scholarly journals An Analysis of the Quantitative and Qualitative Composition of the Nematode Populations in Pineapple Fields in Puerto Rico

1969 ◽  
Vol 45 (4) ◽  
pp. 265-299
Author(s):  
Alejandro Ayala
Keyword(s):  
Puerto Rico ◽  
Population Size ◽  
Great Part ◽  
Northern Region ◽  
Nematode Population ◽  
The Other ◽  
Parasitic Nematodes ◽  
Biological Factors ◽  
Root Knot Nematode ◽  
Potential Yield

In this study undertaken in Puerto Rico during the months from March through September 1957, 60 different samples of plant-parasitic nematodes from roots and soil were taken from various pineapple farms in 3 of the 4 production Regions of Puerto Rico: Northern, Southwestern, and Central. The fields were selected at random, and those showing no symptoms of nematode injury, as well as those showing such symptoms, were studied. The methods employed for field collection were a modification of those used by Cobb. The laboratory methods and the recovery of nematodes from the soil were a combination of the screen and Baermann-funnel methods. Twenty-three different genera of nematodes were recovered, 16 of which were recognized as being plant parasites and the other 7 were suspected. There was no case in which a sample was found to be free of plant nematodes. In fact, the lowest number of genera present in 1 sample was 5 and the highest was 15, with a mean average of 9 genera per sample. The most frequently occurring genera were Rotylenchulus and Helicotylenchus which were present in all the samples. Less frequent but still common were Pratylenchus, Paratylenchus, Aphelenchoides, Dorylaimus, Ditylenchus, and Meloidogyne. This last one was found only in the Northern Region. The other 16 genera were less widely distributed. Populations of the first 2 genera were large, with a general mean average of 0.97 and 0.67 million per square meter (3.90 and 2.70 billions per acre), respectively. Their population size was higher in the Northern Region, while in the Central and Southwestern Regions it was lower. The average nematode population was 1.75 millions per square meter (7.05 billions per acre) at 6 inches depth. Several edaphic, climatological, and biological factors were found to be related to population sizes for all the genera and some specific genera studied. Population size of the genera varied with geographic location, type of soil, age and variety of the plants (although not statistically), previous crops planted, and temperature. No apparent relation was noted between precipitation except for the root-knot nematode and pH of the soil and nematode population size. No study was conducted of other biological factors such as different soil organisms, or cultivation methods and soil additives. It was estimated from the results obtained in this study and the damage observed in the pineapple plantings of this as well as previously scattered experiments that nematodes cause the loss of a great part of the crop yield in the Island. This loss has been calculated by the Extension Service officers to amount to at least 40 percent of the potential yield.

scholarly journals Effect of coffee silver skin and brewers’ spent grain in the control of root-knot nematodes

2019 ◽  
Vol 56 (1) ◽  
pp. 30-41 ◽  
Author(s):  
N. Thligene ◽  
G. N. Mezzapesa ◽  
D. Mondelli ◽  
A. Trani ◽  
P. Veronico ◽  
...  
Keyword(s):  
Control Strategies ◽  
Nematode Population ◽  
Parasitic Nematodes ◽  
Initial Population ◽  
Infested Soil ◽  
Soil Nematode ◽  
Root Knot Nematode ◽  
Tomato Plants ◽  
Industry Waste ◽  
Spent Grain

SummaryPlant parasitic nematodes (PPN) are important pests of numerous agricultural crops especially vegetables, able to cause remarkable yield losses correlated to soil nematode population densities at sowing or transplant. The concern on environmental risks, stemming from the use of chemical pesticides acting as nematicides, compels to their replacement with more sustainable pest control strategies. To verify the effect of aqueous extracts of the agro-industry waste coffee silverskin (CS) and brewers’ spent grain (BSG) on the widespread root-knot nematode Meloidogyne incognita, and on the physiology of tomato plants, a pot experiment was carried out in a glasshouse at 25 ± 2 °C. The possible phytotoxicity of CS and BSG extracts was assessed on garden cress seeds. Tomato plants (landrace of Apulia Region) were transplanted in an artificial nematode infested soil with an initial population density of 3.17 eggs and juveniles/mL soil. CS and BSG were applied at rates of 50 and 100 % (1L/pot). Untreated and Fenamiphos EC 240 (nematicide) (0.01 μL a.i./mL soil) treated plants were used as controls. Reactive oxygen species (ROS) and chlorophyll content of tomato plants were estimated during the experiment. CS extract, at both doses, significantly reduced nematode population in comparison to the untreated control, although it was less effective than Fenamiphos. BSG extract did not reduce final nematode population compared to the control. Ten days after the first treatment, CS 100 %, BSG 50 % and BSG 100% elicited the highest ROS values, which considerably affected the growth of tomato plants in comparison to the untreated plants. The control of these pests is meeting with difficulties because of the current national and international regulations in force, which are limiting the use of synthetic nematicides. Therefore, CS extracts could assume economic relevance, as alternative products to be used in sustainable strategies for nematode management.

