Pathological and molecular genetic variation in the interaction between Sporobolus spp. and Bipolaris spp.

1999 ◽  
Vol 50 (4) ◽  
pp. 583 ◽  
Author(s):  
S. D. Hetherington ◽  
J. A. G. Irwin

Members of the Sporobolus indicus complex, particularly Sporobolus indicus (L.) R. Br. var. major (Buse) Baaijens (Giant Parramatta Grass; GPG) and S. pyramidalis P. Beauv. (Giant Rat’s Tail Grass; GRTG), are serious pastoral weeds in coastal areas of Australia. Ovariicolous fungal pathogens from the genus Bipolaris Shoem. are agents of the disease false smut on these plants. The hosts are morphologically plastic and variation in disease susceptibility may affect the use of the fungus as a biological control agent. Variation was investigated by screening 22 clones representative of 5 taxonomic entities within the S. indicus complex with 39 fungal isolates representative of 4 Bipolaris species. Both weed entities were highly susceptible to B. ravenelii and B. crustacea and only slightly susceptible to B. cylindrica and B. australis. The converse was true for other Sporobolus entities tested. Genomic DNA was extracted from 20 Sporobolus clones (genotypes) and the RAPD technique used to generate an index of variation. This technique was able to separate the members of the complex into taxonomic groupings. There was only a 2% difference in banding patterns of S. indicus var. major clones collected in New South Wales. Variation amongst clones of S. pyramidalis was greater (15%), indicating a more genetically diverse plant population. The more variable genetic background of S. pyramidalis is more likely to provide variation in susceptibility than that of S. indicus var. major

2010 ◽  
Vol 58 (4) ◽  
pp. 205 ◽  
Author(s):  
David Peacock ◽  
Ian Abbott

We reviewed historical literature and obtained nearly 200 records of the mongoose in Australia up to 1942. Although the earliest importations (from 1855) were for its snake-killing prowess, often as entertainment, its perceived potential as a control agent for the European rabbit (Oryctolagus cuniculus) plague saw concerted introductions made in New South Wales, Victoria and South Australia, primarily in 1883 and 1884. At least 1000 mongoose were released to control rabbits at 14 reported release locations in these states. As many as 700 of these mongoose were reported released in one New South Wales rabbit-control trial. These numbers indicate that insufficient propagule pressure does not explain why Australia escaped the additional devastation of an established mongoose population. The only reason stated for the failure of the mongoose releases to control rabbits is destruction of the mongoose by rabbit trappers, both inadvertently and in seeking to protect their employment. Unfavourable climate was implicated by CLIMATCH modelling in the failure of all releases, especially those into semiarid areas such as western New South Wales. No contemporary detail could be located of the reported 1884 failed introduction of ‘numbers’ of mongoose into North Queensland to control rats in sugarcane plantations.


2008 ◽  
Vol 99 (1) ◽  
pp. 51-63 ◽  
Author(s):  
P.B. Edwards ◽  
R.J. Adair ◽  
R.H. Holtkamp ◽  
W.J. Wanjura ◽  
A.S. Bruzzese ◽  
...  

AbstractThe seed fly Mesoclanis polana (Diptera: Tephritidae) was released in Australia in 1996. Its impact on seed production of bitou bush (Chrysanthemoides monilifera subsp. rotundata) was monitored at eight sites along the New South Wales coast from 1996 to 2004. Peak flowerhead production occurred in autumn (March to May); therefore, samples collected in May of each year were used to compare abundance and impact of M. polana across sites and between years. Latitude had a significant effect on abundance and impact of M. polana. By May 2004, 99.6% of flowerheads at the five most northern sites contained at least one egg, while 64% of flowerheads from the two most southern sites contained at least one egg. In May 2004, mean numbers of M. polana eggs per flowerhead were between 13 and 17 at four of the six northern sites and below two at the two southern sites. In May 2004, average seed destruction by M. polana was 58% at the four most northern sites and 11% at the two most southern sites. The highest level of seed destruction recorded was 86% at Kingscliff in May 2003. Percentage seed destruction in May provided a reasonable estimate of seed destruction for the whole year. Parasitoids were found throughout the range of M. polana in Australia. Their attack rate on M. polana was less than 10% at all sites, except at the two most northern sites where parasitism of up to 27% was recorded. Parasitism results are compared with predictions made following an earlier study. The release of Mesoclanis magnipalpis, a species suited to cooler environments, is recommended for the southern range of C. monilifera subsp. rotundata.


