CL50 y variación de la patogenicidad en aislamientos de Beauveria bassiana y Metarhizium anisopliae evaluados en poblaciones de Premnotrypes vorax

Con el fin de evaluar una alternativa "ecológica" para el control de gusano blanco de la papa (Premnotrypes vorax), se trabajó con seis aislamientos de Beauveria bassiana y uno de Metarhizium anisopliae, nativos del departamento de Nariño, Colombia. Inicialmente se estudió su patogenicidad y variabilidad en condiciones de laboratorio usando una concentración de 1x107 esporas.ml-1, observándose que todos los aislamientos fueron patogénicos para el gusano blanco. Sin embargo, se presentaron diferencias significativas entre la mortalidad causada por éstos (F7,14 = 4.64; P<0.0001) pues la mortalidad varió desde 13.3% para Bb2 hasta 96.6% para Bb5. Posteriormente, se establecieron las concentraciones letales mediante Probit - Analysis de Raymons (1985), para cada aislamiento y en dos estadios de desarrollo de P. vorax (larvas y adultos). Los resultados obtenidos presentaron una relación positiva concentración/mortalidad, y los X2 calculados demostraron que los datos fueron homogéneos y se ajustaron a la línea de regresión con un nivel de confianza del 95%. En ambos estadios, los aislamientos Bb4, Bb5, Bb7 y Bb8 presentaron los porcentajes de mortalidad más altos; por esto, la línea base de mortalidad pudo ser establecida con mayor confianza y las CL99 fueron las más bajas, razón por la que fueron preseleccionados para un futuro estudio en campo. CL50 and pathogenic power of Beauveria bassiana and Metharizium anisopliae isolates infecting Premnotrypes vorax populationsIn order to evaluate an “ecologic” alternative for the control of the white worm potato (Premnotrypes vorax), were studied six Beauveria bassiana and one of Metharizium anisopliae isolates, native of Nariño, Colombia.Their pathogenicity and variability were observed under laboratory conditions using a concentration of 1x107 spores.ml-1. All the biocontrol densities evaluated were pathogenic to P. vorax; however, there were big differences among the mortality caused by the isolates (F7,14 = 4.64; P<0.0001), they varied from 13.3% for Bb2 up to 96.6% for Bb5. Later, on lethal concentration made by Probit - Raymon’s analysis (1985), was established for each isolate in two development phases of P. vorax (larve and adults).The results presented a positive relation concentration/mortality and the calculated X2 proved that the data were homogeneous and adjusted to the linear regression with a 95% level of confidence. The higher mortality percentage was found in the two phases of the isolates Bb4, Bb5, Bb7 and Bb8, for that, there was security to establish the mortality base line; on the other hand, the CL99 where smaller, reason why they were pre selected for a future field study.

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Evaluación de la actividad biocontroladora de Beauveria bassiana y Metarhizium anisopliae sobre larvas de Ancognatha scarabaeiodes (Coleoptera: Scarabaeidae)

Ciencia y Tecnología Agropecuaria ◽

10.21930/rcta.vol5_num1_art:23 ◽

2004 ◽

Vol 5 (1) ◽

pp. 43

Author(s):

Any Mercedes Lucero Mafla ◽

Luis Alberto Peña Villamil ◽

Tito Bacca Ibarra

Keyword(s):

