Age determination in individual wild-caughtDrosophila serratausing pteridine concentration

Abstract

SUMMARY Fluorescence spectrophotometry can reliably detect levels of the pteridine 6-biopterin in the heads of individual Drosophila serrata Malloch 1927. Pteridine content in both laboratory and field captured flies is typically a level of magnitude higher than the minimally detectable level(meanlab=0.54 units, meanfield=0.44 units, minimum detectable level=0.01 units) and can be used to predict individual age in laboratory populations with high certainty (r2=57%). Laboratory studies of individuals of known age (from 1 to 48 days old)indicate that while pteridine level increases linearly with age, they also increase in a linear manner with rearing temperature and ambient light levels,but are independent of sex. As expected, the longevity of laboratory-reared males (at least 48 days) is higher than the range of predicted ages of wild-caught males based on individual pteridine levels (40 days). However, the predictive equation based on pteridine level alone suggested that a number of wild-caught males were less than 0 days old, and the 95% confidence limits for these predictions based on the inverse regression are broad. The age of the oldest wild-caught male is predicted to fall within the range of 2 to 50 days. The significant effects of temperature and light intensity determined in the laboratory study (effect sizes ω2=14.3 and 20.4%,respectively) suggests that the calibration of the age prediction equation for field populations would be significantly improved when combined with fine-scaled studies of habitat temperature and light conditions. The ability to determine relative age in individual wild-caught D. serratapresents great opportunities for a variety of evolutionary studies on the dynamics of natural populations.

An evaluation of two biochemical methods of age determination in insects (pteridines and lipofuscins) using the ant Polyrhachis sexpinosa Latrielle (Hymenoptera: Formicidae)

“…Log lipofuscin intensity (arbitrary units) P. sexpinosa. These compounds have now been detected in a variety of arthropod taxa (Robson et al 2006) and are likely to be present in all insects. The ability for these two compounds to predict age in individual ants and the manner in which they varied with body mass (measured as either head weight or body weight) varied with the compound itself.…”

“…These non-polar compounds are typically quantified either by examining histological sections under scanning electron microscopy or through spectrofluorometric measurements of chloroform extractions (Sohal 1987). Increases in FAP with individual age have been documented in a variety of insect (McArthur & Sohal 1982;Ettershank et al 1983;Robson et al 2006), crustacean (Sheehy et al 1999;Bluhm & Brey 2001;Ju et al 2001), and fish (Girven et al 1993;Strauss 1999) taxa. Studies of age-related pigments within the social Hymenoptera are limited.…”

“…Pteridines are a group of polar compounds that accumulate in tissue over time and can be extracted and detected through spectrofluorometry (Ziegler & Harmsen 1969; Robson et al 2006). Studies of the relationship between pteridine concentration and age are much more taxonomically limited than those of lipofuscins, being restricted almost entirely to various dipteran families, such as the Calliphoridae (Wall et al 1991), Culicidae (Penilla et al 2002), Drosophilidae (Robson et al 2006), Muscidae (McIntyre & Gooding 1995, Simulidae (Millest et al 1992) and Tephritidae (Tomic-Carruthers et al 1996).…”

The use of transcriptional profiles to predict adult mosquito age under field conditions

“…Existing methods for age-grading insects, such as scoring modifications to ovarian anatomy, are laborious and discriminate only very young adult age classes. Pteridine concentration has been shown to predict age in various dipteran species (10)(11)(12), and although its initial application to predicting mosquito age showed promise (13), it has proven to be generally unreliable for wild mosquitoes because pteridines occur in limited quantities and their concentration fluctuates with blood feeding (9). In the case of the primary dengue vector, Aedes aegypti, the most recently developed age-grading method utilizes changes in proportions of cuticular hydrocarbons (CHC) from legs to predict adult age (6,14).…”

Age-dependance of pteridines in the malaria vector, Anopheles stephensi

“…By contrast, total fluorescence decreased with age of the mosquito [9]. Pteridine molecules can be detected and characterized in the small quantities by fluorescence spectroscopy; therefore, this technique is very useful for age determination of field population of insects [9,14].…”