Effects of the juvenile hormone analogue methoprene and dietary protein on male melon fly Bactrocera cucurbitae (Diptera: Tephritidae) mating success

The effect of access to dietary protein (P) and the topical application of a juvenile hormone analogue (methoprene (M)) on mating behaviour of male melon fly Bactrocera cucurbitae was assessed in the laboratory and in field cages. Age, dietary protein and methoprene application increased the mating success and influenced the mating behaviour. Treatment with methoprene (M+) to protein-deprived (P−) males had only a modest effect on the acceleration of sexual maturity, but application of methoprene (M+) to protein-fed (P+) males greatly accelerated sexual maturity. Protein diet (P+) increased mating success of males in comparison to protein-deprived (P−) males. Protein and methoprene have a synergistic effect on mating behaviour, since M + P+ treated males exhibit reduced mating latency and achieved higher mating in younger ages than methoprene and/or protein-deprived males. Copulation duration was correlated with nutritional status and M + P+ males copulated longer at the age of advanced sexual maturity than M − P+ males. Our results suggest that in this species with a lek mating system, females discriminate between the males based on their sexual signals, which were influenced by protein in the adult diet, methoprene application and age. The results are discussed in the light of mating competitiveness of precocious treated young males and their relevance to Sterile Insect Technique application against this pest species.     

Methoprene modulates the effect of diet on male melon fly,Bactrocera cucurbitae,performance at mating aggregations

The effect of access to dietary protein (P) (hydrolyzed yeast) and/or treatment with a juvenile hormone analogue, methoprene (M), (in addition to sugar and water) on male aggregation (lekking) behaviour and mating success was studied in a laboratory strain of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). Six‐day‐old males were treated with (1) protein and methoprene (M+P+), (2) only protein (M?P+), or (3) only methoprene (M+P?), and compared with 14‐day‐old sexually mature untreated males (M?P?). The lekking behaviour of the four groups of males when competing for virgin sexually mature females (14 –16 days old) was observed in field cages. The following parameters were measured at male aggregations: lek initiation, lek participation, males calling, male–male interaction, female acceptance index, and mating success. For all these parameters, the M+P+ males significantly outperformed the other males. Moreover, for all parameters, there was a similar trend with M+P+ > M?P+ > M?P? > M+P?. More M+P+ males called and initiated and participated in lek activities than all other types of male, which resulted in higher mating success. They had also fewer unsuccessful copulation attempts than their counterparts. Whereas treatment with methoprene alone had a negative effect in young males with only access to sugar, access to dietary protein alone significantly improved young male sexual performance; moreover, the provision of methoprene together with protein had a synergistic effect, improving further male performance at leks. The results are of great relevance for enhancing the application of the sterile insect technique (SIT) against this pest species. The fact that access to dietary protein and treatment of sterile males with methoprene improves mating success means that SIT cost‐effectiveness is increased, as more released males survive to sexual maturity.     

Influence of methoprene and dietary protein on male Anastrepha suspensa (Diptera:Tephritidae) mating aggregations

The Caribbean fruit fly, Anastrepha suspensa (Loew), like many polyphagous tephritids, exhibits a lek polygyny mating system, and juvenile hormone levels and adult diet are known to have important positive effects on male sexual success. Among the potential components of this success are male lek tenure and female response to the sexual signals of lekking males. Male A. suspensa where submitted to four different treatments: (M⁺P⁺) application of juvenile hormone analog, methoprene (M) and sugar and hydrolyzed yeast as adult food; (M⁺P⁻) application of M and sugar as adult food; (M⁻P⁺) no application of M and sugar and hydrolyzed yeast as adult food; and (M⁻P⁻) no application of M and sugar as adult food. M⁺P⁺ males initiated and participated more in aggregations, mated more frequently, and occupied the lek centers more often. They also had fewer unsuccessful mounting attempts than males in all the other treatments. M⁺P⁺ males also emitted pheromones and acoustically signaled more often and attracted more females than males in other treatments. Male sexual performance was improved due to methoprene, protein supply, and the interaction of methoprene and protein for most of the parameters. Since the success of the sterile insect technique (SIT), a commonly employed technique to control pest tephritids, requires the release of males that can form leks, engage in agonistic sexual interactions, and attract females, these positive effects of protein and methoprene may substantially improve SIT programs.     

