Anastrepha Obliqua Research Articles

Mating, but Not Male Accessory Gland Products, Changes Female Response to Olfactory Cues in Anastrepha Fruit Flies.

Copulation and/or ejaculate components can alter female physiological state and female post-mating behavior. The objective of the present study was to determine if copulation and male reproductive accessory gland products (MAGs) modify the behavior of female Anastrepha ludens (Loew) and Anastrepha obliqua (Macquart; Diptera: Tephritidae) in response to two stimuli: male-emitted pheromone and oviposition host volatiles. Olfactometry studies revealed that mated females of both A. ludens and A. obliqua have a stronger response for host volatiles compared to unmated females, which have a stronger response for male pheromone. We also examined olfactory responses of females mated to testectomized males who could transfer MAGs but not sperm. In both species, MAGs alone did not cause the change in the olfactory response observed after copulation, unlike what has been found in Ceratitis capitata (Wiedemann). Females mated to testectomized males responded equally to the male sex pheromone or to host volatiles, thus suggesting that the whole ejaculate is needed to elicit the complete behavioral switch in olfactory response. The function of MAGs is still unknown in these two pests of economic importance. The response for host volatiles by mated females has implications for the development of baits and traps that should preferably attract and target this population.

Influence of Mineral Particle Films and Biomaterials on Guava Fruits and Implications for the Oviposition of Anastrepha obliqua (Macquart) (Diptera: Tephritidae).

Simple SummaryAmong the main phytosanitary problems that affect the production and commercialization of fresh fruits, the occurrence of fruit flies (Diptera: Tephritidae) is one of the main obstacles. The control of these tephritids is mainly performed through the use of toxic baits. The use of mineral films and biomaterials may constitute a viable alternative in relation to the traditional insecticide method, mainly because they do not contaminate the environment and do not leave toxic residues harmful to humans and animals in treated products. Therefore, by modifying the color and texture of the fruit cuticule that covers the plant tissues, kaolin affects the perception of arthropod pests, impairing the localization process and acceptance of the host plant and, consequently, its feeding and oviposition. In this study, we hypothesized that the color changes of guava fruits because of mineral particle films and biomaterials can affect the oviposition of fruit flies. The results obtained are promising and show that mineral films and biomaterials interfering with the color of guavas inhibited the oviposition of A. obliqua. Therefore, they can be used to protect guava fruits from the damage caused by this pest. Anastrepha obliqua (Macquart, 1835) is an important pest of tropical fruits, especially Anacardiaceae and Myrtaceae, in the Americas. The objective of this study was to evaluate the influence of mineral films and biomaterials on the coloring of guava fruits (Psidium guajava L.) and implications for the oviposition of A. obliqua. Before the bioassays, color, firmness characteristics, total soluble solids, pH, and titratable acidity were determined to characterize the maturation stage of the fruits. Pieces of guava fruit covered in aluminum foil were immersed in suspensions of mineral particles (Surround® WP kaolin; kaolins 605, 607, 608, and 611; and talc) and biomaterials (chitosan, cassava and potato starch, and guar gum) and distilled water (control). After drying, the fruits were exposed to two A. obliqua pairs for 48 h in choice and non-choice tests, and the numbers of eggs per fruit were counted. Mineral films (Surround® WP kaolin, and kaolins 605, 607, 608, and 611) and biomaterials (cassava and potato starch) interfered with the color of guava (luminosity, chroma, and hue angle), inhibiting the oviposition of A. obliqua. Talc, chitosan, and guar gum did not influence the oviposition of A. obliqua in guava.

Effect of fly density and holding period on quality parameters of pre‐release chilled adults of Anastrepha obliqua (Diptera: Tephritidae)

AbstractPacking, shipping, holding and releasing methods of sterile tephritid fruit flies for the control of pest populations have recently received special attention because they are the final steps in the application of the sterile insect technique (SIT). In this study, we examined the effect of four holding densities, 0.524, 0.599, 0.674 and 0.748 sterile adults/cm2, and four holding periods (5, 6, 7 and 8 days) in sterile West Indian fruit flies, Anastrepha obliqua (Diptera: Tephritidae). The key parameters of adult fliers (AF, also known as absolute fliers) and adult survival under stress were measured. We also compared two methods to determine the percentage of AF (called the tray and sample methods) after the holding period and the chilling process. Our results indicate that differences in holding densities and holding periods may not affect the percentage of AF and the survival of sterile adults if they are supplied with enough food and water, allowing the release of higher numbers of sexually mature sterile males. When estimating the percentage of AF, the evaluated methods resulted equivalent and reliable, but the sample method showed a clear advantage by allowing the use of lower numbers of sterile flies to perform the test, which may represent important savings in SIT programmes. These findings will require further studies on sexual competitiveness in field cages to better determine the optimal management of sterile flies in FERFs.

