Luis E. Oroño

PRESENCE OF DIACHASMIMORPHA LONGICAUDATA (HYMENOPTERA: BRACONIDAE) IN A GUILD OF PARASITOIDS ATTACKING ANASTREPHA FRATERCULUS (DIPTERA: TEPHRITIDAE) IN NORTHWESTERN ARGENTINA

Fil: Orono, Luis Eduardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; Argentina

Natural Ocurrence of Hymenopterous Parasitoids Associated with Anastrepha fraterculus (Diptera: Tephritidae) in Myrtaceae Species in Entre Rios, Northeastern Argentina

Abstract Parasitoids of Anastrepha fraterculus (Wiedemann) were monitored on ripe fruit of 3 native and 1 exotic, wild Myrtaceae species in the Province of Entre Rios, NE Argentina, between Jan and Mar 1993 and 1994 with the aim of identifying indigenous parasitoid species and determining natural parasitization rates and fruit infestation levels. The fruit species surveyed were Psidium guajava L. (common guava), Feijoa sellowiana (O. Berg) O. Berg (feijoa), Eugenia uniflora L. (Surinam cherry), and Myrcianthes pungens (Berg) Legrand (mato). Altogether 2,186 tephritid puparia were obtained, 95% of which were A. fraterculus and 5% of which were Ceratitis capitata (Wiedemann). Of 1,667 adult insects that emerged from these puparia, 1,378 were A. fraterculus, 89 C. capitata, and 200 larval-pupal parasitoids, representing 4 species of 2 Hymenoptera families: Doryctobracon areolatus (Szépligeti), D. brasiliensis (Szépligeti), Utetes anastrephae (Viereck) (all Braconidae, Opiinae), and Aganaspis pelleranoi (Brèthes) (Figitidae, Eucoilinae). All these parasitoid species are new reports for Entre Rios. Moreover, these records represent the southernmost natural distribution range in the Americas for these species. Doryctobracon areolatus and A. pelleranoi were recovered from all of the Myrtaceae species sampled, and they were the most abundant parasitoid species. Infestation patterns by A. fraterculus in mato, Surinam cherry, guava, and feijoa varied from 15.2 to 41.8, 21.3 to 49.4, 34.1 to 109.2, and 78.9 to 140.6 larvae per kg of fruit, respectively. Highest levels of parasitism were recorded in P. guajava, whereas M. pungens had the lowest parasitization rates. However, overall mean parasitism levels (i.e., considering all parasitoid species) did not appear to have great differences when comparing Myrtaceae species, collection sites, and years. The relative abundance and parasitization rates data of the recovered parasitoids in the 4 Myrtaceae species suggest some degree of host plant preference by U. anastrephae and D. brasiliensis.

Effect of host plant chemistry on genetic differentiation and reduction of gene flow among Anastrepha fraterculus (Diptera:Tephritidae) populations exploiting sympatric, synchronic hosts

ABSTRACT Herbivore host specialization includes changes in behavior, driven by locally induced adaptations to specific plants. These adaptations often result in sexual isolation that can be gauged through detection of reduced gene flow between host associated populations. Hypothetically, reduced gene flow can be mediated both by differential response to specific plant kairomones and by the influence of larval diet on some adult traits such as pheromone composition. These hypotheses could serve as a model to explain rapid radiation of phytophagous tephritid fruit flies, a group that includes several complexes of cryptic species. The South American Fruit Fly Anastrepha fraterculus (Wiedemann) is a complex of at least seven cryptic species among which pheromone mediated sexual isolation resulted in rapid differentiation. Cryptic species also exhibit differences in host affiliation. In search of a model explaining rapid radiation in this group, we studied host plant chemical composition and genetic structure of three host associated sympatric populations of A. fraterculus. Chemical composition among host plant fruit varied widely both for nutrient and potentially toxic secondary metabolite content. Adaptation to plant chemistry appears to have produced population differentiation. We found host mediated differentiation to be stronger between populations exploiting sympatric synchronic hosts differing in chemical composition, than between populations that exploit hosts that fruit in succession. Gene flow among such host associated populations was extremely low. We propose as a working hypothesis for future research, that for those differences to persist over time, isolating mechanisms such as male produced sex pheromones and female preferences resulting from adaptation to different larval diets should evolve.

Comparison of the host searching and oviposition behaviors of the tephritid (Diptera) parasitoids Aganaspis pelleranoi and Odontosema anastrephae (Hymenoptera: Figitidae, Eucoilinae).

