Renewable and nonrenewable resources: Amino acid turnover and allocation to reproduction in Lepidoptera

Abstract

The allocation of nutritional resources to reproduction in animals is a complex process of great evolutionary significance. We use compound-specific stable isotope analysis of carbon (GC͞combus-tion͞isotope ratio MS) to investigate the dietary sources of egg amino acids in a nectar-feeding hawkmoth. Previous work suggests that the nutrients used in egg manufacture fall into two classes: those that are increasingly synthesized from adult dietary sugar over a female's lifetime (renewable resources), and those that remain exclusively larval in origin (nonrenewable resources). We predict that nonessential and essential amino acids correspond to these nutrient classes and test this prediction by analyzing egg amino acids from females fed isotopically distinct diets as larvae and as adults. The results demonstrate that essential egg amino acids originate entirely from the larval diet. In contrast, nonessential egg amino acids were increasingly synthesized from adult dietary sugars, following a turnover pattern across a female's lifetime. This study demonstrates that female Lepidoptera can synthesize a large fraction of egg amino acids from nectar sugars, using endogenous sources of nitrogen. However, essential amino acids derive only from the larval diet, placing an upper limit on the use of adult dietary resources to enhance reproductive success.

Radiation Biology and Inherited Sterility of Light Brown Apple Moth (Lepidoptera: Tortricidae): Developing a Sterile Insect Release Program

“…Although we are aware of adult nectar feeding in Lepidoptera (Nelson 1936), the experimental rationale we adopted was intended to determine whether there were isotopic differences between the populations that could be used as markers. We suggest that adult nectar feeding would contribute little to the overall isotope signature of the moth as it is quickly used as an available energy source for flight (O'Brien et al 2002). In previous work we have shown that insects fed sugar ad libitum turn over about 50% of their total body C throughout their life time and that about 50% is structural and has minimal turnover (Hood-Nowotny et al 2009).…”

“…From this we assume that chitin-dominant tissues such as wings or front leg tibiae, are chitin rich structures, which will turnover slowly thus retaining their natal isotopic signature. The sugar-rich nectar diet of most moths provides only trace amounts of amino acids and these do not appear to contribute to adult N (O'Brien et al 2002). Moreover studies of N assimilation in adult Lepidoptera have shown minimal N uptake (MolleMan et al 2009).…”

Tracking human travel using stable oxygen and hydrogen isotope analyses of hair and urine

“…Both differences were statistically significant (t-tests: t ¼ 3.94, P ¼ 0.0043 for d 18 O and t ¼ 9.43, P < 0.0001 for dD, both with df ¼ 8). We calculate the contribution of oxygen and hydrogen from drinking water to hair in residents using the following mixing expression: 18,45 % hair oxygen from drinking water ¼ ðd 18 We note that the use of this expression assumes that other sources of hair oxygen in these populations (e.g. diet, atmospheric O 2 ) do not differ isotopically between locations, nor do their fractional contributions of oxygen to hair.…”

Intermediary Metabolism and Life‐History Trade‐Offs: Differential Metabolism of Amino Acids Underlies the Dispersal‐Reproduction Trade‐Off in a Wing‐Polymorphic Cricket

“…The evolution of new life histories is expected to require changes in the relative flux through these pathways, for example, when relative somatic versus reproductive effort is altered during the course of adaptation. Although variation in amino acid acquisition from the diet has been investigated in ecological studies of interspecific life-history trade-offs (Boggs 1997a(Boggs , 1997bO'Brien et al 2002O'Brien et al , 2005, to our knowledge, no study has investigated genetic modifications in amino acid metabolism that contribute to within-species variation in life-history specialization.…”

“…The evolution of new life histories is expected to require changes in the relative flux through these pathways, for example, when relative somatic versus reproductive effort is altered during the course of adaptation. Although variation in amino acid acquisition from the diet has been investigated in ecological studies of interspecific life-history trade-offs (Boggs 1997a(Boggs , 1997bO'Brien et al 2002O'Brien et al , 2005, to our knowledge, no study has investigated genetic modifications in amino acid metabolism that contribute to within-species variation in life-history specialization.Wing polymorphism in insects is a powerful experimental model that has been used extensively to investigate the physiological, and more recently, the biochemical basis of life-history evolution (Zera and Denno 1997;Zera et al , 1998Zera and Harshman 2001; Zhao and Zera 2002;Zera andZhao 2003a, 2004). Gryllus firmus, the most intensively studied species in this regard, exists in natural populations as two genetically specified morphs.…”