Comparative Studies on Life Histories of Three Species of Spider Mites (Acarina : Tetranychidae)
1979 Volume 14 Issue 1 Pages 83-94
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1979 Volume 14 Issue 1 Pages 83-94
Biological studies of three spider mite species, Oligonychus ununguis (JACOBI), Panonychus citri (MCGREGOR) and Tetranychus urticae KOCH, were conducted under fairly constant temperature (25°C) and moisture (52% RH) conditions. The total developmental time was shorter in T.urticae than in the other two species, and the total fecundity and average egg production per day were significantly grater in T. urticae than in the other. The egg hatchability was generaly high in all the three species, while among these it was slightly lower in O. ununguis. Relatively high proportion of females, ca. 70 to 80 percent in P. citri and ca. 65 to 70 percent in T. urticae, was observed, but in O. ununguis it was ca. 50 to 55 percent. The intrinsic rate of natural increase (rm), the net reproductive rate (Ro) and the mean generation time (T) were evaluated as follows : O. ununguis : rm=0.178, Ro=24.72 and T=18.02. P.citri : rm=0.162, Ro=24.36 and T=19.71. T. urticae : rm=0.259, Ro=65.00 and T=16.16. It was concluded that T. urticae had significantly high reproductive petential, and postulated that this fact caused its high adaptability to its herbaceous host plants.
