BIOLOGICAL CONTROL Relationship Between Temperature and Developmental Rate of Stethorus punctillum (Coleoptera: Coccinellidae) and Its Prey Tetranychus mcdanieli (Acarina: Tetranychidae)

Temperature affects insect and mite development, allowing species-speciÞc traits including optimal temperature and low and high temperature thresholds to be observed. Development rate models and biological parameters estimated from them can help determining if synchrony exists between pests and natural enemies. We studied development of the coccinellid Stethorus punctillum Weise and the spider mite Tetranychus mcdanieli McGregor at 12 constant temperatures ranging 10Ð38!C ("0.5!C), and modeled their development rates as a function of temperature. This predatorprey complex is typical of red raspberry,Rubus idaeusL., in Quebec, which is characterized by a short season. Eleven published models were compared for accuracy in predicting development rate of all stages of both species, and estimating their temperature thresholds and optima. The spider mite developed to the adult stage in the 14Ð36!C range, compared with 14Ð34!C for the coccinellid. Males and females did not differ, and the development rates steadily increased from 14 to 30!C, leveling off in the range 34Ð36!C for the spider mite, or 30Ð32!C for its predator. Most models were rejected for failure to satisfy criteria of goodness-of-Þt and estimable temperature threshold parameters. The Lactin-2 model for T. mcdanieli and the Brière-1 model for S. punctillum,were superior at estimating low temperature threshold, which is critical where temperatures are frequently low in the spring, and were separately Þtted to all development stages of both organisms. Based on the predictable early spring development ofS. punctillumandT.mcdanieli, the results indicate potential synchrony between them.