure. In this study, a new resistance-tolerance index (Index RT ) was used to rank 36 advanced sorghum male sterility maintainers (B-lines). Index RT was formulated in such a way that a lower index value indicates increased disease resistance and reduced yield loss (i.e., greater tolerance) and vice-versa after infection. When ranked by LL, ARCH11035B, -11025B and -11011B were the best performing lines against Fusarium stalk rot, whereas the same lines ranked 1, 3, and 9, respectively, using Index RT . Similarly, ARCH11018B, -11010B and -11014B had the lowest LLs respectively against charcoal rot, whereas the same lines were ranked 1, 4, and 30, respectively, based upon Index RT . The LL- or Index RT -dependent ranking differences of certain lines such as FT-inoculated ARCH11011B and MP-inoculated ARCH11014B indicated the effectiveness of deploying Index RT for better evaluating sorghum lines against stalk rot diseases. There was no significant correlation between LL and Index RT , revealing the independence of the two ranking systems. It is anticipated that this novel stalk rot screening procedure could be deployed by sorghum breeders for improved selection of parental lines.

Simultaneous detection of three wheat pathogenic fungal species by multiplex PCR

Abstract: Wheat stem rust, wheat leaf rust, and wheat powdery mildew are three of the most economically damaging fungal diseases of wheat in China, caused by Puccinia graminis f. sp. tritici, Puccinia triticina, and Blumeria graminis f. sp. tritici, respectively. In this study, single-step multiplex polymerase chain reaction (PCR) was developed for the simultaneous detection of the three pathogens. Three sets of specific primers were selected, followed by optimization of the annealing temperature and the dNTPs, Taq DNA polymerase, and primer concentrations for multiplex PCR to establish a method for the simultaneous detection of P. graminis f. sp. tritici, P. triticina, and B. graminis f. sp. tritici at an early stage of infection. The specificity and sensitivity of the multiplex PCR were tested. We observed three specific bands of 395 bp, 151 bp, and 464 bp on amplification with a three-reaction system. The detection sensitivity of the multiplex PCR was 1 ng DNA for P. graminis f. sp. tritici, 10 pg DNA for P. triticina, and 10 pg DNA for B. graminis f. sp. tritici. This study pioneered the use of the triplex PCR system for simultaneous detection of P. graminis f. sp. tritici, P. triticina, and B. graminis f. sp. tritici in infected plant tissues. This novel PCR-based method provides a simple and rapid method for detecting various pathogens in wheat, which will assist in the simultaneous diagnosis and monitoring of multiple plant diseases.

Association of Papaya leaf curl virus with the leaf curl disease of grain amaranth ( Amaranthus cruentus L.) in India

Abstract: A severe leaf curl disease was observed on ~45% of the grain amaranth (Amaranthus cruentus L.) plants growing in experimental plots of CSIR-NBRI, Lucknow, India, during the year 2011. The causal pathogen was transmitted through whiteflies (Bemisia tabaci) from infected to healthy A. cruentus seedlings. Association of Papaya leaf curl virus (PLCV) with the disease was investigated by sequence analysis of ~2.7 kb cloned genome, amplified by Rolling Circle Amplification method from the total DNA of a representative infected A. cruentus sample. The analysis of nucleotide sequence data (accession no. JN135233) revealed 92–94% sequence identities and close phylogenetic relationships with PLCV strains reported from India and Pakistan; hence, the virus isolate of A. cruentus was identified as PLCV. Association of PLCV with leaf curl disease of A. cruentus is being reported for the first time from India.

Effects of Bacillus subtilis, Pseudomonas fluorescens and Aspergillus awamori on the wilt-leaf spot disease complex of tomato

