ISOLATION AND CHARACTERIZATION OF ENTOMOPATHOGENIC ...

Totally eight isolates of N. rileyi, four of Metarhizium anisopliae, three of Verticillium
lecanii, B. bassiana, C. sphaerospermum, Fusarium oxysporum, two of C. oxysporum and
each one of Aspergillus candidus and Fusarium lateritium. They were identified based on their
colony characteristics and microscopic examination (Table 6 and Plate 1). Further, the identity
of the fungi was confirmed at Agarkar Research Institute, Pune (Appendix III).
4.2 MORPHOLOGICAL AND CULTURAL CHARACTERISTIC OF
THE FUNGAL ISOLATES
4.2.1 Colony characteristics
The conidiophores of M. anisopliae appeared in compact to nearly stomatic patches,
mononematous, conidiogenous cells with phialides in whorls, often arranged in a candle like
fashion, clavate to cylindrical and conidia were single celled, hyaline, slightly coloured and
forming long chain often aggregated into prismatic columns. The conidiophores of V. lecanii
was erect and verticillate with loose whorls of phialidic conidiogenous cells. Phialides mostly
awl-shaped and sometimes slightly inflated at the base. Conidia were single celled, hyaline,
smooth walled and produced in slimy heads.
Morphologically, all the isolates exhibited typical Metarhizium and Verticillium
characteristics. Ma1 isolate from rhinoceros grub showed slight yellowish pigment with green
coloured conidia. Ma2 isolated from brown plant hopper produced dark green coloured
conidia with no pigmentation. Ma3 isolated from white grub showed green coloured conidia
and Ma4 isolated from coffee berry borer produced yellowish pigment with green coloured
conidia. In case of V. lecanii Vl3 alone, showed pinkish pigment with white coloured conidia.
Morphological characters of all the M. anisopliae isolates revealed differences with
respect to hyphal and conidial characters except in size of conidia. There was variation in
conidial colour and pigmentation between the isolates. Ma2 produced dark green coloured
spores, while the other three isolates produced green colured spores (Plate 2). Ma3 and Ma4
required 5-6 days to initiate sporulation (Table 7). Ma1 and Ma2 accomplished this in half of
the time.
The hyphal and conidial characters did not vary among the isolates collected from
different localities during survey. However, V. lecanii exhibited significant variation in number
of days for sporulation, colony diameter, sporulation, spore yield and time taken to cover the
given diet for mass production (Table 7).
Among V. lecanii isolates, Vl1 from aphid recorded least spore yield (4.21 x 10 9 ) and
took minimum time (9 days) to cover the entire diet, whereas Vl2 and Vl3 isolates isolated
from teak skelitonizer and citrus scale respectively showed spore yield (4.34 x 10 9 to 4.98 x
10 9 /g) and took maximum time (10 days to 14 days) to cover the entire diet.
4.3 PATHOGENICITY OF Verticillium lecanii AND Metarhizium
anisopliae AGAINST IMPORTANT PESTS
The culture of insects (American bollworm and Rhinocerous beetle for Metarizhium
and aphids, whitefly and mites for Verticillium) were raised from field collected insect
populations on natural diet. The routine surface sterilization of rearing containers and eggs
with 10 per cent formaldehyde was carried out to prevent fungal bacterial and viral
contaminations of the healthy stock. Test insect of uniform age (second/third instar) and
biomass were selected from the laboratory cultures maintained for the purpose to test the
variability of pathogenicity of M. anisopliae Ma2 and V. lecanii Vl1 by Koch postulates. The
pathogen was topically applied @ 1 x 10 8 conidia/l for aerial insects and mixed the conidia
with soil (1 x 10 7 / kg soil) for soil dwelling insects.