Peripheral blood transcriptomic profiling of molecular mechanisms commonly regulated by binge drinking and placebo effects

Molecular responses to alcohol consumption are dynamic, context-dependent, and arise from a complex interplay of biological and external factors. While many have studied genetic risk associated with drinking patterns, comprehensive studies identifying dynamic responses to pharmacologic and psychological/placebo effects underlying binge drinking are lacking. We investigated transcriptome-wide response to binge, medium, and placebo alcohol consumption by 17 healthy heavy social drinkers enrolled in a controlled, in-house, longitudinal study of up to 12 days. Using RNA-seq, we identified 251 and 13 differentially expressed genes (DEGs) in response to binge drinking and placebo, respectively. Eleven protein-coding DEGs had very large effect sizes in response to binge drinking (Cohen's d > 1). Furthermore, binge dose significantly impacted the Cytokine-cytokine receptor interaction pathway (KEGG: hsa04060) across all experimental sequences. Placebo also impacted hsa04060, but only when administered following regular alcohol drinking sessions. Similarly, medium-dose and placebo commonly impacted KEGG pathways of Systemic lupus erythematosus, Neutrophil extracellular trap formation, and Alcoholism based on the sequence of drinking sessions. These findings together indicate the "dose-extending effects" of placebo at a molecular level. Furthermore, besides supporting alcohol dose-specific molecular changes, results suggest that the placebo effects may induce molecular responses within the same pathways regulated by alcohol.

Peripheral blood transcriptomic profiling indicates molecular mechanisms commonly regulated by binge-drinking and placebo-effects

Molecular changes associated with alcohol consumption arise from complex interactions between pharmacological effects of alcohol, psychological/placebo context surrounding drinking, and other environmental and biological factors. The goal of this study was to tease apart molecular mechanisms regulated by pharmacological effects of alcohol - particularly at binge-drinking, from underlying placebo effects. Transcriptome-wide RNA-seq analyses were performed on peripheral blood samples collected from healthy heavy social drinkers (N=16) enrolled in a 12-day randomized, double-blind, cross-over human laboratory trial testing three alcohol doses: Placebo, moderate (0.05g/kg (men), 0.04g/kg (women)), and binge (1g/kg (men), 0.9g/kg (women)), administered in three 4-day experiments, separated by minimum of 7-day washout periods. Effects of beverage doses on the normalized gene expression counts were analyzed within each experiment compared to its own baseline using paired-t-tests. Differential expression of genes (DEGs) across experimental sequences in which each beverage dose was administered, as well as responsiveness to regular alcohol compared to placebo (i.e., pharmacological effects), were analyzed using generalized linear mixed-effects models. The 10% False discovery rate-adjusted DEGs varied across experimental sequences in response to all three beverage doses. We identified and validated 22 protein coding DEGs potentially responsive to pharmacological effects of binge and medium doses, of which 11 were selectively responsive to binge dose. Binge-dose significantly impacted the Cytokine-cytokine receptor interaction pathway (KEGG: hsa04060) across all experimental-sequences that it was administered in, and during dose-extending placebo. Medium dose and placebo impacted pathways hsa05322, hsa04613, and hsa05034, in the first two and last experimental sequences, respectively. In summary, our findings add novel, and confirm previously reported data supporting dose-dependent effects of alcohol on molecular mechanisms and suggest that the placebo effects may induce molecular responses within the same pathways regulated by alcohol. Innovative study designs are required to validate molecular correlates of placebo effects underlying drinking.

Integration of virtual platforms for enhanced conference experience: Data-based evidence from the Society of Interdisciplinary Placebo Studies 2021 conference

BACKGROUND

The Society of Interdisciplinary Placebo Studies (SIPS) was one of many organizations that hosted a virtual scientific conference in response to the COVID-19 pandemic restrictions. Retaining essential benefits of an in-person conference experience was a primary objective for the SIPS conference planning committee and guided the selection of a virtual platform on which to host the 2021 meeting. This article reports on the methods used to design and analyze an engaging, virtual scientific conference, along with the findings and implications for future meetings.

