Jorge Cancino

Functional Response and Superparasitism by Diachasmimorpha longicaudata (Hymenoptera: Braconidae), a Parasitoid of Fruit Flies (Diptera: Tephritidae)

Abstract The functional response and the effect of superparasitism of Diachasmimorpha longicaudata (Ashmead) in larvae of Anastrepha ludens (Loew) was determined under laboratory conditions. Adult parasitoids were tested individually and in groups of 5. Third-instar A. ludens larvae were exposed for 3 h to experienced, 5-d-old females at the ratios of 1, 5, 20, 30, 40, 50, and 60 host larvae per wasp. For individual females, functional response was type III, whereas for females in groups, a type II curve was observed. In the presence of conspecifics, females increased their parasitization activity. Females showed a strong tendency for self-superparasitism (the same female laying >1 egg in the same host) with a range of 38.9–57.9% of larvae superparasitized, even when there was no competition and a high availability of host larvae. In the superparasitism experiment, when the parasitoid/host ratio was 1 or greater, larval mortality was consistently high but never exceeded 90%. Successful parasitoid emergence decreased as the parasitoid/host ratio increased. We discuss and question the detrimental effects that have been attributed to superparasitism in solitary endoparasitoids.

Colonization and domestication of seven species of native New World hymenopterous larval-prepupal and pupal fruit fly (Diptera: Tephritidae) parasitoids

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 (Szépligeti), Doryctobracon crawfordi (Viereck), Opius hirtus (Fischer), Utetes anastrephae (Viereck) (all Braconidae, Opiinae), Aganaspis pelleranoi (Bréthes) 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.

Host size, superparasitism and sex ratio in mass-reared Diachasmimorpha longicaudata, a fruit fly parasitoid

We analyzed the relationship among host size, superparasitism and sex-ratio in mass reared Diachasmimorpha longicaudata (Hymenoptera: Braconidae). Individual host pupae of Anastrepha ludens (Diptera: Tephritidae) were measured (length and width), and the number of oviposition scars per pupa was used as a reliable indicator of superparasitism. The probability of an emerging parasitoid being a female was positively associated with the number of oviposition scars on the host cuticle, but not with the host size. The number of scars per host pupae from which females emerged was slightly but significantly higher than in those pupae giving raise to males. In D. longicaudata, the influence of host size on sex allocation decisions of individual females seems to be overridden by the level of superparasitism, which itself was positively correlated with pupa length. This suggests that larger pupae could experience a higher number of ovipositions than their smaller counterparts, and that a high level of superparasitism may conduct to a female biased sex ratio. We discuss the relevance of these findings which could provide new elements (e.g., the manipulation of superparasitism) for optimizing the mass rearing of this parasitoid.

Reproductive biology of Fopius arisanus (Hymenoptera: Braconidae) on Ceratitis capitata and Anastrepha spp. (Diptera: Tephritidae)

The reproduction of the solitary endoparasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae) in Anastrepha ludens (Loew), Anastrepha obliqua (Macquart), and Anastrepha serpentina (Wiedemann) was compared with that using Ceratitis capitata (Wiedemann), being the host in which it had been reared previously. Eggs of different ages ( 60% for parasitoids that emerged from A. ludens compared to those that emerged from A. serpentina or C. capitata. The reproduction of parasitoid progeny was highest in parasitoids that emerged from and reproduced on C. capitata and lowest for parasitoids reproducing on A. ludens. Parasitoids that emerged from A. ludens were often deformed, but were larger than those that emerged from A. serpentina. Parasitoids that emerged from C. capitata were smaller than those from Anastrepha spp. We conclude that F. arisanus is capable of sustained reproduction in C. capitata and A. serpentina and merits further study as an agent for the control of these fruit flies.

Rearing of five hymenopterous larval-prepupal (Braconidae, Figitidae) and three pupal (Diapriidae, Chalcidoidea, Eurytomidae) native parasitoids of the genus Anastrepha (Diptera: Tephritidae) on irradiated A. ludens larvae and pupae

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.

Discrimination by Coptera haywardi (Hymenoptera: Diapriidae) of hosts previously attacked by conspecifics or by the larval parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

Abstract Coptera haywardi (Oglobin) is an endoparasitoid of fruit fly pupae that could find itself in competition with other parasitoids, both con- and heterospecific, already resident inside hosts. In choice bioassays, ovipositing C. haywardi females strongly discriminated against conspecifically parasitised Anastrepha ludens (Loew) pupal hosts. They also avoided pupae previously attacked by Diachasmimorpha longicaudata (Ashmead), a larval–prepupal koinobiont endoparasitoid, and the degree of larval-parasitoid superparasitism had no effect on this avoidance. There was no difference in the number of ovipositor insertions when hosts previously parasitised by a conspecific and D. longicaudata were exposed simultaneously. As females aged the degree of host discrimination declined. An ability to discriminate against pupae previously attacked as larvae suggests low levels of both conspecific and heterospecific competition in the field.

