Toxicity of Bacillus thuringiensis beta-exotoxin to three species of fruit flies (Diptera: Tephritidae)

The current study describes toxic effects of the Bacillus thuringiensis beta-exotoxin toward 3rd instars of 3 fruit fly species: Anastrepha ludens (Loew), A. obliqua (Macquart), and A. serpentina (Wiedemann). The beta-exotoxin was highly toxic to all 3 species tested, with LC50 values calculated as 0.641, 0.512, and 0.408 microgram/cm2 of filter paper used to expose the larvae, for A. ludens, A. obliqua, and A. serpentina, respectively. Exposure to beta-exotoxin was associated with an increase in the incidence of deformed pupae. The adult survivors from beta-exotoxin treatments showed no negative effects in terms of their longevity, fecundity, or egg eclosion (fertility). We conclude that the beta-exotoxin may have potential as a control agent for fruit fly pests.     

Nonhost status of commercial Persea americana 'Hass' to Anastrepha ludens, Anastrepha obliqua, Anastrepha serpentina, and Anastrepha striata (Diptera: Tephritidae) in Mexico

The objective of this study was to determine the host status in Mexico of commercially cultivated and marketed avocado, Persea americana (Mill.), 'Hass' to Anastrepha ludens (Loew), Anastrepha obliqua (Macquart), Anastrepha serpentina (Wiedemann), and Anastrepha striata (Schiner) (Diptera: Tephritidae). Experiments in Michoacán, Mexico, were carried out in six orchards located at three altitudes above sea level during two times (August-October 2001 and April-June 2002). They included choice ('Hass' avocado plus natural host) and no-choice foraging behavior tests on trees under field cages; no-choice, forced infestation trials on caged, fruit-bearing branches in the field, and with individual fruit under laboratory conditions; infestation trials using 'Hass' avocados left unprotected over 1 and 7 d on the ground of orchards; studies to ascertain depth of oviposition and determine egg hatchability; and experiments to determine susceptibility by using time elapsed since removal of fruit from tree as the experimental variable. We trapped adult Anastrepha (n = 7,936) in all orchards and dissected fruit (n = 7,695) from orchards and packing houses (n = 1,620) in search of eggs or larvae. Most (96.7%) A. ludens, A. obliqua, A. striata, and A. serpentina adults were captured in low-elevation orchards. No eggs or larvae were detected in any of the fruit from foraging behavior studies or dissected fruit from orchards or packing houses. Of 5,200 mature, intact fruit on trees in the field forcibly exposed to no-choice female oviposition activity (five females/fruit), we only found four fruit infested by A. ludens but no adults emerged. 'Hass' avocados only became marginally susceptible to attack by A. ludens (but not A. obliqua, A. serpentina, and A. striata) 24 h after being removed from the tree. Fruit placed on the ground in orchards (n = 3,600) were occasionally infested by Neosilba batesi (Curran) (Diptera: Lonchaeidae), a decomposer, but not Anastrepha spp. Based on our results, commercially cultivated and marketed P. americana 'Hass' should not be considered a natural host of A. ludens, A. obliqua, A. striata, and A. serpentina in Mexico.     

Irradiation of mangoes as a postharvest quarantine treatment for fruit flies (Diptera: Tephritidae)

Mangoes infested with third instar larvae were irradiated using Co-60 gamma rays and a dose interval of 2-250 Gy to assess the irradiation dose required to prevent adult emergence of the Mexican fruit fly (Anastrepha ludens), the West Indies fruit fly (A. obliqua), the sapote fruit fly (A. serpentina), and the Mediterranean fruit fly (Ceratitis capitata). Doses of 76.9, 87.3, 91.4 and 112.7 Gy, were estimated to inhibit 99.9968% (probit 9) of adult emergence forA. obliqua, A. serpentina, A. ludens, and C. capitata, respectively. Using mangoes infested with a total of 100,000 larvae of each species, the results obtained in the laboratory were confirmed using a dose of 100 Gy for the Anastrepha species and 150 Gy for C. capitata. No adult emergence was observed for any of the four species compared with approximately 80% emergence in the controls. A dose of 150 Gy is recommended as a generic quarantine treatment against potential infestation of these species in exported mangoes. A minor decrease in the ascorbic acid content was the only adverse effects observed in irradiated mangoes.     

