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The effects of some environmental factors on development and fecundity of Euseius scutalis (Athias-Henriot) were investigated. Although E. scutalis is a general feeder, pollen and Tetranychus pacificus McGregor eggs were found to be the most favorable foods. Development and fecundity were lowest on Brevipalpus lewisi McGregor. Over a variety of different temperatures and humidities, E. scutalis showed a wider range of environmental tolerances than did E. stipulates. Eggs of E. scutalis hatched at 19 percent relative humidity and immature stages developed at 35°C, indicating that this species is adapted to arid and hot areas. The rate of development varied in a quadratic manner with increase in temperature. Euseius scutalis required mating for egg production, and multiple matings were necessary for full egg production. Euseius scutalis had the greatest intrinsic rate of natural increase (0.325) and the shortest generation time (9.32 days) at 30° C, indicating this as the optimum temperature for population increase. |