Host discrimination and superparasitism in wild and mass-reared Diachasmimorpha longicaudata (Hym.: Braconidae) females

Abstract We compared the oviposition behavior and host discrimination ability of wild and mass-reared Diachasmimorpha longicaudata (Hymenoptera: Braconidae) females parasitizing Anastrepha ludens (Diptera: Tephritidae) larvae. Both kinds of parasitoid females were presented simultaneously with parasitized and non-parasitized larvae in choice tests, and their superparasitism performance was evaluated under a mass-rearing situation. At the time of the test, D. longicaudata had 156 generations under mass-rearing conditions. Our goal was to determine the effect of the mass-rearing process on the foraging decisions of this species. One of the primary findings was the apparent ubiquity of superparasitism by D. longicaudata females. Both types of females showed similar patterns in each of the phases of oviposition behavior evaluated. The only notable differences were among the percentages of transition between behaviors, mainly related to the intensity with which each activity was performed. Under a mass-rearing situation, both strains of females had a similar tendency to increase superparasitism (i.e., number of oviposition scars per puparium and the proportion of superparasitized larvae) over time. The mass-rearing process appears to have induced the selection of more aggressive, fertile and precocious females. Despite these observations, we concluded that the process of adaptation to mass-rearing conditions has not substantially influenced the foraging and ovipositional behaviors in this species.

The suitability of Anastrepha spp. and Ceratitis capitata larvae as hosts of Diachasmimorpha longicaudata and Diachasmimorpha tryoni : Effects of host age and radiation dose and implications for quality control in mass rearing

Abstract The emergence of parasitoids from irradiated tephritid host larvae of different species and ages was evaluated. Parasitoid and fly longevity and fecundity resulting from each treatment were also assessed. Doses of 5, 10, 20, 30, 40, 50, 80, 100 and 150 Gy were applied to samples (100 larvae) of 6-, 7-, 8- and 9-day-old Anastrepha spp. larvae (A. ludens (Loew), A. obliqua (Mcquart) and A. serpentina (Wiedemann)) and 6- and 7-day-old Ceratitis capitata (Wiedemann) larvae. Anastrepha larvae were exposed to Diachasmimorpha longicaudata (Ashmead), and C. capitata larvae to D. tryoni (Cameron). Following larval exposures of 20 Gy, fly emergence was totally suppressed in all larval ages of A. ludens and A. serpentina, while in A. obliqua and C. capitata, total suppression was achieved at 30 Gy. In all species, fly emergence decreased with increasing radiation dosages from 5 to 20 Gy. Emerged fly fertility and longevity also decreased as the radiation increased. On the other hand, parasitoids did not suffer decreases in longevity or fecundity as host radiation dose increased. Larval age at the time of irradiation did not influence emergence, longevity and fecundity of either flies or parasitoids. When the irradiated cohort size was raised to one liter of larvae (about 32,000 Anastrepha or 50,000 C. capitata larvae) a dose of 40 Gy in A. ludens, A. serpentina and A. obliqua totally suppressed fly emergence but permitted D. longicaudata emergence, while for C. capitata larvae, it was necessary to increase the dose to 60 Gy. Quality control tests under mass rearing conditions were applied to D. longicaudata reared using irradiated A. ludens larvae. There was no statistical difference between parasitoids derived from irradiated or non-irradiated host for most parameters. Only percent pupation after 72 h differed, along with the consequent differences between the percent emergence and pupal weight. The conclusions drawn from this study lead to a greater flexibility in the use of irradiated hosts in the mass rearing of the fruit fly parasitoids D. longicaudata and D. tryoni.

Irradiation of Anastrepha ludens (Diptera: Tephritidae) eggs for the rearing of the fruit fly parasitoids, Fopius arisanus and Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

Abstract Irradiated eggs of Anastrepha ludens were evaluated as hosts of two fruit-fly parasitoids for mass rearing. Three different ages of A. ludens eggs (24-, 48- and 72-h-old) were analyzed for hatchability after being subjected to radiation doses of 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5 and 30 Gy. No significant reduction in hatchability occurred with the 72-h-old eggs at any of the radiation dose levels and no adult emergence occurred at radiation doses greater than 25 Gy. Seventy two-h-old eggs irradiated above 25 Gy were found to be the best age and dose for fruit fly egg hosts to be used in mass rearing the egg parasitoid Fopius arisanus. It was demonstrated that larvae hatching from the irradiated A. ludens eggs can also be used as hosts for Diachasmimorpha longicaudata. Parasitoid emergence of both species was not statistically different from the control group (parasitoids emerged from non-irradiated host). The fecundity of parasitoids emerged from irradiated hosts also was similar to that obtained with parasitoids reared with non-irradiated hosts. There were some statistical differences between the curves for longevity. However, these were not clearly correlated with radiation dose. The results of this study will aid in the design of improved methods for mass rearing and release of fruit-fly parasitoids.

Application of Nuclear Techniques to Improve the Mass Production and Management of Fruit Fly Parasitoids

The use of irradiated hosts in mass rearing tephritid parasitoids represents an important technical advance in fruit fly augmentative biological control. Irradiation assures that fly emergence is avoided in non-parasitized hosts, while at the same time it has no appreciable effect on parasitoid quality, i.e., fecundity, longevity and flight capability. Parasitoids of fruit fly eggs, larvae and pupae have all been shown to successfully develop in irradiated hosts, allowing a broad range of species to be shipped and released without post-rearing delays waiting for fly emergence and costly procedures to separate flies and wasps. This facilitates the early, more effective and less damaging shipment of natural enemies within hosts and across quarantined borders. In addition, the survival and dispersal of released parasitoids can be monitored by placing irradiated sentinel-hosts in the field. The optimal radiation dosages for host-sterility and parasitoid-fitness differ among species, and considerable progress has been made in integrating radiation into a variety of rearing procedures.