METHODS

Participant use of and interaction with different features of the conference platform were recorded and exported for analysis. Additionally, all SIPS conference attendees were invited to complete a brief, online post-conference survey that inquired about their perceptions of the SIPS conference specifically as well as their opinions of virtual and hybrid conferences in general. Using these data, we assessed (1) attendance patterns, (2) level of engagement, and (3) attendee satisfaction.

RESULTS

The platform recorded 438 unique, active conference attendees who used either a mobile app, web browser, or both to participate during the 3-day program. Seventy-four percent (N = 324) of active users attended all 3 days with 30 and 26 new attendees on Days 2 and 3, respectively. The connections feature offered on the platform was the most utilized function within the online forum. Attendance in the parallel workshop sessions remained constant across the 3 days, with an average of 44.6% (SD = 6.77) of people moving between workshops within a single session. The two poster sessions had an average of 47.6 (SD = 17.97) and 27.8 (SD = 10.24) unique views per poster, respectively. Eleven percent (N = 48) of attendees completed the post-conference survey. Thirty-six percent of these responders stated they were only able to attend because the conference was offered virtually. Further, the quality of the conference had an average satisfaction rating of 68.08 out of 100 (SD = 22.94).

CONCLUSION

Results of data analyses suggest the virtual platform allowed for those who were unable to attend to join virtually, produced moderate engagement throughout the conference, and that the majority of attendees were satisfied with the quality of the fully-virtual conference. Therefore, incorporating virtual aspects in future in-person conferences could enhance conference experience and participation.

Costly Nutritious Diets do not Necessarily Translate into Better Performance of Artificially Reared Fruit Flies (Diptera: Tephritidae)

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.

Analysis, synthesis, formulation, and field testing of three major components of male mediterranean fruit fly pheromone

Three major components, ethyi-(E)-3-octenoate, geranyl acetate, and (E,E)-α-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 for collecting volatiles while simultaneously attracting tephritid fruit flies

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.

Intrinsic competition and competitor-free-space influence the coexistence of parasitoids (Hymenoptera: Braconidae: Opiinae) of Neotropical Tephritidae (Diptera)

Endoparasitoid larvae may eliminate heterospecific competitors by physical or physiological means. The outcomes of these intrinsic competitions are often predictable with one species typically eliminating the other. The opiine braconids Doryctobracon areolatus (Szepligeti) and Utetes anastrephae (Viereck) are among the most common native parasitoids of frugivorous Tephritidae in the Neotropics and subtropics. U. anastrephae is typically the victor in intrinsic interactions with D. areolatus, but the later has a longer ovipositor and may find a competitor-free-space in larger fruit whose hosts are beyond the reach of U. anastrephae. An Asian opiine species, Diachasmimorpha longicaudata (Ashmead) has been introduced throughout much of the Americas. Its ovipositor is longer than that of D. areolatus and if it is a superior intrinsic competitor it should be able to cause local extinctions of D. areolatus. The outcomes of sequential ovipositions by D. longicaudata and D. areolatus and U. anastrephae found that D. longicaudata significantly suppresses development of D. areolatus. However, competitions between D. longicaudata and U. anastrephae were more equal. The denial of competitor free space may account for the gradual replacement of D. areolatus by D. longicaudata in Florida where both species were introduced ~40 yr ago. Diachasmimorpha longicaudata and D. areolatus continue to coexist in Mexico and this could be because of greater abiotic and biotic environmental complexity that allows for separate niches. Establishment or augmentative releases of D. longicaudata could result in elimination of native parasitoids and this should be considered before its introduction.