Methoprene application and diet protein supplementation to male melon fly,Bactrocera cucurbitae,modifies female remating behavior

Methoprene (an analogue of juvenile hormone) application and feeding on a protein diet is known to enhance male melon fly, Bactrocera cucurbitae Coquillett (Diptera: Tephritidae), mating success. In this study, we investigated the effect of these treatments on male B. cucurbitae's ability to inhibit female remating. While 14‐d‐old females were fed on protein diet, 6‐d‐old males were exposed to one of the following treatments: (i) topical application of methoprene and fed on a protein diet; (ii) no methoprene but fed on a protein diet; (iii) methoprene and sugar‐fed only; and (iv) sugar‐fed, 14‐d‐old males acted as controls. Treatments had no effect on a male's ability to depress the female remating receptivity in comparison to the control. Females mated with protein‐deprived males showed higher remating receptivity than females first mated with protein‐fed males. Methoprene and protein diet interaction had a positive effect on male mating success during the first and second mating of females. Significantly more females first mated with sugar‐fed males remated with protein‐fed males and females first mated with methoprene treated and protein‐fed males were more likely to remate with similarly treated males. Females mating latency (time to start mating) was significantly shorter with protein‐fed males, and mating duration was significantly longer with protein‐fed males compared with protein‐deprived males. These results are discussed in the context of methoprene and/or dietary protein as prerelease treatment of sterile males in area‐wide control of melon fly integrating the sterile insect technique (SIT).     

Raspberry ketone-supplemented diet has no effect on fitness parameters or lure responsiveness in male melon flies,Zeugodacus cucurbitae (Diptera: Tephritidae)

The male annihilation technique (MAT) and sterile insect technique (SIT) are often used to control pestiferous tephritid fruit flies (Diptera: Tephritidae). MAT involves the deployment of traps containing a male attractant and insecticide with the goal of drastically reducing male abundance and ultimately eliminating the entire population. SIT, which involves the mass production, sterilization, and release of the target species, may also be implemented to achieve final extirpation. Generally, simultaneous implementation of MAT and SIT is counterproductive, because the presence of large numbers of male-specific traps in the environment (MAT) would greatly reduce the number of sterile males available for copulating with wild females (SIT). However, studies on the Queensland fruit fly, Bactrocera tryoni (Froggatt), indicate that concurrent use of MAT and SIT may be feasible. Sexually mature males of B. tryoni are attracted to the raspberry ketone and its synthetic analogue cue-lure. Males of B. tryoni fed raspberry-ketone-supplemented diet when newly emerged showed lower attraction to cue-lure baited traps than control males. In addition, newly emerged males provided this diet displayed accelerated sexual maturation, which would allow the early release of sterile males and reduce pre-release holding costs. Here, we examined whether the addition of raspberry ketone to the adult diet of male melon flies, Zeugodacus cucurbitae (Coquillett), produced effects similar to those observed for B. tryoni. Despite using similar methods, no significant effect of raspberry ketone-supplemented diet on time to sexual maturity, survival, mating competitiveness, or attraction to cue-lure baited traps in mass-reared Z. cucurbitae males.     

