Changes in ornithine decarboxylase activity in response to temperature stress and stimulation of juvenile hormone in Anastrepha fraterculus (Diptera, Tephritidae)

Ornithine decarboxylase (ODC) activity was analyzed in Anastrepha fraterculus (Diptera) females (4 days old) submitted to temperature stress (6 degrees C and 20/6 degrees C) and the topical application of juvenile hormone (JH). ODC activity and ejaculatory apodeme measurements (length and width) were made in males (15 days old) after 6 degrees C stress. JH dose of 500 ng and incubation of 3, 7, and 18 h increased ODC activity. Females reared at 6 degrees C and 20/6 degrees C had higher ODC activity than those reared at 25 degrees C. The treatment of 6 degrees C and JH incubation for 1 h increased ODC activity when compared to 6 degrees C treatments only. However, the treatment of 20/6 degrees C only after 3 or 18 h of JH incubation resulted in higher ODC activity than controls (20/6 degrees C) or 20/6 degrees C plus 1 h of JH incubation. Males did not undergo differences in ODC activity when reared at 6 degrees C or 25 degrees C but the ejaculatory apodeme measurements was higher in those reared at 25 degrees C than in those reared at 6 degrees C. The results can be considered an adaptive process to environmental changes.     

X-ray doses to safely release the parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) reared on Anastrepha fraterculus larvae (Diptera: Tephritidae)

Diachasmimorpha longicaudata is a koinobiont larval parasitoid that is currently used to control fruit flies of the genera Anastrepha, Ceratitis and Bactrocera. In the rearing process, a fraction of the host larvae that are exposed to parasitoids escape from parasitism and develop into viable and fertile flies. This creates the need to eliminate emerging flies before the parasitoids are shipped for release, increasing costs due to additional handling steps. Exposure of fly eggs or larvae to gamma-irradiation before they are parasitised has been used to reproductively sterilise hosts, or even inhibit their emergence. Our aim was to determine whether X-ray radiation applied to Anastrepha fraterculus third instar larvae before they are exposed to parasitoids, inhibits fly emergence in non-parasitised larvae without affecting the performance of the parasitoids that emerge from parasitised larvae. Three X-ray doses: 6250.2 R, 8333.6 R and 10417 R (equivalent to 60, 80 and 100 Gy, respectively) and one γ-ray dose (100 Gy) were tested. Fly emergence decreased with increasing doses of radiation, showing null values for the higher X-ray dose and the dose of 100 Gy. Irradiation showed either no impact or a positive effect on parasitism rate and fecundity. Sex rate was biased towards females in almost every dose. We conclude that the two types of radiation evaluated here were equally effective in suppressing fly emergence with no detrimental effects on the biological quality of the produced parasitoids. X-rays offer an alternative method of irradiation than the conventional radiation source, i.e. γ-rays. These results represent a significant improvement in the development of a biological control programme against A. fraterculus.     

Patterns of resource distribution among conspecific larvae in two fruit fly species: Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae)

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Intermediate metabolism during the ontogenetic development of Anastrepha fraterculus (Diptera: Tephritidae)

The fruit fly Anastrepha fraterculus is a major pest of native and exotic fruit trees in South America. Changes in weight, water content and metabolism were observed during its ontogenetic development in standard conditions (25 degrees C, RH=60% and 14 h:10 h photoperiod). The metabolic variables glycogen, total proteins, triglycerides and total lipids were measured by means of spectrophotometric methods. The results were correlated with pupae metamorphosis, temporal pattern, and beginning of adult life. Pupae were observed daily, and a sub-sample of 10 individuals was collected and maintained at -20 degrees C. The same procedure was performed with adults at 4 days after adult eclosion. Levels of total lipids and triglycerides were constant during pupal development, peaking in 312-h-old pupae. In 0-h-old pupae, glycogen levels were high, and decreased progressively until the insects were 312 h old. The peak in total proteins coincides with the post-histolysis period of the larval tissue (96-120 h). These results indicated that glycogen and proteins may be the principal sources of energy for metamorphosis. Total lipid and triglyceride contents remained steady during metamorphosis, and these were consumed in the first 4 days of adult life.     