Augmentative biological control: research and methods to help make it work

Abstract

Augmentative biological control, especially in field situations, can be complex but there are novel or incompletely explored directions for research and methods development that may lead to improved future performance. At the fundamental level, augmentation faces inherent ecological/behavioural challenges such as enemy dispersal, pest refugia and deleterious interactions within predator/parasitoid guilds. However, these may be addressed by the choice of natural enemies with specific or manipulatable dispersal capabilities which attack hosts when most vulnerable. Integration of augmentative biological control with other control methods has not been sufficiently explored. One promising partner is the sterile insect technique (SIT) and related technologies such as conditional-lethality and genetic-drives that perform best at low and declining pest densities and should interact well, even synergistically, with natural enemy augmentation. Other candidates for integration with augmentative biological control include the addition of plants that support natural enemies, infochemicals such as kairomones that could lead pests to occupy more vulnerable microhabitats and even certain pesticides. At the production level, new or not widely adopted technologies for mass-rearing can lower costs. For example, host irradiation simplifies the handling of parasitoids, improves sanitation, facilitates the movement of natural enemies across borders and allows hosts to be exposed in sentinel-traps. Parasitoid rearing expenses could be halved by using thelytokous strains such as those resulting from Wolbachia infections. In some cases, hosts for specialist parasitoids can be obtained inexpensively from the unwanted sex of mass-reared pests: another advantage of integration with SIT. While many innovations are now costly, scientifically sophisticated and planned for use in regional-scale projects, new techniques and genetic modifications could become widely available to the agricultural industry.

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.

Longevity of multiple species of tephritid (Diptera) fruit fly parasitoids (Hymenoptera: Braconidae: Opiinae) provided exotic and sympatric-fruit based diets

While adult parasitic Hymenoptera in general feed on floral and extrafloral nectars, hemipteran-honeydews and fluids from punctured hosts, Diachasmimorpha longicaudata (Ashmead), an Old World opiine braconid introduced to tropical/subtropical America for the biological control of Anastrepha spp. (Tephritidae), can survive on fruit juices as they seep from injured fruit. An ability to exploit fruit juice would allow such a parasitoid to efficiently forage for hosts and food sources simultaneously. Two New World opiines, Doryctobracon areolatus (Szepligeti) and Utetes anastrephae (Viereck), are also prominent Anastrepha parasitoids and are roughly sympatric. All three species were provided with: (1) pulp and juice diets derived from a highly domesticated Old World fruit (orange, Citrus sinensis L.) that is only recently sympatric with the Mexican flies and parasitoids and so offered little opportunity for the evolution of feeding-adaptations and (2) a less-domesticated New World fruit (guava, Psidium guajava L.), sympatric over evolutionary time with D. areolatus and U. anastrephae. Both sexes of D. longicaudata died when provided guava pulp or juice at a rate similar to a water-only control. D. areolatus and U. anastrephae, presumably adapted to the nutrient/chemical constituents of guava, also died at a similar rate. Survival of all three species on orange pulp and juice was greater than on water, and often equaled that obtained on a honey and water solution. In confirmatory experiments in Mexico, D. areolatus and U. anastrephae, as well as other tephritid parasitoids Doryctobracon crawfordi (Viereck) and Opius hirtus (Fisher), all died at a significantly higher rates when provided guava in comparison to a honey and water diet. Such a result is likely due to guavas being repellent, innutritious or toxic. D. longicaudata clearly consumed guava juice tagged with a colored dye. Dilutions of orange and guava juice resulted in shorter lifespans than dilutions of orange juice and water demonstrating that there while diluted orange juice provided nutrition the addition of guava created toxicity. Given the differences in fruit-food quality, adult opiine food sources would not be obtainable at all oviposition sites and in the case of guava, more additional sites and foraging for food than previously postulated may be required.

Effect of larval host food substrate on egg load dynamics, egg size and adult female size in four species of braconid fruit fly (Diptera: Tephritidae) parasitoids

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.

A compound produced by fruigivorous Tephritidae (Diptera) larvae promotes oviposition behavior by the biological control agent Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

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.

