Effect of body weight on reproduction and longevity of the ladybug predator Propylaea japonica

The objective of this research was to evaluate the influence of body weight on survival and reproductive parameters of female adults of Propylaea japonica (Coleoptera: coccinellidae). Treatments were represented by females of this predator with the following mean weight: 3.5±0.5 mg, 5.0±0.5mg, 6.5±0.5mg, 8.0±0.5mg and 9.0±0.5mg. Heavier females of P. japonica showed shorter preoviposition period while the number of eggs and of larvae per day presented a positive linear relationship with female weight of this predator. Longevity of females of P. japonica was similar between treatments with no tendency of variations as a function of body weight of these females. Since the objective of mass rearing facilities of predatory ladybugs is to produce the maximum possible number of larvae per day it is recommended to use females of P. japonica with weight above 8.0 mg.