Grapefruit as a host for the West Indian fruit fly (Diptera: Tephritidae)

The most common hosts for the West Indian fruit fly, Anastrepha obliqua (Macquart) (Diptera: Tephritidae) are fruit in the family Anacardiaceae (mango [Mangifera L.] and mombin [Spondias L.] species). However, similar to many of the tropical fruit flies of major economic importance, this species attacks several other families of crop fruit, including Annonaceae (cherimoya, Annona cherimola Mill.), Myrtaceae (guava, Psidium L.), Oxalidaceae (carambola, Averrhoa carambola L.), Passifloraceae (granadilla, Passiflora quadrangularis Mill.), and Sapotaceae [mamey sapote, Pouteria sapota (Jacq.) H. E. Moore & Steam]. In the family Rutaceae the economically important genus Citrus has been reported and until recently considered a host for this fruit fly. In this study, we reviewed the taxonomy of A. obliqua, tested specific chemicals that may inhibit oviposition, compared egg-to-adult survival of A. obliqua on preferred hosts and on grapefruit (Citrus X paradisi Macfad.), and measured fruit tissue-specific developmental rates of A. obliqua and the known citrus breeding Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), from egg to pupae. Our literature review shows much confusion concerning the taxonomy of this and related Anastrepha species, including synonymies and confusion with other species. The deterrent effect of the highest concentration of flavonoids for oviposition, although significant, was not absolute. Experiments carried out under laboratory conditions showed 15-40 times greater survival of A. ludens (whose preferred hosts include Rutaceae) on grapefruit compared with A. obliqua for both tree attached and harvested fruit. Experiments of survival of developing stages over time showed that the two species oviposit into different tissues in the fruit, and mortality is much higher for the West Indian fruit fly in the flavedo and albedo of the fruit compared with the Mexican fruit fly.     

Anastrepha ludens and Anastrepha serpentina (Diptera: Tephritidae) do not infest Psidium guajava (Myrtaceae), but Anastrepha obliqua occasionally shares this resource with Anastrepha striata in nature

This study examined whether economically important fruit fly species Anastrepha ludens (Loew), Anastrepha serpentina (Wiedemann), and Anastrepha obliqua (Macquart) (Diptera: Tephritidae) may opportunistically exploit guavas, Psidium guajava L. (Myrtaceae), growing near preferred natural hosts. We collected 3,459 kg of guavas and 895 kg of other known host species [sour orange, Citrus aurantium L.; grapefruit, Citrus paradisi Macfadyen; mango, Mangifera indica L.; white sapote, Casimiroa edulis La Llave and Lex.; sapote, Pouteria sapota (Jacq.); sapodilla, Manilkara zapota L.; and wild plum, Spondias purpurea L. and Spondias mombin L.] along an altitudinal gradient over a 4-yr period (2006-2009). Plants were growing in sympatry in 23 localities where the guavas are usually infested in the state of Veracruz, M6xico. The guava samples yielded 20,341 Anastrepha spp. pupae in total (overall mean, 5.88 pupae per kg of fruit). Confirming previous reports, Anastrepha fraterculus (Wiedemann) and Anastrepha striata (Schiner) were found heavily infesting guavas in Veracruz. Importantly, although we did not find evidence that A. ludens and A. serpentina are able to attack this valuable commodity, we document for the first time in the agriculturally important state of Veracruz that P. guajava is an alternative natural host plant of A. obliqua. We recovered two fruit in the mango-growing locality of la Vibora, Tlalixcoyan, that harbored larvae of A. striata and A. obliqua. This finding has important practical implications for management of A. obliqua. Over the entire altitudinal gradient, when individual fruit infestation was examined, a dynamic pattern of species dominance was unveiled with guavas growing below 800 m above sea level mainly attacked by A. striata and a progressive replacement with increasing altitude by A. fraterculus. Interestingly, most individual fruit examined (97%) harbored a single species of fruit fly, a finding that may be taken as evidence of competitive displacement among sympatric species of fruit flies. Based on this study and previously published work by us on this topic, we conclude that literature reports indicating that A. ludens and A. serpentina infest guavas under field conditions should be questioned.     

