Chemistry Reference
In-Depth Information
25
Specii c Accumulation of
Lutein within the Epidermis
of Butterl y Larvae
John T. Landrum, Derick Callejas, and
Francesca Alvarez-Calderon
CONTENTS
25.1 Introduction ........................................................................................................................ 525
25.2 Extraction of Carotenoids ................................................................................................... 526
25.3 Analysis of Carotenoid Extracts ......................................................................................... 527
25.3.1 HPLC ....................................................................................................................527
25.3.2 Mass Spectrometry ............................................................................................... 528
25.3.3 Carotenoid Identii cation ...................................................................................... 528
25.3.4 Comparison of Carotenoid Content in Different Colored Regions of Larvae ...... 528
25.3.4.1 Monarchs ............................................................................................. 528
25.3.4.2 Queen, Eastern Black Swallowtail, and Atala Butterl ies ................... 530
25.4 Discussion ........................................................................................................................... 531
Acknowledgments .......................................................................................................................... 533
References ...................................................................................................................................... 534
25.1 INTRODUCTION
Carotenoids are abundant phytopigments and are essential to the coloration in many birds, i shes,
and insects (Weedon 1971, Kayser 1982). There is growing evidence that non-provitamin A carote-
noids are also signii cant phytonutrients in humans (Krinsky et al. 2005). It has been demonstrated
that lutein and zeaxanthin are specii cally accumulated in the human retina and function there to
protect the retina from oxidative damage (see Chapter 13; Landrum and Bone 2001). Carotenoids
present in insect species affect their coloration but evidence also supports the conclusion that they
function physiologically as antioxidants and photoprotectants in a manner similar to that ascribed
to carotenoids in humans (Felton and Summers 1995, Jenkins et al. 1999, Heller et al. 2000, Carroll
and Berenbaum 2002). The coloration patterns of butterl ies and moths are often striking in both
adult and larval stages and the importance of coloration to the success in butterl y and moth popula-
tions is widely recognized (Carroll and Berenbaum 2002). The bright coloration of larval butterl ies
may also be a factor in predator avoidance; it is known that these organisms can accumulate large
quantities of toxic cardenolide glycosides (Rothschild and Mummery 1986, Mebsa et al. 2005).
In adult butterl ies, the bright coloration of the wings results from the presence of crystalline
pterin pigments within the scales (Britton 1983). In the larval stages, patterns, including yellow
coloration such as that found in the banding of the Monarch butterl y larvae (
Danaus plexippus
),
are not uncommon, Figure 25.1. Surprisingly, little has been reported about the components
525
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