Altitudinal Variation in the Circadian Rhythm of Oviposition inDrosophila Ananassae

Abstract

The effect of altitude on four basic properties of the pacemaker controlling the circadian rhythm of oviposition in two strains of Drosophila ananassae was determined. The high altitude (HA) strain from Badrinath (5123 m above sea level) had a low amplitude peak in the forenoon while the low altitude (LA) strain from Firozpur (179 m a.s.l.) had a high amplitude peak after the lights-off of LD 12:12 cycles. Free running periods in continuous darkness were about 22.6 and 27.4 h in the HA and LA strains, respectively. The light pulse phase response curve (PRC) for the HA strain showed a low amplitude and a dead zone of 8h; the ratio for the advance to delay region (A/D) was less than 1, while the PRC for the LA strain had a high amplitude, which was devoid of a dead zone and showed a ratio of A/D > 1. The magnitude of the delay phase shifts at CT 18 evoked by light pulses of 1 h duration, but varying light intensity was significantly different in the HA and LA strain, which suggests that the photic sensitivity of the clock photoreceptors mediating the phase shifts had been affected by the altitude.

Effects of Photophase and Altitude on Oviposition Rhythm of the Himalayan Strains ofDrosophila Ananassae

“…For example, the POP of the HA strain increased from 60 to 100 as the photophase increased from 6 to 14 h. It was not surprising to see such a noteworthy increment in POP of this strain because it predominantly oviposits in the forenoon in the field or in the subjective midday of LD cycles in the laboratory (Khare et al, 2005). The POP of the HA strain also increased as the light intensity of the 12 h photophase was increased (Satralkar et al, 2007a).…”

“…An increment in duration or intensity of the photophase might be interpreted by females of this strain as long and sunny summer days at Badrinath, which would be conducible to enhance oviposition events during daylight hours. It is rather intriguing to note that the increment in photophase was also followed by increment in POP of the LA strain in the long photophases of 16 and 18 h (see Figure 2), as this strain mostly oviposits in the evening in the field or at lights-off in the laboratory, with the result being its oviposition events are restricted mainly to the scotophase (Khare et al, 2005). The increment in its POP was attributed to the arrhythmicity in the 16 and 18 h photophases, when its oviposition events were distributed over the 24 h of the cycle (see Figure 3B).…”

“…This study conforms to the ethical standards of research on chronobiology as established for the journal (Touitou et al, 2006). The rearing method, the composition of culture medium, and the method of monitoring the oviposition rhythm have been described in detail previously (Khare et al, 2005). However, the method of monitoring the oviposition rhythm in brief is as follows.…”

“…The objectives of the present study were to determine the effects of varying photophase of LD cycles and altitude of origin on the parameters of entrainment and t of the oviposition rhythm of two strains of D. ananassae originating from different altitudes. Data pertaining to the eclosion and oviposition rhythms of these altitudinal strains of D. ananassae are already available (Khare et al, 2002(Khare et al, , 2004(Khare et al, , 2005Satralkar et al, 2007a).…”

Male reproduction is affected by RNA interference of period and timeless in the desert locust Schistocerca gregaria

“…In Drosophila, for example, mating and egg-laying behavior are under the influence of daily rhythms (Beaver and Giebultowicz, 2004;Howlader and Sharma, 2006;Khare et al, 2005;Sakai and Ishida, 2001). RNA interference (RNAi) of the clock genes per and cyc in the bean bug Riptortus pedestris interfere with the photoperiodic regulation of male and female reproductive development and they have opposite effects (Ikeno et al, 2010;Ikeno et al, 2011).…”