Beauveria Bassiana ◽

Metarhizium Anisopliae ◽

Crop Yields ◽

Integrated Management ◽

White Grubs ◽

Promising Alternative ◽

Fungal Entomopathogens ◽

Biocontrol Activity ◽

Mortality Percentage ◽

Lethal Doses

Actualmente, en los municipios del departamento de Nariño (Colombia), en los cultivos de trigo y papa que son los principales sistemas de producción, se presentan altas infestaciones de poblaciones de chisas encontrándose hasta 350 larvas/m2, representando un factor limitante para la producción de los cultivos. Una alternativa promisoria para el manejo de esta plaga es la utilización de métodos biológicos que incluyen el uso de hongos entomopatógenos. El objetivo del presente trabajo fue el de evaluar el efecto de Beauveria bassiana, Metarhizium anisopliae sobre larvas de Ancognatha scarabaeoides en laboratorio e invernadero. Los aislamientos de hongos se obtuvieron de larvas infectadas en los municipios de Yacuanquer y Ospina. En el laboratorio, se seleccionaron 5 de 9 aislamientos de hongos: Mt1, Bb cosmo, Mt2, Bb4 y Bb10 que presentaron mortalidades superiores al 50%, éstas se evaluaron a concentraciones de 1x105 a 1x1010 esporas/ml. El porcentaje acumulado de mortalidad a los 18 días después de la inoculación fueron: del 100% para Bb cosmo, Mt1 y Mt2 en la concentración de 1x1010 esporas/ml y del 90% para Bb4 y Bb10 en la concentración de 1x109 esporas/ml, presentando concentraciones letales 90(CL90) de 1.1x1010, 7.3x109, 2.2x1010, 3.9x1010 y 4.3x1010 esporas/ml respectivamente. En invernadero se evaluaron los mismos microorganismos con sus respectivas concentraciones letales 50(CL50) y 90(CL90), encontrándose porcentajes de mortalidad del 76.00%, 67.50%, 63.50%, 59.00% y 53.50% para Mt1, Bb cosmo, Mt2, Bb4 y Bb10. Estos resultados indican la posibilidad de incluir estos biocontroladores nativos en el manejo integrado de las chisas en Nariño. Evaluation of the biocontrol activity of Beauveria bassiana, Metarhizium anisopliae, on larvae of Ancognatha scarabaeoides (Coleoptera: Scarabaeidae).High grub populations of coleopteran, frequently attack crops of wheat and potato in the Department of Nariño, Colombia. Reports indicate that infestations levels reach more than 350 larvae/ m2, which severely reduce crop yields. Use of biological control measurements as fungal entomopathogens seems to be a promising alternative for management of this pest. The present work aimed to evaluate the effect of Beauveria bassiana and Metarhizium anisopliae on larvae of Ancognatha scarabaeoides both in laboratory and greenhouse conditions. Isolates of entomopathogen fungus were obtained from infected larvae in the municipalities of Yacuanquer and Ospina. A sample of 5 isolates, which previously had shown to cause mortality rates higher than 50%, was selected in the laboratory: Mt1, Bb cosmo, Mt2, Bb4 and Bb10. Isolates concentrations from 1x105 to 1x1010 spores/ml were tested. The cumulative mortality percentage (at 18 days after the inoculation) ranged from 100% with Bb cosmo, Mt1 and Mt2 at concentrations of 1x1010 spores/ml to 90% with Bb4 and Bb10 at concentrations of 1x109 spores/ml. Lethal doses 90 (LD90) of 1.1x1010, 7.3x109, 2.2x1010, 3.9x1010 and 4.3x1010 spores/ml were calculated for each isolate, respectively. An evaluation of the biocontrol activity of the isolates was carried out under greenhouse conditions. Mortality percentages obtained reached 76%, 67.5%, 63.5%, 59% and 53.5% for Mt1, Bb cosmo, Mt2, Bb4 and Bb10, respectively. These results suggest that the use of native biocontrolers is a promising alternative to be included in the integrated management for white grubs in Nariño.

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Selection of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. for the control of the mite Mononychellus tanajoa (Bondar)

Scientia Agricola ◽

10.1590/s0103-90162004000600015 ◽

2004 ◽

Vol 61 (6) ◽

pp. 659-664 ◽

Cited By ~ 8

Author(s):

Rodrigo Soares Barreto ◽

Edmilson Jacinto Marques ◽

Manoel Guedes Corrêa Gondim Jr. ◽

José Vargas de Oliveira

Keyword(s):

