Influence of Temperature on Population Increase of Metaseiulus occidentalis (Acarina: Phytoseiidae)

Constant temperature studies on the biological development of the phytoseiid predator, Metaseiulus occidentalis (Nesbitt), provided the data necessary to construct life tables and to analyze developmental curves. Polynomial regression curves for the egg and larval life stages are quadratic in form, those for the protonymphal and deutonymphal stages are cubic, and the preoviposition period is quartic. From the life history and life table data, M. occidentalis populations were found to attain their optimum developmental and reproductive rates at 32°C. The intrinsic rate of natural increase was found to be 0.279 individuals/female/day and the population possessed the capacity to double every 2.48 days. A curvilinear regression model relating m to developmental period where developmental period is a function of temperature was derived. From this model, the temperature for optimum population development was 33.4°C with a maximum m of 0.305.