Methyl eugenol effects on Bactrocera dorsalis male total body protein,reproductive organs and ejaculate

Methyl eugenol (ME) and inclusion of protein into the adult diet increase the mating competitiveness of the Oriental fruit fly, Bactrocera dorsalis (Hendel). Exposing males to ME or protein is a promising post‐teneral treatment for males being released in the sterile insect technique (SIT). However, the effect of this post‐teneral treatment on male reproductive organs or the male ejaculate is unknown. During mating, males transfer sperm and accessory gland products (AGPs) to females and these compounds are reported to modulate female sexual inhibition. We studied the impact of male exposure to ME and a yeast hydrolysate (YH) diet on the protein reserves of males, male reproductive organ size, and the male ejaculate through sperm and AGPs. We show that males exposed to ME regardless of access to YH accumulated a greater amount of whole body protein. Males fed on YH also had increased total body protein and had bigger reproductive organs than YH‐deprived males, but no apparent effect of ME exposure was observed on reproductive organ size. Females stored less sperm when mated with males fed on YH and ME compared to males not fed on ME. YH and ME had no effect on male AGPs. Females injected with AGPs of males fed on YH and exposed to ME were just as likely to mate as females injected with AGPs of non‐treated males. However, females injected with AGPs of males exposed to ME mated faster than females injected with AGPs of non‐exposed males. We conclude that while exposure to ME increases male copulatory success and protein reserves in the male body, there seem to be some potential trade‐offs such as lower sperm stored by females. We discuss our results in terms of pre‐release protocols that may be used for B. dorsalis in SIT application.     

Enhancing male sexual success in a lekking fly (Anastrepha suspensa Diptera: Tephritidae) through a juvenile hormone analog has no effect on adult mortality

While defending lek-territories, male Anastrepha suspensa (Loew) produce chemical, acoustic and visual courtship signals. In the laboratory and under semi-natural conditions, topical application of the juvenile hormone analog methoprene doubles pheromone production and subsequently doubles sexual success. However, sexual signals and interactions are likely to be physiologically expensive and so result in higher male mortality. Comparison of males kept in isolation for 35 days, but provided daily with a potential mate or a rival male, revealed that both male- and female-interactors shortened focal-male lifespan. In addition, focal males were either treated with methoprene or not, then either provided with protein in their sucrose-based diet or not. Protein proved to similarly double sexual success and also resulted in longer male life spans in all of the interactor-categories. However, there was no evidence that methoprene induced hypersexuality resulted in higher rates of mortality, i.e., the longevity of males treated with methoprene did not significantly differ from untreated males in the same interactor/diet categories. This apparent lack of costs to a putatively sexually selected signal is unexpected but presents an opportunity to increase the sexual competence of sterile flies with few consequences to their survival following mass-release.     

Male lures and male mating competitiveness in a genetic sexing strain of the melon fly (Diptera: Tephritidae)

The Sterile Insect Technique (SIT) has been used to suppress or eradicate populations of the melon fly, Zeugodacus cucurbitae (Coquillett), a pest of various fruits and vegetables throughout Asia, Africa, and South Pacific Islands. The success of the SIT depends largely on the ability of released, sterile males to compete successfully with wild males for copulations with wild females. Unfortunately, both the sterilization process (via gamma irradiation) and artificial selection under mass-rearing conditions generally reduce the biological competence, including the mating competitiveness, of the released males. However, previous data on Z. cucurbitae show that irradiation has minimal adverse effects and prolonged mass-rearing may or may not result in decreased mating ability. The present study first confirms that neither irradiation nor mass-rearing had deleterious effects on male mating ability of males from a pupal-color, genetic sexing strain (termed T1). Then, the influence of male lures (cue-lure and its natural analogue raspberry ketone) on the mating success of sterile T1 males was measured as a potential pre-release procedure to improve the effectiveness of SIT. Feeding on cue-lure enhanced male mating success, but the effect was short-lived (1 d but not 3 d post-feeding). Feeding on raspberry ketone boosted mating success over a longer time, i.e., at least 5 d but not 10 d post-feeding. However, mixing raspberry ketone into the adult diet had no detectable effect on male mating performance. The implications of these results for SIT against Z. cucurbitae are discussed.     