Enhancing male sexual success in a lekking fly (Anastrepha suspensa Diptera: Tephritidae) through a juvenile hormone analog has no effect on adult mortality

While defending lek-territories, male Anastrepha suspensa (Loew) produce chemical, acoustic and visual courtship signals. In the laboratory and under semi-natural conditions, topical application of the juvenile hormone analog methoprene doubles pheromone production and subsequently doubles sexual success. However, sexual signals and interactions are likely to be physiologically expensive and so result in higher male mortality. Comparison of males kept in isolation for 35 days, but provided daily with a potential mate or a rival male, revealed that both male- and female-interactors shortened focal-male lifespan. In addition, focal males were either treated with methoprene or not, then either provided with protein in their sucrose-based diet or not. Protein proved to similarly double sexual success and also resulted in longer male life spans in all of the interactor-categories. However, there was no evidence that methoprene induced hypersexuality resulted in higher rates of mortality, i.e., the longevity of males treated with methoprene did not significantly differ from untreated males in the same interactor/diet categories. This apparent lack of costs to a putatively sexually selected signal is unexpected but presents an opportunity to increase the sexual competence of sterile flies with few consequences to their survival following mass-release.

Influence of a juvenile hormone analog and dietary protein on male Anastrepha suspensa (Diptera: Tephritidae) sexual success

Juvenile hormone levels and adult diet have important effects on the attractiveness and competitiveness of male Anastrepha suspensa (Loew) (Caribbean fruit fly). Because the success of the sterile insect technique requires the release of males that can compete in the wild, these effects are of crucial importance. Laboratory and field cage experiments were conducted to compare male sexual performance on a lifetime basis and daily basis when submitted to four different treatments: (M+P+) application of the juvenile hormone analog, methoprene (M) and sugar and hydrolyzed yeast as adult food; (M+P-) application of M and sugar as adult food; (M-P+) no application of M and sugar and hydrolyzed yeast as adult food; and (M-P-) no application of M and sugar as adult food. On a daily basis, M+P+ males always performed better sexually, and 10% of these individuals were able to mate three consecutive times in the same day. However, the copula duration decreased with the increased number of matings on same day. In addition, M caused earlier maturation. On a lifetime basis, M+P+ males had significantly greater sexual success than other flies. The substantial improvement in male sexual performance because of the hormone application, protein supply, and interaction of hormone and protein has the potential of producing more efficacious sterile males.

Male and female condition influence mating performance and sexual receptivity in two tropical fruit flies (Diptera: Tephritidae) with contrasting life histories

Recent recognition of widespread polyandry in insects has generated considerable interest in understanding why females mate multiple times and in identifying factors that affect mating rate and inhibit female remating. However, little attention has been paid to understanding the question from both a female and male perspective, particularly with respect to factors that may simultaneously influence female remating rates. Here, we report on a study aimed at ascertaining the possible interactive effects that male and female size and diet, and female access to a host could have on mating latency, probability, and duration and female refractory period using two tropical fruit fly species with contrasting life histories. Of all factors tested, adult diet played the most significant role. Both Anastrepha ludens and Anastrepha obliqua males which had constant access to protein and sucrose mated more often, had shorter copulations and induced longer refractory periods in females than males fed a low quality diet (sucrose offered every third day). Female size and the interaction with male diet determined how quickly female A. ludens mated for the first time. Smaller females mated sooner with low quality fed males than with high quality fed males while there was no difference for large females, suggesting that male choice may be at play if high quality fed males discriminate against smaller females. Copulation duration also depended on both male and female nutritional condition, and the interaction between male diet and female size and diet. Large and high quality fed females had shorter copulations regardless of male condition. Importantly, for A. ludens, female refractory period depended on male size and the nutritional condition of both males and females, which could indicate that for this species, female receptivity does not depend only on the condition of the male ejaculate. For A. obliqua refractory period was associated with the interaction between male size and diet and male diet and host presence. We discuss our results in terms of male ability to inhibit female remating and the relative contribution of female condition to this behavior. We also address the importance of studying effects simultaneously on species with contrasting life histories.