Competitive strategies between Anastrepha fraterculus and Anastrepha obliqua (Diptera: Tephritidae) regulating the use of host fruits

AbstractInterspecific competition between individuals of different species can result in reductions in their fecundity, growth or survival, reflecting differential exploitation of resources that become intensified due to spatial co‐occurrence, ecological similarity and increased population densities. As two species cannot occupy the same niche, coexistence is only possible if the available resources are used in non‐overlapping manners such as niche partitioning or the use of refuges. Among agricultural insect pests, such as fruit flies of the family Tephritidae, competitive interactions can result in competitive displacement, host changes, or the expansion or restriction of the numbers of hosts utilized that can have negative consequences for human agricultural activities. We evaluated the competitive interactions between two fruit fly species of the genus Anastrepha, Anastrepha obliqua (Macquart, 1835) and Anastrepha fraterculus (Wiedmann, 1830), on their respective preferred hosts (mangoes and guava). Experiments of larval competition and competition for ovipositioning sites by adult females were performed to compare the parameters of larval development time, numbers of pupae and emerged adults and numbers of ovipositions in the presence or absence of interspecific competition. We observed that the interactions between those species were asymmetrical and hierarchical, and our results suggest a competitive displacement of A. fraterculus by A. obliqua when those two species are present on the same fruit, whether mangoes or guavas.

First record of Anastrepha obliqua (Diptera: Tephritidae) and a tritrophic relation with parasitoids in a citrus orchard in Pará state, Brazil

ABSTRACT Citriculture is a growing industry in Pará state, Brazil, but information regarding fruit flies and their associated parasitoids in this region is lacking. To address this gap in knowledge, we collected oranges (Citrus sinensis), lime oranges (C. sinensis), common sweet limes (C. limettioides), citrons (C. medica) and mandarins (C. reticulata). We recorded field infestation by Anastrepha obliqua in C. sinensis under natural conditions for the first time in the study region, and a tritrophic relationship between C. sinensis, A. obliqua, and the parasitoids Opius bellus and Asobara anastrephae was identified.

Does Ammonia Released from Protein-Based Attractants Modulate the Capture of Anastrepha obliqua (Diptera: Tephritidae)?

Simple SummaryThe West Indian fruit fly, Anastrepha obliqua (family Tephritidae), is an important pest of mango and guava in the Neotropical region. Previous studies have indicated that ammonia is involved in fruit fly attraction to sources of food, particularly if protein is present. In laboratory experiments, flies were attracted to ammonia solutions of increasing concentration. In contrast, fly captures by different protein-based attractants were not related to the quantity of ammonia released by the attractant. Flies also responded differently to yeast suspensions of different alkalinity that released different amounts of ammonia. In field experiments, flies were strongly attracted to yeast in ammonia solutions after 24 h, but this effect did not persist when measured over a 7-day period. We conclude that A. obliqua flies are attracted to ammonia solutions in the absence of other stimuli, but attraction to protein-based attractants or alkaline yeast suspensions is not correlated with the quantity of ammonia released by these substances. Ammonia is an important component in fruit fly attraction, which also seems to depend on the presence of other compounds derived from protein food sources in different stages of decomposition.Tephritid fly responses to food-based attractants involve a complex range of food-derived semiochemicals, including ammonia. We performed laboratory and field experiments to compare the attraction of Anastrepha obliqua (Macquart) to ammonia with the attraction to commercial food attractants and torula yeast at a range of pHs. A positive correlation was established between the concentration of ammonia in solution (1.5–150 mM ammonium solution) and gaseous ammonia released by bottle-type traps. This resulted in an asymptotic response in captures of A. obliqua flies in traps that released 99–295 µg ammonia/h. Pairwise comparisons in laboratory cages revealed that traps baited with 150 mM ammonia solution captured similar numbers of A. obliqua as traps baited with Biolure 2C, CeraTrap, and hydrolyzed protein products (Captor, Winner, and Flyral) plus borax, despite the low quantities of ammonia (11–56 µg/h) released from these attractants. Subsequent choice experiment captures in traps containing ammonia solution were similar or higher than those of commercial attractants, with the exception of Winner + borax, but were not correlated with the ammonia released from attractants. Captures of flies in traps containing ammonia solution were increased by the addition of 1% torula yeast or torula yeast alkalized with sodium hydroxide or borax despite differences in the quantities of ammonia released. Fly captures generally increased with increasing alkalization of torula yeast (pH 7.5–9.5). In the field, torula yeast in ammonia solution captured similar numbers of A. obliqua flies as Captor + borax when traps were evaluated after 24 h but not after a 7-day trapping period. Traps baited with ammonia solution or Winner + borax were significantly less attractive than Captor + borax in both field experiments. We conclude that A. obliqua flies are attracted to ammonia solutions of increasing concentration, up to 150 mM, in the absence of other stimuli, whereas attraction to commercial attractants or alkalized torula yeast is not correlated with the release of ammonia.

