[Entomofungo-l] Mensagem sem o anexo

[Italo Delalibera]

Estou reenviando a mensagem agora com o anexo 
diretamente no corpo do texto, pois a mensagem 
anterior retornou por exceder o tamamho permitido na lista.

Italo



Estou enviando anexo um resumo do Stefan Jaronski 
(trabalhava na época para a MYCOTECH CORP e hoje 
está no USDA) apresentado no SIP em 2000 onde ele conclui que:
"Based on our observations were strongly advise 
against the use of CFU methodology to test viable 
conidial count, such as in shelf life studies or 
quality control. If circumstances require the CFU 
method, then allowance should be made for 
considerable underestimation and reduced precision."

Com relação ao que foi colocado pelo José Eduardo 
eu diria que os testes de viabilidade empregados 
são baratos e não são trabalhosos independente de 
se adicionar fungicida, centrifugações e outros 
passos que são sugeridos em alguns métodos. Neste 
tipo de análise, em primeiro plano deve se 
objetivar precisão e reproducibilidade.

O uso de fungicida aumenta a precisão da avaliação.

Baseado nos dados gerados pelo Daian o método 
apresentado abaixo para formulação em óleo subestima a viabilidade.

PS. Desejo uma boa Páscoa a todos

Italo


Title: Direct Spore Counts Vs. Colony Forming 
Unit Counts As Methods for Quanti Fying Viable Beauveria Bassiana Conidia
Authors

Jaronski, Stefan


Liebmann, Judi - MYCOTECH CORP., BUTTE MT
Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract
Publication Acceptance Date: May 18, 2000
Publication Date: August 13, 2000
Citation: JARONSKI, S., LIEBMANN, J. DIRECT SPORE 
COUNTS VS. COLONY FORMING UNIT COUNTS AS METHODS 
FOR QUANTIFYING VIABLE BEAUVERIA BASSIANA 
CONIDIA. PROCEEDINGS OF THE ANNUAL MTG OF THE 
SOCIETY FOR INVERTEBRATE PATHOLOGY. University of 
Guanajuato, Mexico, Aug.13-18, 2000..
Technical Abstract: Two different methods are 
generally used to quantify spores in fungal 
preparations. One technique is based on colony 
forming units (CFU) resulting from the plating of 
diluted spore suspensions on some agar medium. 
The second method uses direct counts of conidia 
in a diluted spore suspension with a 
hemocytometer. The counts are then adjusted by 
conidial viability determined by the percent 
spore germination after a standard incubation 
time on an agar medium. The purpose of this study 
was to determine the relative accuracy and 
precision of the two methods in estimating the 
viable conidial count of Mycotech technical grade 
Beauveria bassiana spore powder (TGAI) and two 
end product formulations, wettable powder 
(Mycotrol 22WP) and an emulsifiable suspension 
(Mycotrol ES). Direct conidial counts, adjusted 
for conidial viability, were compared with a CFU 
method. Three replicate determinations were 
performed to each of three replicate samples of 
each formulation. CFU-based data consistly 
under-extimated the true viable conidial count of 
all three materials as low as 16% of the direct 
count methods (TGA suspended in .05% Tween 
80).With 22wp & ES the CFU method underestimated 
true count by 58%&50%,respectively. In addition, 
the precision & reproducibility of the CFU method 
as indicated by the Coefficient of Variation of 
replicate determinations & replicate samples, was 
poorer for the CFU method, then for the adjusted 
direct count. Based on our observations were 
strongly advise against the use of CFU 
methodology to test viable conidial count, such 
as in shelf life studies or quality control. If 
circumstances require the CFU method, then 
allowance should be made for considerable 
underestimation and reduced precision.


Professor do Departamento de Entomologia, Fitopatologia e Zoologia Agrícola
ESALQ-USP
Av. Pádua Dias 11 CP 9
Piracicaba-SP 13418-900 Brasil
Tel  19 3429 4122 ramal 231