Effect of Beauveria bassiana on the ovarian development and reproductive potential of Anastrepha ludens (Diptera: Tephritidae)

We investigated the virulence of a native strain of Beauveria bassiana on the mortality, ovarian development, oogenesis, survival, fecundity and fertility of 4-, 8- and 12-day-old Anastrepha ludens females. In the first study, this strain caused 85% mortality in 8-day-old treated females, with a median lethal concentration (LC₅₀) of 3.1×10⁸ (2.1×10⁸–4.7×10⁸) conidia/mL and a median lethal time (LT₅₀) of 6.5 days. In the second study, the ovarian development and oogenesis of A. ludens females treated with 1×10⁹ conidia/mL were monitored daily in sacrificed flies. The fungus infection did not significantly affect ovarian development of the treated females, although there was a delay in vitellogenesis and a reduction in the quantity of mature basal oocytes and oviposition index in these flies. Moreover, the lowest net fecundity was found in 4-, 8- and 12-day-old treated females, and reduced fertility was observed in 4-day-old treated females. An application to test the potential use of this strain under field conditions is discussed.     

Reproductive behaviour of the South American fruit fly Anastrepha fraterculus (Diptera: Tephritidae): laboratory and field studies

Abstract. The mate choice, courtship and oviposition behaviour of laboratory-reared and field-collected Anastrepha fraterculus (Wied.) were compared. In laboratory cultures in Southampton the duration of male calling activity in small leks increased gradually from 1-2h at 5 days old to up to 7 h at 10 days. This finding correlates with previous reports on the time at which male salivary glands, which are believed to produce sex pheromone, are fully developed. Wild flies which emerged from infested fruits in Brazil began to oviposit on the day they mated, whereas in laboratory flies oviposition began 1 day following the first mating. Both types of fly usually defended their position on a particular fruit throughout the day, and re-mated with either virgin or mated males. There was no significant difference in mating duration. Females did not copulate before the mean age (±SE) of 16.8±0.9 days. For both types of flies mating initiation occurred in the first 2h of photophase, with virgin females choosing mainly mated males. The average number of matings in the laboratory was three for females and four for males, and the interval between matings in females was significantly increased after the second mating. It is suggested that the tendency of virgin females to mate with mated males will lead to increased fitness, as males are on average 48 days old at their second mating. The potential life span of around 200 days for both sexes would allow adults to bridge the gap between seasonally available fruits in warm-temperate and sub-tropical South America.     

Microsatellite loci from the Caribbean Fruit Fly,Anastrepha suspensa (Diptera: Tephritidae)

The lack of polymorphic genetic markers suitable for genotyping sperm, eggs, and all life stages of the important agricultural pest, Anastrepha suspensa, have prevented detailed genetic studies of its breeding system, reproductive dynamics, and population dynamics. We describe polymerase chain reaction (PCR) primers and reaction conditions for amplifying nine polymorphic microsatellite DNA loci isolated from this species. The PCR primers were tested on four to five individuals each collected from five geographically distant locations in Florida. Heterozygosity values and the number of alleles per locus varied from 0.11 to 0.89, and from two to 12, respectively.     

Wolbachia endosymbiont in a species of the Anastrepha fraterculus complex (Diptera: Tephritidae)

Summary

In Anastrepha sp.2 aff. fraterculus, the egg-cell harbours a large population of endosymbionts. The bacteria were identified as belonging to genus Wolbachia by PCR assay using primers of the ftsZ gene followed by sequencing of the amplified band. Newly deposited eggs stained in toto by Hoechst show that the bacteria are unevenly dispersed throughout the egg-cell, with a higher accumulation at the posterior pole, and that the degree of infestation varies from egg to egg. Analysis by transmission electron microscopy shows that bacteria are present in the female germ line of embryonic and larval stages, as well as in the different cell types of the ovaries at the adult stage. Mature ova within the follicles harbour a large population of the symbionts. The results indicate the existence of a transovarian transmission of the endosymbionts in this fly.     