Residual control and lethal concentrations of GF-120 (spinosad) for Anastrepha spp. (Diptera: Tephritidae)

The objective of this study was to determine the relationship between residual time of GF-120 (spinosad) treatment and mortality in three species of Anastrepha Schiner. Concentrations of 96, 72, 48, and 24 ppm were aged on mango leaves under field conditions for 0, 3, 7, 10, 14, 17, and 21 d after application. We found that Anastrepha ludens, A. obliqua, and A. serpentina were highly sensitive to spinosad. The effects of spinosad were not reduced over the 4 d after the initial application, even at a concentration of 24 ppm. Mortality at 14 d after the application of 72 and 96 ppm of spinosad was similar in each of the three fruit fly species. In addition, we found that 24 ppm of spinosad was consumed the most by each species even though no direct relationship between the rate of consumption per female and the dose of the product was observed, in this test, higher consumption of active ingredient was observed at a concentration of 72 ppm, for A. ludens, 48 ppm for A. obliqua, and 96 ppm for A. serpentina. Our results suggest that a spinosad concentration of 72 ppm may effectively control these pests for at least 10 d under field conditions.     

Field evaluation of a phototoxic dye, phloxine B, against three species of fruit flies (Diptera: Tephritidae).

The xanthene dye phloxine B (D&C Red #28) bait was sprayed against fruit flies in mango orchards in 1996 and 1997. The flies used for testing were Mexican fruit fly, Anastrepha ludens (Loew), West Indian fruit fly, Anastrepha obliqua (Macquart), and Mediterranean fruit fly, Ceratitis capitata (Wiedeman). Results of the experiments indicate that the toxic efficacy of phloxine B against these fruit flies is as good as that of malathion-bait sprays. Results also indicate that type of protein used with phloxine B can dramatically influence its efficacy. Hydrolyzed proteins of corn origin, Mazoferm 802 and Nutriplus, and one from microbial origin, Coltec yeast broth, were best. Phloxine B-bait applications as complete coverage or alternate swaths reduced fly populations as well as 19.5 or 9.8% (AI) malathion-Captor 300. Applications of phloxine B bait at concentrations of 0.12% phloxine B reduced populations as well as those applied at 0.48% (AI). The fruit fly parasitoid Diachasmimorpha longicaudata was adversely affected when exposed to phloxine B-Nutriplus bait but not when exposed to the other proteins.     

Effects of age, diet, female density, and the host resource on egg load in Anastrepha ludens and Anastrepha obliqua (Diptera: Tephritidae)

Oocyte counts, used as a measure of egg load, were compared among three different age groups (15, 30 and 45 days) of two polyphagous species of tephritid fruit flies, Anastrepha ludens and Anastrepha obliqua, which were exposed to varying conditions of diet (sucrose vs sucrose and protein), availability of oviposition substrate (present vs absent), adult female density (1, 2 and 4 females/cage), and semiochemical context (presence vs absence of male pheromones and fruit volatiles). In both species, oocyte counts were higher in older females and for females fed sucrose and protein than for females fed sucrose only. The presence of artificial oviposition substrates influenced oocyte counts in A. obliqua, but not in A. ludens. Female density influenced oocyte counts in both species. Females maintained in groups had higher egg loads than isolated females. Finally, preliminary evidence suggests that semiochemical context influenced oocyte counts. Counts were highest for females in a room containing both fruit volatiles and male pheromone, lowest for females in a room containing neither volatiles nor pheromone, and intermediate for females in rooms containing either volatiles or pheromone but not both. Our results suggest that egg load is influenced by environmental factors in different ways in these two species. Egg load in A. obliqua, a species whose host fruits are highly ephemeral, is responsive to access to the host resource. By contrast, in A. ludens, a species infesting less ephemeral fruit, female density and age played a more important role than host stimuli. The role of ovarian maturation and oviposition in mediating these effects, as well as implications for mass rearing and pest management, are discussed.     