Latitudinal variation in parasitoid guild composition and parasitism rates of North American hawthorn infesting Rhagoletis

Rhagoletis pomonella (Diptera: Tephritidae) populations in North America have diverged by exploiting host plants with varying fruiting phenologies in environments that differ markedly in temperature and humidity. As a result, four genetically and ecologically distinct R. pomonella populations that display partial reproductive isolation have evolved. Host shifting by Rhagoletis and similar evolutionary histories could have had cascading effects across trophic levels, influencing the diversity and distribution of associated parasitoid guilds. To establish the basis for a future understanding of the possible effect of divergence in R. pomonella populations on the parasitoids attacking these flies, we surveyed parasitoids from five different species of hawthorns distributed over 15 states in México and 2 states in the midwestern United States. Emerging parasitoids were identified, parasitism rates were calculated, and regional fly and parasitoid emergence schedules were determined. Parasitism rate, emergence schedules, Shannon-Weiner diversity indexes, and species accumulation curves were compared across three main geographical regions. Parasitism levels varied greatly among regions from an overall high of 27.2% in the United States to 5.5% in the Sierra Madre Oriental (SMO) mountains of Mexico, to as low as 0.19% in the Eje Volcánico Trans Mexicano (EVTM). Shannon-Weiner diversity indexes showed that parasitoid species diversity was similar across the distribution range of R. pomonella in Mexico and the United States because of the fact that total parasitism was dominated by only two species, one of them recovered across the whole North American range of hawthorn infesting Rhagoletis. Nevertheless, eight parasitoids were found attacking R. pomonella in Mexico compared with only four collected in the United States. Only two diapausing parasitoid species were shared between the U.S. and Mexican R. pomonella populations: Utetes canaliculatus and Diachasmimorpha mellea. Interestingly, many subtropical parasitoid species, usually associated to flies in the subtropical genus Anastrepha, were recovered in the SMO in low numbers. The wide distribution of U. canaliculatus and D. mellea offers an ideal opportunity to test for a shared biogeography and co-evolution between fly and parasitoids. In this regard, one factor contributing to the success of U. canaliculatus seems to be the wasp's ability to modulate its eclosion time to track regional variation in hawthorn fruiting phenology and host (i.e., fly larvae) availability. Both R. pomonella and U. canaliculatus from southern sites emerged later than insects from northern populations, mirroring seasonal differences in hawthorn fruiting times across Mexico and the United States. These results suggest that molecular studies and crossing experiments could show, as they have for Rhagoletis, recent speciation events for parasitoid species of Nearctic origin that were found to be ecologically tracking environmentally driven divergence of their tephritid hosts.

Influence of methoprene and dietary protein on male Anastrepha suspensa (Diptera:Tephritidae) mating aggregations

The Caribbean fruit fly, Anastrepha suspensa (Loew), like many polyphagous tephritids, exhibits a lek polygyny mating system, and juvenile hormone levels and adult diet are known to have important positive effects on male sexual success. Among the potential components of this success are male lek tenure and female response to the sexual signals of lekking males. Male A. suspensa where submitted to four different treatments: (M(+)P(+)) application of juvenile hormone analog, methoprene (M) and sugar and hydrolyzed yeast as adult food; (M(+)P(-)) application of M and sugar as adult food; (M(-)P(+)) no application of M and sugar and hydrolyzed yeast as adult food; and (M(-)P(-)) no application of M and sugar as adult food. M(+)P(+) males initiated and participated more in aggregations, mated more frequently, and occupied the lek centers more often. They also had fewer unsuccessful mounting attempts than males in all the other treatments. M(+)P(+) males also emitted pheromones and acoustically signaled more often and attracted more females than males in other treatments. Male sexual performance was improved due to methoprene, protein supply, and the interaction of methoprene and protein for most of the parameters. Since the success of the sterile insect technique (SIT), a commonly employed technique to control pest tephritids, requires the release of males that can form leks, engage in agonistic sexual interactions, and attract females, these positive effects of protein and methoprene may substantially improve SIT programs.