Methoprene-induced matings of young Queensland fruit fly males are effective at inducing sexual inhibition in females

Pre-release dietary treatment with methoprene, a juvenile hormone analogue, decreases the age at which male Queensland fruit flies mature and hence may decrease the post-release delay until released sterile flies participate in sterile insect technique (SIT) programmes. However, if matings of young methoprene-treated males are not effective at inducing sexual inhibition in their mates, then this treatment may not enhance SIT. The present study investigates efficacy of matings of methoprene-treated males at inducing sexual inhibition in their mates. Methoprene incorporated into a diet of sugar and yeast hydrolysate (w/w 3:1) for 48 hr after emergence resulted in significantly increased male mating propensity when flies were <10 days of age, but not when older, and longer copulations. Copula latency did not vary with methoprene treatment but did decrease with age. The matings of young methoprene-treated males were effective at inducing sexual inhibition in their mates, matching the efficacy of untreated mature males. Regardless of treatment, females had reduced tendency to remate if their first mate was 15 days of age than if their first mate was younger (6, 8 days) or older (20, 25, 30 days). Females mated by methoprene-treated males that did remate tended to remate later in the day than females mated by untreated males. Also, second copula durations of females first mated by a 6- to 10-day-old male were shorter if the male was methoprene treated. These patterns in remating females may indicate greater efficacy of the initial mating of methoprene-treated males. Overall, we find that the additional matings of young methoprene-treated male Queensland fruit flies are effective at inducing sexual inhibition in their mates. This finding supports the incorporation of methoprene into pre-release diet for SIT.     

Laboratory evaluation of the chemosterilant lufenuron against the fruit flies Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons

Four species of tephritid fruit flies, Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons were evaluated for toxic, developmental, and physiological responses to the chemosterilant lufenuron. No significant mortality of laboratory strains of the first three species was observed after their exposure up to 50 μg/mL of lufenuron in agar adult diet, whereas B. latifrons adults fed with 50 μg/mL of lufenuron in the diet caused significant mortality compared to the control. Fertility of C. capitata adults fed on 50 μg/mL lufenuron-fortified diet between 7 and 12 days of age was approximately 46% of the no lufenuron control. Fertility of B. dorsalis and B. latifrons adults fed on 50 μg/mL lufenuron-incorporated diet was about 45% and 62% of the control, respectively. Lufenuron did not significantly affect fertility of B. cucurbitae adults. Lufenuron did not affect fecundity of C. capitata and B. dorsalis. Fecundity of B. cucurbitae and B. latifrons was not evaluated due to difficulty to count the eggs laid deep in the agar diet. Larvae fed on a liquid larval diet with ≤ 0.1 μg/mL of lufenuron were also evaluated. Pupal recovery, adult emergence, adult fliers, mating, egg hatch, and egg production of C. capitata were significantly decreased, while for B. dorsalis, pupal recovery, larval duration and adult emergence were affected. No effect of lufenuron on B. cucurbitae larvae was observed. B. latifrons was not performed because shortage of eggs at the time of this research. Lufenuron is a potential agent for management and control of C. capitata and B. dorsalis.     

Sex differences in phenotypic plasticity of a mechanism that controls body size: implications for sexual size dimorphism

The degree and/or direction of sexual size dimorphism (SSD) varies considerably among species and among populations within species. Although this variation is in part genetically based, much of it is probably due to the sexes exhibiting differences in body size plasticity. Here, we use the hawkmoth, Manduca sexta, to test the hypothesis that moths reared on different diet qualities and at different temperatures will exhibit sex-specific body size plasticity. In addition, we explore the proximate mechanisms that potentially create sex-specific plasticity by examining three physiological variables known to regulate body size in this insect: the growth rate, the critical weight (which measures the cessation of juvenile hormone secretion from the corpora allata) and the interval to cessation of growth (ICG; which measures the time interval between the critical weight and the secretion of the ecdysteroids that regulate pupation and metamorphosis). We found that peak larval mass of males and females did not exhibit sex-specific plasticity in response to diet or temperature. However, the sexes did exhibit sex-specific plasticity in the mechanism that controls size; males and females exhibited sex-specific plasticity in the growth rate and the critical weight in response to both diet and temperature, whereas the ICG only exhibited sex-specific plasticity in response to diet. Our results suggest it is important for the sexes to maintain the same degree of SSD across environments and that this is accomplished by the sexes exhibiting differential sensitivity of the physiological factors that determine body size to environmental variation.     