Abstract: The effects of Bacillus subtilis, Aspergillus awamori and Pseudomonas fluorescens on the wilt–leaf spot disease complex of tomato caused by Meloidogyne javanica, Ralstonia solanacearum and Xanthomonas campestris pv. vesicatoria were observed. Inoculation of B. subtilis, A. awamori and P. fluorescens caused a significant increase in plant growth and chlorophyll contents of pathogen-inoculated plants. Inoculation of P. fluorescens caused a greater increase in plant growth and chlorophyll contents of pathogen-inoculated plants than that caused by A. awamori. Application of P. fluorescens with B. subtilis caused a greater increase in plant growth and chlorophyll contents of pathogen-inoculated plants, but the maximum increase was observed when all the three biocontrol agents were inoculated together. P. fluorescens colonized tomato roots more than colonization by B. subtilis. Root colonization by P. fluorescens and B. subtilis was reduced when pathogens were inoculated with rhizobacteria. Inoculation of P. fluorescens caused a greater reduction in galling and nematode reproduction, followed by B. subtilis and A. awamori. Maximum reduction in galling, nematode reproduction, wilt and leaf spot disease indices was observed when all three biocontrol agents were used together.

Nursery treatments with non-conventional products against crown and root rot, caused by Phytophthora capsici, on zucchini

Abstract: Phytophthora capsici, a pathogen causing crown and root rot of zucchini in southern Italy since the 1980s, has recently been observed in open field in northern Italy, causing severe losses. Since chemical control on zucchini is complicated by a limited availability of registered chemicals, as well as by the scalar harvest, a number of resistance inducers, organic amendments, biocontrol agents and fungicides were tested against P. capsici, under greenhouse conditions. Experiments were carried out at the nursery level, with different timing and number of applications. In the presence of a very high disease pressure, the best disease control was provided by mefenoxam, followed by the phosphite-based products, which acted as resistance inducers and also provided a positive effect on plant biomass. Acibenzolar-S-methyl, although effective, was sometimes phytotoxic. The biocontrol agents tested as well as the patented formulation of Brassica carinata defatted seed meals were not effective, providing results statistically similar to the untreated control. The efficacy of resistance inducers is interesting in view of their possible use in alternation with chemicals, or as stand-alone treatments in cultivation systems which do not adopt chemical control.

High-Resolution Melting approaches towards plant fungal molecular diagnostics

Abstract: Reliable and early molecular detection of phytopathogenic fungi is crucial in an era where the expansion of global trade in plant material is undoubtedly increasing the risk of invasive outbreaks, with devastating effects in crop production. Genetic variation within and between fungal species or strains is also important for screening isolates regarding various resistance attributes. Until today many approaches have been employed in fungal diagnostics which are either labor- and time-consuming or costly and of reduced sensitivity. Here, we demonstrate and review recent advances on high-resolution melting (HRM) analysis as a rapid, accurate and powerful tool, capable of differentiating even closely related fungal isolates. HRM technique is based on monitoring the melting of PCR amplicons, using saturating concentrations of a fluorescent intercalating dye that binds to double-stranded DNA. Additionally, we discuss the four case studies inferring applications of HRM analysis towards either genotyping of closely related fungal species or screening for fungicide resistance. We focus on the promising results of these studies, giving some technical considerations and describing the advantages of the application of this approach. Finally, we discuss current prospects and applications for research and development related to this innovative HRM technique in plant fungal diagnostics.

Molecular diversity of Bipolaris oryzae infecting Oryza sativa in India

Abstract: Thirty-six strains of Bipolaris oryzae collected from infected seed from different geographical locations in India were used for the analysis of genetic variability by using molecular markers. The molecular characterization using three marker systems, i.e., universal rice primers (URPs), inter-simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) was carried out, which revealed differences in strains from different geographical origins as well as by clustering of various B. oryzae strains which otherwise could not be revealed through conventional characterization. Out of 13 URPs, 20 ISSR and 30 RAPD primers screened, seven URPs, eight ISSR and 14 RAPD markers gave very good reproducibility banding patterns. Polymorphic bands ranging between 86.3% and 100% in URP, 81.8% and 100% in ISSR, and 91.6% and 100% were recorded in the case of RAPD markers. The total number of bands recorded was 1791 with an average of 255.86 in URP, 2541 with an average of 317.63 in ISSR, and 3226 with an average of 230.42 in RAPD markers. Maximum heterozygosity (Hn) was revealed by URP 30F (0.26), ISSR 6 (0.36) and RAPD marker OPB-1 (0.31). The polymorphism information content (PIC) values ranged between 0.69 and 6.43 in URP, 3.86 and 8.03 in ISS, and 2.58 and 8.55 in RAPD marker profiles. Maximum cophenetic correlation was found in URP (r = 1.000), followed by ISSR (r = 0.813) and RAPD (r = 0.784). The combined analysis of all three marker systems showed high cophenetic correlation (r = 0.848), which indicated a good fit of the data for genetic diversity analysis. Hence, combined use of three marker systems would be more sensitive and reliable in characterizing genetic variability in B. oryzae strains.