Fruit infesting tephritids [Dipt.: Tephritidae] and associated parasitoids in Chiapas,Mexico

A total of 1,302 parasitoids representing 8 species and 4 families were recovered from 9,818 fruit fly host fruits sampled. The most common parasitoid species wasDiachasmimorpha longicaudata (Ashmead). Average percent parasitism ranged between 0.44 and 29.23%. Parasitoid emergence data indicate thatAnastrepha ludens (Loew),A. obliqua (Sein),A. serpentina (Wiedeman),A. striata (Schiner) andToxotrypana curvicauda (Gerstaecker) were subject to parasitism. We provide information on the population fluctuation ofAnastrepha ludens, A. obliqua, A. serpentina, A. distincta (Greene),A. striata, A. fraterculus (Wiedeman),A. chiclayae (Greene),A. montei (Costa Lima),A. leptozona (Hendel) andA. tripunctata (Wulp).Anastrepha ludens andA. obliqua were the most common species, representing 95.3% of all fruit fly species caught in McPhail traps.      

Long aculeus and behavior of Anastrepha ludens render gibberellic acid ineffective as an agent to reduce 'ruby red' grapefruit susceptibility to the attack of this pestiferous fruit fly in commercial groves

Treating Mexican grapefruit with gibberellic acid (GA3) before color break, significantly delayed peel color change and increased peel puncture resistance, but it did not reduce grapefruit susceptibility to Mexican fruit fly, Anastrepha ludens (Loew) attack under natural conditions. Despite GA3 treatments, larval infestation levels increased with higher fruit fly populations, which also increased as the season progressed. Late in the season, infestation levels were even higher in GA3-treated fruit compared with untreated fruit, possibly because treated fruit were in better condition at that stage. Egg clutch size was significantly greater in very unripe, hard, GA3-treated fruit at the beginning of the harvest season and in December, compared with control fruit. Under laboratory conditions, egg injection into different regions of the fruit suggested that A. ludens eggs are intoxicated by peel oil content in the flavedo region. However, A. ludens' long aculeus allows females to oviposit eggs deeper into the peel (i.e., albedo), avoiding toxic essential oils in the flavedo. This makes A. ludens a particularly difficult species to control compared with other citrus-infesting species such as Anastrepha suspensa (Loew), Anastrepha fraterculus (Wiedemann), and Ceratitis capitata (Wiedemann) (fly species with significantly shorter aculei), which can be effectively managed with GA3 sprays. We discuss our findings in light of their practical implications and with respect to the oviposition behavior of various fruit flies attacking citrus.     

Understanding long-term fruit fly (Diptera: Tephritidae) population dynamics: implications for areawide management

Fruit flies (Diptera: Tephritidae) are devastating agricultural pests worldwide but studies on their long-term population dynamics are sparse. Our aim was to determine the mechanisms driving long-term population dynamics as a prerequisite for ecologically based areawide pest management. The population density of three pestiferous Anastrepha species [Anastrepha ludens (Loew), Anastrepha obliqua (Macquart), and Anastrepha serpentina (Wiedemann)] was determined in grapefruit (Citrus x paradisi Macfad.), mango (Mangifera indica L.), and sapodilla [Manilkara zapota (L.) P. Royen] orchards in central Veracruz, México, on a weekly basis over an 11-yr period. Fly populations exhibited relatively stable dynamics over time. Population dynamics were mainly driven by a direct density-dependent effect and a seasonal feedback process. We discovered direct and delayed influences that were correlated with both local (rainfall and air temperature) and global climatic variation (El Ni?o Southern Oscillation [ENSO] and North Atlantic Oscillation [NAO]), and detected differences among species and location of orchards with respect to the magnitude and nature (linear or nonlinear) of the observed effects, suggesting that highly mobile pest outbreaks become uncertain in response to significant climatic events at both global and local levels. That both NAO and ENSO affected Anastrepha population dynamics, coupled with the high mobility of Anastrepha adults and the discovery that when measured as rate of population change, local population fluctuations exhibited stable dynamics over time, suggests potential management scenarios for the species studied lie beyond the local scale and should be approached from an areawide perspective. Localized efforts, from individual growers will probably prove ineffective, and nonsustainable.     

