Pandora delphacis (Entomophthorales: Entomophthoraceae) infection affects the fecundity and population dynamics of Myzus persicae (Homoptera: Aphididae) at varying regimes of temperature and relative humidity in the laboratory

Apterae of the green peach aphid, Myzus persicae, on detached cabbage leaves were exposed to a Pandora delphacis conidial shower (112 conidia/mm2) and were then observed for reproduction and mycosis development at different temperatures (10–30 °C) and relative humidities (74–100% RH). Based on daily counts of nymphs and adults (living and mycosed) at each regime, the fecundity of apterae exposed to P. delphacis was greatly reduced with the net reproductive rate (R0) and the innate capacity for increase (rm) declining at all temperature and humidity regimes compared to those of unexposed aphids. Moreover, the rm estimates for batches of exposed aphids were significantly different among the temperature regimes, being parabolically related to temperature, with the largest rm being obtained at 20–25 °C. However, there was no significant effect of RH on rm. During a 30-day period of observation, the development of P. delphacis mycosis greatly suppressed the increase of aphid populations relative to the control and the fungus played a more important role in the control of aphids at the regimes of 20–30 °C and greater-or-equal, slanted95% RH than at the others. The cumulative mortality caused by P. delphacis was greater-or-equal, slanted80% at all humidity regimes at 30 °C and at 74%, 95%, and 100% RH at 25 °C. However, the mortality was <50% at 10, 15, and 20 °C for all humidity regimes, except for 100% RH. The results suggest that P. delphacis has the potential as a useful fungal agent for control of aphids.