2009 ◽  
Vol 100 (2) ◽  
pp. 159-166 ◽  
Author(s):  
K. Dhileepan ◽  
D. Bayliss ◽  
M. Treviño

AbstractThe specialist tingid, Carvalhotingis visenda, is a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae). Cat's claw creeper is an invasive liana with a wide climatic tolerance, and for biological control to be effective the tingid must survive and develop over a range of temperatures. We evaluated the effect of constant temperatures (0–45°C) on the survival and development of C. visenda. Adults showed tolerance for wider temperature ranges (0–45°C), but oviposition, egg hatching and nymphal development were all affected by both high (>30°C) and low (<20°C) temperatures. Temperatures between 20°C and 30°C are the most favourable for adult survival, oviposition, egg hatching and nymphal development. The ability of adults and nymphs to survive for a few days at high (40°C and 45°C) and low (0°C and 5°C) temperatures suggest that extreme temperature events, which usually occur for short durations (hours) in cat's claw creeper infested regions in Queensland and New South Wales states are not likely to affect the tingid population. The potential number of generations (egg to adult) the tingid can complete in a year in Australia ranged from three to eight, with more generations in Queensland than in New South Wales.


Plant Disease ◽  
2021 ◽  
Author(s):  
Leslie Amanda Holland ◽  
Renaud Travadon ◽  
Daniel P. Lawrence ◽  
Mohamed Taieb Nouri ◽  
Florent P Trouillas

Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning wounds act as major infection courts. Prior to this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint and a sealant were evaluated for preventing fungal pathogen infection via pruning wounds. In four field trials conducted over two dormant seasons, sixteen pruning wound treatments were tested using hand-held spray applications, against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide thiophanate-methyl (Topsin M) provided 82% overall disease prevention against four fungal pathogens. The biological control agent, Trichoderma atroviride SC1 (Vintec), tested at three application rates, resulted in 90 to 93% protection of pruning wounds in field trials, and for individual pathogens ranged from 81-100% protection for the three rates. At the time of this publication, Vintec is being considered for registration as a biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning wounds from infection by almond canker pathogens can be achieved with a one-time spray application of thiophanate-methyl or the biocontrol, T. atroviride SC1 (recommended 2 g/liter) after pruning.


Toxins ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 322 ◽  
Author(s):  
Shuwu Zhang ◽  
Qi Zheng ◽  
Bingliang Xu ◽  
Jia Liu

Postharvest fungal disease is one of the significant factors that limits the storage period and marketing life of peaches, and even result in serious economic losses worldwide. Biological control using microbial antagonists has been explored as an alternative approach for the management of postharvest disease of fruits. However, there is little information available regarding to the identification the fungal pathogen species that cause the postharvest peach diseases and the potential and mechanisms of using the Bacillus subtilis JK-14 to control postharvest peach diseases. In the present study, a total of six fungal isolates were isolated from peach fruits, and the isolates of Alternaria tenuis and Botrytis cinerea exhibited the highest pathogenicity and virulence on the host of mature peaches. In the culture plates, the strain of B. subtilis JK-14 showed the significant antagonistic activity against the growth of A. tenuis and B. cinerea with the inhibitory rates of 81.32% and 83.45% at 5 days after incubation, respectively. Peach fruits treated with different formulations of B. subtilis JK-14 significantly reduced the mean disease incidences and lesion diameters of A. tenuis and B. cinerea. The greatest mean percent reduction of the disease incidences (81.99% and 71.34%) and lesion diameters (82.80% and 73.57%) of A. tenuis and B. cinerea were obtained at the concentration of 1 × 107 CFU mL−1 (colony forming unit, CFU). Treatment with the strain of B. subtilis JK-14 effectively enhanced the activity of the antioxidant enzymes-superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in A. tenuis and B. cinerea inoculated peach fruits. As such, the average activities of SOD, POD and CAT were increased by 36.56%, 17.63% and 20.35%, respectively, compared to the sterile water treatment. Our results indicate that the isolates of A. tenuis and B. cinerea are the main pathogens that cause the postharvest peach diseases, and the strain of B. subtilis JK-14 can be considered as an environmentally-safe biological control agent for the management of postharvest fruits diseases. We propose the possible mechanisms of the strain of B. subtilis JK-14 in controlling of postharvest peach diseases.


1984 ◽  
Vol 26 (2) ◽  
pp. 194-208 ◽  
Author(s):  
P. C. Gregg ◽  
G. C. Webb ◽  
M. A. Adena