Host status of grapefruit and Valencia oranges for Anastrepha serpentina and Anastrepha ludens (Diptera: Tephritidae)

Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) is sporadically captured in the Rio Grande Valley of Texas. Although its preferred hosts are in the Sapotaceae family, several varieties of Citrus, including grapefruit and oranges are listed as alternate hosts. Although Mexican fruit fly, Anastrepha ludens (Loew), is known to be a major pest of Citrus, doubt exists as to the status of Citrus as a breeding host for A. serpentina. To evaluate the host status of commercial Citrus for A. serpentina we compared oviposition and development with that of A. ludens under laboratory conditions with 'Rio Red' grapefruit (Citrus paradisi MacFayden) and 'Valencia' oranges [Citrus sinensis (L.) Osbeck] in different stages of maturity. Both fly species oviposited in early season fruit in which the eggs and larvae died in the fruit albedo. Survival of either species to the adult stage occurred in later season grapefruit. In oranges, no A. serpentina larvae survived compared with 150 A. ludens surviving to adults. Survival on both Citrus species was much lower for A. serpentina, only approximately 5% of eggs eclosed into larvae in grapefruit compared with approximatley 50% for A. ludens. In oranges approximately 16% of A. serpentina eggs eclosed compared with approximately 76% for A. ludens. In grapefruit, only one fourth as many A. serpentina larvae survived to the adult stage compared with A. ludens. Additional experiments were performed in a greenhouse on small, caged trees of la coma (Sideroxylon celastrinum H.B.K.), a Texas species of Sapotaceae. The A. serpentina females readily oviposited into these berries and normal adults emerged. The present low incidence of the adults, coupled with the high mortality during development of the larvae, suggests that Texas citrus is unlikely to support a breeding population of A. serpentina.     

Efficacy of ground spray application of bait sprays with malathion or spinosad on Mexican fruit fly (Diptera: Tephritidae) in Texas citrus

An important component in the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), eradication program is bait spray application to knock down localized A. ludens infestations enhancing the sterile to wild fly ratio and increasing the effectiveness of the sterile insect release program. Efficacy tests were conducted using spray equipment that applies ultralow application rates of malathion NU-LURE or GF-120 spinosad by ground into citrus. Trapit Dome traps located in fields treated with malathion NU-LURE and GF-120 spinosad high rate caught significantly fewer flies than the control in all replications. Treatments reduced the Mexican fruit fly populations by 99.1 and 92.5% with malathion and 98.2 and 89.9% with GF-120 spinosad high rate. Traps in plots with lower rates of GF-120 reduced fly populations by 76.3 and 74.3% in winter and summer test, respectively. There was no indication of fly repulsion from either malathion or GF-120 spinosad during this test. The bait spray option using ground spray equipment to apply ultra-low rates of either malathion NU-LURE or GF-120 spinosad high rate is a viable cost effective treatment method to treat small acreages for A. ludens. For organic growers, the ground spray equipment is effective in applying GF-120 spinosad at the labeled rates.     

Composition of the surface hydrocarbons from the vitelline membranes of dipteran embryos

Hydrocarbons were the major lipid class extracted by hexane from the vitelline membrane surface of dechorionated eggs of the house fly, Musca domestica, the New World screwworm, Cochliomyia hominivorax, the secondary screwworm, Cochliomyia macellaria, the green bottle fly, Phaenicia sericata, the sheep blow fly, Lucilia cuprina and the Mexican fruit fly, Anastrepha ludens. The length of time the embryos must be exposed to hexane with or without a small amount of alcohol in order to attain permeability was species-dependant. Long-chain n-alkanes comprised the major lipid class removed from vitelline membranes of all species except A. ludens where 2-methylalkanes were the major class. The range in size by the total number of carbon atoms in the hydrocarbons was: C23-C49 in C. hominivorax, C27-C33 in C. macellaria, C24-C35 in L. cuprina, C25-C36 in M. domestica, C25-C33 in P. sericata and C21-C51 in A. ludens. The major hydrocarbon component, expressed as percent of the total hydrocarbons, was n-nonacosane (C29) in C. hominivorax (40%), C. macellaria (43%), L. cuprina (38%), M. domestica (39%) and P. sericata (60%). However, in A. ludens, 2-methyloctacosane (32%) was the major hydrocarbon. Unsaturated hydrocarbons, monoenes (16%) and dienes (11%), were abundant only in A. ludens. Since prior studies indicated that the length of time the embryos must be exposed to hexane with or without a small amount of alcohol in order to attain permeability is species dependant, we suggest that the differences in hydrocarbon composition may contribute to this variation in lipid extractability.     

