ISOLATION AND CHARACTERIZATION OF ENTOMOPATHOGENIC ...

Among the non-grain substrates, the fungus took 5 to 8 days to initiate mycelial
growth and 8 to 10 days to produce spores. In general, mycelial growth and conidiation
ncreased with increase in DAI only upto 15 DAI with no further conidiation.
4.6 COMPATIBILITY OF Metarhizium anisopliae (Ma2) AND
Verticillium lecanii (Vl1) WITH AGROCHEMICALS
The effect of different fungicides, insecticides and weedicides were tested for their
compatibility with M. anisopliae. The effectiveness was measured in terms of conidial
germination of the fungus in vitro using the food poison technique. Inhibition of the conidial
germination over untreated control was worked out for the respective concentration and
analysed for statistical significance. The results are presented in Tables 18 to 23, Fig. 4
and 5.
In general, the results indicated on an average that fungicides were highly inhibitory
and toxic (mean per cent inhibition of 73.65% and 86.45% on M. anisopliae and V. lecanii
respectively) followed by insecticides (44.22% and 53.24%) and weedicides (23.42% and
22.02%).
4.6.1 Fungicides
All the fungicides, tested for their interaction with M. anisopliae inhibited the conidial
germination (19.90 to 100%) considerably (Table 18) at all the four concentrations tested. At
the recommended concentration, the fungicides inhibited the germination of conidia to the
extent of 61.31 to 100 per cent. Propiconazole and mancozeb were highly toxic inhibiting cent
per cent of conidia from germination followed by wettable sulphur (88.35%), carbendazim
(85.60%), chlorothalonil (69.21%) and triadimefon (74.37%). Iprodione was least inhibitory as
it allowed maximum of 38.69 per cent conidia to germinate. The next safe fungicide was
chlorothalonil, which inhibited 69.21 per cent conidial germination. The per cent inhibition of
conidia increased as the dosage increased from 54.46 per cent to 88.94 per cent.
In case of V. lecanii (Table 19), fungicides completely inhibited the conidial
germination considerably at all the four concentrations tested (24.10 to 100%). At the
recommended concentration, the fungicides completely inhibited the germination of condiia to
the extent of 100 per cent in case of carbendazim, chlorothalonil, propiconazole, mancozeb
and wettable sulphur except iprodione and triadimefom as they allowed maximum of 37.38
and 41.62 per cent conidia to germinate respectively.
4.6.2 Insecticides
All the insecticides tested for their interaction with M. anisopliae in general, inhibited
germination of the fungal conidia to the extent of 18.96, 34.10, 49.74 and 74.41 per cent at
low, medium recommended and high dosages respectively.
All the insecticides tested for their effect on M. anisopliae, irrespective of
concentration tested had 34.33 to 55.89 per cent inhibition of conidial germination (Table 20).
Among them, Dichlorvos was significantly detrimental (55.89% inhibition) than all other
insecticides except monocrotophos in which the inhibition of conidia recorded 54.22 per cent.
Conversely, malathion and dimethoate were signficinatly safer (34.33 to 36.99% inhibition),
followed by endosulfan, quinolphos and chlorpyriphos (38.96 to 42.96% inhibition). At the
recommended concentration, the insecticides inhibited the germination of conidia to the
extent of 37.67 to 69.16 per cent (Plate 6).