Random mating among Anastrepha ludens (Diptera: Tephritidae) adults of geographically distant and ecologically distinct populations in Mexico

The Mexican fruit fly Anastrepha ludens (Loew) (Diptera: Tephritidae) is a polyphagous pestiferous insect with a geographical range encompassing highly variable environmental conditions. Considering that cryptic species have been recently found among South American representatives of the same taxonomic group as A. ludens, we tested whether or not some populations of A. ludens have evolved assortative mating as an isolating mechanism that maintains intrapopulation genetic differences and behavioral adaptations to local conditions. Males and females stemming from widely separated locations with similar environmental conditions and males and females stemming from populations within individual-flight range, but collected in different hosts (a native and an exotic one), mated randomly amongst themselves when placed in a field cage. Despite the fact that sibling males and females from two distinct populations also mated randomly amongst themselves, siblings engaged in significantly longer copulations than non-siblings, indicating that perhaps adults discriminated mates with similar genetic compositions. Our results have important practical implications as A. ludens is the most devastating pest of citrus in Mexico and Central America, and large-scale releases of sterile flies are used to control it.

Larval feeding substrate and species significantly influence the effect of a juvenile hormone analog on sexual development/performance in four tropical tephritid flies

The juvenile hormone (JH) analog methoprene reduces the amount of time it takes laboratory-reared Anastrepha suspensa (Caribbean fruit fly) males to reach sexual maturity by almost half. Here, we examined if methoprene exerted a similar effect on four other tropical Anastrepha species (Anastrepha ludens, Anastrepha obliqua, Anastrepha serpentina and Anastrepha striata) reared on natural hosts and exhibiting contrasting life histories. In the case of A. ludens, we worked with two populations that derived from Casimiroa greggii (ancestral host, larvae feed on seeds) and Citrus paradisi (exotic host, larvae feed on pulp). We found that the effects of methoprene, when they occurred, varied according to species and, in the case of A. ludens, according to larval host. For example, in the case of the two A. ludens populations the effect of methoprene on first appearance of male calling behavior and number of copulations was only apparent in flies derived from C. greggii. In contrast, males derived from C. paradisi called and mated almost twice as often and females started to lay eggs almost 1 day earlier than individuals derived from C. greggii, but in this case there was no significant effect of treatment (methoprene) only a significant host effect. There were also significant host and host by treatment interactions with respect to egg clutch size. A. ludens females derived from C. paradisi laid significantly more eggs per clutch and total number of eggs than females derived from C. greggii. With respect to the multiple species comparisons, the treatment effect was consistent for A. ludens, occasional in A. serpentina (e.g., calling by males, clutch size), and not apparent in the cases of A. obliqua and A. striata. Interestingly, with respect to clutch size, in the cases of A. ludens and A. serpentina, the treatment effect followed opposite directions: positive in the case of A. ludens and negative in the case of A. serpentina. We center our discussion on two hypotheses (differential physiology and larval-food), and also interpret our results in light of the life history differences exhibited by the different species we compared.

Wolbachia in two populations of Melittobia digitata Dahms (Hymenoptera: Eulophidae)

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.

Psyttalia cf. concolor (Hymenoptera: Braconidae) for biological control of olive fruit fly (Diptera: Tephritidae) in California

The larval parasitoid, Psyttalia cf. concolor (Szépligeti), reared on Mediterranean fruit fly, Ceratitis capitata (Weidemann), by the USDA-APHIS-PPQ, Guatemala City, Guatemala, was imported into California for biological control of olive fruit fly, Bactrocera oleae (Gmelin), in olives, Olea europaea L. Mean percentage parasitism of olive fruit fly third instars infesting fruit in field cages ranged from 7.0 in Grapevine to 59.7 in Santa Barbara and in free releases ranged from 0 in Grapevine to 10.6 in Santa Barbara after 4- to 6-d exposures. In the laboratory, more parasitoids developed to adults in olive fruit fly larvae that were 11-13 d old than in larvae 8-10 d old. Adult parasitoids lived significantly longer when provided with water than adults without water in environmental chambers at 5 degrees C, 85% RH; 15 degrees C, 65% RH; 25 degrees C, 25% RH; and 35 degrees C, 25% RH. Adult parasitoids lived for 48 d with honey for food and water and 32 d with food and sugar solution at 15 degrees C and 65% RH. Survival of adult parasitoids without food and water in greenhouse tests was approximately 4 d in a simulated coastal climate and 1 d in a simulated inland valley climate and was significantly increased by providing food and water. The parasitoid did not develop in the beneficial seedhead fly, Chaetorellia succinea (Costa), in yellow star thistle. The rate of parasitism of walnut husk fly, Rhagoletis completa Cresson, larvae in green walnut husks was 28.4% in laboratory no-choice tests. In choice tests, the rate of parasitism of walnut husk fly versus olive fruit fly larvae in olives was 11.5 and 24.2%, respectively.