Bioactive Male-Produced Volatiles from Anastrepha obliqua and their Role in Attraction of Conspecific Females.

The study of insect semiochemicals, especially pheromones, is of fundamental importance for the development of strategies for controlling agricultural pests. In this study, volatile compounds involved in the communication between males and females of the fruit fly, Anastrepha obliqua (Diptera: Tephritidae), for mating purposes were characterized to develop attractant formulations for females of this species. Extracts containing volatile compounds released by males of A. obliqua were obtained by the dynamic headspace technique and analyzed by gas chromatography coupled with an electroantennographic detector (GC-EAD) and gas chromatography coupled with mass spectrometry (GC-MS). Twenty-one volatile compounds were identified in the aeration extracts of males. Five of them caused EAD responses from the antennae of females: 1-heptanol, linalool, (Z)-3-nonen-1-ol, (E,Z)-3,6-nonadien-1-ol, and (Z,E)-α-farnesene. Six synthetic mixtures of these compounds, including the five-component blend and all possible four-component blends, were formulated in a biopolymer and used in behavioral bioassays conducted in the laboratory arena with conspecific virgin females. One blend of 1-heptanol, linalool, (Z)-3-nonen-1-ol, and (Z,E)-α-farnesene attracted more females than the collection of volatiles from virgin males used as control. The other mixtures were as attractive to A. obliqua females as the control treatment. This study indicates potential for use of these compounds in monitoring and control strategies for this pest.

First report of Anastrepha obliqua (Macquart) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) and the parasitoid Doryctobracon areolatus (Szépligeti) (Hymenoptera: Braconidae) in the oceanic archipelago of Fernando de Noronha, Brazil

We recorded for the first time the presence of the two fruit flies pests, Anastrepha obliqua (Macquart) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) and the parasitoid Doryctobracon areolatus (Szépligeti) (Hymenoptera: Braconidae) in the oceanic archipelago of Fernando de Noronha, Pernambuco, Brazil. The specimens were collected in traps installed during June/2019 to February/2020. The fruit flies and the parasitoid species are widespread in the Brazilian mainland and have most likely been introduced accidentally in the archipelago.

The ripeness stage but not the cultivar influences the attraction of Anastrepha obliqua to guava

The West Indian fruit fly, Anastrepha obliqua (Macquart), infests a wide diversity of tropical fruit. Previous studies suggest that A. obliqua adults are attracted to volatile compounds common in different hosts. However, to date, most studies have used ripe fruit for the identification of attractive compounds. In this study, we investigated the attraction of sexually mature A. obliqua females and males to two cultivars and three ripening stages of guava. We also identified the attractive compounds to A. obliqua by combined gas chromatography-electroantennographic detector (GC-EAD) and gas chromatography-mass spectrometry (GC–MS) and evaluated the biological activity of the identified compounds in field-cage tests. We found that individuals of both sexes of A. obliqua showed no preference to the volatiles of either of the two cultivars of guava evaluated. In contrast, flies were more attracted to ripe and half-ripe fruit than to unripe ones. GC-EAD analyses of extracts of ripe “Creole” or “Thai” cultivars identified six compounds that elicited antennal responses by A. obliqua females and males. The compounds were identified by GC–MS as ethyl butyrate, cis-3-hexen-1-ol, ethyl hexanoate, cis-3-hexenyl acetate, ethyl benzoate, and ethyl octanoate. Half-ripe guava emit ethyl butyrate, cis-3-hexen-1-ol, ethyl hexanoate, and cis-3-hexenyl acetate, while only traces of cis-3-hexenyl-acetate were found in unripe guava. Field-cage tests with synthetic standards confirmed that the compounds identified are responsible for the attraction of A. obliqua flies to ripe guava.

Big particles, best nutrition? Absorption and excretion of protein by Anastrepha obliqua larvae (Diptera: Tephritidae).

