Mass production, survival and evaluation of solid substrate inocula of Beauveria brongniartii (Saccardo) Petch against Holotrichia serrata (Coleoptera: Scarabaeidae).
The entomopathogenic fungus Beauveria brongniartii (Saccardo) Petch has emerged as a promising biological control agent for soil-inhabiting scarabs including Holotrichia serrata F., a serious constraint to the production of rainy season (July-October) crops in India. Use of these fungi in practical biocontrol programmes will require production of large amounts of inoculum. In the present study, a two-stage system of mass production method was used to produce infective propagules in which fungal inoculum of mycelium or hyphal bodies are produced in liquid culture and transferred to solid substrates. The effects of various solid substrate inocula and other production parameters were evaluated for their suitability to virulent B. brongniartii isolates production. The results showed that the moisture content of the solid media is the most important factor for the growth and nutrient consumption of the fungi. Solid substrate rice was most suitable for growth and sporulation of B. brongniartii as compared to other solid substrates tested. The maximum conidia production reached >1 x 10(9) conidia/g rice substrate with 50% moisture content after 14 days incubation at 25 degrees C. There was a general decline in the number of conidia viability with time of storage at--20, 4 and 25 degrees C, with the highest decline occurring from 90-120 days. The maximum conidial viability was reduced with time and at 25 degrees C, except for conidia stored at--20 degrees C. Fresh fungus-colonized rice grains (FCRG) obtained from B. brongniartii resulted in high mortality (> 80%) to third-instar H. serrata larvae. These results show that rice grains has potential as substrate for production of B. brongniartii, suitable rice formulation for soil application and could be a feasible method to produce conidia in a village co-operative scenario in India.
Hadapad
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Institute of Phytomedicine, Department of Applied Entomology, University of Hohenheim, DE-70593 Stuttgart Germany.
Zebitz
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D000818:Animals; D052982:Beauveria / Q000254:growth & development / Q000502:physiology*; D001517:Coleoptera / Q000254:growth & development*; D015169:Colony Count, Microbial; D018556:Crops, Agricultural / Q000469:parasitology*; D007194:India; D012275:Oryza / Q000469:parasitology*; D010572:Pest Control, Biological; D011891:Rain; D012621:Seasons; D013696:Temperature; D013997:Time Factors