scholarly journals Greenhouse Tests with Nematocides for Control of Nematodes Attacking Tomato (Lycopersicon esculentum var. Rutgers) in Puerto Rico

1969 ◽  
Vol 46 (4) ◽  
pp. 319-327
Author(s):  
Alejandro Ayala
Keyword(s):  
Puerto Rico ◽  
Field Experiments ◽  
Percent Level ◽  
Parasitic Nematodes ◽  
Root Knot Nematode ◽  
High Infection ◽  
The Difference ◽  
Reniform Nematodes ◽  
Susceptible Tomato ◽  
Very High

It has been found that, in Puerto Rico, tomatoes are severely attacked by several species of plant parasitic nematodes and particularly by Meloidogyne incognita (the root-knot nematode) and Rotylenchulus reniformis, the reniform or kidney-shaped nematode. Several experiments were conducted to determine the efficacy of different nematocides against these pests. The last experiment conducted in the greenhouse using eight different nematocides and one of the most susceptible tomato varieties, Rutgers, is discussed. Evidence presented in the form of graphs and tables demonstrates that at least the four fumigants D-D, Dorlone, EDB, and Nemagon are effective in the control of both species of nematodes mentioned. Two compounds, Telone and Fumazone, although not completely effective against root knot, gave a perfect control of the reniform nematodes. Dorlone was superior to all other nematocides, giving the best results in relation to growth, weight of stem, yield, and general appearance of the plants. It also gave perfect control of the reniform and root-knot nematodes. The difference in height of plants over the control was statistically significant at the 5-percent level with EDB and at the 1-percent level with Dorlone and Nemagon. There was no significant statistical difference among the chemicals tested nor between the rest of the chemicals and the control. The severity of root-knot infection varied from degree 0, no infection, to degree 5, very high infection. Root knot was outstanding in the control plants, which showed a very high infection average of degree 5 for galling. At time of harvesting the plants were smaller than those under all the other treatments, but exhibited very little chlorosis and yellowing. In previous trials symptoms developed to a maximum only after blooming or the first picking of fruits. Blooming was retarded, which was shown by the small amount and weight of fruits. A very heavy gall and secondary root-formation was observed. Dorlone gave the best results and showed no phytotoxic effects. Similar observations have been made in field experiments. Phytotoxicity was shown by treatments with Nemagon, EDB, and DCB-60. This condition can be avoided using a lower dosage of the first two nematocides. DCB-60 proved to be ineffective.

scholarly journals Mineral composition of beetroot treated with potential elicitors and inoculated with Meloidogyne javanica

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Paula Juliana Grotto Débia ◽  
Beatriz Cervejeira Bolanho ◽  
Claudia Regina Dias-Arieira
Keyword(s):  
Population Density ◽  
Mineral Composition ◽  
Integrated Management ◽  
Meloidogyne Javanica ◽  
Nematode Population ◽  
Root Knot Nematode ◽  
Cu Content ◽  
Manganese Zinc ◽  
Nematode Population Density ◽  
Elicitor Treatments

Abstract Background The root-knot nematode Meloidogyne javanica can infect beetroots, causing extensive damage to this food crop. As chemical and genetic control tactics have shown limited efficacy, new strategies are needed to improve the integrated management of this parasite. This study assessed the influence of potential defence elicitors and M. javanica infection on the mineral composition of beetroot. Plants were treated with acibenzolar-S-methyl (ASM), citrus biomass, or a mannanoligosaccharide-based product (MOS) and inoculated with 1000 eggs and second-stage juveniles of M. javanica. At 60 days after inoculation, beetroot plants were harvested and evaluated for nematode population density, vegetative growth, and mineral content. Results All potential elicitors reduced nematode population density in beetroots (p ≤ 0.10) and improved the vegetative parameters of inoculated plants (p ≤ 0.05), except shoot fresh weight. Some minerals were found to be negatively affected by treatments, particularly calcium, whose levels were consistently lower in treated plants. On the other hand, M. javanica inoculation increased magnesium, iron, manganese, zinc, and copper contents in beetroots. However, the latter mineral (Cu content) of inoculated plants was positively influenced by MOS and ASM. Conclusion Potential elicitor treatments did not improve the mineral composition of beetroot, but were effective in reducing nematode population density. Plants inoculated with M. javanica had higher mineral levels. However, gall formation decreases the commercial value of the crop and might render it unsuitable for commercialisation. M. javanica-infected beetroots may be used for nutrient extraction or sold to food processing industries.

