LIFE TABLES OF Mononychellus progresivus DORESTE AND Tetranychus urticae (KOCH) (ACARINA: TETRANYCHIDAE) IN YUCCA

Abstract

Tetranychid mites are considered im­portant pests of casava, Manihot escu­lenta Crantz in different regions of the world, especially during the dry season. M. progresivus Doreste prefers the genus Manihot as a food source while T. urticae (Koch) is a generalist that attacks a number of crops. The objective of this study was to know some aspects of the biology of the two species such as the developmental time, minimum developmental thres­hold, and physiological time. Experiments were carried out in environ­mentally controlled chambers at 15, 20, 25 and 30°C and 75 ± 5⁰/o R.H. For adult females, longevity, and re­productive periods duration, as well as reproductive capacity, was studied at 20, 25 and 30°C. Egg-to-adult develop­menta! time was 41.4, 19.05, 10.26, and 7.82 days for M. progresivus and 29.7, 15.9, 9.05, and 6.56 days for T. urticae at 15, 20, 25 and 30°C respectively. For total development, M. progresivus required 140 degree­days while T. urticae required 123.6 degree-days. A survivorship curve was constructed for all stages and lifetable statistics as a net reproductive rate (R₀), generation time, and intrinsic rate of natural increase were estimated.