Biological Control ◽

Beauveria Bassiana ◽

Metarhizium Anisopliae ◽

Total Mortality ◽

Mortality Rates ◽

Mononychellus Tanajoa ◽

Control Programs ◽

Green Mite ◽

Mortality Percentage ◽

Selection Of

The green mite, Mononychellus tanajoa (Bondar) (Acari: Tetranychidae), is considered to be one of the key pests in cassava, Manihot esculenta Crants, leading to considerable field losses. In this study, ten Beauveria bassiana (Bals.) Vuill. and ten Metarhizium anisopliae (Metsch.) Sorok. isolates were evaluated with regard to their potential as biological control agents against adult M. tanajoa females. The total mortality percentage of M. tanajoa caused by B. bassiana ranged from 13.0 to 97.0%, with confirmed mortality rates extending from 9.0 to 91.0% and LT50 varying from 4.2 to 17.0 days. The M. anisopliae isolates showed total mortality percentages ranging from 12.0 to 45.0% with confirmed mortality rates extending from 8.0 to 45.0%, and LT50 varying from 8.6 to 19.8 days. Lethal Concentrations (LC50) of 3.93 × 10(6) conidia mL-1 and 7.44 × 10(8) conidia mL-1 were determined for B. bassiana and M. anisopliae, respectively. B. bassiana isolate 645 was the most efficient, being an alternative for use in biological control programs against the cassava green mite.

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Pathogenicity of Metarhizium anisopliae and Beauveria bassiana against Phyllophaga crinita and Anomala flavipennis (Coleoptera: Scarabaeidae)

Journal of Entomological Science ◽

10.18474/0749-8004-40.1.67 ◽

2005 ◽

Vol 40 (1) ◽

pp. 67-73 ◽

Cited By ~ 5

Author(s):

L. A. Rodríguez-del-Bosque ◽

F. Silvestre ◽

V. M. Hernández ◽

H. Quiroz ◽

J. E. Throne

Keyword(s):

Biological Control ◽

Beauveria Bassiana ◽

Metarhizium Anisopliae ◽

Biological Control Agent ◽

Challenge Test ◽

Control Agent ◽

The Other ◽

White Grub ◽

Test Protocol ◽

Lethal Time

Five isolates of Beauveria bassiana (Balsamo) Vuillemin and 3 isolates of Metarhizium anisopliae (Metschnikoff) Sorokin were tested against third-instar larvae of Phyllophaga crinita (Burmeister) and Anomala flavipennis Burmeister under laboratory conditions using the “maximum challenge test” protocol. The M. anisopliae strains were more virulent than the B. bassiana strains, with the isolates MAGL3N and MAGL4N of M. anisopliae causing the highest mortality in both white grub species. Regardless of scarab species, mortality caused by MAGL3N was >63% after 4 days and >96% after 10 days. The other strain of M. anisopliae, MAGC2N, also caused high mortality in A. flavipennis, but at a slower rate than MAGL3N. Median lethal time (LT50) for MAGL3N was 2.9 days for P. crinita and 3.0 d for A. flavipennis. The LT50 for MAGL4N was 5.3 d for P. crinita and 7.6 d for A. flavipennis while the LT50 for MAGC2N was 4.4 d for A. flavipennis. Metarhizium anisopliae is a potential biological control agent for P. crinita and A. flavipennis and should be further investigated for possible development.

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Selection of Metarhizium anisopliae (Metsch.) and Beauveria bassiana (Bals.) isolates to control Alabama argillacea (Huebner) caterpillars

Scientia Agricola ◽

10.1590/s0103-90162002000300008 ◽

2002 ◽

Vol 59 (3) ◽

pp. 457-462 ◽

Cited By ~ 7

Author(s):

Everardo César Filho ◽

Edmilson Jacinto Marques ◽

Reginaldo Barros

Keyword(s):

