[show abstract][hide abstract] ABSTRACT: The courtship acoustics of five species of parasitoid wasps (Hymenoptera: Braconidae), potential candidates for augmentative
biological control of Anastrepha (Schiner) species (Diptera: Tephritidae), were compared between recently colonized individuals and those continuously reared
70–148 generations. During courtship, males of these parasitoid species fan their wings and produce a series of low amplitude
pulses. The first series of 15 or more continuous courtship pulses was used to measure the pulse duration, frequency, and
interpulse interval (IPI) from the beginning, middle, and end of the pulse series. Each parameter was compared between young
and old colonies, and among species. Several differences in courtship acoustics were detected in colonies that had been continuously
reared. The pulse duration at the end of the pulse series was longer in old colonies for Doryctobracon crawfordi (Viereck) (Hymenoptera: Braconidae), but shorter for old colonies of Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). The IPI of the middle pulse was shorter in old colonies of Opius hirtus (Fischer) (Hymenoptera: Braconidae), and was also shorter at the last pulse for old colonies of both Utetes anastrephae (Viereck) (Hymenoptera: Braconidae) and D. longicaudata. The duration of the middle pulse distinguished the three native species, and separated the two introduced species from each
other. We discuss our findings in light of their biological and applied implications, particularly those dealing with quality
control of mass-reared parasitoids.
-Mass rearing-Laboratory selection-Quality-Rearing substrate-Courtship vibration
[show abstract][hide abstract] ABSTRACT: 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.
Journal of Economic Entomology 08/2011; 104(4):1204-11. · 1.60 Impact Factor
[show abstract][hide abstract] ABSTRACT: Life history theory predicts that individuals will allocate resources to different traits so as to maximize overall fitness. Because conditions experienced during early development can have strong downstream effects on adult phenotype and fitness, we investigated how four species of synovigenic, larval-pupal parasitoids that vary sharply in their degree of specialization (niche breadth) and life history (Diachasmimorpha longicaudata, Doryctobracon crawfordi, Opius hirtus and Utetes anastrephae), allocate resources acquired during the larval stage towards adult reproduction. Parasitoid larvae developed in a single host species reared on four different substrates that differed in quality. We measured parasitoid egg load at the moment of emergence and at 24 h, egg numbers over time, egg size, and also adult size. We predicted that across species the most specialized would have a lower capacity to respond to changes in host substrate quality than wasps with a broad host range, and that within species, females that emerged from hosts that developed in better quality substrates would have the most resources to invest in reproduction. Consistent with our predictions, the more specialized parasitoids were less plastic in some responses to host diet than the more generalist. However, patterns of egg load and size were variable across species. In general, there was a remarkable degree of reproductive effort-allocation constancy within parasitoid species. This may reflect more "time-limited" rather than "egg-limited" foraging strategies where the most expensive component of reproductive success is to locate and handle patchily-distributed and fruit-sequestered hosts. If so, egg costs, independent of degree of specialization, are relatively trivial and sufficient resources are available in fly larvae stemming from all of the substrates tested.
Journal of insect physiology 07/2011; 57(11):1471-9. · 2.24 Impact Factor
[show abstract][hide abstract] ABSTRACT: Tephritid fruit fly parasitoids use fruit-derived chemical cues and the vibrations that result from larval movements to locate hosts sequestered inside fruit. However, compounds produced by the larvae themselves have not been previously described nor their significance to parasitoid foraging determined. We collected the volatiles from four species of tropical and subtropical Tephritidae: Anastrepha suspensa (Loew), Bactrocera dorsalis Hendel, Bactrocera cucurbitae Coquillett, and Ceratitis capitata (Wiedemann), representing two subfamilies (Dacinae and Trypetinae). Para-ethylacetophenone, an analog of a known tephritid parasitoid attractant, was a major constituent of all four, and was not associated with larvae of another acalypterate fly, Drosophila melanogaster Meigen, or with the calypterate Musca domestica L. It also was present in volatiles from whole, A. suspensa infested fruits of Eugenia uniflora (L.). Para-ethylacetophenone was not necessarily produced as a direct consequence of fruit consumption because it also was detected from larvae that developed in two artificial diets and in spent diets subsequent to larval development. Sensillae on both the antennae and ovipositor of the opiine braconid fruit fly parasitoid, Diachasmimorpha longicaudata (Ashmead) responded to the para-ethylacetophenone in larval volatiles and as a synthetic. Although a potential cue to foraging parasitoids, para-ethylacetophenone showed no long range (>1m) attractiveness to the adult female parasitoid, but did stimulate ovipositor-insertion and oviposition into both a natural (fruit) and an artificial (parafilm) substrate. Thus it may prove useful in colonizing and mass-rearing opine fruit fly parasitoids.
