Garden Symphylan: Reproduction and Development in the Laboratory12

Abstract

Scutigerella immaculata (Newport) exhibited a reproductive periodicity in the laboratory consisting of a 2-month period during which large numbers of eggs were deposited followed by a 3- to 4-month period of very low egg deposition. The amplitude of the peaks of oviposition gradually decreased during the 18 months of the experiment because of cannibalism on the eggs and a reduction in the number of eggs deposited, both of which were attributed to overcrowding. Results of an experiment in which adult symphylans were collected from the field at monthly intervals showed that soil temperature was a major factor governing reproduction in the field. The rate of oviposition of field-collected symphylans held at room temperature was higher when the average soil temperatures were low than for symphylans collected in the field when temperatures were high. Adults collected in the field, when soil temperatures were low oviposited readily at room temperature (5.2 days) compared with symphylans collected when temperatures were high (23.5 days). These data suggest that mature eggs were present in the ovaries during months when soil temperatures were low but were not deposited in the field became of low soil temperature. Results of experiments on the developmental rate of symphylans indicate that stadial development is temperature dependent. The incubation period for eggs was 39.8±3.6 days at 10, 24.9±2.4 days al 20, and 12.8±2.2 days at 25. The duration of all immature stadia was 120.0 days at 10, 658 days at 20, and 40.4 days at 25. Total developmental time from egg to adult was 159.9 days at 10, 86.6 days at 20, and 53.2 days at 25. Immature symphylans, in the 1st stadium, did not molt at 0, although they survived an average of 15.8 ±8.4 days at this temperature.