ISOLATION AND CHARACTERIZATION OF ENTOMOPATHOGENIC ...

4.5 EVALUATION OF FOOD GRAINS AND AGRO WASTES FOR
SPORULATION OF Metarhizium anisopliae (Ma2) AND V.
lecanii (Vl1)
4.5.1 Food grains
Different food grains were evaluated for their suitability to support the conidial
production of the mycopathogens based on the time taken to initiate mycelial growth,
sporulation and conidial yield at 6, 8, 15, 20 and 25 days after inoculation (DAI).
In general, the mycelial growth and production of conidia increased with increase in
DAI and by 20 DAI, it covered the surface of the media almost completely. The conidial yield
was influenced significantly by the source of grain at all intervals of observation.
The growth of M. anisopliae was significantly higher on bajra (22.77 x 10 8 conidia/g)
followed by sorghum (11.60 x 10 8 conidia/g), rice (8.4 10 8 conidia/g) and maize (6.76 x 10 8
conidia/g) (Table 14 and Fig. 2). On the other hand, wheat supported least yield 3.22 x 10 8
condiia/g, conidial production increased from 6 th to 20 th day and remained constant further in
all the treatments. The conidial production on the 20 th day was high in bajra (24.90 x 10 8
condia/g), whereas in navane (7.78 x 10 8 conidia/g) and wheat (3.76 x 10 8 conidia/g) grain, as
at the previous interval faired, as poor substrate for fungal productivity.
In case of Verticillium lecanii, rice proved superior by producing significantly higher
spore load (24.59 x 10 8 conidia/g) followed by sorghum (17.49 x 10 8 conidia/g) bajra (10.34 x
10 8 conidia/g). On the other hand, navane supported the least yield (3.52 x 10 8 conidia/g) and
its suitability was no better than wheat (3.54 x 10 8 conidia/g). The conidial load was maximum
after 20 DAI against all the treatments tested (Table 15 and Fig. 2).
4.5.2 Agro waste
In all, five agro wastes (viz., maize cobs, wheat bran, rice bran, baggase and press
mud) singly and along with 10 per cent molasses were evaluated for their suitability as
principle substrate for the mass production of fungal insect pathogens. Among the agro
wastes, rice bran enhanced the productivity of both the fungi compared to other agro wastes.
The conidial mass harvested per gram of dietary grain used, increased steadily with
inoculation of molasses in both the strains.
Among the agro waste tested with Ma-2 (Table 16 and Fig. 3), rice bran + 10 per cent
molasses proved to be superior in producing significantly higher spore load (33.24 x 10 4
conidia/g) followed by wheat bran + 10 per cent molasses (19.03 x 10 4 conidia/g) rice bran
and wheat bran with a spore yield of 12.80 x 10 4 and 10.16 x 10 4 conidia/g, respectively. In
others, the spore count was considerably less. Pressmud + 10 per cent molasses supported
least yield 0.42 x 104 spore/g, where initiation of growth and sporutation resulted only after 20
DAI.
In general, mycelial growth and conidiation increased with increase in DAI upto 20
DAI but significant reduction of conidial yield was observed at 25 DAI in some substrate viz.,
rice bran, rice bran + 10 per cent molasses and in baggasse + 10 per cent molasses.
The growth and sporulation of V. lecanii Vl1 (Table 17 and Fig.3) was found to be
better on rice bran + 10 per cent molasses (30.86 x 10 4 conidia/g) followed by wheat bran +
10 per cent molasses (18.76 x 10 4 conidia/g) and rice bran (15.98 x 10 4 conidia/g). Complete
inhibition of growth and reproduction of the fungus was noticed on bagasse and pressmud
with 1 per cent yeast extract alone. However, growth was recorded when baggasse and
pressmud was supplemented with 10 per cent molasses (10.88 and 7.90 conidia/g
respectively).