Effects of age, diet, female density, and the host resource on egg load in Anastrepha ludens and Anastrepha obliqua (Diptera: Tephritidae)

Oocyte counts, used as a measure of egg load, were compared among three different age groups (15, 30 and 45 days) of two polyphagous species of tephritid fruit flies, Anastrepha ludens and Anastrepha obliqua, which were exposed to varying conditions of diet (sucrose vs sucrose and protein), availability of oviposition substrate (present vs absent), adult female density (1, 2 and 4 females/cage), and semiochemical context (presence vs absence of male pheromones and fruit volatiles). In both species, oocyte counts were higher in older females and for females fed sucrose and protein than for females fed sucrose only. The presence of artificial oviposition substrates influenced oocyte counts in A. obliqua, but not in A. ludens. Female density influenced oocyte counts in both species. Females maintained in groups had higher egg loads than isolated females. Finally, preliminary evidence suggests that semiochemical context influenced oocyte counts. Counts were highest for females in a room containing both fruit volatiles and male pheromone, lowest for females in a room containing neither volatiles nor pheromone, and intermediate for females in rooms containing either volatiles or pheromone but not both. Our results suggest that egg load is influenced by environmental factors in different ways in these two species. Egg load in A. obliqua, a species whose host fruits are highly ephemeral, is responsive to access to the host resource. By contrast, in A. ludens, a species infesting less ephemeral fruit, female density and age played a more important role than host stimuli. The role of ovarian maturation and oviposition in mediating these effects, as well as implications for mass rearing and pest management, are discussed.

Parasitoids of medfly, Ceratitis capitata, and related tephritids in Kenyan coffee: a predominantly koinobiont assemblage

Arabica coffee was sampled from two sites in the central highlands of Kenya (Rurima, Ruiru) and one site on the western side of the Rift Valley (Koru). Three species of ceratitidine Tephritidae, Ceratitis capitata (Wiedemann), C. rosa Karsch and Trirhithrum coffeae Bezzi, were reared from sites in the central highlands, and an additional species, C. anonae Graham, was recovered from the western-most site. Ten species of parasitic Hymenoptera were reared from these tephritids. The parasitoid assemblage was dominated by koinobionts. Eight of the species are koinobiont endoparasitoids, but only one idiobiont larval ectoparasitoid was reared, and only one idiobiont pupal endoparasitoid. The effects of sampling bias on determination of parasitoid assemblage size associated with concealed hosts are discussed. The potential for use of these parasitoids in biological control is also discussed. Most of the parasitoid species recovered during this study are capable of developing on C. capitata, while several also attack C. rosa. Both flies are notorious pests of tropical and subtropical fruits.

Metabolic effects of clofibrate in insulin-dependent ketosis-prone diabetic man

This study examined the effects of clofibrate therapy on basal plasma substrate and hormone concentrations in ketosis-prone insulin-dependent diabetic man. A double-blind crossover design was utilized during a 3-mo period in which clofibrate treatment (1 g b.i.d.) was compared to that of a lactose placebo (1 g b.i.d.). Our results demonstrate that clofibrate treatment resulted in a significant reduction in the concentration of plasma glucose, ketone bodies, free fatty acids, triglyceride, and cholesterol in diabetic man. These beneficial effects were observed without demonstrable changes in circulating concentrations of insulin and glucagon. These observations suggest that in ketosis-prone diabetic man, clofibrate therapy may provide an adjunct to exogenous insulin administration.