Effects of Artificial Ultraviolet Light Exposure on Reproductive Success of the Female Panther Chameleon (Furcifer pardalis) in Captivity

Abstract

Having previously documented experimentally the need for ultraviolet B (UVB) irradiation (290-315 nm) in the light environment of captive female panther chameleons (Furcifer pardalis) to ensure hatching success of their eggs, we investigated optimal UVB irradiation levels. From 1996-1998 28 hatchling female panther chameleons were raised to maturity and bred (using vitamin and mineralfortified insect diets low in vitamin D) in nine different artificial UVB light environments. Seven of the environments included long (12 hr/day) low irradiation exposures ranging from 1.7 to 22 mW/cm 2 UVB, with a corresponding conversion of provitamin D 3 to photoproducts in in vitro models of 0.18 to 1.52% in 2 hr. Two environments included short (0.5 and 1.0 hr/day), high irradiation exposures of 55 and 49 mW/cm 2 UVB, respectively, with a corresponding conversion of provitamin D 3 to photoproducts in in vitro models of 8.3% to 14.6% in the respective 0.5-and 1.0-hr time periods. Females raised with the mid-level long/low exposures (5-15 mW/cm 2 UVB; 0.52-1.32% conversion to photoproducts in in vitro models) produced viable eggs with a significantly higher percentage of hatching compared to those with the extreme (highest or lowest) long/low exposures. Those raised with the short-/high-exposure environments produced viable eggs with a generally high percentage of hatching, but success was variable. The results and techniques for light quality assessment are interpreted, with recommendations for practical application by the *Correspondence to:

Voluntary exposure of some western‐hemisphere snake and lizard species to ultraviolet‐B radiation in the field: how much ultraviolet‐B should a lizard or snake receive in captivity?

“…In a study of panther chameleons [Ferguson et al, 2002], neonate females were raised through maturity and reproduction under different enforced daily UVB levels. Their reproductive success was measured in terms of the number of second-generation hatchlings produced.…”

“…On the contrary, high doses of UVB, given a light source with similar spectral power distribution (SPD) to sunlight, do not cause excess vitamin D 3 and the associated toxic effects, because biologically inert photoproducts are produced in the skin with higher UVB exposures [Webb et al, 1989;Holick, 2004]. Optimum levels of UVB or Vitamin D are largely unknown for most species [but see Ferguson et al, 2002].…”

“…Exposure to excess UVB can cause eye and skin damage, skin cancer and poor reproduction in reptiles and amphibians [Hays et al, 1995;Blaustein et al, 1998;Ferguson et al, 2002;Gehrmann, 2006;Baines, 2007].…”

A comparison of responses by three broadband radiometers to different ultraviolet‐B sources

“…Further studies of the relationship of the in vitro vitamin D-synthesizing potential of a UVB source to organismic processes, such as growth and reproduction in exotic species, are called for and may have practical applications. For example, Ferguson et al [2002] reported that UVB irradiation resulting in 0.52 to 1.32% ampule conversion to photoproducts after a 2-hr exposure resulted in viable eggs in the panther chameleon. This occurred when the exposure to the source continued for 12 hr per day and the daily intake of dietary vitamin D was negligible; conversion percentages below or greater than these values significantly reduced hatchability.…”

“…The currently available Model DMX from Spectronics Corp. (Westbury, NY), has a resolution of 10 mW/cm 2 and may not be able to adequately differentiate among irradiance levels from low wattage lamps. The older model (DM-300N), which did measure at the desired resolution, is no longer available, but literature reporting baseline data using this meter exist [Gehrmann, 1987;Ferguson et al, 2002Ferguson et al, , 2003. Most broadband radiometers tend to underestimate the actual irradiance within a band because they progressively undervalue the irradiances toward the two boundaries of the band.…”