Beauveria Bassiana ◽

Metarhizium Anisopliae ◽

Integrated Control ◽

Gossypium Hirsutum L ◽

Alabama Argillacea ◽

Lethal Time ◽

Beauveria Bassiana Isolates ◽

Lepidoptera Noctuidae ◽

Mortality Percentage ◽

Selection Of

The cotton leafworm, Alabama argillacea (Huebner, 1818) (Lepidoptera: Noctuidae), is considered to be one of the key pests in herbaceous cotton (Gossypium hirsutum L. r. latifolium Hutch) cropping, with constant occurrence in all cotton-growing states of Brazil. In this study Metarhizium anisopliae and Beauveria bassiana isolates were screened and evaluated for pathogenicity against Alabama argillaceae. Initially, a screening of ten isolates of each fungus in a concentracion of 10(8) conidia mL-1, was carried out on 3rd instar larvae of A. argillacea. Further studies were conducted to determine the pathogenicity and virulence of six and seven isolates of M. anisopliae and B. bassiana, respectively, against 3rd instar larvae of A. argillacea and using the concentrations of 10(6), 10(7), 10(8), and 10(9) conidia mL-1. The experiments were carried out in Recife, PE, Brazil, at 27 ± 2ºC, RH 70 ± 5% and a photophase of 12 hours. Mortalities caused by M. anisopliae isolate at the different concentrations ranged from 4.5 to 91.2%, the highest mortality percentage being found for the isolate 1189 at 10(9) conidia mL-1. The isolate 645 of B. bassiana caused the highest mortality at the highest concentration, followed by isolates 634, 604, and IPA 198. The lowest lethal time for B. bassiana and M. anisopliae, was achieved by the isolates 483 (4.1 days) and 1189 (2.0 days), respectively. The isolates 1189, 1022 e 866 of M. anisopliae and 483, IPA198 and 604 of B. bassiana, at 10(8) e 10(9) conidia mL-1 are promissing for use the integrated control of A. argillacea larvae, but M. anisopliae seems more effective.

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Comparative Virulence of Metarhizium anisopliae and Four Strains of Beauveria bassiana Against House Fly (Diptera: Muscidae) Adults With Attempted Selection for Faster Mortality

Journal of Medical Entomology ◽

10.1093/jme/tjab027 ◽

2021 ◽

Author(s):

Roxie L White ◽

Christopher J Geden ◽

Phillip E Kaufman ◽

Dana Johnson

Keyword(s):

Beauveria Bassiana ◽

Metarhizium Anisopliae ◽

House Fly ◽

The Other ◽

Biological Control Agents ◽

High Concentration ◽

House Flies ◽

Lethal Time ◽

Selection For ◽

Time Required

Abstract Entomopathogenic fungi such as Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae/brunneum (Metchnikoff)/Petch have shown promising results for managing the house fly, Musca domestica L. A primary challenge of using these biological control agents (BCAs) in field situations is the time required to induce high adult house fly mortality, typically 6–7 d post-exposure. In this study, virulence of M. anisopliae (strain F52) and four B. bassiana strains were compared. The B. bassiana strains GHA and HF23 are used in commercial products and those were compared with two strains that were isolated from house flies on dairy farms (NFH10 and L90). Assays were conducted by exposing adult house flies to fungal-treated filter paper disks for 2 h. The lethal time to 50% mortality (LT50) at the high concentration of 1 × 109 conidia ranged from 3.8 to 5.2 d for all five strains. GHA, NFH10, and L90 killed flies faster than M. anisopliae strain F52; HF23 did not differ from either the M. anisopliae or the other B. bassiana strains. Attempts with the NFH10 strain to induce faster fly mortality through selection across 10 fungal to fly passages did not result in shorter time to fly death of the selected strain compared with the unselected strain.

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Pathogenicity of Entomopathogenic Fungi on the Weevil of the Andes (Premnotrypes vorax Hustache) of the Potato (Solanum tuberosum L.) in Chimborazo Province, Ecuador

European Scientific Journal ESJ ◽

10.19044/esj.2018.v14n27p205 ◽

2018 ◽

Vol 14 (27) ◽

pp. 205

Author(s):

Erazo Sandoval N. S. ◽

Lindao Córdova V. A. ◽

Echeverría Guadalupe M. M. ◽

Manzano Ocaña J. C. ◽

Inca Chunata N. M.

