Nutrients, not caloric restriction, extend lifespan in Queensland fruit flies (Bactrocera tryoni)

Caloric restriction (CR) has been widely accepted as a mechanism explaining increased lifespan (LS) in organisms subjected to dietary restriction (DR), but recent studies investigating the role of nutrients have challenged the role of CR in extending longevity. Fuelling this debate is the difficulty in experimentally disentangling CR and nutrient effects due to compensatory feeding (CF) behaviour. We quantified CF by measuring the volume of solution imbibed and determined how calories and nutrients influenced LS and fecundity in unmated females of the Queensland fruit fly, Bactocera tryoni (Diptera: Tephritidae). We restricted flies to one of 28 diets varying in carbohydrate:protein (C:P) ratios and concentrations. On imbalanced diets, flies overcame dietary dilutions, consuming similar caloric intakes for most dilutions. The response surface for LS revealed that increasing C:P ratio while keeping calories constant extended LS, with the maximum LS along C:P ratio of 21:1. In general, LS was reduced as caloric intake decreased. Lifetime egg production was maximized at a C:P ratio of 3:1. When given a choice of separate sucrose and yeast solutions, each at one of five concentrations (yielding 25 choice treatments), flies regulated their nutrient intake to match C:P ratio of 3:1. Our results (i) demonstrate that CF can overcome dietary dilutions; (ii) reveal difficulties with methods presenting fixed amounts of liquid diet; (iii) illustrate the need to measure intake to account for CF in DR studies and (iv) highlight nutrients rather than CR as a dominant influence on LS.

Cost of reproduction in the Queensland fruit fly: Y-model versus lethal protein hypothesis

The trade-off between lifespan and reproduction is commonly explained by differential allocation of limited resources. Recent research has shown that the ratio of protein to carbohydrate (P : C) of a fly's diet mediates the lifespan–reproduction trade-off, with higher P : C diets increasing egg production but decreasing lifespan. To test whether this P : C effect is because of changing allocation strategies (Y-model hypothesis) or detrimental effects of protein ingestion on lifespan (lethal protein hypothesis), we measured lifespan and egg production in Queensland fruit flies varying in reproductive status (mated, virgin and sterilized females, virgin males) that were fed one of 18 diets varying in protein and carbohydrate amounts. The Y-model predicts that for sterilized females and for males, which require little protein for reproduction, there will be no effect of P : C ratio on lifespan; the lethal protein hypothesis predicts that the effect of P : C ratio should be similar in all groups. In support of the lethal protein hypothesis, and counter to the Y-model, the P : C ratio of the ingested diets had similar effects for all groups. We conclude that the trade-off between lifespan and reproduction is mediated by the detrimental side-effects of protein ingestion on lifespan.

A review of 16 years of quality control parameters at a mass-rearing facility producing Queensland fruit fly, Bactrocera tryoni

From 1996 to 2012, the mass-rearing facility at Camden (NSW, Australia) has been producing Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). During this time, the facility has regularly recorded fly quality parameters, creating a unique data set that provides an invaluable opportunity to evaluate the interrelationships among standard quality control (QC) parameters and test for redundant QC variables. Here, we conducted an exploratory data analysis to reveal relationships among the QC parameters. We found that pupal weight, adult lifespan, and longevity under nutritional stress (i.e., survival duration without food or water) had distinct monthly trends, suggesting that these QC parameters are sensitive to seasonal conditions. Furthermore, emergence percentage, flight ability, and adult lifespan were adversely affected by the dyeing/handling/irradiation process associated with sterile insect releases. Using a multivariate approach and controlling for monthly and yearly patterns, we showed that pupal weight and egg hatch are consistently negatively related and that percentage male and emergence rates are consistently negatively related. These results suggest that these correlation pairs measure similar quality information and hence one QC variable from each pair could be dropped. Flight ability was not strongly correlated with any of the QC variables, suggesting that this QC variable remains a useful QC metric. Finally, the longevity under nutritional stress QC appears to be fairly insensitive to QCs and we suggest that it should be replaced by the standard mortality under stress test.

