ISOLATION AND CHARACTERIZATION OF ENTOMOPATHOGENIC ...

More documents

Recommendations

Info

For continuous growth and extension of the hyphae and to prevent autolysis, an exogenous nitrogen source is required (Smith and Grula, 1981). Hence, certain nitrogen source were tested. Among them KNO 3 (5.769/250 ml) was found to be the best source followed by NH4NO3 for biomass production of M. anisopliae Ma2. However, when NaNO3 was used as a nitrogen source, there was reduction in the growth. Vl2 on the other hand grew better in the medium supplemented with (NH4)SO4 and least with medium supplemented with KNO3. In an earlier study KNO3 was found to be better for better growth and sporulation than (NH 4)SO 4 (Li and Holdom, 1994). The use of NH 4 ion is known to acidify the media much more than NO3. It is known that the acidity at certain levels encourages the growth of fungi beyond certain limits probably is responsible for the sporulation as inferred by Rath et al. (1995), while characterizing M. anisopliae strain on different source of organic acids as carbon sources. 5.5 COST EFFECTIVE MASS MULTIPLICATION OF ENTOMOPATHOGENIC FUNGI Ensuring survival and persistence of the fungi is one of the greatest challenges of mycoinsecticide formulation and this technology has to be optimized for individual species or even strains (Burges, 1998). Inexpensive culture medium is required in order to increase the benefit:cost ratio. Hence, several sources were tested for mass multiplication. Food grains Low cost sources of nutrients like bajra, sorghum, navane, maize, rice and wheat were assessed for their utility in terms of conidial yield of M. anisopliae Ma2 and V. lecanii Vl1. It was found that growth of Ma2 on bajra yielded the maximum conidia (22.47 x 10 8 conidia/g of substrate) Vl1 on the other grew better and produced more conidia on rice grains (24.59 x 10 8 conidia/g). It has been earlier shown that fungi could be multiplied on polished rice grains (Silva and Loch, 1987) and crushed sorghum (Vimaladevi, 1994). The high amount of conidia in bajra and rice could be due to maltose released by the action of starch hydrolyzing enzymes present in the fungus induces sporulation. Disaccharide like maltose are known to induce more sporulation in unicellular fungi, Hansenula than monosaccharides (Crandall and Lawrence, 1980). Since chitinase and exochitinase activities are low in conidia and germinating seeds (Preez et al., 1985), crushing of grains is necessary to release the substrate for action of amylase. This indicates that rice and bajra grits as economical sources of mass production of M. anisopliae Ma2 and V. lecanii Vl1. The use of such grains as low cost and rapid technique to produce mycopathogen compared to expensive and synthetic SMAY medium has been suggested earlier too (Vimaladevi, 1994, 1996). During the present study, wheat and navane grains proved inferior for spore production, perhaps due to less content of starch in wheat (53%) and thus led low productivity. However, wheat is also known to have appreciable amounts of protein. Higher nitrogen has been shown to be necessary for mycelial growth of fungi (Riba and Glander, 1980; IM et al., 1988) and thus could be reason for lower spore yield are profused mycelial growth. Pilot studies using substrate fermentation will help to confirm these findings. Agro-wastes Accumulation of agro-wastes, post harvest of economically important plant part accounts for 300-500 million ton/year (Patel and Yadav, 1990). To utilize such agro-waste more efficiently, their utility in supporting the growth of Ma2 and Vl1 was assessed by using crushed maize cobs, wheat bran, rice bran, bagasse and pressmud singly and along with 10 per cent molasses supplementation. Rice bran supported the maximum growth of both Ma2 and Vl1 followed by wheat bran. When supplemented with 10 per cent molasses, the conidial yield increased two folds. On the other hand, growth and sporulation of both Ma2 and Vl1 was completely absent on bagasse and pressmud. Maize cobs also did not show any growth of Vl1.
