Anastrepha Species Research Articles

Behavioural plasticity in relation to egg and time limitation: the case of two fly species in the genus Anastrepha (Diptera: Tephritidae)

Reproductive opportunities in insects that deposit their eggs in discrete resource patches are frequently limited because the availability of oviposition substrates is often spatially and temporally restricted. Such environmental variability leads individuals to confront time‐ or egg‐limitation constraints. Additionally, species with different oviposition strategies (i.e. single egg layers vs clutch layers) commonly deal with different structural and ecological characteristics of larval host plants. To test the hypothesis that oviposition strategies such as laying eggs singly or in batches (clutches) are related to these constraints (i.e. egg vs time limitation), we compared the lifetime oviposition patterns of two closely related sympatric species of Anastrepha (Diptera: Tephritidae) with different oviposition strategies. We exposed five cohorts of A. obliqua and A. ludens females, over the course of their adult lifetimes, to three conditions of “habitat quality” (measured as host density per cage): unpredictable habitat quality (host density varied randomly from day to day between 1, 5, 15, 30 and 60 hosts/cage), low habitat quality (fixed density of one host/cage) and high habitat quality (fixed density of 60 hosts/cage). Responses to host density conditions were strikingly different in the two species. (1) Frequency of host visits and oviposition events increased in A. obliqua but not in A. ludens when host densities increased. (2) Anastrepha ludens females accepted low quality hosts (i.e. fruits on which eggs had already been laid and were therefore partially covered with host marking pheromone) significantly more often than A. obliqua females did. (3) Females of A. obliqua adjusted their oviposition activity to variations in host density, whereas A. ludens females exhibited a constant oviposition pattern (i.e. did not respond to variations in host density). Based on the above, it is likely that in A. obliqua oviposition is governed by egg‐limitation and in A. ludens by time‐limitation constraints. We discuss the relationship between the oviposition strategies of each fly species and the fruiting phenology and density of their native host plants. We also address the possible influence of oogenesis modality and parasitism by braconid wasps in shaping oviposition behaviour in these insects.

Parasitismo Sazonal e Flutuação Populacional de Opiinae (Hymenoptera: Braconidae), Parasitóides de Espécies de Anastrepha (Diptera: Tephritidae), em Seropédica, RJ

O presente estudo foi conduzido com o objetivo de avaliar variacoes anuais na abundância de parasitoides Opiinae e nas suas percentagens de parasitismo em larvas de Anastrepha spp., sob a influencia de fatores climaticos e da disponibilidade dos frutos hospedeiros em Seropedica, RJ. Os opiineos Doryctobracon areolatus (Szepligeti), Utetes (Bracanastrepha) anastrephae (Viereck) e Opius bellus Gahan foram coletados em associacao com cinco especies de Anastrepha: A. fraterculus (Wied.), A. leptozona Hendel, A. obliqua (Macquart), A. serpentina (Wied.) e A. sororcula Zucchi. Nos dois anos de amostragem (1998 e 1999), D. areolatus foi a especie mais abundante e esteve presente em todos os meses de coleta. U. anastrephae e O. bellus nao ocorreram nas amostras de frutos coletadas durante o inverno (junho a agosto). Observou-se que esses opiineos responderam similarmente as variacoes sazonais das condicoes climaticas (precipitacao e temperatura) e do numero de moscas emergidas. Embora as percentagens de parasitismo de Anastrepha pelas tres especies de Opiinae nao se tenham correlacionado com os fatores climaticos, houve uma tendencia dos parasitoides exercerem mais ativamente seu parasitismo nos meses mais quentes e chuvosos do ano (verao). Esses meses caracterizaram-se por maior disponibilidade de frutos nativos. As correlacoes entre o numero mensal de adultos de cada especie de parasitoides e as medias mensais de precipitacao e temperatura foram significativas e positivas. Nao houve correlacao com a umidade relativa do ar. As tres especies de parasitoides foram mais abundantes nos periodos relativamente mais quentes e chuvosos do ano (verao, dezembro a fevereiro, e outono, marco a maio). Decrescimos de temperatura e precipitacao pluviometrica, registrados a partir de maio, determinaram a diminuicao no numero de parasitoides e moscas emergidos durante o inverno. Verificou-se tambem que as flutuacoes das populacoes dos opiineos, entre as estacoes, foram significativamente correlacionadas com as variacoes numericas nas populacoes das especies de Anastrepha, indicando uma relacao dependente da densidade direta. Observou-se tambem que os opiineos tornaram-se mais efetivos em altas densidades de seus hospedeiros, indicando exibir baixa capacidade de encontra-los.

