**4. Discussion**

These studies demonstrated that sugar and nitrogen sources significantly effect the growth of blastospores produced by cultures of *B. bassiana*, *M. anisopliae* and *I. fumosorosea*. Higher blastospores growth and dried fungal biomass was produced in cultures grown on media supplemented with sugarcane molasses (Fig. 1a, c). Previous studies with *Paecilomyces farinosus* (Hotmskiold) and *Paecilomyces lilacinus* (Thom.) showed that media supplemented with SM supported the highest growth of the studied fungi (Leena et al, 2003).

Mass production technology is an important way for improving mycoinsecticides based on the blastospores. Accelerated blastospores growth rates in the current study from the media supplemented with SM and corn steep liquor (CSL) greatly improved the dried fungal biomass production of the studied entomopathogenic fungi. While, our results disagreed with the findings of Leite et al, (2003) who concluded that replacement of CSL as nitrogen source gave relatively low yield of the three studied fungal strains. Our findings revealed that the fungal organisms directly interact with the culture conditions and strongly influence the growth of blastospores.

All the studied fungi did not have the same characteristics when cultivated in media with different complex sources of nitrogen and sugar. Sugarcane molasses, a by-product from the sugar industry, supported higher growth of dried biomass of *M. anisopliae* and *I. fumosorosea*, compared to the media supplemented with glucose. Thus, it may be speculated that SM efficiently enhanced the growth of blastospores, which ultimately led to the production of higher fungal biomass of the fungi. The complete media SM + G + CSL + PE + YE, greatly enhanced the growth of *M. anisopliae* and *I. fumosorosea*. These components when evaluated separately afforded lower growth for *M. anisopliae*. This suggests that these components differ concerning types of nutrients, and therefore provide complete nourishment when offered together.

CSL, peptone and yeast extract afforded higher growth of *B. bassiana* in fungal cultures supplemented with glucose, while these nitrogen sources did not enhance the growth of fungi in the presence of SM. On the other hand, these nitrogen sources when used in combinations (SM + CSL + PE, SM + CSL + YE, SM + PE + YE, SM + CSL + PE + YE), did not increase fungal production of *B. bassiana*. These combinations in the presence of glucose greatly enhanced the dried fungal biomass. Even, the complete medium showed significantly lower growth. On the basis of above findings, we may suggest that nutrition greatly influenced the growth of *B. bassiana*. The result of our study corroborates similar research on the effect of nutrition and propagule production in *Metarhizium* spp. and other entomopathogenic hyphomycetes (Inch et al, 1986; Rombach, 1989; Kleespies & Zimmermann, 1992; Jackson et al, 1997; Vidal et al, 1998).

CSL, a by-product from the corn industry, supported higher growth of the blastospores (Fig. 3a-c), and also ultimately led to the production of spores with higher enzymatic activity of Pr1. Since, peptone and yeast extract are expensive sources of nitrogen; CSL was chosen because of its stimulatory effect and cost economics and could be used to replace the nitrogen sources used previously. Supplementation with 1% CSL with 2.66% SM enhanced not only the growth of all the studied fungi but also enzymatic activity of spore bound Pr1 of only *M. anisopliae*. This is in agreement with the results of McCoy et al, (1988), that nutrition is one of the several factors that may determine the specificity of a fungal pathogen. The results suggest that the growth of blastospores can be efficiently improved from inexpensive CSL and SM, making fermentation an economical and environmental friendly process.

The management of arthropod pests generally involves preventive measures and remedial control (Lewis, 1997; Su & Scheffrahn, 1998). Currently registered insecticides have undergone rigorous field-testing, efficacy results have been mixed. Some insecticides are expensive and less persistent, leading to reduced longevity and the failure of the chemical barrier (Su and Scheffrahn, 1998). In addition, large quantities of persistent insecticides are raising concerns about applicator safety, environmental contamination and possible deleterious effects on non-target animals. By keeping in mind the above mentioned drawbacks, it is the urgent requirement to standardise the microbe base products against insects for the safety of human beings, animals and environment.