Competitive strategies between Anastrepha fraterculus and Anastrepha obliqua (Diptera: Tephritidae) regulating the use of host fruits

Interspecific competition between individuals of different species can result in reductions in their fecundity, growth or survival, reflecting differential exploitation of resources that become intensified due to spatial co-occurrence, ecological similarity and increased population densities. As two species cannot occupy the same niche, coexistence is only possible if the available resources are used in non-overlapping manners such as niche partitioning or the use of refuges. Among agricultural insect pests, such as fruit flies of the family Tephritidae, competitive interactions can result in competitive displacement, host changes, or the expansion or restriction of the numbers of hosts utilized that can have negative consequences for human agricultural activities. We evaluated the competitive interactions between two fruit fly species of the genus Anastrepha, Anastrepha obliqua (Macquart, 1835) and Anastrepha fraterculus (Wiedmann, 1830), on their respective preferred hosts (mangoes and guava). Experiments of larval competition and competition for ovipositioning sites by adult females were performed to compare the parameters of larval development time, numbers of pupae and emerged adults and numbers of ovipositions in the presence or absence of interspecific competition. We observed that the interactions between those species were asymmetrical and hierarchical, and our results suggest a competitive displacement of A. fraterculus by A. obliqua when those two species are present on the same fruit, whether mangoes or guavas.     

The Identity of Specimens of the Anastrepha fraterculus Complex (Diptera, Tephritidae) with Atypical Aculeus Tip

Several specimens collected in Paraguay along with Anastrepha fraterculus (sensu lato) have an aculeus tip similar to species from the fraterculus complex, but the teeth of the aculeus of these specimens are poorly defined. As Anastrepha species identification is based mostly on subtle differences in the aculeus tip, we studied these specimens with atypical aculeus tips (with poorly defined teeth) that slightly differs from the aculeus tip of species of the fraterculus complex (with well-developed blunt teeth), to determine if this is due to intraspecific variation or if it can characterize a full species. The Paraguayan specimens were separated in six groups under stereomicroscope according to variation in their aculeus tip. Specimens within each group were studied by means of morphometrics (traditional and geometric) and gene sequence analysis (COI and ITS1). Morphometric analyses were significant, but no clear groups were formed by the discriminant analyses of the aculeus and wing, and the COI and ITS1 sequence analysis clustered specimens with all six aculeus variations. Therefore, the subtle morphological differences observed in the aculeus tip of Paraguayan specimens are intraspecific variations and the Paraguayan specimens were more genetically closely related to Anastrepha sp. 3 from the fraterculus complex.     

An integrative multidisciplinary approach to understanding cryptic divergence in Brazilian species of the Anastrepha fraterculus complex (Diptera: Tephritidae)

An integrative multidisciplinary approach was used to delimit boundaries among cryptic species within the Anastrepha fraterculus complex in Brazil. Sexual compatibility, courtship and sexual acoustic behaviour, female morphometric variability, variation for the mitochondrial gene COI, and the presence of Wolbachia were compared among A. fraterculus populations from the Southern (Vacaria, Pelotas, Bento Gonçalves, São Joaquim) and Southeastern (Piracicaba) regions of Brazil. Our results suggest full mating compatibility among A. fraterculus populations from the Southern region and partial pre‐zygotic reproductive isolation of these populations when compared with the population from the Southeastern region. A. fraterculus populations from both regions differed in the frequency of courtship displays and aspects of the calling phase and mounting acoustic signal. Morphometric analysis showed differences between Southern region and Southeastern region samples. All populations analyzed were infected with Wolbachia. The trees generated from the COI sequencing data are broadly congruent with the behavioural and morphometric data with the exception of one Southern population. The likely mechanisms by which A. fraterculus populations might have diverged are discussed in detail based on behavioural, morphometric, molecular genetics, and biogeographical studies.     

