| Euseius nicholsi nicholsi is an important natural enemy of many kinds of pest mites Studies on the habits, development, survivorship and reproduction of Euseius Nicholsi (Ehara et Lee) as well as its predation efficiency on Tetranychus cinnabarinus were systematically conducted at six constant temperatures and three diets. The major results were as follows:1. Biological characteristics of E. nicholsiE. nicholsi undergoes four development stages, including egg, larva, nymph and adult. E. nicholsi was sexual reproduction and there was pre-ovipositing period after copulation. The female adult mites like spawning on cotton textile fiber and eggs are often laid single. When food was deficient, the predatory mites killed each other. In Chongqing, there were two occurrence peaks of E. nicholsi population in spring (from May to June) and autumn (from September to first 10 days of November) on the wild mulberry trees.2. Effects of temperature on development and reproduction of is. nicholsi2.1 The relationship between development and temperatureWithin the range of 19-32℃, the developmental durations were shortened with the increasment of temperatures. The developmental spans of a generation were 8.94, 6.52, 4.97, 3.94, 3.80 and 4.03 days at 19℃, 22℃, 25℃, 28℃, 30℃ and 32℃, respectively. The analysis suggested that the relationship between development and temperatures were fit for Logistic equation model. The developmental threshold temperatures of each stage (egg, larva, nymph and adult) were 10.43,10.71, 8.40, 6.53℃, and the corresponding effective thermal summations were 32.42, 13.84, 30.30, and 121.24 days / ℃, respectively.2.2 The experimental population life tables of E. nicholsiThe experimental population life tables of E. nicholsi, with T. cinnabarinus as its prey, were constructed at 19℃, 22℃, 25℃, 28℃, 30℃, 32℃. The results showed that the net reproductive rate (Ro) and finite rate of increase (λ) of E. nicholsi reached the highest values of 9.8908, 1.2481...
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