The mode of evolution of aggregation pheromones in Drosophila species

Aggregation pheromones are used by fruit flies of the genus Drosophila to assemble on breeding substrates, where they feed, mate and oviposit communally. These pheromones consist of species-specific blends of chemicals. Here, using a phylogenetic framework, we examine how differences among species in these pheromone blends have evolved. Theoretical predictions, genetic evidence, and previous empirical analysis of bark beetle species, suggest that aggregation pheromones do not evolve gradually, but via major, saltational shifts in chemical composition. Using pheromone data for 28 species of Drosophila we show that, unlike with bark beetles, the distribution of chemical components among species is highly congruent with their phylogeny, with closely related species being more similar in their pheromone blends than are distantly related species. This pattern is also strong within the melanogaster species group, but less so within the virilis species group. Our analysis strongly suggests that the aggregation pheromones of Drosophila exhibit a gradual, not saltational, mode of evolution. We propose that these findings reflect the function of the pheromones in the ecology of Drosophila, which does not hinge on species specificity of aggregation pheromones as signals.

Sex differences in insect immune function : a consequence of diet choice?

Males often have reduced immune function compared to females but the proximate mechanisms underlying this taxonomically widespread pattern are unclear. Because immune function is resource-dependent and sexes may have different nutritional requirements, we hypothesized that sexual dimorphism in immune function may arise from differential nutrient intake (acquisition hypothesis). To test this hypothesis, we examined patterns of phenoloxidase (PO) activity in relation to nutrient consumption in Queensland fruit flies (Q-flies). In the first experiment, flies were allowed to choose their preferred nutrient intake. Compared with males, female Q-flies had higher PO activity, consumed more calories, and preferred a higher protein:carbohydrate (P:C) diet, suggesting that differential acquisition could explain sex differences. In the second experiment, we restricted flies to one of 12 diets varying in protein and carbohydrate concentrations and mapped PO activity for each sex onto a nutritional landscape. Counter to our hypothesis, females had higher PO activity than males at any given level of nutrient intake. Both carbohydrate and protein intake affected PO activity in females but only protein affected PO activity in males. Our results indicate that sex differences in Q-fly immune function are not solely explained by sex differences in nutrient intake, although nutrition does contribute to the magnitude of these sex differences.

Evaluating irradiation dose for sterility induction and quality control of mass-produced fruit fly Bactrocera tryoni (Diptera : Tephritidae)

The sterile insect technique has been routinely used to eradicate fruit fly Bactrocera tryoni (Froggatt) incursions. This study considers whether fly quality in a mass-rearing facility can be improved by reducing irradiation doses, without sacrificing reproductive sterility. Pupae were exposed to one of five target irradiation dose ranges: 0, 40-45, 50-55, 60-65, and 70-75 Gy. Pupae were then assessed using routine quality control measures: flight ability, sex ratio, longevity under nutritional stress, emergence, and reproductive sterility. Irradiation did not have a significant effect on flight ability or sex ratio tests. Longevity under nutritional stress was significantly increased at 70-75 Gy, but no other doses differed from 0 Gy. Emergence was slightly reduced in the 50-55, 60-65, and 70-75 Gy treatments, but 40-45 Gy treatments did not differ from 0 Gy, though confounding temporal factors complicate interpretation. Reproductive sterility remained acceptable (> 99.5%) for all doses--40-45 Gy (99.78%), 50-55 Gy (100%), 60-65 Gy (100%), and 70-75 Gy (99.99%). We recommend that B. tryoni used in sterile insect technique releases be irradiated at a target dose of 50-55 Gy, providing improved quality and undiminished sterility in comparison with the current 70-75 Gy standard while also providing a substantial buffer against risk of under dosing.

Anaerobic treatment of juice and fruit-processing effluents

Effluents from the juice and fruit processing industries have high organic matter content. Discharge of these effluents without appropriate treatment would therefore have a negative impact on the environment. High organic contents and low contamination levels make such effluents suitable for biological treatment, especially anaerobic digestion. In the latter process, significant amounts of digester gas can be produced, turning a waste stream into a source of renewable energy that can be used for electricity and heat production, leading to financial benefits.This paper investigates the feasibility of anaerobic digestion and the gas generation potential of five different effluents from the carrot-juice, orange-juice and sultana processing industries. Benefits are assessed in terms of digester gas production and organic matter reduction. The results show that the specific gas production ranges between 665 and 860 m3 per tonne of effluent treated (as organic dry matter). Furthermore, nearly 100% of the organic matter is converted into gas in the case of the carrot- and orange-juice processing residues, while a 84.5% reduction of the organic matter was found to be achievable in the case of the sultana wastes. While these results are promising, further testing will be required to validate them in a larger scale.