[show abstract][hide abstract] ABSTRACT: F. ceratitivorus Wharton es un parasitoide Braconido de la mosca del Mediterráneo (= moscamed), Ceratitis capitata (Wied.), recientemente descubierto. A diferencia de otros parasitoides previamente usados en el control biológico de la moscamed, F. ceratitivorus fue colectado originalmente de moscamed en su supuesta región de origen, al este de Africa. Envíos de pupa de tephritidos desde Kenia hacia la recientemente construida instalación de Cuarentena en Guatemala, produjeron especimenes de F. ceratitivorus y su congener F. caudatus (Szepligeti). Solo la primera especie fue colonizada exitosamente mediante el uso de frutos de café infestados por moscamed. En el proceso de colonización se determinó que F. ceratitivorus oviposita sobre los huevos y larvas recientemente eclosionadas de moscamed, y que completa su desarrollo en la pupa huésped. Este es un comportamiento relativamente raro dentro de los parasitoides de moscas de la fruta, y debido a que los huevos de los tephritidos cercanos a la superficie del fruto son particularmente vulnerables, ello podría contribuir a su éxito como agente de control biológico.
[show abstract][hide abstract] ABSTRACT: Doryctobracon areolatus (Szepligeti) (Hymenoptera: Braconidae) es un parasitoide común de Anastrepha spp. (Diptera: Tephritidae). Un método eficiente de criarlos en el laboratorio incorpora unos químicos de la fruta de la pera en las unidades de oviposición. La producción en las generaciones F1 y F2 fueron 12.1 y 9.3 descendientes por hembra, respectivamente. El promedio de la producción diaria de los descendientes para las hembras de F2 fué entre 1-2 descendientes por hembra para casi todas las edades de 9 a 22 dias. Un bioensayo fué diseñado para determinar la fuente de las señales químicas usadas para la ubicación del hospedero. Los parasitoides podian escoger entre dos unidades de oviposición: un control positivo que tenia todas las señales posibles, y una unidad de tratamiento con las señales derivadas ya sea de la mosca hospedera, de la fruta hospedera, ó ambas, ó ninguna de las dos. Se registró el número de hembras activas sobre cada unidad de oviposición. Este experimento demostró que las señales químicas derivadas de la fruta hospedera, probablemente la cascara, estan envueltas en la localización del hospedero.
[show abstract][hide abstract] ABSTRACT: The apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is an important pest of apples (Malus spp.) and model system for sympatric speciation via host shifting for phytophagous insects. The distribution of R. pomonella is well-characterized in the United States and Canada, but it is poorly characterized in Mexico, where it may represent a different, allopatrically isolated taxon. Here, we report results of a nationwide survey aimed at determining the distribution and host range of hawthorn-infesting Rhagoletis in Mexico. Eight of the 13 endemic species of hawthorn (Crataegus spp.) were collected in temperate high-altitude habitats (1,600–2,800 m) across 21 Mexican states. Five of the eight hawthorns were confirmed to be hosts for Mexican R. pomonella. Fly populations were found throughout most of the natural distribution of hawthorn in Mexico. Mean pupal mass for fly populations clustered into two large weight groups associated with hawthorn species exhibiting different fruiting phenologies. Pupae infesting early fruiting hawthorns along the Sierra Madre Oriental were lighter than pupae infesting late-fruiting hawthorns across the Eje Volcánico Trans Mexicano. The differences in pupal weight may reflect host-related environmental effects or be genetically based, the latter implying the possible existence of two phenologically differentiated and geographically distinguishable fly taxa in Mexico. We discuss the significance of our findings for the phylogeography and adaptive radiation of the R. pomonella sibling species group, to which the hawthorn race belongs.