Wolbachia strains in cryptic species of the Anastrepha fraterculus complex (Diptera,Tephritidae) along the Neotropical Region

Infection by Wolbachia was described previously in eleven species of Anastrepha fruit flies some of which are important pests of fruticulture. One such species is the nominal Anastrepha fraterculus, the South American fruit fly, which actually comprises a complex of cryptic species. The suggestions of using Wolbachia for the control of these pest species, make imperative a more precise characterization of the existing strains of the bacteria. In this study, population samples of the A. fraterculus complex from Brazil, Argentina, Peru, Ecuador, Colombia, Guatemala and Mexico were analyzed for Wolbachia infection. The bacteria were genotyped by the MLST and WSP Typing methodologies. All samples were infected with Wolbachia of supergroup “A”. For each of the five MLST genes, unique as well as already known alleles were detected. Nineteen sequence types for the concatenated sequences of the five MLST genes, and twenty wsp alleles were found in the samples. Host-specific haplotypes, shared strains among distinct hosts, and more than one strain of Wolbachia were found in some population samples. Recombination among the MLST genes and intragenic recombination between wsp haplotypes was rare. Phylogenetic analysis showed a great similarity among the Wolbachia strains in the A. fraterculus complex. However, some strains of Wolbachia are found throughout the Neotropical Region and there are specific strains in determined geographical areas.     

Intraspecific variation of cuticular hydrocarbon profiles in the Anastrepha fraterculus (Diptera: Tephritidae) species complex

The goal of this study was to define whether cuticular hydrocarbons (CHs) could be used for taxonomic determination of putative species hidden in the Anastrepha fraterculus cryptic species complex, widespread from Argentina to Mexico. Recently, increasing evidence of phenotypic and genetic variability has resulted in the characterization of eight morphotypes within this complex. The CH profiles of six A. fraterculus populations from Argentina, Brazil, Peru, Colombia and Mexico were analysed in this study by two‐dimensional gas chromatography coupled with mass spectrometry. In parallel, multiple factorial analyses were used to elucidate population structures. Vector populations segregated into four distinct groups. The analysis demonstrated that the studied populations from Peru, Argentina and southern Brazil (Vacaria) might be classified in accordance with the earlier division of the A. fraterculus complex into Peruvian, and Brazilian‐1 cryptic species, using the specific CH profiles. Population from south‐eastern Brazil (Piracicaba) formed separated group. Mexican and Andean (Colombian) putative species had similar CH signatures, when compared to each other.     

Population genetics of Anastrepha fraterculus (Diptera,Tephritidae) in different hosts: Genetic differentiation and heterozygosity

An allozymic survey of 11 populations of Anastrepha fraterculus Wied. (Diptera, Tephritidae) in 8 different hosts from the same orchard revealed very small levels of genetic distance (D = 0.002±0.001) between hosts. The data thus provide no evidence for host-dependent genetic differentiation. Low values of heterozygosity were observed (H = 0.050±0.28) and 6 loci out of 11 were monomorphic. Biological attributes of the species, such as its polyphagic regime, multivoltine pattern of reproduction, and seasonal changes in population size, are discussed in an attempt to explain the low variability.     

Morphometry and distribution of sensilla on the antennae of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae)

Antennal sensilla of Anastrepha fraterculus (Wied.) were examined using scanning electron microscopy. In the flagellum, there are trichoid, basiconic, clavate type I and II, and styloconic sensilla and microtrichia. Only microtrichiae and chaetica sensilla were observed in the scape and pedicel. The number of sensilla in the flagellum was similar between sexes. At the apex there was a higher density of trichoid and an absence of clavate sensilla, while basiconic sensilla were more abundant in the proximal region.     

Comparative demography of three neotropical larval-prepupal parasitoid species associated with Anastrepha fraterculus (Diptera: Tephritidae)

The South American fruit fly, Anastrepha fraterculus (Wiedemann), is one of two fruit fly species of economic importance in Argentina, which along with the exotic Mediterranean fruit fly, Ceratitis capitata (Wiedemann) produce annual losses of nearly US$ 90 million for fruit production in this country.Biological control may contribute to integrated approaches to manage both pestiferous species.Information on survival, reproduction and population growth parameters, critical for successful augmentation of natural enemies, is provided for three fruit fly neotropical parasitoids, Aganaspis pelleranoi (Hymenoptera: Figitidae), Opius bellus and Doryctobracon crawfordi (Hymenoptera: Braconidae). A. pelleranoi had the highest intrinsic reproductive rate (r), survival time and reproductive time, followed by O. bellus. Meanwhile D. crawfordi showed the lowest values for reproductive and population growth parameters.     