Keyword(s):

Entomopathogenic Fungi ◽

Metarhizium Anisopliae ◽

Laboratory Tests ◽

Integrated Management ◽

Solanum Tuberosum L ◽

Probit Analysis ◽

Fourth Instar ◽

The Other ◽

The Andes ◽

Randomized Design

From thirty native isolates of entomopathogenic fungi, which were obtained from corpses of larvae and adults of Andean weevil (Premnotrypes vorax Hustache); two fungi with entomopathogenic characteristics were selected through laboratory tests, which will be used in a program of integrated management of this pest in the Ecuadorian inter-Andean region. The pathogenicity of the 30 isolates was determined by the mortality that they caused in larvae and adults and it was expressed in percentage; for this, a complete randomized design (CRD) was used. The LC50 and TL50 were determined by Probit analysis. The two selected isolates corresponded to: Metarhizium anisopliae (Metschnikoff 1879) Sorokin 1883 (A13) and Beauveria bassiana (Bals.-Criv.) Vuill. 1912 (A21), which proved to be the best, because they caused the highest mortality in larvae of the fourth instar and adults of P. vorax. The Probit analysis showed that LC50 for A21 isolate (B. bassiana) in fourth instar larvae was obtained with a concentration of 1,75x109 spores/ml and 1,08x109 spores/ml for adults. Instead for A13 isolate (M. anisopliae), the LC50 was obtained with a concentration of 1,65x109 spores/ml for larvae and 2,42x109 spores/ml for adults. The LT50 for the selected isolates at the indicated concentrations, was 4,84 and 4,32 days for larvae with A13 and A21 isolates respectively, while, for adults, the shortest time was obtained with A21 isolate in 4.36 days, compared with A13 isolate, that delayed 20,70 days. The larval stage of P. vorax was the most susceptible to A13 isolate, on the other hand, larvae and adults were equally susceptible to A21 isolate at the indicated concentrations. According to the results obtained, the two selected isolates can be used as an alternative to the use of conventional agrochemicals, which will contribute to a more ecological production.

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Virulence of Some Entomopathogenic Fungi Isolates of Beauveria bassiana (Hypocreales: Cordycipitaceae) and Metarhizium anisopliae (Hypocreales: Clavicipitaceae) to Aulacaspis tubercularis (Hemiptera: Diaspididae)and Icerya seychellarum (Hemiptera: Monophlebidae) on Mango Crop

Journal of Economic Entomology ◽

10.1093/jee/toz187 ◽

2019 ◽

Author(s):

Atef M M Sayed ◽

Christopher A Dunlap

Keyword(s):

Beauveria Bassiana ◽

Entomopathogenic Fungi ◽

Metarhizium Anisopliae ◽

Insect Pests ◽

Microbial Control ◽

Probit Analysis ◽

Scale Insects ◽

Elapsed Time ◽

Fungal Isolates ◽

Further Development

Abstract Six fungal isolates of Beauveria bassiana (Balsamo) Vuillemin and one isolate of Metarhizium anisopliae (Metschnikoff) Sorokin were isolated and evaluated for their pathogenicity to Icerya seychellarum (Westwood) and Aulacaspis tubercularis Newstead. There is a positive correlation between the concentration of the fungal blastospore concentrations and the percentage of mortality. Bio-efficacy increased significantly after inoculation with increasing concentration of blastospores and elapsed time up to 12 d after inoculation. The mortality of nymphs exposed to fungal isolates at various concentrations varied between 2.5 and 88.8%. Probit analysis of data at 95% confidence limits of LC50 and LT50s showed significant differences in the susceptibility of nymphs of I. seychellarum and A. tubercularis to the tested fungal isolates. The fungal isolates of Egy-6 and Egy-9 were the most effective against I. seychellarum and A. tubercularis, respectively. They had the lowest LC50 (4.20 × 105 and 5.71 × 103 blastospore ml−1) and LT50 (ranged from 4.61 to 9.79 and 4.84 to 8.71 d), respectively. The current study showed that all the fungal isolates yielded moderate mortality rates of nymphs and adult female populations of both the tested insect pests. To our knowledge, this is the first report of bio-efficacy of Beauveria and Metarhizium isolates against members of the Diaspidadae and Monophlebidae family insects. These results establish that the use of these native entomopathogenic fungi isolates of B. bassiana (Egy-3, Egy-4, Egy-6, Egy-7, Egy-9, and Egy-10) and M. anisopliae (Egy-5) could be considered for further development as microbial control agents of the mealybug and scale insects as a potential biological agent for use in an IPM program.