Effect of water temperature on dietary protein requirement,growth and body composition of Asian catfish, Clarias batrachus fry

This study aimed to evaluate the protein requirement of Clarias batrachus fry, were estimated at two different water temperatures, 28 and 32 °C. The influence of dietary protein level and water temperature on body composition, weight gain, food and nutrient utilization were estimated. The Asian catfish, C. batrachus fry were fed four diets containing 28% (diet 1), 32% (diet 2), 36% (diet 3) and 40% (diet 4) protein levels and reared at two water temperatures 28 and 32 °C for 60 days. Fry fed with diet 3 containing 36% protein showed the highest mean final body weight at 32 °C. Final body weight was significantly (P<0.05) affected by dietary treatments and temperatures. Clarias batrachus fry raised at 28 °C had higher feed efficiency (93.20%) than the fry reared at 32 °C (87.58%) with 28% dietary protein level. Further, feed efficiency decreased with increase in dietary protein level. Higher daily protein retention (0.089%) observed at lower (0.0217 g) daily protein intake at 28 °C than 0.0283 g at 32 °C. While, optimal (0.0282 g) daily protein intake showed higher daily weight gain at 32 °C. Productive protein value (% PPV) was maximum (1.76%) at 32 °C than at 28 °C (0.76%). Final body lipid recorded higher value than initial body lipid at both the temperatures. Hepatosomatic index (HSI) observed to have been influenced (P<0.05) by diets and temperatures, while viscerosomatic index (VSI) affected (P<0.05) by only diets and not (P>0.05) by temperatures. The study concluded that the diet 3 containing 36% protein was optimal for growth of C. batrachus fry at both the temperatures.     

Epithelial transport and barrier function in occludin-deficient mice

Background and Aims

This study aimed at functional characterization of the tight junction protein occludin using the occludin-deficient mouse model.

Methods

Epithelial transport and barrier functions were characterized in Ussing chambers. Impedance analysis revealed the ionic permeability of the epithelium (R^e, epithelial resistance). Conductance scanning differentiated transcellular (G^c) and tight junctional conductance (G^tj). The pH-stat technique quantified gastric acid secretion.

Results

In occludin+/+ mice, R^e was 23±5 Ω cm² in jejunum, 66±5 Ω cm² in distal colon and 33±6 Ω cm² in gastric corpus and was not altered in heterozygotic occludin+/− or homozygotic occludin−/− mice. Additionally, [³H]mannitol fluxes were unaltered. In the control colon, G^c and G^tj were 7.6±1.0 and 0.3±0.1 mS/cm² and not different in occludin deficiency. Epithelial resistance after mechanical perturbation or EGTA exposition (low calcium switch) was not more affected in occludin−/− mice than in control. Barrier function was measured in the urinary bladder, a tight epithelium, and in the stomach. Control R^t was 5.8±0.8 kΩ cm² in urinary bladder and 33±6 Ω cm² in stomach and not altered in occludin−/− mice. In gastric corpus mucosa, the glandular structure exhibited a complete loss of parietal cells and mucus cell hyperplasia, as a result of which acid secretion was virtually abolished in occludin−/− mice.

Conclusion

Epithelial barrier characterization in occludin-deficiency points against an essential barrier function of occludin within the tight junction strands or to a substitutional redundancy of single tight junction molecules like occludin. A dramatic change in gastric morphology and secretory function indicates that occludin is involved in gastric epithelial differentiation.     

