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Pathogenicity of Aspergillus parasiticus Speare on Sugarcane Mealybug, Sacchariococcus sacchari Cockerell
Thesis Abstract:
Experiments were conducted to determine the cultural characteristics and pathogenicity of A. parasiticus on sugarcane mealybug and mice.
Glucose or fructose and yeast extract were observed to enhance the growth and sporulation of the fungus. Among the locally produced materials for mass production of the fungus, sweet potato meal agar mixed with coconut water and coconut milk proved to be better than either mungo, corn or rice with coconut mixture.
Favorable temperature for mass-producing the fungus was lower than that needed for fungus infection on mealybug. Room temperature (26-30°C) was found to be the most favorable for fungus mass production on sweet potato and coconut media.
Spraying with Tween 80 and Triton X-100 as spreader and sticker, respectively, was the most effective method of fungal application under greenhouse conditions, although dusting was the most suitable method of inoculum application on the mass-reared mealybug in the laboratory.
The primary mechanism of fungal pathogenicity was the mechanical destruction of the vital organs of the insect. First invaded were the ovarioles, followed by the alimentary canal. The caudal part where the reproductive organ is located was less affected by mycelial growth of the fungus. The toxic effect of aflatoxin partly contributed to the cause of death.
Mammalian test showed a fatal effect of the fungus on shite mice, Mus musculus, which consumed a high dosage of moldy coconut of about 11% of body weight. Toxic symptoms due to aflatoxin were observed on the lungs and intestinal membrane.