Age, sex, adult and larval diet shape starvation resistance in the Mediterranean fruit fly: an ecological and gerontological perspective.

The ability of an animal to withstand periods of food deprivation is a key driver of invasion success (biodiversity), adaptation to new conditions, and a crucial determinant of senescence in populations. Starvation resistance (SR) is a highly plastic trait and varies in relation to environmental and genetic variables. However, beyond Drosophila, SR has been studied poorly. Exploiting an interesting model species in invasion and ageing studies-the Mediterranean fruit fly (Ceratitis capitata)- we investigated how age, food and gender, shape SR in this species. We measured SR in adults feeding in rich and poor dietary conditions, which had been reared either on natural hosts or artificial larval diet, for every single day across their lifespan. We defined which factor is the most significant determinant of SR and we explored potential links between SR and ageing. We found that SR declines with age, and that age-specific patterns are shaped in relation to adult and larval diet. Females exhibited higher SR than males. Age and adult diet were the most significant determinants of SR, followed by gender and the larval diet. Starvation resistance proved to be a weak predictor of functional ageing. Possible underlying mechanisms, ecological and gerontological significance and potential applied benefits are discussed

Trapping of <i>Ceratitis capitata</i> Using the Low-Cost and Non-Toxic Attractant Biodelear

Trapping is considered a powerful tool in the monitoring and control of fruit flies of high economic importance such as the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae). However, the cost of trapping and, in some cases, the safety of the chemicals used as baits are concerning for growers and the environment. Here we present a novel, low cost, environmentally friendly, female-specific bait for C. capitata, called Biodelear, that consists of a mixture of attracting compounds such us pyrazines, pyranones and amorphous nitrogen-based polymers. The new bait was compared to the commercially available attractant Biolure® (Suterra LLC, Bend, OR, USA) in Greece. McPhail-type traps were deployed in an orange orchard located in Athens. Five traps per treatment were used for several weeks during 2009 and four traps per treatment in 2010. Traps contained either 17 g of Biodelear or one Biolure Unipack dispenser. The results showed that both baits were highly efficient in attracting C. capitata females, and to a lesser extent, males. Although Biolure initially appeared to outperform Biodelear, later in the season the two attractants converged in efficacy. In both years, female captures were similar in traps baited with Biolure and Biodelear. However, male captures were higher in Biodelear-baited traps in 2010. In addition, Biodelear seemed to be longer lasting than Biolure, despite not being formulated into a slow-release dispersion system. The low cost of Biodelear and its strong, long-lasting effects render it suitable for mass trapping of the Mediterranean fruit fly

Age Related Assessment of Sugar and Protein Intake of Ceratitis capitata in ad libitum Conditions and Modeling Its Relation to Reproduction

In the inquiry on the age related dietary assessment of an organism, knowledge of the distributional patterns of food intake throughout the entire life span is very important, however, age related nutritional studies often lack robust feeding quantification methods due to their limitations in obtaining short-term food-intake measurements. In this study, we developed and standardized a capillary method allowing precise life-time measurements of food consumption by individual adult medflies, Ceratitis capitata (Diptera: Tephritidae), under laboratory conditions. Protein or sugar solutions were offered via capillaries to individual adults for a 5 h interval daily and their consumption was measured, while individuals had lifetime ad libitum access to sugar or protein, respectively, in solid form. Daily egg production was also measured. The multivariate data-set (i.e., the age-dependent variations in the amount of sugar and protein ingestion and their relation to egg production) was analyzed using event history charts and 3D interpolation models. Maximum sugar intake was recorded early in adult life; afterwards, ingestion progressively dropped. On the other hand, maximum levels of protein intake were observed at mid-ages; consumption during early and late adult ages was kept at constant levels. During the first 30 days of age, type of diet and sex significantly contributed to the observed difference in diet intake while number of laid eggs varied independently. Male and female adult longevity was differentially affected by diet: protein ingestion extended the lifespan, especially, of males. Smooth surface models revealed a significant relationship between the age dependent dietary intake and reproduction. Both sugar and protein related egg-production have a bell-shaped relationship, and the association between protein and egg-production is better described by a 3D Lorenzian function. Additionally, the proposed 3D interpolation models produced good estimates of egg production and diet intake as affected by age, providing us with a reliable multivariate analytical tool to model nutritional trends in insects, and other organisms, and their effect upon life history traits. The modeling also strengthened the knowledge that egg production is closely related to protein consumption, as suggested by the shape of the medfly reproduction-response function and its functional relationship to diet intake and age

Daily pattern on male sexual siganlling.

