Winter prevalence of obligate aphid pathogen Pandora neoaphidis mycosis in the host Myzus persicae populations in southern China: modeling description and biocontrol implication.

Abstract

Pandora neoaphidis overwintering had been investigated by monitoring its prevalence in Myzus persicae populations in open fields. Cabbage plants in field plots were weekly taken after mycosis initiation, to count and examine the living and dead aphids infected by P. neoaphidis . Based on the field data, infection levels ( I) varied with field temperature (T), relative humidity (RH) and aphid count (numbers of living aphids per plant, N) over days ( D), fitting well to the modified logistic equation I =0.91/[1+exp(8.5+(2.0 H T H RH-20.2 NI 0) D)] ( r 2=0.897), where H T indicated daily hours of low temperature (<4°C), H RH daily hours of high air humidity (>90% RH) and I 0 primary infection level. The model demonstrated the abiotic and biotic factors influencing P. neoaphidis mycosis development in winter, and also verifies the fungal overwintering by infecting available host aphids without a resting stage. Ultimately, P. neoaphidis mycosis reduced 81.4% of aphid populations, presenting great potential for biocontrol.