Aims: Producing granular cultures of obligate aphid pathogen Pandora nouryi for improved sporulation and storage.
Methods and results: Small millet-gel granules were made of the mixtures of 80-95% millet powder with 5-20% polymer gel (polyacrylamide, polyacrylate or acrylate-acrylamide copolymer) and inoculated with mycelia at 30 mg biomass g(-1) dry granules plus 87.5% water, followed by static incubation at 20 degrees C for 4-12 days. The fungus grew well on 12 preparations but best on that including 10% copolymer. An 8-day culture of this preparation discharged maximally 58.5 x 10(4) conidia mg(-1) granule at 100% RH and was capable of ejecting conidia at the nonsaturated regimes of 86-97% RH. During storage at 6 degrees C, granular cultures with >85% water content had twofold longevity (120 days) and half-decline period (34-36 days) of those stored at room temperature. The steadily high water content preserved the cultures better than that decreasing at 6 degrees C. However, conidia from 70-day-stored granules were less infective to Myzus persicae nymphs than those from fresh ones based on their LC(50)s.
Conclusions: The millet-gel granules had higher sporulation capacity than reported Pandora cultures and a capability of spore discharge at nonsaturated humidity.
Significance and impact of the study: The granular cultures are more useful for aphid control.