Native Hymenopteran Parasitoids Associated with Anastrepha spp. (Diptera: Tephritidae) in Seropedica City, Rio de Janeiro, Brazil

Parasitoids associated with five species of Anastrepha were recovered from host fruits that belong to 12 species of plants growing in Seropedica city, Rio de Janeiro, Brazil. We recovered six native hymenopteran parasitoid species: Doryctobracon areolatus (Szepligeti), Utetes (Bracanastrephae) anastrephae (Viereck), Opius bellus Gahan (Braconidae, Opiinae), Aganaspis pelleranoi (Brethes) (Figitidae, Eucoilinae), Trichopria anastrephae Lima (Diapriidae, Diapriinae) and an unidentified species of Pteromalidae. The most abundant parasitoid species was D. areolatus, representing 61.8% of all parasitoids. The parasitoid species recovered were well established in a wide diversity of fruit and Anastrepha fly species, including economically important pests such as A. fraterculus, A. obliqua and A. sororcula. The analysis of the relative abundance of the recovered parasitoids in different fruit species suggests, at least for the three encountered opiine parasitoids, that the host-parasitoid relationship was influenced by certain physical characteristics such as size and weight of the host fruit. Our results support the original proposal of M. Aluja and J. Sivinski (pers. comm.) that some native host plant species for the Anastrepha flies facilitate parasitoid multiplication. They deserve attention as natural enemy reservoirs and may be important to biological control strategies within fruit fly integrated management programs.

Phylogenetic Relationships Among Species of the fraterculus Group (Anastrepha: Diptera: Tephritidae) Inferred from DNA Sequences of Mitochondrial Cytochrome Oxidase I

A fragment of 808 base pairs within the mtDNA gene cytochrome oxidase I (COI) was analyzed for 15 species of Anastrepha: 12 within the fraterculus group, one unplaced species and two outgroups. Phylogenetic relationships among the included taxa were inferred using neighbor-joining and maximum parsimony methods. The average Jukes-Cantor genetic distance among the species was 0.033±0.006 and the level of sequence divergence ranged from 0.0 to 0.083. Our results of COI indicate the placement of A. acris Stone, an unplaced species, in the fraterculus group. The membership of A. barbiellinii Lima in the fraterculus group and the monophyly of the aforementioned group are also discussed. Moreover, the presence of multiple gene pools in the nominal species A. fraterculus (Wiedemann) and the nonmonophyly of A. fraterculus are corroborated by data obtained in our study. The species A. amita Zucchi, A. turpiniae Stone and A. zenildae Zucchi were genetically studied for the first time.

Volatile substances from male Anastrepha fraterculus wied. (Diptera: Tephritidae): identification and behavioural activity

Volatile compounds produced by calling males of Anastrepha species have previously been reported from A. ludens and A. suspensa. Both species mate in the afternoon, release a similar range of compounds in different proportions, and only differ in the production of monoterpenes. When calling, male A. fraterculus releases two isomers of the sesquiterpene alpha-farnesene, three lactones (anastrephin, epianastrephin and (E,E)-suspensolide), and two monoterpenes (limonene and (Z)-beta-ocimene). The dimorphic male salivary glands produce and/or store the same isomers of alpha-farnesene and suspensolide, and four pyrazines. Two of these compounds have been previously reported from male A. ludens and A. suspensa. Salivary glands from virgin calling male A. fraterculus showed behavioural activity when bioassayed with virgin mature female flies, but immature females were not attracted.