scholarly journals Precrop Effect of Red Clover (Trifolium pratense L.) and Alfalfa (Medicago sativa L.) on the Population Development of the Northern Root-Knot Nematode Meloidogyne hapla Chitwood, 1949 and on Succeeding Crops—A Pot Study

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 722
Author(s):  
Renata Dobosz ◽  
Roman Krawczyk
Keyword(s):  
Population Density ◽  
Medicago Sativa ◽  
Trifolium Pratense ◽  
Red Clover ◽  
Continuous Cultivation ◽  
Nematode Population ◽  
Meloidogyne Hapla ◽  
Root Knot Nematode ◽  
Crop Species ◽  
Tomato Growth

The northern root-knot nematode, Meloidogyne hapla, is a major pest of many crop species. The objective of the study was to determine how M. hapla population dynamics is affected by two precrops, i.e., Trifolium pratense and Medicago sativa, in three crop durations: one, two and three years of continuous cultivation. Moreover, we set ourselves the task of evaluating the effect of the legume precrop soil on the growth of the succeeding tomato plant (Solanum lycopersicum) and on the nematode population. The experiment was performed outdoors in pots with naturally infected soil. Both precrop species investigated were found to modify the J2 nematode population density in the soil. The galls and nematode females with egg masses were observed on the roots of both studied plant species at the end of each growing season. They appeared to be more abundant on the red clover roots than on those of the alfalfa. The obtained data indicate that the spring soil sampling is more appropriate for the estimation of the M. hapla population density in the red clover precrop soil. The legume precrop soil had a limiting effect on tomato growth and fruit yield. The nematode population negatively influenced tomato growth. The experiment revealed that tomato plants could be planted in alfalfa precrop soil following at least three years of continuous alfalfa cultivation. The same cannot be said of the cultivation of red clover as a precrop for tomatoes.

scholarly journals Toward genetic modification of plant-parasitic nematodes: delivery of macromolecules to adults and expression of exogenous mRNA in second stage juveniles

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Olaf Kranse ◽  
Helen Beasley ◽  
Sally Adams ◽  
Andre Pires-daSilva ◽  
Christopher Bell ◽  
...  
Keyword(s):  
Food Security ◽  
Genetic Modification ◽  
The Body ◽  
Forward Genetics ◽  
Heterodera Schachtii ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Cyst Nematodes ◽  
Plant Parasitic

Abstract Plant-parasitic nematodes are a continuing threat to food security, causing an estimated 100 billion USD in crop losses each year. The most problematic are the obligate sedentary endoparasites (primarily root knot nematodes and cyst nematodes). Progress in understanding their biology is held back by a lack of tools for functional genetics: forward genetics is largely restricted to studies of natural variation in populations and reverse genetics is entirely reliant on RNA interference. There is an expectation that the development of functional genetic tools would accelerate the progress of research on plant-parasitic nematodes, and hence the development of novel control solutions. Here, we develop some of the foundational biology required to deliver a functional genetic tool kit in plant-parasitic nematodes. We characterize the gonads of male Heterodera schachtii and Meloidogyne hapla in the context of spermatogenesis. We test and optimize various methods for the delivery, expression, and/or detection of exogenous nucleic acids in plant-parasitic nematodes. We demonstrate that delivery of macromolecules to cyst and root knot nematode male germlines is difficult, but possible. Similarly, we demonstrate the delivery of oligonucleotides to root knot nematode gametes. Finally, we develop a transient expression system in plant-parasitic nematodes by demonstrating the delivery and expression of exogenous mRNA encoding various reporter genes throughout the body of H. schachtii juveniles using lipofectamine-based transfection. We anticipate these developments to be independently useful, will expedite the development of genetic modification tools for plant-parasitic nematodes, and ultimately catalyze research on a group of nematodes that threaten global food security.