Rice yellow dwarf phytoplasma (16Sr XI-B subgroup) infecting Jasminum sambac in India

Abstract: Leaf yellowing and witches’ broom symptoms were recorded on Jasminum sambac (L.) plants in August 2012 at Jaipur, Rajasthan, India. Total DNA was isolated from symptomatic jasmine plants and nested PCR was performed using primers pairs P1/P7 and 3Far/3Rev. Expected size amplicons of ~1.3 kb were obtained in nested PCR from symptomatic jasmine plants which were cloned and sequenced. BLASTn analysis of partial 16S rRNA gene sequence of jasmine leaf yellows and witches’ broom (Jas LY and WB) isolate revealed highest sequence identity (99%) with phytoplasma associated with sugarcane white leaf, sugarcane grassy shoot, coconut root wilt, sorghum grassy shoot and goose grass white leaf, all members of the rice yellow dwarf phytoplasma (16Sr XI) group. Phylogenetic analysis of the Jas LY and WB phytoplasma sequence revealed further its closest relationship with members of the 16Sr XI group. This confirms the association of 16Sr XI group phytoplasma with Jas LY and WB disease. Real and virtual RFLP analysis of 16S rRNA gene of jasmine phytoplasma further confirmed that it belonged to the 16Sr XI-B subgroup. This is the first report of 16SXI-B subgroup phytoplasma infection on Jasminum sambac in the world.

Identification of a novel phytoplasma (16Sr XIV-A subgroup) associated with little leaf and witches' broom of Cannabis sativa L. ssp. sativa and C. sativa L. ssp. indica in India.

Abstract: Symptoms of yellowing, little leaf and witches’ broom on Cannabis sativa L. ssp. sativa and C. sativa L. ssp. indica plants were recorded in and around sugarcane fields at Shahjahanpur, Uttar Pradesh, India, during May–June 2013. Symptomatic plants yielded phytoplasma DNA bands of ~1.2 kb from nested PCR assays using universal phytoplasma primers P1/P6 and R16F2n/R16R2. BLASTn search analysis of both C. sativa ssp. phytoplasma isolates showed that the 16S rDNA sequences shared a 99 % of sequence identity between each other and with those of the phytoplasma strains of 16SrXIV group (‘Candidatus Phytoplasma cynodontis’). Phylogenetic analysis of the 16SrDNA sequences of both phytoplasma isolates revealed their closest relationship with members of the 16SrXIV group. This supports the association of phytoplasma strains of the 16Sr XIV group with Cannabis little leaf and witches’ broom diseases (Can LL-WB). Actual and virtual RFLP analysis of the 16S rDNA sequences of Can LL-WB phytoplasma isolates confirmed that they belonged to the 16Sr XIV-A subgroup. This is the first world report of a 16SXIV-A subgroup phytoplasma infection in C. sativa sp. sativa and C. sativa sp. indica plants.

Development, growth, feeding and reproduction of Ceratomegilla undecimnotata , Hippodamia variegata and Coccinella septempunctata fed on the tobacco aphid, Myzus persicae nicotianae