Faunistic analysis of fruit flies (Diptera: Tephritidae) in the Northern and Northwestern Regions of Rio de Janeiro State, Brazil

This study aimed to characterize the fruit fly populations in three municipalities of the Northern region and two municipalities of the Northwestern region of Rio de Janeiro State, Brazil, and to evaluate the similarity among their populations. A faunistic analysis was performed from the fruit fly specimens captured in plastic McPhail traps with an aqueous solution of hydrolyzed protein to 5% placed in orchards of guava (Psidium guajava L.) and/or other fruits during 26 months. The total of 3,952 females of 15 species of Anastrepha Schiner and 277 females of Ceratitis capitata (Wied.) was captured. The species richness differed among the municipalities, with the highest value in S?o Francisco do Itabapoana (S = 14), resulting on the highest Shannon-Wiener index (H = 1.27). The equitability was low in the five municipalities due to the dominance of one unique fruit fly species. The predominant species (more frequent, constant and dominant) were Anastrepha obliqua (Macquart) in Campos dos Goytacazes and S?o Francisco do Itabapoana, Anastrepha fraterculus (Wied.) in Cambuci and Itaocara, and Anastrepha sororcula Zucchi in S?o Jo?o da Barra. Fruit fly populations had low diversity index of Margalef (alpha = 0.58 to 1.82). Regarding to fruit fly species composition, the populations in S?o Jo?o da Barra and Cambuci were more similar between each other, composing a distinct group from the populations in Campos dos Goytacazes and Itaocara. These two groups differed quite a lot from the population in S?o Francisco do Itabapoana.     

Pupariation time as a source of variability in mating performance in mass-reared Anastrepha ludens (Diptera: Tephritidae)

The effect of time of pupariation on pupal weight and adult sexual competitiveness under field cage conditions was studied in mass-reared Anastrepha ludens (Loew) males. Larvae that took 72 h to pupariate after separation from diet resulted in lighter pupae than those that took 24 and 48 h. Wild pupae were heavier than the 48- and the 72-h pupae but not the 24-h pupae. Interestingly, no differences in mating performance were found between males of the 24- and 48-h pupae despite differences in pupal weight. In general, lower-than expected levels of mating compatibility between sterile and wild A. ludens resulted from the interaction of both strains as more homotypic pairs were observed. Discussion focuses on the effect of the mass-rearing process on male fruit fly mating performance.     

Effect of Adult Nutrition on Male Sexual Performance in Four Neotropical Fruit Fly Species of the Genus Anastrepha (Diptera: Tephritidae)

Fruit flies (Diptera: Tephritidae) have been used previously as a model to explore the effect of nutrition on male reproduction. Here we tested the hypothesis that adult feeding history influences male sexual performance in four species of neotropical fruit flies of the genus Anastrepha (A. ludens, A. obliqua, A. serpentina, and A. striata), an approach that allowed us to consider species-specific ecological factors independent of phylogenetic constraints. We fed, from the moment of emergence, four experimental groups of males of each species with either (1) dry sucrose, (2) a mixture of dry sucrose and hydrolyzed protein (enzymatic yeast hydrolyzate), (3) a mixture of dry sucrose and bird feces, or (4) an open fruit [Citrus sinensis (orange), Mangifera indica (mango), Manilkara zapota (chico zapote), and Psidium guajava (guava) for A. ludens, A. obliqua, A. serpentina, and A. striata, respectively]. Cohorts of 12-day-old individuals (28 males [7 of each diet treatment] and 14 females) were released simultaneously into species-specific field cages and the following parameters recorded over a 4-day period (procedure repeated with five different cohorts for each species): number of males involved in calling activities every hour (i.e., pheromone emissions, wing fanning, wing motions, or extensions of the mouthparts), identity of copulating males, and copula duration. In the case of A. obliqua, we also observed separately cohorts of 20-day-old individuals. In A. obliqua, A. serpentina, and A. striata, males fed on a protein-supplemented diet had higher copulatory success when competing against males fed on other diets. Anastrepha serpentina and A. striata were sensitive to diet on all but two of the parameters analyzed (i.e., males with consecutive copulas and copula duration in the case of A. serpentina and males with multiple and consecutive copulas in the case of A. striata). In sharp contrast to this, the male mating performance of A. ludens was not affected by diet. Anastrepha obliqua was sensitive to different parameters depending on age. We discuss our findings and their sexual selection implications in light of each species' habits.     