Annals of the Entomological Society of America 01/2009; · 1.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: The geographic distribution of three braconid parasitoids of the Caribbean fruit fly, Anastrepha suspensa (Loew), was determined by collecting host fruit throughout central and southern Florida. Diachasmimorpha longicaudata (Ashmead) was most abundant in southern Florida, occurring at higher latitudes along the Atlantic and Gulf coasts. Distribution of this species was negatively related to variance of monthly temperatures. This suggests that D. longicaudata may be dependent on a relatively constant supply of hosts. Doryctobracon areolatus (Szepligeti) was the dominant species at the majority of interior locations, but it was uncommon or absent along both coasts. Utetes anastrephae (Viereck) was widespread but usually less common than the other species. Parasitism levels of both D. areolatus and D. longicaudata were positively related to density of common guava, Psidium guajava L., trees. Parasitism levels of both D. longicaudata and U. anastrephae were positively related to numbers of A. suspensa captured in McPhail traps. Abundance of D. areolatus was inversely related to that of both D. longicaudata and U. anastrephae. The absence of D. areolatus in southeastern Florida, where it was originally established, suggests that a process of competitive displacement may have occurred. Parasitoid distribution is consistent with the hypothesis that D. areolatus is a superior searcher and D. longicaudata is a superior intrinsic competitor.
Annals of the Entomological Society of America 01/2009; · 1.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: The spatial and temporal patterns of oviposition-resource use of various Anastrepha spp. fruit flies within the canopies of individual fruit trees were determined over periods of 4–6 yr in the state of Veracruz, Mexico. The flies examined were Anastrepha obliqua (Macquart), Anastrepha striata Schiner, Anastrepha fracterculus (Wiedemann), and Anastrepha alveata Stone, and their respective hosts were Spondias mombin L. (Anacardiaceae), Psidium guajava L., Psidium sartorianum (Berg.) Ndzu (Myrtacaea), and Ximenia americana L. (Olacaceae). The canopies were divided into six sectors: three strata (vertical planes of low, middle, and high canopy) and an exterior and interior component of the various heights. All ripe fruits produced by each tree species were individually harvested, weighed, and maintained until all larvae had exited and pupated. Because of the commonly positive correlation between fruit size and infestation, fly distributions were described using a novel technique, two-level hierarchal regression analysis, as deviations from the expected numbers of insects in a sector given the distributions of fruit weights within the canopy. Overall, there was a tendency for A. alveata to be more abundant in the lower portions of the tree, for A. striata to be more abundant in the upper, for A. obliqua to be less abundant in the upper, and for A. fraterculus to be uniformly distributed. The yearly densities of A. striata and A. fraterculus within the P. guajava tree were negatively correlated, and this seems to be due to annual changes in environment rather than to exploitive competition for oviposition resources. Along an altitudinal gradient (0–1,800 m), A. striata was more abundant than A. fraterculus at sea level and relatively less abundant at altitudes of 1000 m and higher. We suggest that habitat characteristics (oviposition-resource availability and quality, and microclimatic variables), intraspecific competition, and the behaviors of natural enemies and frugivores are potentially important interactive factors that influence the distribution of resource use to a different extent in each of the tephritid species.
Annals of the Entomological Society of America 01/2009; · 1.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: We describe the techniques used to colonize and domesticate seven native New World species of hymenopterous parasitoids that attack flies within the genus Anastrepha (Diptera: Tephritidae). All parasitoid species successfully developed on artificially reared Mexican fruit fly, Anastrepha ludens (Loew) larvae or pupae. The parasitoid species colonized were the following: Doryctobracon areolatus (Szepligeti), Doryctobracon crawfordi (Viereck), Opius hirtus (Fischer), Utetes anastrephae (Viereck) (all Braconidae, Opiinae), Aganaspis pelleranoi (Brethes) and Odontosema anastrephae Borgmeier (both Figitidae, Eucoilinae) (all larval-pupal parasitoids), and the pupal parasitoid Coptera haywardi (Ogloblin) (Diapriidae, Diapriinae). We provide detailed descriptions of the different rearing techniques used throughout the domestication process to help researchers elsewhere to colonize local parasitoids. We also describe handling procedures such as number of hosts in parasitization units and compare optimal host and female age, differences in parasitism rate, developmental time, life expectancy and variation in sex ratios in each parasitoid species over various generations. In the case of D. crawfordi and C. haywardi we also provide partial information on mass-rearing techniques such as cage type, parasitization unit, larval irradiation dose and adult handling.
