Thermal Oviposition Performance of the Ladybird Stethorus gilvifrons Preying on Two-Spotted Spider Mites

SIMPLE SUMMARY: This study models the effects of temperature on age-dependent fecundity of the ladybird Stethorus gilvifrons, which is an important predator of herbivorous spider mites such as Tetranychus urticae. Based on the fecundity of S. gilvifrons fed on T. urticae, examined at six constant temperatures from 15 to 34 °C, we generated thermal performance curves by using four non-linear models (Enkegaard, Analytis, Bieri-1, and Bieri-2). The thermal performance models presented here can be used to determine the optimal temperature for mass-rearing, simulate daily egg production, and predict field occurrence patterns and seasonal population dynamics of this predator. The models constitute an essential step towards developing temperature-based simulation models of the population dynamics of S. gilvifrons interacting with its spider mite prey. ABSTRACT: The ladybird, Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae), is an important predator of two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae), in southeastern Europe and western and southwestern Asia, such as Iran, India, and Turkey. To enhance forecasting the occurrence and performance of this predator in natural control and improve its usage in biological control, we evaluated and compared four non-linear oviposition models, i.e., Enkegaard, Analytis, Bieri-1, and Bieri-2. The models were validated by using data of age-specific fecundity of female S. gilvifrons at six constant temperatures (15, 20, 25, 27, 30, and 34 °C). All four models provided good fit quality to age-dependent oviposition at 15 to 30 °C (R(2) 0.67 to 0.94; R(2)(adj) 0.63 to 0.94) but had a poor fit at 34 °C (R(2) 0.33 to 0.40; R(2)(adj) 0.17 to 0.34). Within temperatures, the best performing models were Bieri-1 (R(2)), Bieri-2 (R(2)(adj)), and Analytis (RSS) at 15 °C, Bieri-1 at 27 °C, and Analytis at 20, 25, and 30 °C. Analytis was the best suited model across the wide temperature range tested (from 15 to 30 °C). The models presented here allow for prediction of the population dynamics of S. gilvifrons in field and greenhouse crops in temperate and subtropical climates.