Socio-economic inequalities in women`s fruit and vegetable intakes: a multilevel study of individual, social and environmental mediators

Objective: This study employed a multilevel design to test the contribution of individual, social and environmental factors to mediating socio-economic status (SES) inequalities in fruit and vegetable consumption among women. Design: A cross-sectional survey was linked with objective environmental data. Setting: A community sample involving 45 neighbourhoods. Subjects: In total, 1347 women from 45 neighbourhoods provided survey data on their SES (highest education level), nutrition knowledge, health considerations related to food purchasing, and social support for healthy eating. These data were linked with objective environmental data on the density of supermarkets and fruit and vegetable outlets in local neighbourhoods. Results: Multilevel modelling showed that individual and social factors partly mediated, but did not completely explain, SES variations in fruit and vegetable consumption. Store density did not mediate the relationship of SES with fruit or vegetable consumption. Conclusions: Nutrition promotion interventions should focus on enhancing nutrition knowledge and health considerations underlying food purchasing in order to promote healthy eating, particularly among those who are socio-economically disadvantaged. Further investigation is required to identify additional potential mediators of SES–diet relationships, particularly at the environmental level.

Fruit and vegetable consumption and stroke : meta-analysis of cohort studies

Background
Increased consumption of fruit and vegetables has been shown to be associated with a reduced risk of stroke in most epidemiological studies, although the extent of the association is uncertain. We quantitatively assessed the relation between fruit and vegetable intake and incidence of stroke in a meta-analysis of cohort studies.

Methods
We searched MEDLINE, EMBASE, the Cochrane Library, and bibliographies of retrieved articles. Studies were included if they reported relative risks and corresponding 95% CIs of stroke with respect to frequency of fruit and vegetable intake.

Findings
Eight studies, consisting of nine independent cohorts, met the inclusion criteria. These groups included 257 551 individuals (4917 stroke events) with an average follow-up of 13 years. Compared with individuals who had less than three servings of fruit and vegetables per day, the pooled relative risk of stroke was 0·89 (95% CI 0·83–0·97) for those with three to five servings per day, and 0·74 (0·69–0·79) for those with more than five servings per day. Subgroup analyses showed that fruit and vegetables had a significant protective effect on both ischaemic and haemorrhagic stroke.

Interpretation
Increased fruit and vegetable intake in the range commonly consumed is associated with a reduced risk of stroke. Our results provide strong support for the recommendations to consume more than five servings of fruit and vegetables per day, which is likely to cause a major reduction in strokes.

Increased consumption of fruit and vegetables is related to a reduced risk of coronary heart disease: meta-analysis of cohort studies

Increased consumption of fruit and vegetables has been shown to be associated with a reduced risk of coronary heart disease (CHD) in many epidemiological studies, however, the extent of the association is uncertain. We quantitatively assessed the relation between fruit and vegetable intake and incidence of CHD by carrying out a meta-analysis of cohort studies. Studies were included if they reported relative risks (RRs) and corresponding 95% confidence interval (CI) of CHD with respect to frequency of fruit and vegetable intake. Twelve studies, consisting of 13 independent cohorts, met the inclusion criteria. There were 278 459 individuals (9143 CHD events) with a median follow-up of 11 years. Compared with individuals who had less than 3 servings/day of fruit and vegetables, the pooled RR of CHD was 0.93 (95% CI: 0.86–1.00, P=0.06) for those with 3–5 servings/day and 0.83 (0.77–0.89, P<0.0001) for those with more than 5 servings/day. Subgroup analyses showed that both fruits and vegetables had a significant protective effect on CHD. Our meta-analysis of prospective cohort studies demonstrates that increased consumption of fruit and vegetables from less than 3 to more than 5 servings/day is related to a 17% reduction in CHD risk, whereas increased intake to 3–5 servings/day is associated with a smaller and borderline significant reduction in CHD risk. These results provide strong support for the recommendations to consume more than 5 servings/day of fruit and vegetables.

