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The phoretic sphaerocerid fly Norrbomia frigipennismates on scarabid dung beetles, follows them underground, and lays eggs in the collected dung. We found that male and female flies distribute themselves nonrandomly on beetles with respect to fly group size. The proportion of virgin females increased with group size, and females with mature eggs were most frequently found on beetles carrying fewer flies. Laboratory experiments revealed that mated females avoided larger groups, virgin females seemed to prefer large groups and mated females, small groups. Males showed no such pattern. These results suggest that N. frigipenniscan estimate group size, presumably an adaptation with a reproductive function. However, flies did not join hosts on the basis of the sex of already mounted flies.

We surveyed 15 wild and cultivated plant species in search of fruit fly (Diptera: Tephritidae) parasitoids during 4 years (1993–1996) in the state of Veracruz, Mexico. The following species were infested by Anastrephalarvae: Spondias purpureaL., S. mombinL., Tapirira mexicanaMarchand, Mangifera indicaL. (all Anacardiaceae), Ximenia americanaL. (Olacaceae), Citrus sinensisL. and Casimiroa edulisLlave & Lex. (Rutaceae), Psidium guajavaL., P. sartorianum(Berg.), P. guineenseSw., Syzygium jambosL., Myrciaria floribunda(West) O. Berg. (all Myrtaceae), Chrysophyllum mexicanum(Brandegce) ex. Standley and Calocarpum mammosumL. (Sapotaceae), and Passiflora foetidaL. (Passifloraceae). Of these, only C. mexicanum, C. edulis,and P. foetidadid not harbor parasitoids. We identified 10 native and exotic larval–pupal parasitoid species (all Hymenoptera): Doryctobracon areolatus(Szépligeti), D. crawfordi(Viereck), Utetes(Bracanastrepha) anastrephae(Viereck), and Opius hirtus(Fisher) (all Braconidae), Aganaspis pellenaroi(Brethes) and Odontosema anastrephaeBorgmeier (Eucoilidae) (all native species), and Diachasmimorpha longicaudata(Ashmead) and Aceratoneuromyia indica(Silvestri) (Braconidae and Eulophidae, respectively; both exotic species). We also identified two pupal parasitoids: Coptera haywardi(Ogloblin) (Diapriidae; native) and Pachycrepoideus vindemiae(Rondani) (Pteromalidae; exotic). Parasitization levels ranged between 0.4 and 83.8%. Native, wild plants harbored significantly more parasitoids per fruit than cultivated ones. Interestingly, in P. guajava2 fly species and 5 parasitoid species were once identified in a single fruit. We found a negative correlation between fruit size and number of parasitoids/fruit. We rank parasitoids based on host breadth (fruit fly species attacked) and number of plant species visited. We discuss some general ecological and practical implications of our findings (e.g., effect of fruit size on parasitism, mass-rearing, and augmentative releases of native vs exotic parasitoids) and compare our findings with previous surveys carried out in Mexico and in Central and South America. We also discuss the need to protect native vegetation because of the important role such vegetation plays as reservoirs of fruit fly parasitoids.

Three major components, ethyi-(E)-3-octenoate, geranyl acetate, and (E,E)-a-farnesene, emitted as volatiles by laboratory-reared and wild male medflies were collected and analyzed qualitatively and quantitatively. Peak emission of these compounds occurred during the third to fifth hours of the photophase and differences were observed in the ratios of the three components emitted by male laboratory-reared and wild flies. These three compounds were synthesized, and a method was developed to formulate a synthetic blend that released the compounds in a ratio similar to that emitted by wild male medflies. Attractiveness of the blend to female medflies was demonstrated under field conditions by comparing trap catches. Black spherical traps, baited with the synthetic blend to release 1.6 male equivalents, caught significantly more females than blank traps and traps from which the blend released was 0.3, 3.2 or 6.4 male equivalents.

A bioassay system was developed that permits the testing of various substrates for biological activity in a flight tunnel, while simultaneously collecting a portion of the volatiles from the attractive source for subsequent chemical identification and quantification. Bioassays of the response of virgin female Caribbean fruit flies,Anastrepha suspensa (Loew) (Diptera: Tephritidae), to volatiles released by calling males were conducted in a greenhouse under natural light cycles and fluctuating environmental conditions, similar to those in the field. Using this system, the periodicity of response of the female flies between 1300 and 1845 hr (EST) was tested. Fifty to 75% response occurred between 1700 and 1845 hr. Male pheromone release was greatest between 1500 and 1800 hr. Videotaped records of insects, taken between 1700 and 1800 hr as flies approached and entered the traps, were analyzed to interpret the communicative role of the volatiles released. Significantly more flies landed on and entered the pheromone-emitting trap than the control trap. There was no difference in the amount of time spent on the trap face, an indication that volatiles were attractants. The system described should be of general utility in determination of the attraction of pest fruit flies to suspected attractants.