A semi-hybrid model for malaria with limited superinfection

1998 ◽  
Vol 30 (04) ◽  
pp. 1027-1057 ◽  
Author(s):  
Philippe Picard
Keyword(s):  
Stochastic Model ◽  
Population Size ◽  
Hybrid Model ◽  
Human Population ◽  
Threshold Level ◽  
The Other ◽  
The Difference ◽  
The One

Modelling malaria with consistency necessitates the introduction of at least two families of interconnected processes. Even in a Markovian context the simplest fully stochastic model is intractable and is usually transformed into a hybrid model, by supposing that these two families are stochastically independent and linked only through two deterministic connections. A model closer to the fully stochastic model is presented here, where one of the two families is subordinated to the other and just a unique deterministic connection is required. For this model a threshold theorem can be proved but the threshold level is not the one obtained in a hybrid model. The difference disappears only when the human population size approaches infinity.

The role of plant-parasitic nematodes in reducing yield of sugarcane in fine-textured soils in Queensland, Australia

2007 ◽  
Vol 47 (5) ◽  
pp. 620 ◽  
Author(s):  
B. L. Blair ◽  
G. R. Stirling
Keyword(s):  
Growth And Yield ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Population Densities ◽  
Lesion Nematode ◽  
Yield Responses ◽  
The Impact ◽  
Stalk Length ◽  
Plant Parasitic

Damage to sugarcane caused by root-knot nematode (Meloidogyne spp.) is well documented in infertile coarse-textured soils, but crop losses have never been assessed in the fine-textured soils on which more than 95% of Australia’s sugarcane is grown. The impact of nematodes in these more fertile soils was assessed by repeatedly applying nematicides (aldicarb and fenamiphos) to plant and ratoon crops in 16 fields, and measuring their effects on nematode populations, sugarcane growth and yield. In untreated plant crops, mid-season population densities of lesion nematode (Pratylenchus zeae), root-knot nematode (M. javanica), stunt nematode (Tylenchorhynchus annulatus), spiral nematode (Helicotylenchus dihystera) and stubby-root nematode (Paratrichodorus minor) averaged 1065, 214, 535, 217 and 103 nematodes/200 mL soil, respectively. Lower mean nematode population densities were recorded in the first ratoon, particularly for root-knot nematode. Nematicides reduced populations of lesion nematode by 66–99% in both plant and ratoon crops, but control of root-knot nematode was inconsistent, particularly in ratoons. Nematicide treatment had a greater impact on shoot and stalk length than on shoot and stalk number. The entire community of pest nematodes appeared to be contributing to lost productivity, but stalk length and final yield responses correlated most consistently with the number of lesion nematodes controlled. Fine roots in nematicide-treated plots were healthier and more numerous than in untreated plots, and this was indicative of the reduced impact of lesion nematode. Yield responses averaged 15.3% in plant crops and 11.6% in ratoons, indicating that nematodes are subtle but significant pests of sugarcane in fine-textured soils. On the basis of these results, plant-parasitic nematodes are conservatively estimated to cost the Australian sugar industry about AU$82 million/annum.

Limnetic Zooplankton Assemblages in Atlantic Canada with Special Reference to Acidification

1986 ◽  
Vol 43 (2) ◽  
pp. 444-456 ◽  
Author(s):  
J. C. H. Carter ◽  
W. D. Taylor ◽  
R. Chengalath ◽  
D. A. Scruton
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Fish Predation ◽  
Low Ph ◽  
Buffering Capacity ◽  
The Other ◽  
Bay Of Fundy ◽  
Factor Scores ◽  
Multiple Discriminant Analysis ◽  
Biological Factors

Crustacean and rotifer plankton assemblages of 93 lakes in Labrador, 107 in Newfoundland, and 142 in New Brunswick – Nova Scotia were investigated for evidence of correlations with lake morphometric, chemical, or biological factors. Labrador assemblages were almost completely lacking in identifiable structure. Newfoundland species clustered into two groups of different body size, suggesting the influence of fish predation. Only one species in Labrador and Newfoundland was significantly correlated with a derived factor related to lake water buffering capacity. New Brunswick – Nova Scotia species clustered into two groups, one featuring significant positive and the other significant negative correlations with the buffering factor. From this we conclude that acidification is having an impact on the limnetic zooplankton of these two provinces. Multiple discriminant analysis was used to demonstrate that New Brunswick – Nova Scotia lakes differing in their buffering capacity were also distinct in zooplankton composition. Lakes with low factor scores (low pH, alkalinity, and calcium) were mainly located in the Bay of Fundy region; this area has above average fog and precipitation, and lies within the summer air flow carrying pollutants from the south.