In an earlier experiment, bagasse was shown to support multiplication (Silva and Loch, 1987) of N. rileyi. When 10 per cent molasses was supplemented to N. rileyi, the spore yield was almost on par with wheat bran. These results indicate that, addition of molasses could increase the conidial yield of entomopathogenic fungi when grown on different agro wastes. Refined experiment using other easily available nutrient sources like corn steap liquor will probably yield more information on the utility of different agrowastes for production of mycopathogen. 5.6 TOXICITY OF PESTICIDES TO Metarhizium anisopliae (Ma2) AND Verticillium lecanii (Vl1) Compatibility with other agents for pest control or with naturally occurring mortality agents are important in developing strategies for the efficient utilization of entomopathogens in the integrated pest management. Deleterious effects or enhanced activity resulting from integrating of control agents will have a major impact on the role of potential of entomopathogens in IPM options. Among the three types of pesticides studied for their compatibility with M. anisopliae Ma2 and V. lecanii Vl1 in the present investigation, weedicides were least inhibitory followed by insecticides. But, the fungicides on the other hand were highly detrimental to the entomopathogenic fungi and higher toxicity of fungicides to the mycopathogens as compared to other agro chemicals have been presented in the earlier findings (Ignoffo et al., 1975; Kulkarni, 1999; Patil, 2000). Fungicides All the fungicides in vitro inhibited the conidial germination of M. anisopliae Ma2 and V. lecanii Vl1 considerably at low, medium, recommended and high dose (table 18 and 19 respectively). Propiconazole and mancozeb being highly detrimental prevented the conidial germination of M. anisopliae Ma2. In addition to these two fungicides, chlorothalonil and carbendazim also inhibited the germination V. lecanii Vl1 totally triadimefon and chlorothalonil were comparatively safe allowing 35-39 per cent conidia of M. anisopliae to germinate on the media and only iprodione proved to be relatively safer with V. lecanii allowing 41.50 per cent conidia. Inhibition of the fungus growth by different fungicides even at the 1/10 th of the recommended dose was observed by Ignoffo et al. (1975). High toxicity of carbendazim and mancozeb to the fungus N. rileyi has been reported by Kulkarni (1999). According to Gopalkrishna and Mohan (2000), chlorothalonil and wettable sulphur were completely safe to the fungus, but the results of the present study, contrast their study with an observed per cent inhibition 100 and 96.57 per cent with M. anisopliae Ma2 and 64.01 and 74.84 per cent inhibition in case of V. lecanii Vl1 germination respectively. In general, N. rileyi has been adversely affected by many fungicides (Roberts and Campbell, 1977). Teddeur (1981) reported Triphenyltin hydroxids to be more toxic to M. anisopliae and B. bassiana. Triadimefon and Iprodione were relatively safer giving an indication that these fungicides can be compatible with the both (M. anisopliae Ma2 and V. lecanii Vl1) mycopathogen in field and it may be feasible to mix the fungicides with higher loads of inoculum as practiced with seed coating of seed with biofertilizer and pesticides. However, it has to be confirmed under field situation. Insecticides Combination of synthetic insecticides and microbial insecticides have been used to stress the insect population thus making them more susceptible to disease (Roberts and Campbell, 1977). The results of the present study reveal significant variation in the toxicity of insecticides representing different groups to M. anisopliae Ma2 and V. lecanii Vl1. The detrimental effects on the mycopathogen increased with concentration.
