ISOLATION AND CHARACTERIZATION OF ENTOMOPATHOGENIC ...

occurred in a 5 per cent emulsion of the oil in water even after homogenization. Conidia of
Metarhizium flavoviride in sprays of oil and oil in water emulsion survived longer on foliage
than those in water, which they presumed to be because, the oil component gave greater
protection from environmental stresses (Jenkins and Thomas, 1996).
Nutrients such as cereal flour can be formulated as the carrier in a dust on wettable
powder. The best known example is Verticillium lecanii in the products Vertalec and Mycotal,
used against aphid and whitefly intermittently since 1980 (Burges, 1981; Ravensberg et al.,
1990). Flour based V. lecanii products gave better pest control than sprays of spores alone
(Kanagaratnam et al., 1982).
Very few oils have been tested in the presence of dried silica gel. With M. flavoviride,
there was no consistent difference between diesel oil, odourless kerosene, shellsol k, aviation
fuel, groundnut oil or soy oil. Anti oxidants improved conidial survival in groundnut oil and in
soy oil by 23-26 per cent (Moore et al., 1996).
For conidial storage, mineral oils collectively, were similar to vegetable oils, some of
which have the disadvantages of rancidity and solidification over long periods at high ambient
temperature. Kerosene was found to be slightly better than groundnut (Stathers et al., 1993).
Certain fatty acids from rancid oil inhibit germination of M. flavoviride conidia (Barnes and
Moore, 1997).
Hayler (1993) reported that the addition of rape seed oil to the fungus, V. lecanii
increased efficiency upto 90 per cent when tested on. A. gossypii and Frankliniella
occidentalis on cucumber in a greenhouse experiment.
2.7 EFFICACY OF ENTOMOPATHOGENIC FUNGI AGAINST
INSECTS
2.7.1 Efficacy of Verticillium lecanii (Zimm.) against aphids
Verticillium lecanii (Zimm.) (Monilales:Moniliaceae), an entomopathogenic fungus
found world wide, has been used successfully as biological control agent against various
species of aphids for number of years (Hall, 1982).
The suspension of Verticillium lecanii with concentration of 16 x 10 6 spores/ml, when
used against coffee green bug, Coccus viridis (Green) in Tamil Nadu, gave 16.6 per cent
morality. The sprays containing surface active agents like Teepol, Triton x 100 at 0.03 per
cent or glycerol at 0.1-0.3 per cent gave 48.9, 79.9 and 22.4 to 31.0 per cent mortality,
respectively. Khalil et al. (1983) in Czechoslovakia, while studying on V. lecanii, found that
when the fungus was applied at concentration of 10 8 spores/ml in sprays to plants in
glasshouse was highly effective against the aphid species, Aphis fabae on sugar beet and
Myzus persicae on cucumber.
The effect of a range of humidities on the transmission and sporulation of a
commercial preparation (Vertalec) of V. lecanii was investigated in greenhouse at 20°C on
capsicum against aphid M. persicae by Milner and Lutton (1986). They found that at least 36
hours is required for infection at 100 per cent relative humidity. After 96 hours of spraying,
94.5 per cent of M. persicae were infected.
Evaluation of the entomopathogen V. lecanii in the control of the aphid, M. persicae
on chrysanthemum was conducted by Hincapie et al. (1990). Three strains of the fungus viz.,
VL-A, isolate from M. persicae, VL-GC isolated from Erinnyis ello and VL-MR from
trialeurodes vaporariorum Weshw were used. VL-A caused 100 per cent mortality compared
to 37.5 per cent for VL-GC and 30 per cent for Vl-MR. Three concentrations of VL-A was
evaluated (1x10 4 , 1x10 6 , 1x10 8 ) and the mortality increased from 39.5 to 100 per cent.