The B chromosomes of Chortoicetes terminifera possess an accumulation mechanism. B chromosomes were transmitted at a rate of 0.766 in one B(♂) × zero B(♀) crosses and 0.477 in zero B(♂) one × B(♀) crosses. In crosses where the female had a B chromosome, there were significant differences in transmission rates between pods, but these were not related to differences in G-banding patterns of the B chromosomes involved. In crosses where either the male or female parent had two B chromosomes the B chromosomes did not segregate perfectly, nor did they segregate in a random fashion. The closest resemblance to the behaviour of normal bivalents occurred when the two B chromosomes were of the same, rather than different, G-banding variants, and when they were present in the male rather than the female parent. B chromosomes occurred at eight localities scattered throughout New South Wales. No locality was found where they were not present. The average frequency of B chromosomes was 14.0% for one-B individuals and 0.8% for two-B individuals. There were no significant differences in B-chromosome frequency between males and females. Of the eight localities, only one had a B-chromosome frequency significantly different from any other locality. This relatively uniformity of B-chromosome distribution is interpreted as a consequence of the migratory nature of C. terminifera. A model was constructed to simulate the dynamics of B chromosomes in locust populations. Three main dynamic patterns were recognized, and these were related to differences in the fitness of one-B and two-B individuals. It was concluded that the B chromosome of C. terminifera is probably parasitic, although the simulation model revealed some difficulties which suggest that caution should be applied to the description of any B chromosome as purely parasitic.Key words: B chromosomes, locust, meiotic drive, G-banding, fitness. Chortoicetes terminifera (Walker).


2020 ◽  
Vol 113 (3) ◽  
pp. 1088-1096
Author(s):  
Ehdibaldo Presa-Parra ◽  
Francisco Hernández-Rosas ◽  
Julio S Bernal ◽  
Jorge E Valenzuela-González ◽  
Alma Altúzar-Molina ◽  
...  

Abstract The Mexican fruit fly, Anastrepha ludens Loew, is a significant pest in mango and citrus production areas of Mexico. In this study, we evaluated the effects of some geographic characteristics, rainfall period, soil micro-environmental, and soil coverage variables on the occurrence of entomopathogenic fungi (EPF) associated with A. ludens larvae in soils of mango, grapefruit and mixed crops in central Veracruz state, Mexico. EPF isolates were characterized morphologically and identified by sequence analysis of elongation factor (EF1-1018F, EF1-1620R). We recorded four species of EPF (Metarhizium robertsii J.F. Bisch, S.A. Rehner & Humber [Hypocreales: Cordycipitaceae], M. brunneum Petch [Hypocreales: Cordycipitaceae], M. pinghaense Q.T. Chen & H.L. Guo [Hypocreales: Cordycipitaceae], and Beauveria bassiana (Balsamo) Vuillemin [Hypocreales: Cordycipitaceae]), of which Metarhizium robertsii was the most abundant and the most virulent. Also, we found that rainfall period, organic matter, coverage of herbs and forbs, and calcium levels modulated EPF occurrence. We estimated lethal concentrations for A. ludens larvae of the four most promising isolates, V3-123, V3-160, V1-332, and V3-369. Our results suggest that M. robertsii obtained from agricultural soils holds potential as a biological control agent for A. ludens.


2020 ◽  
Vol 9 (24) ◽  
Author(s):  
Nathan Liang ◽  
Suha Jabaji

ABSTRACT Bacillus velezensis strain E68 is a biosurfactant-producing bacterium isolated from an oil battery near Chauvin, Alberta, Canada. Strain E68 exhibited antimicrobial activity against fungal pathogens and could potentially serve as a biological control agent. Its genome was sequenced and annotated, revealing the presence of multiple lipopeptide biosynthetic gene clusters.


2009 ◽  
Vol 57 (2) ◽  
pp. 77 ◽  
Author(s):  
Gopal Murugan ◽  
Hortencia Obregón-Barboza ◽  
Alejandro M. Maeda-Martínez ◽  
Brian V. Timms

The only species of the genus Triops in Australia, T. australiensis, is found to reproduce by gonochorism. Morphological and reproductive data and molecular analyses of fragments of mitochondrial genes 12S rRNA (12S) and cytochrome oxidase I (COI) indicate that a Triops population from the middle Paroo in north-western New South Wales is composed of two different entities, Triops cf. australiensis lineage A, and T. cf. australiensis lineage B. Gonad histology in individuals with ovisacs of lineage A revealed no evidence of testicular tissue; however, large testicular lobes were found in individuals with ovisacs of lineage B, indicating that they were anatomically hermaphrodites. This is the first record of Australian hermaphroditic Triops. For each lineage, a single haplotype of each gene was obtained. Molecular genetic distance and phylogenetic analyses confirmed the closer relationship and monophyly of the two lineages with T. australiensis (GenBank) when compared with Triops species from other continents. COI haplotypes of lineage A and lineage B differed by 7.7% from each other and differed by 10.2% and 9.6% from a published T. australiensis sequence, respectively. The 12S haplotypes of lineage A and lineage B differed by 3.3% from each other and differed by 2% and 2.5% from a published T. australiensis sequence, respectively. Our results suggest that the two co-occurring Triops lineages probably represent two species that are distinct from T. australiensis.


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