Effect of photoperiod on the biomass and survivorship of juvenile scorpions Jaguajir rochae (Scorpiones, Buthidae)

Abstract

Photoperiod is an important environmental characteristic involved in the regulation of circadian physiological processes in living organisms. This experiment verified the effect of photoperiod on biomass gain and mortality in juvenile scorpions of the species Jaguajir rochae (Borelli, 1910). We maintained the juvenile scorpions under two different photoperiod conditions; group A under a light and dark cycle (LD) 12L:12D (n = 36), and group B (n = 35) was subjected to a total dark cycle 0L:24D. Each juvenile was fed cockroaches twice a week and weighed every 15 days until 120th day. We analyzed the relationship between body mass and time, as well as the mortality between groups. Our results showed that group B had a lower biomass gain than that did group A, and no difference in mortality between the two groups was found. Since the locomotory activity of scorpions is associated with a decrease in luminosity, we suggest that group B had a lower gain in biomass due to a higher locomotor activity, resulting in greater energy expenditure. Though our data showed high mortality across both groups, it was not attributed to the photoperiod but to the high mortality rate of the scorpions of this genus during their initial instars and to them being R-strategist organisms. Thus, this study is important for understanding the relationship between photoperiod and biomass gain in invertebrates, especially in scorpions

Keywords

• arthropods; Caatinga; physiology; photoperiodism; semiarid.