Fresh kids: the efficacy of a health promoting schools approach to increasing consumption of fruit and water in Australia

The Fresh Kids programme utilized the Health Promoting Schools (HPSs) framework to design a whole-of-school, multifaceted intervention targeting specific behaviours to promote healthy eating and reduce the risk factors associated with childhood obesity. The aim of the programme was to evaluate the effectiveness of the HPS framework to increase fruit and water consumption among primary school-aged children over a 2-year period. The study design was an interrupted time series. Four primary schools in the inner west of Melbourne, Australia, participated in the programme intervention. Baseline data were collected using a lunch box audit to assess the frequency of children with fresh fruit, water and sweet drinks, either brought from home or selected from canteen lunch orders. The lunch box audit was repeated periodically for up to 2 years following programme implementation to assess the sustainability of dietary changes. Across all participating schools, significant increases between 25 and 50% were observed in the proportion of children bringing fresh fruit. Similarly, all schools recorded increases between 15 and 60% in the proportion of students bringing filled water bottles to school and reductions between 8 and 38% in the proportion of children bringing sweet drinks. These significant changes in dietary patterns were sustained for up to 2 years following programme implementation. Targeting key nutrition behaviours and using the HPS framework is an effective and simple approach which could be readily implemented in similar childhood settings. Effective strategies include facilitating organizational change within the school; integrating curriculum activities; formalizing school policy and establishing project partnerships with local community nutrition and dietetic services.

Evaluation of brief dietary questions to estimate vegetable and fruit consumption - using serum carotenoids and red-cell folate

Objective To evaluate responses to self-administered brief questions regarding consumption of vegetables and fruit by comparison with blood levels of serum carotenoids and red-cell folate.

Design A cross-sectional study in which participants reported their usual intake of fruit and vegetables in servings per day, and serum levels of five carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin and lycopene) and red-cell folate were measured. Serum carotenoid levels were determined by high-performance liquid chromatography, and red-cell folate by an automated immunoassay system.

Settings and subjects Between October and December 2000, a sample of 1598 adults aged 25 years and over, from six randomly selected urban centres in Queensland, Australia, were examined as part of a national study conducted to determine the prevalence of diabetes and associated cardiovascular risk factors.

Results Statistically significant (P<0.01) associations with vegetable and fruit intake (categorised into groups: ≤1 serving, 2–3 servings and ≥4 servings per day) were observed for α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin and red-cell folate. The mean level of these carotenoids and of red-cell folate increased with increasing frequency of reported servings of vegetables and fruit, both before and after adjusting for potential confounding factors. A significant association with lycopene was observed only for vegetable intake before adjusting for confounders.

Conclusions These data indicate that brief questions may be a simple and valuable tool for monitoring vegetable and fruit intake in this population.

Properties of ectin isolated from Lawulu (Crysophylum roxbergi G Don) and development of jam and fruit leather using Lawulu and pineapple

Lawulu fruit (Crysophylum roxberghi GDon) possess nutritional, medicinal and functional properties. However, it is less consumed due to its  characteristic off flavour. The present study was carried out to investigate the potential of utilizing lawulu fruit for isolation of pectin and to develop jam and fruit leather. Products were evaluated based on physico-chemical and sensory properties.

Pectin isolated fromf irm ripe lawuluf ruit using 0.1 M hydrochloric acid  followed by 96% ethanol precipitation yielded 7. 3% pectin on wet weight basis and 26.1% on dry weight basis. The isolated pectin contained 0.74% ash, 0.02% acetyl content and 7.85% methoxyl content with equivalent weight 993.5. These values were comparable with commercial high methoxyl pectin. In addition, Iawulu pectin at 1.5% concentration formed a gel within 12-14 min in the presence of 68% sucrose and 0.5% citric acid.

Jam was prepared by using Iawulu-pineapple ratio as 1:2, 1:1 and 2:1 respectively. The gel strength of jam (65⁰ Brix and pH 3.1) at 0.35% commercial high methoxyl pectin was comparable with commercial mixed fruit jam. Sensory evaluation indicated a significant preference (p<.05) for jam containing lawulu-pineapple ratio of 1:2 and 1.1 respectively overthe ratio of 2:1. With increased lawulu percentage both yellowness and lightness of jam increased significantly (p<0.05).

Fruit leather was prepared by changing lawulu-pineapple ratio as 1:2, 1:1 and 2:1 respectively with 20% sucrose, 0.3% citric acid, 0.05% pectin and 100 ppm potassium metabisulphite followed by drying at 65±1⁰C for 12-14 h. Sensory evaluation data revealed that changes in lawulu-pineapple ratio had no significant effect on taste, texture and overall quality of fruit leather.   However, significant preference (p<0.05) for colour was observed with increasing lawulu percentage. Both yellowness (b' value) and lightness (L'value) of fruit leather were sign[icantly increased (p<0.05) with increasing lawulu percentage.