Abstract: The demographic parameters and the larval aphid consumption of the predatory coccinellids Hippodamia variegata (Goeze) and Ceratomegilla undecimnotata (Schneider) were examined at five constant temperatures (17, 20, 23, 26, and 29 °C). The same parameters were determined for Coccinella septempunctata L. at 23 °C. A red Myzus persicae nicotiannae Blackman clone reared on tobacco leaves was used as prey. Preimaginal development of H. variegata and C. undecimnotata ranged from 12.4 to 40.6 days and 14.4 to 48.5 days at 17 °C to 29 °C, respectively. The corresponding thermal summation constants were 211 and 256 DD (day-degrees). Total and mean daily larval consumption at 26 °C were 84.2 and 8.7 aphids, for H. variegata and 129.1 and 9.4 aphids, for C. undecimnotata, respectively. At 23 °C, the mean fecundity of H. variegata, C. undecimnotata and C. septempunctata was 882, 656 and 586 eggs, respectively. The duration of the oviposition periods was 47.6, 50.4 and 73.4 days, respectively. The demographic parameters calculated for H. variegata, C. undecimnotata and C. septempunctata, were as follows: intrinsic rate of increase (rm) 0.129, 0.084, and 0.061 female/female/day; mean generation time (T) 42.4, 59.1, and 69.3 days; net reproductive rate (Ro) 241.9, 142.7, 67.3 female/female; and population duplication time (DT) 5.4, 8.3, and 11. 4 days. Total aphid consumption by a pair of adult male and female was 2381 aphids in H. variegata and 3242 aphids in C. undecimnotata. The possible role of the three predator species as biocontrol agents is discussed.

Variability in yellow leaf symptom expression caused by the Sugarcane yellow leaf virus and its seasonal influence in sugarcane

Abstract: Yellowing of leaf midrib, its extending to adjoining lamina and necrosis of discoloured tissues from the tip portion are the common yellow leaf (YL) symptoms observed in tropical climatic conditions in India. As symptoms of this disease vary among the varieties, the progress of these symptoms was studied in Coimbatore from disease free status in the plant, using a newly devised YL 0-5 disease severity scale. Progress of recovery of symptoms in symptomatic leaves was monitored with a 0-4 symptom severity scale for four seasons. Detailed observations with ten symptomatic varieties have very clearly indicated a clear variation in symptom expression among them. First symptoms were recorded in leaf 1 and 2 in few plants of the cvs CoPant 84211 and B38192. Apart from yellow discoloration of midrib, reddish discoloration, pinkish midrib and laminar discoloration were recorded in cvs B38192, Co 86010 and Co 85019, respectively. Progress of laminar discoloration on both sides parallel to the midrib varied from ~0.5 to 3.0 cm in different varieties. Apart from severe laminar discoloration progressive leaf drying from the tip region along the midrib towards leaf base and bunching of leaves in the crown were identified as the severe form of disease in sugarcane varieties. For such leaf drying with characteristic pattern of ‘V’ or ‘Y’ shape and in a bunchy top, leaf yellowing was recorded up to -7th leaf and drying was recorded up to -1st leaf in severe YL-affected variety B38192. Progressive increase in disease symptom was noticed in most of the varieties till nine months after planting and later a fluctuation in disease expression was noticed among the varieties. Subsequently decrease of yellowing was observed leaving behind the dried laminar region at the tip. The correlation and regression analyses with meteorological parameters established that ~ 50 % of variability in disease severity grades is explained by minimum temperature and relative humidity in the afternoon. This study on the disease symptomology has clearly revealed variation in YL symptom expressions among the varieties and impact of prevailing weather factors on the fluctuation of disease expressions.

Resistance in sorghum to Sitophilus oryzae (L.) and its association with grain parameters

Abstract: Sorghum is the fifth most important cereal and suffers heavy damage from rice weevil Sitophilus oryzae, reducing their quality and quantity. Studies were conducted to identify the association of grain characteristics and their relationship with resistance to the rice weevil. The paper discusses the associations between sorghum seed parameters, insect oviposition, development data and grain weight loss. The important grain characteristics, viz., 100 seed weight was significantly positively correlated with grain hardness (0.55**) and median development period (0.47**) and significantly negatively correlated with grain weight loss (- 0.43*). However, the grain hardness was significantly negatively correlated with oviposition (- 0.49**), adult emergence (- 0.75**) and grain weight loss (- 0.82**) and was significantly positively correlated with median development period (0.85**). The pest parameter, viz., oviposition was significantly positively correlated with adult emergence (0.43*) and grain weight loss (0.55**). Two principal components (PCs) were extracted explaining cumulative variation of 76.2 %. Seed weight, grain hardness, oviposition, adult emergence, median development period and grain weight loss were the reliable variables for characterization of resistance to S. oryzae. The sorghum lines EC 24, EC 22, PEC 8, PEC 7, EP 78, EP 57, AKR 354 were classified as resistant to S. oryzae and these could be used in future breeding program as resistant sources.