At least two regions of the oncoprotein Tre2 are involved in its lack of GAP activity

The product of the human Tre2 oncogene is structurally related to the Ypt/Rab GTPase-activating proteins (Ypt/Rab GAPs). Particularly, the oncoprotein shares with the yeast proteins Msb3p and Msb4p, and with the human protein RN-tre the highly conserved TBC domain, forming the catalytically active domain of Ypt/Rab GAPs. Yet, the Tre2 oncogene seems to encode a nonfunctional Rab GAP. As regions flanking the TBC domain may be crucial for catalytic activity, regions located N- and C-terminally with respect to this domain were explored. For this, chimeric proteins created by sequence exchanges between the Tre2 oncoprotein and RN-tre were tested for their ability to replace functionally the Msb3p and Msb4p proteins in double-mutant yeast cells. These complementation experiments revealed, in addition to the TBC domain, a second Tre2 region involved in the oncoprotein's lack of GAP activity: a 93-aa region flanking the TBC domain on the C-terminal side.     

Influence of dietary protein levels and water temperature on growth,body composition and nutrient utilization of Cirrhinus mrigala (Hamilton, 1822) fry

The experiment was conducted to determine the protein requirement of Cirrhinus mrigala fry at three different water temperatures, 28, 30 and 32 °C, and to investigate the influence of dietary protein levels and water temperatures on weight gain, body composition, food and nutrient utilization. The 36% protein concentration in the diet yielded highest weight gain at all temperatures from 28 to 32 °C. However, daily protein intake was lower at 28 °C than at 30 and 32 °C. The diet with 36% dietary protein and 32.17% carbohydrate produced the best weight gain and gross conversion efficiency (GCE) at 30 °C. The protein-sparing effect was observed at temperatures 30 and 32 °C in diets 1 and 2, having carbohydrate levels 37.36–44.91%. Highest protein efficiency ratio (PER) was recorded at 28% dietary protein level, while it was lowest at 40% dietary protein level in all three temperatures. Lipid in the body of fishes increased at the end of the experiment in comparison to the initial body lipid. The body protein was found to be related to daily protein intake at 30 and 32 °C. Significant difference (P<0.05) was also noted between temperatures, the hepatosomatic index (HSI) and viscerosomatic index (VSI). The diet with 36% dietary protein and 32.17% carbohydrate was observed to be the best diet for C. mrigala fry at 28–32 °C.     

Increased dietary cholesterol promotes enhanced mutagenesis in DNA polymerase kappa-deficient mice

DNA polymerase kappa (Polκ) bypasses planar polycyclic N²-guanine adducts in an error-free manner. Cholesterol derivatives may interact with DNA to form similarly bulky lesions. In accordance, these studies examined whether increased mutagenesis of DNA accompanies hypercholesterolemia in Polk^−/− mice. These mice also carried apoE gene knockouts to ensure increased levels of plasma cholesterol following exposure to a high cholesterol diet. The mice carried a reporter transgene (the λ-phage cII gene) for subsequent quantitative analysis of mutagenesis in various tissues. We observed significantly increased mutation frequencies in several organs of apoE^−/−Polk^−/− mice following a high cholesterol diet, compared to those remaining on a standard diet. Regardless of dietary regime, the mutation frequency in many organs was significantly higher in apoE^−/−Polk^−/− than in apoE^−/−Polk^+/+ mice. As expected for polycyclic guanine adducts, the mutations mainly consisted of G:C transversions. The life expectancy of apoE^−/−Polk^−/− mice maintained on a high cholesterol diet was reduced compared to apoE^−/−Polk^+/+ mice. Overall, this study demonstrates a role for Polκ in bypass of cholesterol-induced guanine lesions.     