Abstract: Among the host fruits of the Caribbean fruit fly there are a variety of sizes and shapes. These morphological differences may influence the vulnerability of the larvae to parasites. In the laboratory, Caribbean fruit fly larvae placed in the smaller of 2 different sizes of artificial ‘fruit’ (cloth spheres filled with a diet material) were parasitized at a higher rate by the braconid,Diachasmimorpha longicaudata (Ashmead) when spheres were presented separately. However, when parasites were simultaneously presented with 6 different sizes of ‘fruit’ there was no significant relationship between size and parasitization rate. This may be due to the parasites preference to search for larvae in larger ‘fruit’. In field collections of different species of host fruit, a significant inverse correlation exists between fruit radius and rate of parasitization. However, host fruit size accounts for only about 5% of the variance in yearly parasitization rates.

Norrbomia frigipennis (Diptera: Sphaeroceridae) is phoretic on dung-feeding scarab beetles (Coleoptera: Scarabaeidae). In this study we investigate the attractiveness of three beetle species,Phanaeus ignius, P. vindex, andCanthon pilularis, to the fly. Stationary, moving-dead, and live beetles were used. More flies were attracted toPhanaeus. However, this attractiveness may be due to the larger average size ofPhanaeus. A preference for larger individuals was found withinPhanaeus, though not withinC. pilularis. Flies mounted beetles on the thorax and the elytra at similar rates.Phanaeus males that possesed horns did not attract more flies than did hornless ones, and there was no effect of host sex on attractiveness. In hornedPhanaeus, about 11–16% of the flies mounting those beetles landed on the horn.

Protein, lipid, carbohydrate, and energy contents of three artificial diets (Xal2, Met1, and Met2) used for laboratory-rearing and mass-rearing the Mexican fruit fly, Anastrepha ludens (Loew), for a sterile insect technique program were measured. The larval survival, pupation, pupal weight, adult emergence, sex ratio, and flight capacity of the flies reared on each of these diets were also quantified. The diet with the highest nutrient and energy content was Xal2 followed by Met2 and Met1, but larval recovery and percent pupation was significantly higher in flies reared on either the Met1 or Met2 diets. A. ludens reared on Xal2 exhibited the highest proportion of adults capable of flight. No other response variable differed significantly among the three diets tested. This suggests that a high content of nutrients and multiple sources of protein (dried yeast and wheat germ in the case of the Xal2 diet) do not necessarily improve overall performance or fly quality. We conclude that nutritious diets for A. ludens can be modified to reduce their cost without compromising the performance of artificially reared flies.

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.

Female Caribbean fruit flies with oviposition opportunities remate frequently, two-thirds of them after 1 wk and approximately one-third every subsequent week. Those with limited chances to oviposit remate less frequently, and about half of them mate only once during their lifetime. Ovipositing females regain receptivity to male-produced pheromones within a week, unlike nonlaying females. Mortality rates also are higher for egglaying females.

Male Anastrepha suspensa (Loew) produce two female-directed sounds, the calling and precopulatory songs. Aspects of these were correlated to factors thought important in male sexual success and compared in males that copulated and males that failed to mate. Both sounds became more intense with male size. Larger males tended to have calling songs of lower fundamental frequency, but frequency of precopulatory songs and size was uncorrelated. The calling song's fundamental frequency bandwidth was broader in unsuccessful flies, perhaps reflecting physical disability. Precopulatory songsmay be the last acoustic opportunity for males to demonstrate their “quality” and receive further cooperation from females they have mounted. Unsuccessful precopulatory songs were not as loud and had a broader bandwidth than successful songs. Greater distortion in unsuccessful songs appeared to be due to female movement during rejection. The longer a precopulatory song, the shorter the subsequent mating. This may have been due to males making greater efforts toward less sexually responsive mates. Larger males coupled longer, suggesting a potential conflict of interest between the sexes over copulation duration that bigger males are more apt to win.

Two species of Braconidae, Diachasmimorpha longicaudata (Ashmead) and Doryctobracon areolatus (Szepligeti), commonly attack the Caribbean fruit fly, Anastrepha suspensa (Loew), in central Florida. There are temporal changes in the relative abundance of the 2 parasitoids, with a tendency for D. longicaudata to become more common as the fruiting periods of various host trees progress. An exception occurs when D. longicaudata declines relative to D. areolatus during the late-autumn and winter fruiting of the citrus fruit calamundin, ? Citrofortuella mitis J. Ingram & H. E. Moore. During the year there is a spring rise and then an autumn decline in the relative abundance of D. longicaudata. This pattern is not explained by any within-tree changes in fruit size or host larval densities. Many changes in relative abundance are consistent with D. areolatus being superior to D. longicaudata in finding host patches, but inferior at exploiting hosts (counter-balanced competition). Seasonal changes in maximum temperatures are also correlated to changes in the relative abundance of D. longicaudata to D. areolatus. It appears that the outcome of the competition between the 2 species is influenced by climatic conditions.