Evaluation of Streptomyces saraciticas as Soil Amendments for Controlling Soil-Borne Plant Pathogens

Soil-borne diseases are the major problems in mono cropping. A mixture (designated LTM-m) composed of agricultural wastes and a beneficial microorganism Streptomyces saraceticus SS31 was used as soil amendments to evaluate its efficacy for managing Rhizoctonia solani and root knot nematode (Meloidogyne incognita). In vitro antagonistic assays revealed that SS31 spore suspensions and culture broths effectively suppressed the growth of R. solani, reduced nematode egg hatching, and increased juvenile mortality. Assays using two Petri dishes revealed that LTM-m produced volatile compounds to inhibit the growth of R. solani and cause mortality to the root knot nematode eggs and juveniles. Pot and greenhouse tests showed that application of 0.08% LTM-m could achieve a great reduction of both diseases and significantly increase plant fresh weight. Greenhouse trials revealed that application of LTM-m could change soil properties, including soil pH value, electric conductivity, and soil organic matter. Our results indicate that application of LTM-m bio-organic amendments could effectively manage soil-borne pathogens.

Bacterial volatile-mediated suppression of root-knot nematode (Meloidogyne incognita)

Root-knot nematodes (Meloidogyne spp.) are obligate plant parasites that cause severe economic losses to agricultural crops worldwide. Due to serious health and environmental concerns related to the use of chemical nematicides, the development of efficient alternatives is of great importance. Biological control through exploiting the potential of rhizosphere microorganisms is currently accepted as an important approach for pest management in sustainable agriculture. In our research, during screening of rhizosphere bacteria against the root-knot nematodes Meloidogyne incognita, Ochrobactrum pseudogrignonense strain NC1 from the rhizosphere of healthy tomatoes showed strong nematode inhibition. A volatile nematicidal assay showed that the cell-free fermentation filtrate in the first-row wells of 12-well tissue culture plates caused M. incognita juvenile mortality in the second-row wells. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that dimethyl disulfide (DMDS) and benzaldehyde were the main volatile compounds produced by strain NC1. The nematicidal activity of these compounds indicated that the LC50 against the M. incognita juveniles in the second-row wells and the fourth-row wells were 23.4 μmol/mL and 30.7 μmol/mL for DMDS and 4.7 μmol/mL and 15.2 μmol/mL for benzaldehyde, respectively. A greenhouse trial using O. pseudogrignonense strain NC1 provided management efficiencies of root-knot nematodes of 88 to 100% compared with the untreated control. This study demonstrated that nematode-induced root-gall suppression mediated by the bacterial volatiles DMDS and benzaldehyde presents a new opportunity for root-knot nematode management.

Aggression and Competition for Space and Food in Captive Juvenile Tuatara (Sphenodon Punctatus)

<p>Intraspecific competition is of importance in the wild and captivity, as the interaction among individuals for resources can affect growth, survival, and ultimately fitness. Tuatara, Sphenodon punctatus, are endemic to New Zealand and the sole representatives of the reptile Order Rhynchocephalia, and their recovery plan outlines the importance of head-started individuals to supplement existing populations and provide stock to start new populations. Head-starting is a widespread conservation tool for raising juveniles in captivity prior to release in the wild, with the aim of reducing juvenile mortality and providing populations with more individuals. However, mortality differs between sexes and juvenile tuatara show enormous variation in size in captivity. I investigated aggression and competition for space and food in a tuatara head-starting facility to determine whether intraspecific competition may affect mortality and growth. Pairs of one-year-old tuatara, S. punctatus, were chosen according to sex and relative size, e.g. a big male and a small female or two similar sized females. Seven scenarios were replicated four times with different pairs. Behaviour (including two feeding trials) was recorded over a six day period via security cameras and direct observations. The number of aggressive conflicts differed among scenarios, and male-male dyads were significantly more aggressive than female-female dyads. Dominance hierarchies were established in 18 of 28 experimental pairs, with bigger animals being dominant. Conflicts include chasing, biting or colliding at full speed. One year old juveniles did not compete for space. They did not use space exclusively, but stopped clustering and had developed aggressive behaviour, suggesting that they are not territorial yet but in an early stage of transition towards territoriality as seen in older juveniles and adults. Space use and avoidance in space and time did not differ among social scenarios and the latter were negligible, but they marked a novel enclosure with urine and faeces. Juveniles competed directly and indirectly for food. Dominant individuals were likely to secure more food than submissive individuals. Females acquired less food when paired with males of bigger or similar size, and acquired about equal shares when paired with a smaller male. While bigger males acquired slightly more food when paired with smaller males, this was not the case in differently sized females. Interference behaviours such as chasing and food stealing were mostly directed from bigger towards smaller individuals. Captive group housing has consequences for competition and aggression, and may directly influence survival. As juvenile tuatara mortality is female-biased, and aggression against females in bigger male-biased groups common, I recommend keeping sexes separate, and assorting groups by size with more spacious enclosures for male groups. These modifications should improve health and numbers of juveniles for release, improve recruitment into the reproductive adult population, and ultimately create more successful head-starting facilities.</p>

