Modeling analysis on sporulation capacity, storage and infectivity of the aphid-specific pathogen Conidiobolus obscurus (Entomophthoromycota: Entomophthorales)

• Conidiobolus obscurus alginate pellets sporulated at 4−32 °C.
• The infectivity of C. obscurus to Myzus persicae was high at 28 °C.
• The storage time of the alginate pellets lasted eight months.
• Sporulation capacity of the pellets was 22.3 times larger than that of cadavers.

Entomophthorales are important natural enemies against agroforestry pests. Conidiobolus obscurus in this order, a common obligate aphid pathogen, possesses features of rapid growth in vitro and ease to mass production. This study sought to evaluate the potential of C. obscurus in aphid biocontrol, by modeling analyzing on the sporulation capacity and storage of its alginate formulation and infectivity to Myzus persicae. The C. obscurus mycelia-entrapping alginate pellets discharges 0.12–18.26 × 104 conidia per pellet at 4−32 °C. The optimal temperature for the fungal sporulation was computed as 23.3 °C. Each pellet could sporulated for 7 d, releasing 22.3-fold more conidia than a cadaver at 24 °C. Moreover, it had longevity of 8 mo at 4 °C, with half decline time of 2.3 mo. The infectivity of C. obscurus was assessed by multi-concentration bioassays at 10−28 °C and 8−16 h light per d. The median lethal concentration (LC50) at each temperature-photoperiod regime was computed based on the morality-concentration trend. The LC50 values reached the lowest one of 15 conidia per mm2 at 28 °C and 16:8 L:D cycles. The total results suggest that C. obscurus mycelia-inclusive alginate pellets meet the requirement of aphid biocontrol in the high-temperature surroundings of 24–28 °C.