Physiological energetics of the green abalone, Haliotis fulgens, fed on a balanced diet

A regression of different physiological responses against body size enables populations or stock cultures of various size ranges to be compared. Thus, the aim of the present work was to evaluate the physiological responses from juvenile green abalone (Haliotis fulgens), grouped according to size, in a standard controlled culture condition within their optimal range to create the balanced growth equation within an allometric relation, providing a basic framework for physiological research into H. fulgens. Feed intake, absorption efficiency, respiration and excretion were measured as functions of dry tissue weight (DTW) in juvenile abalone acclimated on a balanced diet. The daily feed intake (I) was related to body mass by the relationship I (mg day⁻¹)=24.25W^0.59. Absorption efficiency averaged 87% and was independent of body size. The equation relating daily respiration rate (R) to body mass was R (ml O₂ day⁻¹)=12.013W^0.704, including night correction. The rate of ammonia excretion (U) was related to dry tissue weight by the equation U (μmol N-NH₄ day⁻¹)=43.57W^0.85. The energetic value of food was 18.8 J mg⁻¹. The low feeding activity (<1% of abalone live weight per day) was compensated for by a relatively high absorption efficiency and a depression of 23% in the metabolic rate during diurnal activity. Gross and net growth efficiencies were constant throughout the size range, with average values of 36.4% and 41.5%, respectively. Values of the O/N ratio, with an average of 31.5, showed a higher use of proteins from the diet as an energy source for the size range studied.     

The effect of dietary restriction on longevity,fecundity, and antioxidant responses in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Recent studies in fruit flies have imposed dietary restriction (DR) by diluting yeast and have reported increased lifespan as the yeast-to-sugar ratio decreased. In this study, the effects of DR on the lifespan of Bactrocera dorsalis were investigated using constant-feeding diets with different yeast:sugar ratios and an intermittent-feeding diet in which flies ate every sixth day. Antioxidant enzyme activities and the malondialdehyde concentration were also measured in virgin females under constant-feeding DR protocols to investigate their relationships with lifespan. The results showed that B. dorsalis lifespan was significantly extended by DR, and carbohydrate-enriched diet may be important for lifespan-extension. Female flies lived significantly longer than males at all dietary levels under both feeding regimes, indicating no interaction between diet and sex in determining lifespan. Antioxidant enzyme activities increased with the amount of yeast increased in the diets (0–4.76%) between starvation and DR treatments, indicating that the antioxidants may have influences in determining lifespan in B. dorsalis under starvation and DR treatments. However, antioxidants cannot keep up with increased oxidative damage induced by the high yeast diet (25%). These results revealed that the extension of lifespan by DR is evolutionarily conserved in B. dorsalis and that yeast:sugar ratios significantly modulate lifespan in this species.     

Capture of melon flies, Zeugodacus cucurbitae (Diptera: Tephritidae), in a food-baited Multilure trap: Influence of distance,diet, and sex

Many countries operate trapping programs to detect invasions of pestiferous fruit fly species (Diptera: Tephritidae). Surveillance relies heavily on traps baited with male lures, which, while highly attractive, have limited effectiveness, because (i) they are sex-specific and (ii) males of some species do not respond to the lures currently in use. For these reasons, detection programs also include food-baited traps that are neither sex- nor species-specific. Compared to male lure-baited traps, however, few studies have measured the attractiveness of food-based traps. The present study describes a mark-release-recapture study conducted in a fruit orchard in Hawaii that measured the attractiveness of a liquid protein hydrolysate-based (torula yeast/borax slurry) trap to adults of the melon fly Zeugodacus cucurbitae (Coquillett). Multiple release points were used at varying distances from a single, central trap to generate estimates of distance-dependent capture probabilities. The potential influences of sex and pre-release diet on capture probability were also examined. Flies were released at 14 d of age and were maintained on one of four dietary regimes that offered a protein hydrolysate-rich diet for varying intervals (i.e., 0, 3, 7, or 14?d, respectively). Recapture rates were similar between the sexes and over both sexes and all diets averaged 3.6%, 3.2%, and 0.6% for release distances of 10, 25, and 50?m, respectively. Pre-release diet had a significant effect on recapture probability for releases at 10 and 25?m: flies fed sugar only or protein hydrolysate-rich diet for only 3?d were captured more frequently than flies that had longer access to yeast extract prior to release.