Biological attributes of three introduced parasitoids as natural enemies of fruit flies,genus Anastrepha (Diptera: Tephritidae)

The biological attributes of three introduced species of parasitoids which attack the fruit fly Anastrepha ludens were evaluated. Larvae and eggs of A. ludens were exposed to larval parasitoids Diachasmimorpha longicaudata and D. tryoni and the egg parasitoid Fopius arisanus. Parasitoid longevity and fecundity were determined using larvae and eggs of A. ludens. Likewise, the parasitism rates of these parasitoid species in infested host fruits were recorded. The intrinsic rate of increase for F. arisanus was 0.1019 followed by D. tryoni with a rate of 0.1641 and D. longicaudata with the highest rate of 0.2233. Although F. arisanus females had the highest levels of fecundity, only 50% of them remained alive until reproductive age. These results in combination with the longer generation time (in comparison with D. longicaudata and D. tryoni), can be considered as the most important factors explaining F. arisanus reduced rate of increase. However, we note that oviposition activity caused egg mortality which reduced Anastrepha egg hatch by ca. 20%. This result suggests that F. arisanus has a high potential as a natural enemy of A. ludens, in accordance with our research efforts to develop a new F. arisanus strain specialized for development in Anastrepha eggs. The results show that D. tryoni is not a good candidate for biological control of Anastrepha. Meanwhile, D. longicaudata continues to be the most important exotic parasitoid for suppression of Anastrepha fruit fly populations.     

Ornithine decarboxylase activity during development of the mouse inner ear in vivo and in vitro

Summary Ornithine decarboxylase activity was determined during the development of the peripheral auditory system in the murine otocyst with the goal of understanding the role of this enzyme in the morphological and functional maturation of the inner ear. At gestational days 11 and 12 enzyme activity was more than 10-fold higher than adult levels. A sharp decline occured between day 12 and 13 after which activity rose to a peak around day 15. Activity then dropped continuously until near-adult levels were reached at birth. A lower specific activity of ODC but a similar time-course was seen in otocysts explanted at gestational day 13 and subsequently cultured for 6 days. For two stages of development, enzyme activity and binding of ³H--difluoromethylornithine were compared. The four-fold difference in enzymatic activity on gestational days 15 and 17 was paralleled by a similar difference in binding. Ornithine decarboxylase activity during inner ear development therefore seems primarily regulated at the level of protein synthesis. Ornithine decarboxylase activity correlates with major inductive events in the morphogenesis of the cartilagenous otic capsule that serves as a template for the formation of the bony labyrinth. The pattern of activity may reflect the changes in the head mesenchyme that is recruited by the otocyst to aggregate and form its protective otic capsule.     

Olfactory response of Anastrepha striata (Diptera: Tephritidae) to guava and sweet orange volatiles

The behavioral responses of virgin and mated female Anastrepha striata Schiner (Diptera: Tephritidae) to guava (Psidium guajava L.) or sweet orange (Citrus sinensis L.) were evaluated separately using multilure traps in two‐choice tests in field cages. The results showed that flies were more attracted to guava and sweet orange volatiles than to control (unbaited trap). The physiological state (virgin or mated) of females did not affect their attraction to the fruit volatiles. Combined analysis of gas chromatography coupled with electroantennography (GC‐EAD) of volatile extracts of both fruits showed that 1 and 6 compounds from orange and guava, respectively elicited repeatable antennal responses from mated females. The EAD active compounds in guava volatile extracts were identified by gas chromatography‐mass spectrometry (GC‐MS) as ethyl butyrate, (Z)‐3‐hexenol, hexanol, ethyl hexanoate, hexyl acetate, and ethyl octanoate. Linalool was identified as the only antennal active compound in sweet orange extracts. In field cage tests, there were no significant differences between the number of mated flies captured by the traps baited with guava extracts and the number caught by traps baited with the 6‐component blend that was formulated according to the relative proportions in the guava extracts. Similar results occurred when synthetic linalool was evaluated against orange extracts. From a practical point of view, the compounds identified in this study could be used for monitoring A. striata populations.