Biocontrol Science and Technology 09/2008; 19:49-79. · 0.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aim of this study was to ascertain if eight species of native larval-prepupal and pupal Anastrepha (Diptera: Tephritidae) parasitoids which have been recently domesticated and colonized (Aluja et al. in press) could be reared on irradiated larvae and pupae, and if such was the case, determine the optimal irradiation dose so that only adult parasitoids (not flies) would emerge. The species considered were: Doryctobracon crawfordi, Utetes anastrephae, Opius hirtus (all larval-prepupal braconids), Aganaspis pelleranoi, Odontosema anastrephae (both larval-prepupal figitids), Coptera haywardi, Eurytoma sivinskii and Dirhinus sp. (diapriid, eurytomid and chalcidoid pupal parasitoids). Eight-day-old A. ludens larvae or 3-day-old A. ludens pupae were irradiated with 0, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60 and 70 Gy under free oxygen and then subjected to parasitoid attack. Emergence of the unparasitized host was completely halted at 20-25 Gy but such was not the case with the three braconid parasitoids that emerged even if subjected to doses as high as 70 Gy. In the case of the figitids, the emergence of the host and the parasitoids was completely halted at 20 and 25 Gy, respectively. Some parasitoid emergence was recorded at 5-15 Gy but at this irradiation dose, fly adults also emerged rendering the fly/parasitoid separation procedures impractical. Finally, in the case of the pupal parasitoids, A. ludens adults emerged from unparasitized pupae irradiated at 15 Gy. Beyond this dose, only parasitoids emerged. With the exception of the figitid larval-prepupal parasitoids, irradiation did not negatively affect adult longevity or fecundity. Our results show that parasitoid mass rearing with irradiated hosts is technically feasible.
Biocontrol Science and Technology 09/2008; 19:193-209. · 0.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: Many adult hymenopteran parasitoids, even host-feeding species, consume the nectar of flowering plants. Previous field studies had identified plants attractive (Lobularia maritima L.) and unattractive (Spermacoce verticillata L) to certain opiine braconids (Hymenoptera). Under laboratory conditions, Diachasmimorpha longicaudata (Ashmead), a parasitoid of tephritid fruit fly larvae and representative opiine, responded in flight tunnels to L. maritima but not to S. verticillata. Volatile chemicals of the two flowers were collected and analyzed by using capillary gas liquid chromatography and mass spectral analysis. Acetophenone was isolated from L. maritima but not from S. verticillata. In flight tunnels, D. longicaudata were exposed to 10 concentrations (doses) of acetophenone. Female parasitoids showed a significant attraction to several acetophenone doses, with concentrations of 25 and 50 ng the most attractive. No odor source, either floral or floral-derived, was attractive to male parasitoids. Reliable trapping systems for parasitoid species, particularly species such as D. longicaudata used for augmentative biological control, would be a valuable monitoring tool. At present, there are few, if any, florally derived synthetic lures for attracting hymenopteran parasitoids.
Journal of Chemical Ecology 05/2008; 34(4):549-57. · 2.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: We investigated two populations of Melittobia digitata Dahms, a gregarious parasitoid (primarily upon a wide range of solitary bees, wasps, and flies), in search of Wolbachia infection. The first population, from Xalapa, Mexico, was originally collected from and reared on Mexican fruit fly pupae, Anastrepha ludens Loew (Diptera: Tephritidae); the other, from Athens, Georgia, was collected from and reared on prepupae of mud dauber wasps, Trypoxylon politum Say (Hymenoptera: Crabronidae). PCR studies of the ITS2 region corroborated that both parasitoid populations were the same species; this potentially provides a useful molecular taxonomic profile since females of Melittobia species are superficially similar. Amplification of the Wolbachia surface protein gene (wsp) confirmed the presence of this endosymbiont in both populations. Sequencing revealed that the Wolbachia harbored in both populations exhibited a wsp belonging to a unique subgroup (denoted here as Dig) within the B-supergroup of known wsp genes. This new subgroup of wsp may either belong to a different strain of Wolbachia from those previously found to infect Melittobia or may be the result of a recombination event. In either case, known hosts of Wolbachia with a wsp of this subgroup are only distantly related taxonomically. Reasons are advanced as to why Melittobia - an easily reared and managed parasitoid - holds promise as an instructive model organism of Wolbachia infection amenable to the investigation of Wolbachia strains among its diverse hosts.