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.

Host Species and Host Plant Effects on Preference and Performance ofDiachasmimorpha longicaudata(Hymenoptera: Braconidae)

Naive female Diachasmimorpha longicaudata (Ashmead), a solitary endoparasitoid of tephritid fruit flies, exhibited positive responses toward volatiles of host fruits in olfactometer and wind tunnel bioassays. Although no significant preference for one of the test fruits, mango, Mangifera indica L., or grapefruit, Citrus paradisi Macfaden, was observed, the number of flights in the wind tunnel was higher in the presence of mangos. In the olfactometer trials, parasitoids preferred fly infested over noninfested grapefruits, and infested over noninfested mangos. Reproductive performance bioassays were conducted using Anastrepha ludens (Loew) larvae (Diptera: Tephritidae) reared in grapefruit, orange, mango, or artificial diet, and Anastrepha obliqua (Macquart) larvae reared in mango as parasitoid hosts. Parasitoid performance was compared for 2 Anastrepha species and 3 fruit species. Significant effects of fruit fly species and of the diet of fruit fly larvae on longevity, size, and progeny production of D. longicaudata were observed. Anastrepha ludens reared in grapefruit was the best host in terms of offspring longevity, size, and number of female progeny, but parasitoids that developed in A. ludens reared in mango had higher overall fecundity. Anastrepha ludens reared in mango was a better host than A. obliqua in the same fruit. No correlation between parasitoid size and demographic parameters was found. The results of this laboratory study showed that host preference and offspring performance are partially related.

Acoustic component and social context of the wing display of the walnut fly Rhagoletis juglandis

Courtship signaling via wing vibration, accompanied by sound production, has been reported in several species of tephritids. In this large family of flies, sound communication as well as complex courtship displays appears to be restricted to species with lekking mating systems (i.e., Mediterranean fruit fly, Anastrepha and Dacus species). In contrast, in tephritid species with resource-defense mating systems, such as species in the genus Rhagoletis, little or no courtship behavior, acoustical or otherwise, has been described. Wing displays in Rhagoletis species have been considered to play a visual role. This study describes a distinctive wing display performed by males of the walnut fly, Rhagoletis juglandis. Laboratory experiments and field observations demonstrate that the male wing display plays a role in courtship. We used sound and vibration detectors to record the signals produced by this wing display. Using a combination of techniques, we were able to record both the very low-frequency vibration and its accompanying airborne infrasound (12–22 Hz) produced by the males.

Description of Anastrepha sororcula and A. serpentina (Diptera: Tephritidae) Eggs

The morphology of Anastrepha sororcula Zucchi and A. serpentina (Wiedemann) eggs are described by scanning electron microscopy. A. sororcula eggs present a conspicuous sculpturing of the chorion at the micropylar end while the eggs of A. serpentina are devoid of such ornamentation. The sculpturing of the A. sororcula eggs, represented by ridges in a polygonal arrangement, is more developed in the ventral than in the dorsal side of the egg. The micropyle is located in the dorsal side near the egg apex and is surrounded by a row of chorionic polygons. In A. serpentina the micropyle is located in a prominent rim very near the extremity of the egg. Aeropyles are found at the anterior end usually at the ventral side of the eggs. Fractured eggs of both species showed that the chorion is cavernous throughout the egg body. It is suggested that these eggs may be able to perform a plastron-mediated respiration. The results suggest that egg morphology may be useful to elucidate taxonomic and phylogenetic relationship among Anastrepha species.

Parasitoids Reared from Species of Anastrepha (Diptera: Tephritidae) in Valle Del Cauca, Colombia

Parasitoids associated with 8 species of Anastrepha were recovered from host fruits that belonged to 9 species of plants in the Cauca Valley, Colombia. These parasitoids were identified and quantified. The most common parasitoid was Doryctobracon zeteki, which was associated with the species A. leptozona, A. serpentina, A. nunezae and A. striata recovered from Pouteria caimito, Chrysophyllum cainito and Campomanesia lineatifolia host fruits.

