BIOLOGY AND POST-EMBRYONIC DEVELOPMENT OF Onychiurus armatus (COLLEMBOLA: ONYCHIURIDAE)

Abstract

The present work was conducted, under controlled environ­mental conditions (T= 20°C; R.H.= 67%) to determine the life cycle and postembryonic growth in Onychiurus armatus Tullberg. Individuals were reared in colonization chambers containing a 1: 1 mixture of plaster of Paris and charcoal, following a modification of the Vail's method. Initiative eggs are spheric and lo through three until hatching, with an average incubation period of 18. 2 ± 2.3 days. This species has three immature stages with an average duration of 12.45; 11.85 and 13.34 days. They may have up to eight instars after sexual maturity is reached. All of the individuals observed through nine generations were females, so Chis is a parthenogenetic teliotokious species.  Oviposition has an irregular pattern both in time and num­ber of eggs oviposited. Egg viability of 94% was record­ed. Relative growth was determined by measuring total body length, antennal length, head length, and head width. In the study of the rate and pattern of postembryonic growth a decrease in absolute growth was observed when individuals reached their adult stage (38th day). Averaged size of adult individuals observed: 1.27 mm with a longe­vity of 350 days.