[show abstract][hide abstract] ABSTRACT: The genetic origins of species may not all trace to the same time and place as the proximate cause(s) for population divergence. Moreover, inherent gene-flow barriers separating populations may not all have evolved under the same geographical circumstances. These considerations have lead to a greater appreciation of the plurality of speciation: that one geographical mode for divergence may not always be sufficient to describe a speciation event. The apple maggot fly, Rhagoletis pomonella, a model system for sympatric speciation via host-plant shifting, has been a surprising contributor to the concept of speciation mode plurality. Previous studies have suggested that past introgression of inversion polymorphism from a hawthorn-fly population in the trans-Mexican volcanic belt (EVTM) introduced diapause life-history variation into a more northern fly population that subsequently contributed to sympatric host race formation and speciation in the United States (US). Here, we report results from a microsatellite survey implying (i) that volcanic activity in the eastern EVTM may have been responsible for the initial geographical isolation of the Mexican and northern hawthorn-fly populations c. 1.57 mya; and (ii) that flies in the Sierra Madre Oriental Mountains (SMO) likely served as a conduit for past gene flow from the EVTM into the US. Indeed, the microsatellite data suggest that the current US population may represent a range expansion from the northern SMO. We discuss the implications of these findings for sympatric race formation in Rhagoletis and speciation theory.
[show abstract][hide abstract] ABSTRACT: Categorizing speciation into dichotomous allopatric versus nonallopatric modes may not always adequately describe the geographic context of divergence for taxa. If some of the genetic changes generating inherent barriers to gene flow between populations evolved in geographic isolation, whereas others arose in sympatry, then the mode of divergence would be mixed. The apple maggot fly, Rhagoletis pomonella, has contributed to this emerging concept of a mixed speciation mode "plurality." Genetic studies have implied that a source of diapause life-history variation associated with inversions and contributing to sympatric host race formation and speciation for R. pomonella in the United States may have introgressed from the Eje Volcanico Trans Mexicano (EVTM; a.k.a. the Altiplano) in the past. A critical unresolved issue concerning the introgression hypothesis is how past gene flow occurred given the current 1200-km disjunction in the ranges of hawthorn-infesting flies in the EVTM region of Mexico and the southern extreme of the U.S. population in Texas. Here, we report the discovery of a hawthorn-infesting population of R. pomonella in the Sierra Madre Oriental Mountains (SMO) of Mexico. Sequence data from 15 nuclear loci and mitochondrial DNA imply that the SMO flies are related to, but still different from, U.S. and EVTM flies. The host affiliations, diapause characteristics, and phylogeography of the SMO population are consistent with it having served as a conduit for gene flow between Mexico and the United States. We also present evidence suggesting greater permeability of collinear versus rearranged regions of the genome to introgression, in accord with recent models of chromosomal speciation. We discuss the implications of the results in the context of speciation mode plurality. We do not argue for abandoning the terms sympatry or allopatry, but caution that categorizing divergence into either/or geographic modes may not describe the genetic origins of all species. For R. pomonella in the United States, the proximate selection pressures triggering race formation and speciation stem from sympatric host shifts. However, some of the phenological variation contributing to host-related ecological adaptation and reproductive isolation in sympatry at the present time appears to have an older history, having originated and become packaged into inversion polymorphism in allopatry.
[show abstract][hide abstract] ABSTRACT: Following oviposition, females of many Tephritid flies deposit host marking pheromones (HMPs) to indicate that the host fruit has been occupied. We describe the foraging behavior of these three economically important species (Anastrepha ludens and A. obliqua from the fraterculus species group and A. serpentina from the serpentina species group) when they encounter an artificial fruit (green agar spheres wrapped in Parafilm) marked with intra- and interspecific feces extracts that contain, among other substances, host marking pheromone. When flies encountered fruit treated with either 1 or 100 mg/ml feces extract, there were drastic and statistically significant reductions in tree residence time, mean time spent on fruit, and in the number of oviposition attempts or actual ovipositions when compared to the control treatment (clean fruit). These responses were almost identical irrespective of extract origin (i.e., fly species), indicating complete interspecific HMP cross-recognition by all three Anastrepha species tested. We discuss the ecological and practical implications of our findings.