Nutritive value of diets with different carbohydrates for adult Anastrepha obliqua (Macquart) (Diptera, Tephritidae)

Adult Tephritidae, especially of the genus Anastrepha (Schiner, 1868), have been observed to feed on a wide variety of natural diets. The fruit on which they feed, in general, are rich in sugar content, chiefly glucose, frutose and sucrose, which are also the sugars that those insects utilise better. Neither the behavioural mechanisms, nor the physiological ones, that control food selection by insects, are well known. Because some of those aspects are not known for the species Anastrepha obliqua (Macquart, 1835) either, and in order to understand their biology better, three experiments were conducted. In the first experiment, it was checked whether there was a difference in metabolic profit by those insects, when fed the carbohydrates more frequently found in nature, as resulting in a bigger egg production and higher survival rate at the end of the experiment. In the second, it was checked whether A. obliqua can regulate diet ingestion according to carbohydrate content in dry as well as wet diets. In the third experiment, measurements were made to establish the lowest carbohydrate concentration flies are able to recognise in the diet. Analysis of the data showed that ingestion of carbohydrates which are commonly found in nature, in association with a protein source, is very well utilised by females of A. obliqua. It was also shown that .those insects are not probably able to compensate for the difference in carbohydrate content in dry diets, whereas they do so for wet diets. In relation to discrimination threshold, it seems that it is related to the higher occurrence of the carbohydrate in their normal diet, that is, they can recognise carbohydrates that are common in their natural diet better than the less frequent ones.

Níveis de infestação de goiaba por Anastrepha zenildae Zucchi (Diptera: Tephritidae), em pomares comerciais do Norte de Minas Gerais

The infestation levels by Anastrepha zenildae Zucchi in common guava (Psidium guajava L.) were evaluated. The surveys were carried out in commercial groves of three counties of the North of the State of Minas Gerais, Brazil, from January to April 1996. A. zenildae should be considered a species of economic importance in the region as infestation indices (larvae/kg and larvae/fruit) were higher than those obtained for A. sororcula Zucchi. Only these two species were obtained directly from guava fruits. Besides A. zenildae and A. sororcula, specimens of A. fraterculus (Wied.), A. obliqua (Macquart) and of a new species of Anastrepha were also collected in traps set in the area.

Ecological Evidence for Diapause in Four Native and One Exotic Species of Larval-Pupal Fruit Fly (Diptera: Tephritidae) Parasitoids Tropical Environments

We provide ecological evidence for the existence of diapause in 4 native and an exotic species of larval-pupal fruit fly (Diptera: Tephritidae) parasitoids inhabiting tropical environments. We worked in central Veracruz, Mexico, in perturbed tropical deciduous and subdeciduous forests and in diversified agroecosystems during 4 yr (1993-1997). The native parasitoid species Doryctobracon areolatus (Szepligeti), Utetes (B.) anastrephae (Viereck) (Hymenoptera: Braconidae), Aganaspis pellenaroi (Brethes), Odontosema anastrephae Borgmeier (Hymenoptera: Eucoilidae), and the introduced species, Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) all exhibited diapause. Importantly, none of the 6 Anastrepha species serving as hosts for these parasitoids entered diapause. The larval-pupal parasitoids Doryctobracon crawfordi (Viereck) (Hymenoptera: Braconidae; native) and Aceratoneuromyia indica (Silvestri) (Hymenoptera: Eulophidae; introduced) and the pupal parasitoids Coptera haywardi (Hymenoptera: Diapriidae; native), and Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae; introduced) did not exhibit diapause even though they were collected in the same region and at the same time of year. Importantly, in diapausing species not all populations exhibited the phenomenon and, furthermore, in those that did, patterns were polymodal (proportion of a given population entering diapause fluctuated between 0.4 and 100% depending on species). All diapausing individuals dissected from fly pupae were 3rd instars. Diapause lasted up to 11 mo (depending on the particular species) and was predominantly observed in fly pupae collected between the months of September and December (time of year when temperature and rainfall drops and days become shorter). Based on observations on tree fruiting phenology, we conclude that diapause is an effective mechanism allowing parasitoids to bridge periods during which fruit fly hosts (i.e., larvae) are scarce or not available. We discuss our findings in light of their ecological and practical implications.

