Experimental studies on the growth and breeding of Hyale barbicornis (Amphipoda, Crustacea) at different temperatures.

Abstract

The individual of population growth and breeding of the hyalid amphipod Hyale barbicornis were examined at five temperatures of 12, 16, 20, 24 and 28°C in the laboratory. Males and females attained sexual maturity at the 10th instar (molted 9 times) and at the 11th instar (molted 10 times), respectively. The age and size at the time of sexual maturity in both sexes tended to decrease with increasing temperatures ( ?? : 35.0-109.0 days, 5.9-7.8mm; ?? : 31.8-51.0 days, 6.8-7.2mm). The daily growth rate of body length was higher in males than in females at all life stages. From hatching to sexual maturity, the daily growth rate was generally higher than at later stages. The intermolt period was shorter at higher temperatures. Maximum values of the average number of broods and the total number of offsprings per female throughout the life were 6.0 at 20°C and 67.5 individuals at 16°C, respectively. The number of flagellar segments of the second antenna of all the individuals of both sexes increased by a segment per molt until the 4th instar (six segments).