Al Din, S.S.

Stephan, Z.A.

Horizon / Pleins textes

INFLUENCE OF TEMPERATURE  AND  CULTURE  MEDIA ON THE  GROWTH 
OF THE FUNGUS PAECILOMYCES  LILACINUS 
Zuhair A. STEPHAN* and  Saad Shems AL-DIN* 
The  fungus Paecilomyces  lilucinus (Thom.)  Samson  is 
an effective  parasite of root-knot  nematode eggs and so 
provides a possible potential alternative to chemical 
control of this nematode (Jatala, 1985). Production in 
great  quantities of the  fungus requires the best know- 
ledge of two important  factors : the most  suitable 
growth medium and the optimal temperature. These 
two factors have been  studied for P. lilacinus. 
Materials  and  methods 
In laboratory  test, the effect of temperature  on  the 
radial growth of P. lilucinus was studied by inoculating 
9 cm plates of potato  dextrose  agar  with  1  cm  diameter 
mycelium piece of P. lilacinus and  incubated  at 5 ,  10, 
15,20,25,30,32,34  and 35", and colony diameters  (cm) 
and  number of spores/cm3 were determined. Four plates 
were placed in each  temperature. 
To study  the  effect of different  media on P. lilacinus 
growth 50 g of each of rice grains  (peeled and unpeeled), 
wheat, barley and corn were sooked in water for 12h. 
Seeds were then  dried  and  placed in Erlenmeyer flasks 
containing 3 g of CaC03 and 60 ml distilled water. 
Flasks were then  sterilized in an autoclave at 110" for 
40 minutes, and inoculated  with  discs of 1 gram 
containing  mycelium of P. lilacinus. Each  treatment was 
replicated four times  and the  culture media were 
maintained at 20" for seven days after which fungus 
growth was determined and number of spores from 
spore  suspension (1 gram fungus diluted in 30 ml 
distilled  water)/cm3  counted. 
- 
Results 
Results show that  the  optimum  temperature  for radial 
growth and spore  production of P. lilacinus  in  vitro was 
in  the range 20-25" (Tab. 1). At 34" poor mycelial growth 
occurred  (after twelve days) with no spore  production, 
however, mycelial growth was reduced  when  tempera- 
ture was less than 20" or higher than 25". The optimal 
temperature  for mycelial growth (20-25") corresponded 
well with the  temperature at which  greatest  nematode 
reduction  occurred  (Mankau, 1964; Stirling 1979). 
Peeled rice g r r i s  pro-wxl CO be the best growth 
medium  for  the  fungus P. lilacinus (Tab. 2). Unpeeled 
rice, wheat and barley were also good media for this 
fungus  but corn was not. 
* Plant Protection  Research  Centre, Abu-Gkraib, Baghdad,  Iraq. 
494 
Table 1 
Colony  diameter  (cm)  and  number  of  spores/cm3 
of Paecilomyces lilacinus grown on potato  dextrose  agar 
at various  temperatures  for  one  week 
Ternperature Radial  fungal Spores  number 
growth (cmjf per 1 cm3" 
50 1 O 
1 0" 2-3  427 
15O 3-5  470 
200 9  623 
25O 8  579 
30"  5  257 
320  2.2 O 
340 1.2** O 
350 1** O 
L.S.D. 1 '/O 0.6 97 
* Means of four replicates. 
** Growth after 12 days. 
Table 2 
Mycelial  growth  and  number  of  spores/cm3  of  the fungus 
P. lilacinus maintained at 20" for 7 days  on  different  media 
Media Mycelial Spores number 
growth  per 1 cm3 
Peeled  rice  grain + +* 609 
Unpeeled  rice  grain + f +  714 
Wheat ++ 618 
Barley ++ 597 
corn -- O ** 
* Positive. 
** Negative  mycelial  growth. 
REFERENCES 
JATALA, P. (1985). Biological  control  of  nematodes.  In :Sasser, 
J. N. & Carter, C. C. (Eds), A n  advanced  Treatise  on 
Meloidogyne. Vol. 1. Biology and Control. Raleigh, USA, N. 
Carol.  St.  Univ.  Graphics : 303-308. 
MANKAU, R. (1964). Ecological relationships of predacious 
fungi associated  with the citrus  nematode. Phytopathology, 
54 : 1435. 
STIRLING, G. R. (1979). Effect  of  temperature  on  parasitism 
of Meloidogyne incognita eggs  by Dactylella oviparasitica. 
Nematologica, 25 : 104-110. 
Accepté pour  publication le 13 mai 1987. 
Revue Neinatol. 10 (4) : 494 (1987) 


Influence of temperature and culture media on the growth of the fungus Paecilomyces lilacinus

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