Eggshell Morphology in Two Cryptic Species of the Anastrepha fraterculus Complex (Diptera: Tephritidae)

The external morphology of eggs of 2 cryptic species of the Anastrepha fraterculus (Wiedemann) complex, species 1 and species 2, was studied by scanning electron microscopy. Eggs of species 1 are, on the average, shorter than those of species 2 whereas they do not differ in their cross diameter. In species 1, the egg apex is asymmetric and papillate, whereas in species 2, the end is blunt and symmetrical. The micropyle is located on the dorsal side of the papilla in species 1 and near the egg apex in species 2. The anterior end of both types of eggs is decorated by a lattice of ridges in a polygonal arrangement. The sculpturing of the chorion covers a larger area of the anterior pole in species 1 than in species 2 eggs. In the remainder of the egg, the chorion is smooth without any clear reticulation. In species 2 eggs, the polygons near the micropyle are arranged in a rosette configuration which is absent in species 1. Aeropyles were found almost exclusively in the chorionic ridges on the ventral side in both types of eggs. Eggs of species 1 have a larger number of aeropyles than those of species 2. The external morphology of the eggs presents reliable characteristics that distinguish the 2 cryptic species of A. fraterculus.

Facultative polar extrusion of yolk masses and of hatching at the posterior egg pole in tephritid fruit flies (Diptera)

The eggs of Anastrepha fracterculus, A. sororcula, A. obliqua, A. serpentina and of Ceratitis capitata (Diptera : Tephritidae) show considerable morphological differences. Differences were also observed in the depth the eggs are inserted into the host fruits. In vivo inspection of the embryos of Anastrepha species showed that they may extrude polar masses of yolk before dorsal closure. In A.fracterculus and A. sororcula, 4 classes of embryos were found : (1) yolk masses at both ends; (2) masses only at the anterior end; (3) just a posterior mass and (4) embryos without any free mass. Only embryos of classes 3 and 4 were found in A. obliqua, while in A. serpentina, all the embryos extruded masses by the posterior end (class 3). There are variations in the frequencies of the classes as well as in the size of the extruded masses. Just before eclosion, the larvae of the Anastrepha species ingest the anterior mass of yolk (when present), turn round inside the egg, suck the posterior extruded mass, and eclose near the posterior-third of the eggs. No masses were present in samples of Ceratitis capitata embryos and the larvae do not present these complex behaviors and eclose near the anterior pole of the egg. The few previous studies on the embryology of other tephritid species did not report similar phenomena. The differences found among the species in relation to the phenomenon of yolk mass extrusion correlate, apparently, to the taxonomic relationship among them, as established before by genetic and morphologic parameters. Additional analyses of other species and genera are required to confirm if yolk mass extrusion is distinctive for the genus Anastrepha.

A New Host Record for the Caribbean Fruit Fly (Diptera: Tephritidae)