Page 1 and 2:
ISOLATION AND CHARACTERIZATION OF E
Page 3 and 4:
Chapter No. I INTRODUCTION C O N T
Page 5 and 6:
Contd….. Table No. Title 14. Spor
Page 7 and 8:
Contd….. Table No. Title 39. Per
Page 9 and 10:
Plate No. LIST OF PLATES Title 1. M
Page 11 and 12:
I.INTRODUCTION The increased use of
Page 13 and 14:
II. REVIEW OF LITERATURE The variou
Page 15 and 16:
The entomopathogenic fungi so far i
Page 17 and 18:
Table 1. Contd….. Sl. No. Insect
Page 19 and 20:
Milner et al. (2002) studied the ef
Page 21 and 22:
25°C for sporulation and biomass p
Page 23 and 24:
Pathogencity of various strains/iso
Page 25 and 26:
Gopalkrishnan and Mohan (2000) test
Page 27 and 28:
necessary serial dilutions under ph
Page 29 and 30:
Sl. No. Table 2. Details of differe
Page 31 and 32:
3.9 EVALUATION OF DIFFERENT FORMULA
Page 33 and 34:
Fig. 1. Mycopathogens of insect pes
Page 35 and 36:
Table 5. Contd….. Month/s visited
Page 37 and 38:
Table 5. Contd….. Month/s visited
Page 39 and 40:
Table 5. Contd….. Mycosis noticed
Page 41 and 42:
Totally eight isolates of N. rileyi
Page 43 and 44:
Metarhizium anisopliae Vertucillium
Page 45 and 46:
Ma 1 (Dharwad) Ma2 (Dharwad) Ma 3 (
Page 47 and 48:
Table 8. Mortality caused by the is
Page 49 and 50:
Helicoverpa armigera Dimond Black M
Page 51 and 52:
Plate 5. The moratality of Hlelicov
Page 53 and 54:
Table 11. Total biomass production
Page 55 and 56:
Table 12. Total biomass production
Page 57 and 58: Table 14. Sporulation of Metarhiziu
Page 59 and 60: Mean spore yield x 10 8 /g 25 20 15
Page 61 and 62: Among the non-grain substrates, the
Page 63 and 64: Mean spore yield x 10 4 /g 35 30 25
Page 65 and 66: Sl. No. Table 19. Effect of fungici
Page 67 and 68: Per cent inhibition 100 90 80 70 60
Page 69 and 70: Sl. No. Table 21. Effect of insecti
Page 71 and 72: Out of nine insecticides, endosulfa
Page 73 and 74: Sl. No. Table 23. Effect of weedici
Page 75 and 76: Days after storage Table 25. Persis
Page 77 and 78: Table 26. Survival of Metarhizium a
Page 79 and 80: Table 28. Survival of Metarhizium a
Page 81 and 82: Sl. No. Table 29. Survival of Metar
Page 83 and 84: Sl. No. Table 30. Survival of Metar
Page 85 and 86: Per cent germination 90 80 70 60 50
Page 87 and 88: Sl. No. Table 33. Survival of Verti
Page 93 and 94: 4.9 PATHOGENICITY OF Verticillium l
Page 95 and 96: Sl. No. Table 39. Per cent mortalit
Page 97 and 98: Culture grown on rice grains Harves
Page 99 and 100: Tr. No. Table 41. Per cent reductio
Page 101 and 102: Tr. No. Table 43. Per cent reductio
Page 103 and 104: The fungal spray at higher dosage (
Page 105 and 106: Table 46. Effect of wild types and
Page 107: The hyphal and conidial characters
Page 111 and 112: M. anisopliae exhibited rapid reduc
Page 113 and 114: higher mortality of aphids. The com
Page 115 and 116: 14. Oil formulations proved better
Page 117 and 118: CHARNLEY, A.K. AND ST. LEGER, R.J.,
Page 119 and 120: IGNOFFO, C.M., MARSTON, N.L., HOSTE
Page 121 and 122: MULLER, E.J., 2000, Control of the
Page 123 and 124: ST LEGER, R.J., BUTT, T.M., STAPLES
Page 125 and 126: APPENDIX I Mean monthly weather dat
Page 127 and 128: Maharashtra Association for the Cul
Page 129: ISOLATION AND CHARACTERIZATION OF E
show all

ISOLATION AND CHARACTERIZATION OF ENTOMOPATHOGENIC ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?