Aggression and Competition for Space and Food in Captive Juvenile Tuatara (Sphenodon Punctatus)

<p>Intraspecific competition is of importance in the wild and captivity, as the interaction among individuals for resources can affect growth, survival, and ultimately fitness. Tuatara, Sphenodon punctatus, are endemic to New Zealand and the sole representatives of the reptile Order Rhynchocephalia, and their recovery plan outlines the importance of head-started individuals to supplement existing populations and provide stock to start new populations. Head-starting is a widespread conservation tool for raising juveniles in captivity prior to release in the wild, with the aim of reducing juvenile mortality and providing populations with more individuals. However, mortality differs between sexes and juvenile tuatara show enormous variation in size in captivity. I investigated aggression and competition for space and food in a tuatara head-starting facility to determine whether intraspecific competition may affect mortality and growth. Pairs of one-year-old tuatara, S. punctatus, were chosen according to sex and relative size, e.g. a big male and a small female or two similar sized females. Seven scenarios were replicated four times with different pairs. Behaviour (including two feeding trials) was recorded over a six day period via security cameras and direct observations. The number of aggressive conflicts differed among scenarios, and male-male dyads were significantly more aggressive than female-female dyads. Dominance hierarchies were established in 18 of 28 experimental pairs, with bigger animals being dominant. Conflicts include chasing, biting or colliding at full speed. One year old juveniles did not compete for space. They did not use space exclusively, but stopped clustering and had developed aggressive behaviour, suggesting that they are not territorial yet but in an early stage of transition towards territoriality as seen in older juveniles and adults. Space use and avoidance in space and time did not differ among social scenarios and the latter were negligible, but they marked a novel enclosure with urine and faeces. Juveniles competed directly and indirectly for food. Dominant individuals were likely to secure more food than submissive individuals. Females acquired less food when paired with males of bigger or similar size, and acquired about equal shares when paired with a smaller male. While bigger males acquired slightly more food when paired with smaller males, this was not the case in differently sized females. Interference behaviours such as chasing and food stealing were mostly directed from bigger towards smaller individuals. Captive group housing has consequences for competition and aggression, and may directly influence survival. As juvenile tuatara mortality is female-biased, and aggression against females in bigger male-biased groups common, I recommend keeping sexes separate, and assorting groups by size with more spacious enclosures for male groups. These modifications should improve health and numbers of juveniles for release, improve recruitment into the reproductive adult population, and ultimately create more successful head-starting facilities.</p>

Resilience of Resprouting Temperate Forests is Diminished by Coupled Severe Drought and Fire

Elevated tree mortality and reduced recruitment of new trees linked to drought and fires has been reported across a range of forests over the last few decades. Forests that resprout new foliage epicormically from buds beneath the bark are considered highly resilient to disturbance, but are potentially at risk of elevated mortality, demographic shifts and changes to species composition due to synergistic effects of drought and fire. Despite this, the effects of drought-fire interactions on such forests remain largely unknown. We assessed the effects of drought severity and fire frequency on juvenile mortality, post-fire seedling recruitment and replacement of juvenile trees (balance of recruitment minus mortality) following fire. We compared dry ridgetop and wet gully assemblages across a temperate forest in southern Australia. Both forest types experienced higher rates of fire-induced juvenile mortality in areas that had experienced severe drought compared to moderate drought, though mortality rates were generally low across all drought and fire combinations. This result indicated that topographic position (i.e. wet gullies) did little to moderate juvenile mortality when exposed to severe drought plus fire. In wet forest, severe drought also reduced recruitment and replacement of dead juveniles by post-fire seedlings compared to moderate drought. In dry forest net-negative replacement increased with the severity of drought. Across both forest types, the total pool of juveniles was reduced under severe drought. Future increases in the frequency of coupled severe drought and fire will likely increase the susceptibility of resilient temperate forests to major changes in structure and function.