The Caribbean fruit fly, Anastrepha suspensa (Loew), has been established in Florida since 1965 (Weems 1965). It has been found in the Bahamas, Cuba, Dominican Republic, Haiti, Jamaica, Puerto Rico and the United States (Florida) (Hernandez-Ortiz & Aluja 1993). In Florida, it has been recovered from 84 different host fruit species in 23 families, but is most common in fruits in the family Myrtaceae (Swanson & Baranowski 1972). In the family Rosaceae, species in the genera Eriobotrya, Malus, Prunus, Pyrus and Rubus have been recorded as hosts. Chrysobalanus icaco L. (Chrysobalanaceae, formerly Rosaceae) is also reported as a host (Norrbom & Kim 1988). The most important rosaceous host in Florida is loquat, Eriobotrya japonica Lindl., because it bears fruits in the winter months when other hosts are not available. Swanson & Baranowski (1972) found Caribbean fruit fly infesting blackberry identified as Rubus sp. Here we report that red raspberry, Rubus idaeus L. is also a host for the Caribbean fruit fly. Raspberry primocanes of three cultivars, 'Autumn Bliss', 'Heritage' and 'Summit' were planted in February 1997 in an evaluation trial at the Tropical Research and Education Center in Homestead, Florida. In May 1997, it was noticed that a larva was feeding inside the fruit. Collections of ripe fruit were made on 29 May, 2 June, 11 June, and 27 June 1997. The fruits were counted and weighed and then placed in plastic boxes with screen tops containing vermiculite and held in the laboratory. For the first and last collections, all of the fruit picked was used. For the other two collections, because of the large number of fruits harvested, a subsample of uncrushed berries was used. After 7-10 days the fruit was removed and the vermiculite was passed through a sieve to collect the pupae. Pupae were held in separate petri dishes for each variety. After emergence was complete, the sex of the adults was determined and the flies counted. Specimens of both sexes were pinned and sent to the Florida State Collection of Arthropods in Gainesville, Florida for species confirmation (accession # E1997-003269-001). Table 1 shows the number of fruits collected, the number of pupae and the number of male and female Caribbean fruit fly that emerged. A total of 294 pupae from 5552 fruits was recovered. The percent of adult emergence was 82% for 'Autumn Bliss', 83% for 'Heritage' and 86% for 'Summit'. Very few males emerged from 'Autumn Bliss' fruits (26%) compared to percentages of 44% males in 'Summit' and 46% males in 'Heritage'. Also, 2 specimens of the parasitoid Diachasmimorpha longicaudata (Ashmead) (Braconidae) were recovered. This is an introduced species that was released and established in Florida as a biological control agent for Caribbean fruit fly (Baranowski et al. 1993). The importance of raspberry as a host for Caribbean fruit fly remains to be determined. The only other species of Anastrepha reported feeding on Rubus fruits isAnastrepha fraterculus (Wiedemann) (Norrbom & Kim 1988). The other major host trees that had some fruit during this study were Surinam cherry (Eugenia uniflora L.) and guava (Psidium guajava L.). Adult Caribbean fruit flies were active in these hosts as indicated by captures in McPhail traps baited with torula yeast pellets. Both these hosts were planted within the dispersal distance of Caribbean fruit fly as reported by Wolfenbarger et al. (1976). Although relatively few pupae were recovered, this could be due to a number of causes. Caribbean fruit fly females may not oviposit readily into

ANÁLISE FAUNÍSTICA DE ESPÉCIES DE MOSCA-DAS-FRUTAS (DIP., TEPHRITIDAE) EM MINAS GERAIS

Em seis locais de quatro municípios (Janaúba, Jaíba, Nova Porteirinha e Itacarambí) do norte do Estado de Minas Gerais, foram coletados 29.454 espécimes de mosca-das-frutas, pertencentes a Ceratitis capitata e a 20 espécies de Anastrepha. O levantamento foi feito entre janeiro de 94 e dezembro de 96, utilizando armadilhas plásticas tipo McPhail. Ceratitis capitata foi a espécie predominante em áreas urbanas. As espécies de Anastrepha predominaram em áreas rurais. A. obliqua, A. zenildae e Anastrepha n. sp.3 foram as espécies predominantes do gênero, entretanto, essa predominância variou de local para local em função da disponibilidade de hospedeiros. As comunidades apresentaram índices de diversidade baixos e quocientes de similaridade entre 73 e 100%.