First record of Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae), in Turkey

Abstract: In this study, the occurrence of Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae) was recorded for the first time on Eucalyptus camaldulensis (Myrtaceae) leaves in Turkey. In addition the generalist predator Anthocoris nemoralis Fabricius (Hemiptera: Anthocoridae) and the parasitoid of the red gum lerp psyllid Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) were also found as natural enemies. P. bliteus is also for the first time recorded in Turkey.

Occurrence and identification of grapevine phytoplasmas in main viticultural regions of Turkey

Abstract: Intensive surveys were conducted in the main viticultural areas of Turkey in 2009-2010. Two hundred eighty nine symptomatic and 20 non-symptomatic plant samples were collected and subjected to nucleic acid extraction followed by PCR, nested PCR and RFLP analyses to detect phytoplasma presence and for their identification. The incidence rate of phytoplasma infection was 18.33% and the majority of the symptomatic grapevines were infected with grapevine yellows phytoplasmas belonging to 16SrXII-A subgroup (“bois noir”). Phytoplasmas of 16SrV group, aster yellows (16SrI-B) and pigeon pea witches’ broom (16SrIX) groups were also detected in the surveyed vineyards. Phytoplasma-associated infections were present more on wine grapevine cultivars (73.6%), such as Alphonse Lavallee, Alicante Bouschet, Chardonnay, Shiraz, Cabernet Sauvignon, Merlot, Sauvignon Blanc and Pinot Noir, compared to table grapes (26.4%), such as Bogazkere, Sirfani, Tahannebi and Emir.

Comparison of analytical techniques used to identify tomato-pathogenic strains of Fusarium oxysporum

Abstract: Two Fusarium oxysporum f. sp. lycopersici (Fol race 2 and Fol race 3) and two f. sp. radicis-lycopersici (Forl) isolates plus eight to ten monosporic descendants from each were identified through molecular analysis and pathogenicity tests using differential varieties under different thermal conditions. The results for molecular and pathogenicity test for Fol were variable and to some extent contradictory. The Fol race 3 isolate and its progeny were amplified by the primers SIX1 and SIX3b but, depending on the test temperatures, the parental plus two descendants lost virulence, and one isolate completely lost virulence in all the tests. The Fol race 2 isolate was amplified by the SIX1 primer, but two descendants were not. The monosporic isolates and the parentals did not show pathogenicity on plants. All Forl isolates and progenies were amplified by the Forl primer, but one of the parentals plus all of its descendants did not show pathogenicity on plants. In addition, temperatures influenced the pathogenicity tests, yielding different virulences for Fol, which was enhanced at higher temperatures, whereas on the contrary a lower temperature was preferable for Forl.

Biological control of Glycaspis brimblecombei (Hemiptera: Aphalaridae) in eucalyptus plantations

Abstract: The genus Eucalyptus, native to Australia, is the host of psylloid insects such as the red gum lerp psyllid Glycaspis brimblecombei, a major Eucalyptus pest introduced into Brazil among other countries. The encyrtid Psyllaephagus bliteus is a primary parasitoid used in the biological control of G. brimblecombei .T his study aimed to determine the parasitism of G. brimblecombei by P. bliteus released in eucalyptus plantations. Investigations were carried out in a 19-ha eucalyptus plantation comprised of 9-year-old Eucalyptus camaldulensis (Myrtaceae) in the munici- pality of Luiz Antonio, Sao Paulo State, Brazil. Twenty P. bliteus pairs were released at five points in the study area between May and September 2006 and 2007 ap- proximatelyevery20days.Forevaluationofparasitism, ten leaves per twig were randomly selected and unpar- asitized nymphs of G. brimblecombei ,m ummies (parasitized nymphs of G. brimblecombei) and empty mummies (after emergence of P. bliteus adults) were counted on their abaxial and adaxial parts before and after each release of P. bliteus. The parasitism rates of G. brimblecombei in 2006 and 2007 were 0.21-5.92% and 0.28-7.03% in the control; these values rose to 28.28-78.57%and30.32-79.34%,respectively,inareas involved in parasitoid release. Parasitism levels of G. brimblecombei nymphs in areas with P. bliteus re- lease were affected by the environmental temperature, which is discussed as a potential limitation to the estab- lishment of this parasitoid and to its effectiveness as a biological control agent.