Journal of Chemical Ecology 03/2006; 32(2):367-89. · 2.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: We report the results of a study on potential food sources of the widely distributed Indo-Australian braconid fruit fly parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). Adults sustained life on diets of fruit juice or fruit pulp, a homopteran and its associated honeydew, or extrafloral nectary secretions. Longevities on all these foods and fecundity on fruit juice were comparable to those achieved on the honey that is typically provided in mass-rearing programs. Certain of the flower species Bidens alba (L.), Spermacoce verticillata L., Lobularia maritima (L.) Desv., Brassica nigra (L.), Lantana camara L., their nectar or pollen, provided a diet that resulted in longer maximum life spans than water alone. Unlike some tephritid flies, the braconid did not feed on fresh bird feces or leaf-surface exudates. Feeding by D. longicaudata on wounded host fruits of tephritid flies suggests that adult parasitoids would not need separate forays for adult food and oviposition sites, as these occur in the same locations. We conclude that an inventory of adult foods may help target inundative releases of D. longicaudata and lead to improvements in diets used for mass rearing.
[show abstract][hide abstract] ABSTRACT: Area-wide control of the Mediterranean fruit fly (=medfly), Ceratitis capitata (Wiedemann), typically involves sterile insect technique (=SIT), and at present the “Temperature Sensitive Lethal” (=TSL) strain is commonly mass-reared for such releases. In theory, and with some experimental support, the augmentative addition of parasitoids to sterile releases can suppress pest populations to a greater extent than either technique alone. The efficacies of TSL males, parasitoids, and TSL males and parasitoids were compared in large field cages erected over coffee grown at four locations and three altitudes (relatively high, medium and low for the crop) in Guatemala. Two species of opiine braconid parasitoids, the larval–pupal parasitoid Diachasmimorpha krausii (Fullaway) and the egg-pupal parasitoid Fopius arisanus (Sonan), were released either together or in combination with sterile males into cages along with fertile medflies. Results of this evaluation were assessed by comparing the number of pupae and adult insects that completed development (F1 generation) as a result of the reproduction of a parental generation released into each field cage. The TSL males significantly suppressed F1 fly populations but only in one of four study sites. However, the inclusion of F. arisanus and D. krausii always provided significant suppression and the effect was frequently substantial. In one site there was a significant interaction between the capacity of sterile males and parasitoids to suppress caged fly populations. There was no effect of host-fruit abundance on the numbers of flies recovered, however, there were significant interactions between maximum and minimum temperatures and the effects of sterile males and parasitoids, respectively. The results suggest that mass-reared sterile medflies and biological control agents should be tested for both consistent sexual-quality and their ability to perform in the various environments in which they will be released.
[show abstract][hide abstract] ABSTRACT: The Rhagoletis pomonella sibling species complex is a model for sympatric speciation by means of host plant shifting. However, genetic variation aiding the sympatric radiation of the group in the United States may have geographic roots. Inversions on chromosomes 1-3 affecting diapause traits adapting flies to differences in host fruiting phenology appear to exist in the United States because of a series of secondary introgression events from Mexico. Here, we investigate whether these inverted regions of the genome may have subsequently evolved to become more recalcitrant to introgression relative to collinear regions, consistent with new models for chromosomal speciation. As predicted by the models, gene trees for six nuclear loci mapping to chromosomes other than 1-3 tended to have shallower node depths separating Mexican and U.S. haplotypes relative to an outgroup sequence than nine genes residing on chromosomes 1-3. We discuss the implications of secondary contact and differential introgression with respect to sympatric host race formation and speciation in Rhagoletis, reconciling some of the seemingly dichotomous views of Mayr, Dobzhansky, and Bush concerning modes of divergence.
Proceedings of the National Academy of Sciences 06/2005; 102 Suppl 1:6573-80. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Tephritid fruit flies belonging to the Rhagoletis pomonella sibling species complex are controversial because they have been proposed to diverge in sympatry (in the absence of geographic isolation) by shifting and adapting to new host plants. Here, we report evidence suggesting a surprising source of genetic variation contributing to sympatric host shifts for these flies. From DNA sequence data for three nuclear loci and mtDNA, we infer that an ancestral, hawthorn-infesting R. pomonella population became geographically subdivided into Mexican and North American isolates approximately 1.57 million years ago. Episodes of gene flow from Mexico subsequently infused the North American population with inversion polymorphism affecting key diapause traits, forming adaptive clines. Sometime later (perhaps +/-1 million years), diapause variation in the latitudinal clines appears to have aided North American flies in adapting to a variety of plants with differing fruiting times, helping to spawn several new taxa. Thus, important raw genetic material facilitating the adaptive radiation of R. pomonella originated in a different time and place than the proximate ecological host shifts triggering sympatric divergence.
Proceedings of the National Academy of Sciences 10/2003; 100(18):10314-9. · 9.74 Impact Factor