UTILIZAÇÃO DA ANÁLISE DISCRIMINANTE EM ESTUDOS TAXONÔMICOS DE MOSCAS-DAS-FRUTAS DO GÊNERO Anastrepha Schiner, 1868 (DIPTERA: TEPHRITIDAE)

As moscas-das-frutas Anastrepha fraterculus (Wiedemann, 1830), A. obliqua (Macquart, 1835), A. sororcula (Zucchi, 1979) e A. zenildae (Zucchi, 1979) foram submetidas a uma análise discriminante. Essas espécies do grupo fraterculus distinguem-se unicamente com base em detalhes do ápice do acúleo, que por serem muito semelhantes, dificultam a identificação específica. A análise discriminante permitiu a separação das quatro espécies de Anastrepha, com base em oito medidas do acúleo. Portanto, essa é mais uma técnica para auxiliar as identificações de espécies de Anastrepha, como já acontece em muitos outros grupos de insetos.

Evaluation of techniques for C and ASG banding of the mitotic chromosomes of Anastrepha species (Diptera, Tephritidae)

Methods previously described by Canovai et al. (Caryologia 47: 241-247, 1994) which produced C and ASG bands in mitotic chromosomes of Ceratitis capitata were applied to the chromosomes of several Anastrepha species. Metaphase plate yield was substantially increased by use of imaginal disks together with cerebral ganglia. The C-bands were quite prominent allowing the resolution of tiny blocks of heterochromatin. The ASG method produced G-like banded chromosomes, which permitted recognition of each individual chromosome. These simple techniques do not require special equipment and may be valuable for karyotype variability studies in fruit flies and other Diptera

Spatial and Temporal Distributions of Parasitoids of Mexican Anastrepha Species (Diptera: Tephritidae) within the Canopies of Fruit Trees

In Veracruz State, Mexico, the temporal and spatial distributions of 5 species of parasitic Hymenoptera attacking larvae of 5 Anastrepha species in 7 species of fruit tree canopies were examined. Parasitism by Doryctobracon areolatus (Szepligeti) (Braconidae), Diachasmimorpha longicaudata (Ashmead) (Braconidae), and Utetes anastrephae (Viereck) (Braconidae) was higher in 3 of 4 significant cases in the lower portions of the canopies. U. anastrephae was more abundant in the interior of canopies (2 cases), whereas D. areolatus was more common in the margins (1 case). In 6 of 7 instances the mean sizes of fruits containing parasitoids were smaller than those of infested fruits without parasitoids. U. anastrephae attacked larvae in a narrow range of smaller host-fruit species relative to other parasitoids. The efficiency (proportion of larvae attacked in a fruit) of D. longicaudata compared to that of other parasitoids increased with fruit size. D. longicaudata may be better able to locate or attack hosts in larger fruits. In all of 17 instances there were on average more host larvae in fruits containing parasitoids than in fruits without parasitoids. In all of 18 significant instances the larval density (larvae per gram weight of fruit) was higher in fruits that contained parasitoids than in fruits that did not. Parasitism by D. areolatus, Doryctobracon crawfordi (Viereck), D. longicaudata , and U. anastrephae often changed over time during the fruiting period, but was as likely to decrease as increase. D. areolatus had a pattern of decreasing parasitism during the fruiting periods of individual trees as the season changed from rainy to dry. There were only a few instances of significant relationships between parasitism and local differences in the canopy with respect to fruit numbers, host numbers, and host density. In 2 instances there were significant negative relationships between parasitism caused by the commonly cooccurring D. areolatus and U. anastrephae . In 2 other cases, parasitism by D. crawfordi and D. longicaudata was positively correlated. D. longicaudata is a recent introduction to Mexico and the positive relationships may indicate a niche overlap not present between the 2 native species, D. areolatus and U. anastrephae. Fewer than expected numbers of fruits containing both D. areolatus and U. anastrephae together was further evidence of niche differences. This pattern did not occur in fruits containing D. crawfordi and D. longicaudata . Information on the distribution of parasitoids at levels ranging from within canopies to across regions may guide biological control efforts, allowing the match of candidate species to locations.