We compared the host-searching and oviposition behaviors of two Neotropical figitid parasitoids (Hymenoptera) that exploit the same resource: ripe fruit infested by fruit fly larvae (Tephritidae) that have fallen to the ground. Sexually mature Aganaspis pelleranoi (Brèthes) and Odontosema anastrephae Borgmeier females were exposed individually, under no choice conditions, to four types of fruit: 1) Clean, intact guavas, Psidium guajava L. (no fruit fly larvae, no perforations); 2) clean, with artificial perforations; 3) artificially infested (with larvae), no perforations; 4) infested with artificial perforations. A behavioral transition matrix and sequence diagram of the following behaviors was constructed: walking on fruit, detection of larvae via the antennae, tarsi or aculeus, fruit perforation and penetration, and oviposition. Overall, we found that infested fruit (intact and with artificial perforations) elicited the most activity in the females of both species and that A. pelleranoi females exhibited a significantly more diverse behavioral repertoire (i.e., more transitions) and were significantly more active than O. anastrephae females. Females of both species penetrated the fruit in search of larvae by biting through the epi- and mesocarp, but O. anastrephae remained inside for significantly longer periods (up to eight hours). A. pelleranoi females used both their antennae and tarsi to detect larvae but the use of these structures varied depending on context: in infested fruit tarsi were used preferentially (usually while standing still) while in uninfested fruit, antennae were mainly used (usually while walking). In the case of O. anastrephae females the reverse pattern was usually observed with antennae most commonly used to detect larvae in infested fruit. We discuss our findings in light of their evolutionary, ecological and practical implications.

Two New Native Host Plant Records for Anastrepha fraterculus (Diptera: Tephritidae) in Argentina

Fil: Orono, Luis Eduardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; Argentina

The effect of four fruit species on the parasitization rate of Anastrepha fraterculus (Diptera: Tephritidae, Trypetinae) by Diachasmimorpha longicaudata (Hymenoptera: Braconidae, Opiinae) under laboratory rearing conditions

Abstract In the laboratory, the effect of host fruit species Citrus paradisi, C. aurantium, Prunus persica, and Psidium guajava on A. fraterculus parasitism by Diachasmimorpha longicaudata was studied. The number of ovipositor-probing events and the probing-time were documented to evaluate the role of fruit chemistry, and epicarp and mesocarp thickness, respectively. The relationship between the parasitization rate and fruit size in particular plant species was analyzed by applying a simple regression. Results showed that guava and peach yielded significantly more parasitoids than both Citrus spp. Probably, the parasitization rate of D. longicaudata on A. fraterculus would be influenced in part by chemical and physical factors from fruit species.

A Survey of Hymenopterous Larval-Pupal Parasitoids Associated with Anastrepha fraterculus and Ceratitis capitata (Diptera: Tephritidae) Infesting Wild Guava (Psidium guajava) and Peach (Prunus persica) in the Southernmost Section of the Bolivian Yungas Forest

ABSTRACT Parasitoids of Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann) infesting wild guava (Psidium guajava L.) and peach (Prunus persica (L.) Batsch) fruits in the southernmost extension of the Bolivian Yungas forest, in the Province of Tarija, were surveyed in Dec (early summer), Feb (mid summer) and Mar (late summer) 1999 and 2000. The abundance patterns and diversity of fruit fly larval-pupal parasitoid species were similar to previously published data for the southern and northern Yungas forests of Argentina. A total of 1,600 guavas and 800 peaches, weighing 57.713 kg and 24.544 kg, respectively, were collected yielding 13,080 tephritid puparia, 78.4% of which were A. fraterculus and 21.6% Ceratitis capitata (Wiedemann). We reared 712 larval-pupal parasitoids of the following species: Doryctobracon areolatus (Szépligeti), D. brasiliensis (Szépligeti), D. crawfordi (Viereck), Opius bellus Gahan, Utetes anastrephae (Viereck) (all Braconidae, Opiinae), Aganaspis pelleranoi (Brèthes) Odontosema anastrephae Borgmeier, and Lopheucoila anastrephae (Rohwer) (all Figitidae, Eucoilinae). Utetes anastrephae, O. anastrephae, and L. anastrephae are new fruit fly parasitoid reports for Bolivia, as well as O. anastrephae in the South American Yungas forest. A thorough sampling of other C. capitata and Anastrepha host plants, mostly native fruit species, will be necessary in the Yungas forest of Bolivia before further conclusions on abundance and composition of all fruit fly parasitoids can be reached.