<p>Daily rhythm of sexual signalling on adult day 6 of sterilized male <i>C</i>. <i>capitata</i> of the Vienna 8 GSS in four different exposure compounds (orange oil, limonene, mixture of 5 pure compounds and control) on yeast hydrolyzate & sugar (YS, left column) and sugar only (S, right column). Values on y axis indicate the mean number (±SE) of males signalling per cage. Ten cages were considered containing 10 males each.</p

Age specific ratio on male sexual signaling.

<p>Ratio between signalling rates of Vienna 8 GSS sterilized male medflies fed on either yeast hydrolyzate & sugar (YS) or sugar only (S) in relation to age. Males had been exposed during day 4 and 5 of adult life to orange essential oil, limonene, and a mixture of 5 pure compounds (limonene, linalool, myrcene, <i>α</i>-pinene and <i>β</i>-myrcene, 1:1:1:1:1 ratio) or left unexposed (control). On each day of age, observations took place hourly from 07:00 to 20:45 hours in 10 cages (replicates) containing 10 males each. The ratio was estimated considering the average calling for each day of the observation during 07:00 to 20:45 for protein and sugar treatments.</p

Effects of exposure to citrus compounds on male sexual signaling.

<p>Overall levels of sexual signalling activity (mean number of males signalling through the ages of 6 to 10 days old and 16 days old) of Vienna 8 GSS sterilized males medflies that were exposed during day 4 and 5 of adult life to orange essential oil, limonene, and a mixture of 5 pure compounds (limonene, linalool, myrcene, <i>α</i>-pinene and <i>β</i>-myrcene 1:1:1:1:1 ratio) or left unexposed (control) fed on (A) yeast hydrolyzate & sugar (YS) and (B) sugar only (S). On each day of age, observations took place hourly from 07:00 to 20:45 hours in 10 cages (replicates) containing 10 males each. Values on y-axis are mean numbers (±SE) of males signalling per cage per hour observation. Means followed by the same lowercase letter are not significantly different (P>0.05, Tukey’s HSD test).</p

Diet specific effects on male sexual signaling.

<p>Effect of yeast hydrolyzate and sugar (YS) and sugar only (S) on the overall levels of sexual signalling activity (mean daily activity through the ages of 6 to 10 days old and 16 days old) of Vienna 8 GSS sterilized male medflies, that were exposed during day 4 and 5 of adult life to orange essential oil, limonene and a mixture of 5 pure compounds (limonene, linalool, myrcene, <i>α</i>-pinene and <i>β</i>-myrcene, 1:1:1:1:1 ratio) or left unexposed (control). On each day of age, observations took place hourly from 07:00 to 20:45 hours in 10 cages (replicates) containing 10 males each. Values on y-axis are mean numbers (±SE) of males signalling per cage per hour observation (** P<0.001, *P<0.01, <i>t</i>-test YS vs S in each treatment).</p

Longevity parameters of adult medflies that were exposed and non-exposed to the aroma of citrus oil and held in diet restriction (sugar fed only) and in full diet (yeast and sugar fed) food conditions.

<p>Within diet regime, numbers followed by different letters are significantly different (pairwise comparisons log-rank test, P < 0.05).</p

Repeated measures ANOVA on the effect of exposure compound (orange oil, limonene, mixture of 5 pure compounds and control), food (yeast hydrolyzate and sugar and sugar only) and time of day (repeated factor) on daily rhythms of sexual signalling on sterilized (Vienna 8 GSS) <i>C</i>. <i>capitata</i> males.

<p>Times of the day between 07:00 and 20:45 hours of adult day 6 were considered in the analysis.</p

Repeated measures ANOVA on the effect of exposure compound (orange oil, limonene, mixture of 5 pure compounds and control), food (yeast hydrolyzate and sugar and sugar only) and age (repeated factor) on sexual signalling on sterilized (Vienna 8 GSS), <i>Ceratitis capitata</i> males.

<p>Males from adult age day 6 to adult day 10 and adult day 16 were considered in the analysis.</p