Nutritional balancing in fruit flies: performance of wild adult females of Anastrepha obliqua (Diptera: Tephritidae) fed on single-food or food-pair treatments

The aim of the present study was to investigate the effects of different artificial diets, in which sucrose and brewer's yeast were offered separately (food-pair treatment) or mixed (single-food treatment), on the regulation of nutrient ingestion and the performance of wild adult females of Anastrepha obliqua. The amount of diet consumed by females of A. obliqua increased as the concentration of yeast in the diet increased, revealing a phagostimulant effect of yeast. The amount of sucrose ingested was constant in all groups, showing that these flies regulate the ingestion of sucrose. Longevity and production of eggs/female were similar in both groups. Our results suggest that A. obliqua females regulate the ingestion of nutrients to obtain an adequate performance. Dietary self-selective behavior was more efficient for the females of A. obliqua than feeding on a single-food, because the self-selecting flies ingested less food and had a similar performance as the ones fed on the single-food treatment.     

Attractiveness to Anastrepha ludens (Diptera: Tephritidae) of plant essential oils and a synthetic food-odour lure

Abstract:  Experiments were conducted in a citrus orchard to investigate the attractiveness of 26 plant essential oils individually and in combination with a synthetic food odour lure to the Mexican fruit fly, Anastrepha ludens Loew. Anise, rose/grape seed, and tea tree oils were more attractive than unbaited traps but none approached the attractiveness of Advanced Pheromone Technologies' AFF lure, a synthetic food-odour lure that emits several nitrogenous chemicals attractive to this fly. Traps baited with most of the oils were less attractive than unbaited traps. Rose/grape seed oil and pure-rose oil enhanced attractiveness of AFF lures to both males and females by about 68%. Grape seed oil did not enhance the attractiveness of AFF lures demonstrating that rose oil was the active component of the rose/grape seed oil. No other oil enhanced attractiveness of AFF lures and most decreased attraction to AFF lures. The possibility that highly attractive chemicals may be present in rose oil as minor components is discussed. Traps baited with the combination of clove bud oil and the AFF lure captured only 3% as many flies as traps baited only with the AFF lure indicating that clove bud oil is highly repellent to Mexican fruit flies.     

Sperm allocation and cost of mating in a tropical tephritid fruit fly

Males that copulate repeatedly may suffer from reduced sperm stores. However, few studies have addressed sperm depletion from both the female and male perspective. Here, we show that male Anastrepha obliqua (Diptera: Tephritidae) do not ejaculate all available sperm and are left with mature sperm in the seminal vesicles even after copulating as often as three times in half a day. Ejaculate size was not related to male mating history; time elapsed since the last mating, copulation duration, female thorax length or head width. Larval host origin did not affect the number of sperm stored by females. More sperm was found in the ventral receptacle compared to sperm stored in the three spermathecae. Males apparently do not suffer a cost of mating in terms of longevity, although we cannot rule out other fitness costs. Sperm production in this species may not be as costly as it is for other species. Results suggest that males strategically allocate similar numbers of sperm among successive mates without exhausting sperm reserves for future encounters. We discuss the role that differential sperm storage may have in mediating sperm competition and tie our results to the unique natural history of A. obliqua.