Host suitability of summer cover crops to Meloidogyne arenaria, M. enterolobii, M. incognita and M. javanica

Nematology ◽  
2021 ◽  
pp. 1-9
Author(s):  
Hung X. Bui ◽  
Johan A. Desaeger
Keyword(s):  
Cover Crops ◽  
Nematode Species ◽  
Host Suitability ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Root Knot Nematode ◽  
Sunn Hemp ◽  
Host Status ◽  
Susceptible Control ◽  
Sorghum Sudangrass

Summary Cover crops can be a useful tool for managing plant-parasitic nematodes provided they are poor or non-hosts for the target nematode species. A glasshouse experiment was done to determine the host status of four common cover crops in Florida, sunn hemp, cowpea, sorghum sudangrass and sunflower, to pure populations of four common tropical root-knot nematode (RKN) species Meloidogyne javanica (Mj), M. incognita (Mi), M. enterolobii (Me) and M. arenaria (Ma). Tomato was included as a susceptible control. Eight weeks after nematode inoculation (WAI), tomato showed the highest root gall damage for all tested RKN species, with gall indices (GI) between 7 (Ma) and 8.5 (Me) and reproduction factor (RF) ranging from 20 (Ma) to 50 (Mj). No visible root galls were observed for any of the RKN species on sunn hemp and sorghum sudangrass at 8 WAI. However, Mj and Mi were able to reproduce slightly on sorghum sudangrass (RF = 0.02 and 0.79, respectively). Sunflower and cowpea were infected by all four tested RKN species, but host suitability varied. Sunflower root galling ranged from 1.1 (Me) to 4.5 (Mj) and RF = 3.2 (Me) to 28.7 (Mj), while cowpea root galling ranged from 0.6 (Mi) to 5.1 (Me) and RF = 0.8 (Mi) to 67.3 (Mj). Sunn hemp and, to a lesser extent, sorghum sudangrass were poor hosts to all four tested RKN species. Sunflower was a good host to all RKN species, but root gall damage and RF were lowest for Me. Cowpea was a good host to Mj, Me and Ma, but a poor host to Mi. Our results confirm and stress the importance of RKN species identification when selecting cover crops as an RKN management strategy.

Compatibility of Pasteuria penetrans with fungal parasite Paecilomyces lilacinus against root knot nematode on Chilli (Capsicum annuum L.)

2011 ◽  
Vol 1 (1) ◽  
pp. 36-42
Author(s):  
K.K. Chaudhary ◽  
R. K. Kaul
Keyword(s):  
Capsicum Annuum ◽  
Dry Weight ◽  
Nematode Population ◽  
Paecilomyces Lilacinus ◽  
Infested Soil ◽  
Pasteuria Penetrans ◽  
Root Knot Nematode ◽  
Capsicum Annuum L ◽  
Combined Application ◽  
Spore Culture

Chilli (Capsicum annuum L.) crop is highly susceptible for the root knot nematode Meloidogyne incognita and every year this nematode causes great loss to the crop. The present study investigated the cumulative effect of two biocontrol agents viz. Pasteuria penetrans and Paecilomyces lilacinus against M. incognita. Two doses of P. penetrans i.e. 50g/Kg and 100g/Kg infested soil were applied either alone or in combination with two doses of P. lilacinus i.e. 4g spore culture/Kg and 6g spore culture/Kg of soil. Application of P. penetrans with P. lilacinus resulted into relatively better improvement in various growth attributes of chilli when compared with the individual application. Amongst the various treatments tested combined application with the higher dose of both bioagents (i.e. 100g P. penetrans infested soil with 6g of P. lilacinus/Kg) showed maximum improvement in fresh and dry weight of shoot and root over the nematode check and it was almost at par with that of the absolute check. The combined application of both the bioagents at higher dose resulted in 139 and 84% increase in dry weight of shoot and root over the nematode check respectively. The combined application of both the bioagents was also observed to cause higher reduction in gall number and nematode population than their individual application except for the treatment having lower dose of the P. penetrans with P. lilacinus where reduction in both the parameters was observed to be at par with that of the either dose of P. penetrans or higher dose of P. lilacinus. Combined application with higher dose of P. penetrans and P. lilacinus showed maximum reduction of 62.6 and 82.2% in gall numbers and nematode population over the nematode check.

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