Development of an immunocapture–reverse transcription–polymerase chain reaction (IC-RT-PCR) using modified viral RNA release protocol for the detection of Grapevine leafroll-associated virus 3 (GLRaV-3)

Abstract: Grapevine leafroll-associated virus 3(GLRaV-3) is the most destructive virus causing leaf roll disease in grapevine. ELISA has been widely used to screen the propagating materials for indexing of this virus at nursery stage. But the uneven distribution of GLRaV-3 in vines, its confinement to phloem tissues and impact of seasonal influences on its concentration limit the scope of ELISA. RT-PCR (reverse transcription-polymerase chain reaction), is a more sensitive technique, but not feasible for large scale screening purpose because of the tedious process of RNA isolation. Furthermore, location of virus particles and the presence of inhibitory compounds in the woody tissues of grapevine make RNA isolation problematic. Immunocapture-RT-PCR (IC-RT-PCR), more sensitive than ELISA and RT-PCR alone, is a technique where the virus can be detected without isolating the RNA. In this study, IC-RT-PCR was performed using different combinations of three virus extraction buffers and two virus nucleic acid releasing buffers along with one virus RNA releasing condition for the detection of GLRaV-3. The modified extraction and RNA release protocol developed in this study was validated for specific detection of the virus in the vines of five infected grapevine cultivars. This protocol can help in complementing the GLRaV-3 specific certification program of the country.

Baseline susceptibility and resistance stability of Earias vittella fabricius (Lepidoptera: Noctuidae) to cypermethrin, deltamethrin and spinosad

Abstract: Spotted bollworm, Earias vittella Fabricius (Lepidoptera: Noctuidae) is a serious pest of cotton in South Asia, including Pakistan, and has developed resistance to most chemical classes of insecticides. The aim of this study was to determine the baseline susceptibility and stability of resistance to cypermethrin, deltamethrin and spinosad in a field collected population of E. vittella. The baseline susceptibility values of E. vittella to cypermethrin, deltamethrin and spinosad were 1.24, 0.94 and 0.16, respectively. Resistance to tested insecticides was unstable and spinosad was more toxic than cypermethrin and deltamethrin. The results suggest that deltamethrin, cypermethrin and spinosad can be included in a control program of E. vittella due to high reversion rates. These results have significant implications for the use of insecticides in E. vittella management.

Genetic diversity and differentiation of Leptosphaeria biglobosa on oilseed rape in China

Abstract: Phoma stem canker (blackleg), caused by the fungi Leptosphaeria maculans and L. biglobosa, is the most devastating disease in oilseed rape (canola) production worldwide. In this study, 84 Leptosphaeria isolates were collected in China from rapeseed (Brassica napus) plants with blackleg symptoms and identified using multiplex PCR and rDNA-ITS sequence analysis. Results showed that all these isolates are L. biglobosa and no L. maculans was detected. A total of 99 isolates was analyzed, including 15 other L. biglobosa isolates from the UK, Canada and Poland using rDNA-ITS sequences, and all isolates were found to belong to the L. biglobosa 'brassicae' subclade. The genetic variation of these 99 isolates was tested using ISSR (inter simple sequence repeats) markers using 24 polymorphic primers pairs that generated 241 bands by ISSR-PCR amplification. A dendrogram based on weighted pair group mean analysis of these bands revealed that L. biglobosa isolates from China clustered into different groups from those obtained from Canada and Europe. Furthermore, Chinese isolates from seven provinces, except those from Jiangsu, could be placed within the same cluster, based on geographical location. Nei’s gene diversity ranged from 0.25 in Jiangsu to 0.11 in Sichuan, and Shannon’s information index from 0.16 to 0.37. Genetic identity ranged from 0.784 to 0.834 when isolates from China were compared with those from Canada and the UK, respectively. Analysis of gene flow among populations (Nm) indicated that almost no gene exchange has occurred between L. biglobosa in China and the populations of the fungus from the UK or Canada.