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Study the effect of some acids on the viability of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae and their growth ability on chitin agar

Journal of Biotechnology Research Center ◽

10.24126/jobrc.2014.8.1.299 ◽

2014 ◽

Vol 8 (1) ◽

pp. 37-42

Author(s):

Hussein Magtoff Diwan ◽

Majed Ibrahim Abdela ◽

Belasim Ahmed Abas ◽

Husein Neayma Keshmer

Keyword(s):

Citric Acid ◽

Oxalic Acid ◽

Boric Acid ◽

Beauveria Bassiana ◽

Metarhizium Anisopliae ◽

Maximum Rate ◽

Radial Growth ◽

The Other ◽

Hand Control ◽

Growth Ability

This study aimed to evaluate the effects of three acids; Citric, Oxalic and Boric acids 0.05% on the viability of Beauveria bassiana and Metarhizium anisopliae spores after 1,2, 3 days of exposure 27±1 C° and the growth on chitin agar was obtained after 5 days at 26 ± 1C°.The results showed that the rate of viability of B. bassiana and M. anisopliae with boric acid was 312.3,209,150.3 colony/ml and 318,294.7,157.5 colony/ml respectively during three period time of in comparison with control and spore suspensions with the other acids. Spores of both fungi B. bassiana and M. anisopliae showed maximum rate of viability in the suspension supplied with citric acid which were 266 and 293.6 colony/ml, respectively after 1day of exposures to this acid in comparison with viability of control and other periods. Spores viability was lost with oxalic acid. On the other hand, control recorded highest rate of radial growth in the control was 1.92, 4.4 cm on the medium chitin agar after 3 days of incubation in comparison with other treatments. Both fungi showed best rate of radial growth 3.12, 1.88cm after 1and 3 days of exposure to citric acid, respectively in comparison with other treatments. There were no such growths on chitin agar after exposure the oxalic acid.

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Virulence of Beauveria bassiana and Metarhizium anisopliae on different stages of the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae)

Egyptian Journal of Biological Pest Control ◽

10.1186/s41938-021-00447-w ◽

2021 ◽

Vol 31 (1) ◽

Author(s):

Gamal Omar ◽

Ahmed Ibrahim ◽

Khalid Hamadah

Keyword(s):

Toxic Effect ◽

Beauveria Bassiana ◽

Entomopathogenic Fungi ◽

Metarhizium Anisopliae ◽

Total Mortality ◽

Pink Bollworm ◽

Pectinophora Gossypiella ◽

The Other ◽

Toxicity Effect ◽

Fungal Isolates

Abstract Background The pink bollworm, Pectinophora gossypiella, is the most destructive pests of the cotton plant in Egypt. Due to the several problems of insecticides, the present study was conducted to evaluate the toxicity effect of the entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisopliae, against the different stages of the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) Results The fungal isolates exhibited a toxic effect against the treated stages, egg, larva, and pupa. According to the obtained data of LC50, B. bassiana was more potent in inducing toxicity than M. anisopliae. However, eggs of P. gossypiella were less susceptible to the EPF than the other stages. Based on total mortality, LC50 was 4.97×1011, 6.03×1012 spores/ml for egg; 8.25×108, 6.03×109 spores/ml for neonate; 2.52×108, 1.29×1010 spores/ml for early 4th instar larvae; and 6.79×108, 8.36×109 spores/ml for pupae after treatment with B. bassiana and M. anisopliae, respectively. Conclusions Entomopathogenic fungi exhibited an activity in inducing mortality against different stages of P. gossypiella.

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Aggregation of Cat Platelets in Vitro

Thrombosis and Haemostasis ◽

10.1055/s-0038-1654191 ◽

1970 ◽

Vol 23 (03) ◽

pp. 601-620 ◽

Cited By ~ 14

Author(s):

Th. B Tschopp

Keyword(s):

Adenosine Monophosphate ◽

Blood Collection ◽

Base Line ◽

Reversible Aggregation ◽

Low Concentrations ◽

Irreversible Aggregation ◽

High Concentrations ◽

Two Phases ◽

Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

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