Endophytic Fungi as Potential Bio-Control Agents against Root Knot Nematode, Meloidogyne incognita in Banana

A Survey was conducted in 12 districts of Assam to collect 92 healthy banana root samples. A total of 55 fungal isolates were successfully isolated from commercial banana cultivars. The culture filtrates were extracted from 55 endophytic fungal isolates and screened against root knot nematode, Meloidogyne incognita in vitro and pot culture studies. Among them, five fungal isolates viz., EF4, BF7, BF27, BF28 and BF35 showed 100% inhibition of egg hatching and 96.33 to 81.33% juvenile mortality of M. incognita with an exposure period of 72h when compared to other isolates and control. On paddy seed treatment with endophytic fungi of five promising isolates, two isolates viz., BF7 and BF28 significantly enhanced germination percentage (82.67%, 73.33%) and vigour index (62.91, 47.24%), respectively. The selected five endophytic fungal isolates were evaluated for their efficacy against M. incognita in banana under pot culture conditions. The study revealed that culture filtrates of BF7 and BF28 significantly reduced the soil and root nematode population, number of adult females, egg masses and root gall index of M.incognita compared to untreated control. The isolates BF7 and BF28 also significantly increased the growth parameters viz., pseudostem height, root length and pseudostem girth. These promising endophytic fungal isolates viz., BF7 and BF28 were identified as non-pathogenic Fusarium oxysporum strains (Accession no. MN567668) and (Accession no. MN567710), respectively by PCR -18S rRNA of ITS region of gene sequence and phylogenetic tree construction.

Epidermal galactose spurs chytrid virulence and predicts amphibian colonization

The chytrid fungal pathogens Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans cause the skin disease chytridiomycosis in amphibians, which is driving a substantial proportion of an entire vertebrate class to extinction. Mitigation of its impact is largely unsuccessful and requires a thorough understanding of the mechanisms underpinning the disease ecology. By identifying skin factors that mediate key events during the early interaction with B. salamandrivorans zoospores, we discovered a marker for host colonization. Amphibian skin associated beta-galactose mediated fungal chemotaxis and adhesion to the skin and initiated a virulent fungal response. Fungal colonization correlated with the skin glycosylation pattern, with cutaneous galactose content effectively predicting variation in host susceptibility to fungal colonization between amphibian species. Ontogenetic galactose patterns correlated with low level and asymptomatic infections in salamander larvae that were carried over through metamorphosis, resulting in juvenile mortality. Pronounced variation of galactose content within some, but not all species, may promote the selection for more colonization resistant host lineages, opening new avenues for disease mitigation.

FACTORS RELATED TO ADOLESCENT DELAY IN PANEMBONG GIRANG CIANJUR

The juvenile delinquency rate in Panembong girang has long been very high. The environment is not good. For parents who have teenagers, they will be very worried if their teenagers are released to hang out with teenagers in such an environment. Many behaviors that lead to juvenile delinquency. The teenager's acquaintance with the Panembong Girang teenager has led to a legal case, which has ended at the court. These include being involved in drug abuse, beating other people until they are seriously injured and sentenced to prison, drinking alcohol, promiscuity, stealing, and others. The impact of juvenile delinquency The juvenile mortality rate in Panembong Girang is very high, compared to the death rate of adults and parents. The cause of the high mortality rate of adolescents in Panembong girang indirectly is the lack of control of adolescents in managing themselves. Often gather, in groups with peers, who incidentally have bad behavior. So that teenagers do what they should not do. Having an uncontrollable personality, causing the teenager to fall into drinking liquor or alcohol. One of the causes of death in adolescents worldwide due to accidents. in Panembong Girang the number of causes of death for adolescents is directly due to alcohol and accidents. The purpose of the study was to determine the cause of death of adolescents and to determine the lifestyle of panembong happy adolescents. The research method is a qualitative descriptive research design. The informants were taken by 3 neighbors next door to the meatball seller's house, teenagers and members of the Youth Organization. Results and Discussion: the cause of the death rate of adolescents due to alcohol died immediately and when drunk driving a motor vehicle an accident. Conclusion: the factors of the high mortality rate of adolescents in Panembong Girang are due to alcohol and accidents after drinking alcohol

Life Stage of Neighbors Determines Neighborhood Effect on Tree Mortality in a Subtropical Forest

Neighborhood effects are a crucial ecological process that allow species to coexist in a forest. Conspecific and heterospecific neighbors, as major classified groups, affect tree mortality through various mechanisms associating with neighbor life stages. However, how neighbor life stages influence neighborhood effects and by what mechanisms remains a knowledge gap. Here we censused the mortality of 82,202 trees representing 30 species in a 20-ha subtropical forest and classified their neighbors into the following life stages: earlier, same and later. Then, we ran generalized linear mixed models to estimate the effect of neighbors at different life stages on tree mortality. Our results showed that conspecific later stage neighbors have effects on increasing tree mortality overall, whereas conspecific earlier stage neighbors have effects on decreasing. Furthermore, these opposing effects could offset each other so that the overall effect of conspecific neighbors on juvenile mortality seems small. In contrast, heterospecific neighbors have effects on decreasing tree mortality overall. These effects are consistent with those of later stage heterospecific neighbors. Our findings demonstrate that neighbors importantly impact tree mortality, and their specific effects are closely related to neighbor life stages. Any single effect from one neighbor life stage could disturb or dominate the total effects of the neighbors. Therefore, the neighbors must be divided into different life stages to best explain the neighborhood effect on forest dynamics.