For purposes of mass-rearing fruit flies, nutrient intake through artificial diets is a challenge, artificial food content and processing should promote sufficient absorption and availability to ensure fly fitness. Bulking agents play an essential role in creating a quality diet, but its physical characteristics, such as particle size, may establish a better microenvironment for feeding and development. Currently, there is a lack of information about protein metabolism in mass-reared fruit flies. Therefore, we evaluated whether the particle size of the bulking agent affects the absorption and excretion of the proteins, as well as their effect on the life-history traits of Anastrepha obliqua. We determined the protein content of hemolymph and feces, as well as the presence of nitrogen end-products as indicators of their level of absorption in a diet elaborated with coarse and fine corn cob particles as a bulking agent. The bromatological composition showed that coarse particles increased the bioavailability and content of crude, digestible, and soluble protein for the diet and hemolymph protein of larvae alike. We found an inverse relationship between the protein content of the hemolymph and feces of the larvae. Ammonium was determined to be a product of the catabolism of proteins. Also, A. obliqua improved its development (yield and pupal weight) and fitness (adult emergence and flight ability) when larvae were reared on a coarse particle diet. In conclusion, a diet elaborated with a coarse bulking agent features increased protein bioavailability and nutritional quality, which, in turn, increases the life-history traits of A. obliqua.

Competitive interactions and partial displacement of Anastrepha obliqua by Ceratitis capitata in the occupation of host mangoes (Mangifera indica)

AbstractWe examined the competitive interactions between a native fruit fly species (Anastrepha obliqua Macquart) and the invasive medfly (Ceratitis capitata Wiedemann) when these co‐occur on a shared mango fruit host (Mangifera indica L.). Using mango fruits of distinct levels of ripeness, we investigated both competition among larvae and among adult females for oviposition. We quantified competition by the numbers of eggs laid and the intensity of agonistic interactions between adult females. Interactions between immature fruit flies led to reduced size and number of emerged adults of both species. These impacts were felt more acutely in the native species. Interspecific competition between females led to fewer eggs laid on semi‐ripe fruit by both species, which may be the result of niche overlap associated with oviposition. Intraspecific interactions between A. obliqua individuals led to intense agonistic behaviour, with a concurrent decrease in number of landings on these host fruits. These results suggest that the native species undergoes a partial niche displacement when facing the invasive species. A portion of the fundamental niche of A. obliqua remained unoccupied by the invading C. capitata, which may allow their coexistence under natural conditions.

Attractiveness and Sexual Competitiveness of Anastrepha obliqua Males (Diptera: Tephritidae) Fed on a Diet Enriched With Providencia rettgeri.

The West Indian fruit fly, Anastrepha obliqua (Macquart), is the second most important tephritid fruit fly in Mexico, infesting mango, hog plum and guava fruits. To control this pest, the Mexican government has implemented the use of the sterile insect technique (SIT), which involves the mass production, sterilization and release of flies. However, the A. obliqua laboratory males used in SIT are selected to a lesser extent by the wild females during competitiveness tests. The objective of this study was to compare the effects of males fed on fruit fly food enriched with Providencia rettgeri to those in males fed on food alone, assessing male mating competitiveness, capture of females using traps baited with males fed with the enriched diet and sex pheromone components. The results indicated that males fed with the diet enriched with P. rettgeri had increased mating competitiveness and captured more females in the field cage tests. However, no difference was observed in the proportion of volatile sex pheromone components identified during the calling of A. obliqua males. The results suggest the value of incorporating bacteria into the mass rearing technique of A. obliqua adults in order to improve the sexual competitiveness of males from the laboratory compared to wild males.

Anastrepha, Ceratitis capitata, distribución, fluctuación poblacional, trampas caseras

El sistema Carrizal-Chone representa el proyecto hídrico más importante de Manabí, Ecuador donde existen huertos, compuestos por frutales, que son afectados por “moscas de la fruta” (Diptera: Tephritidae), reportadas como las principales plagas de cultivos hortofrutícolas en el mundo. La investigación tuvo como objetivo identificar las especies de moscas de la fruta, sus hospederos y su distribución geográfica en el área de influencia del sistema de riego Carrizal-Chone (Bolívar, Chone, Tosagua y Junín). Se implementaron dos rutas de monitoreo en el área de estudio, evaluando 24 trampas caseras, utilizando como atrayente extracto fermentado de maracuyá. Las trampas fueron recolectadas cada 15 días, recuperando las “moscas de la fruta” en frascos con alcohol y reponiendo en cada fecha el atrayente. Paralelamente, fueron recolectados frutos con evidencia de la plaga. Las muestras fueron procesadas en los laboratorios de Entomología de la Escuela Superior Politécnica Agropecuaria de Manabí y del Instituto Nacional de Investigaciones Agropecuarias. A partir de los datos, se obtuvo la identificación de especies, hospederos, distribución, dinámica poblacional e índice Mosca por Trampa por Día (MTD). Se identificaron seis especies, de las cuales Anastrepha fraterculus y Anastrepha obliqua son las de más amplia distribución. Los frutos más frecuentes fueron: guayaba, ovo, mango, arazá, zapote, fruta china, y mamey colorado. Se determinó que la disponibilidad y abundancia de frutas hospederas y especies nativas, son factores importantes que influyen sobre la fluctuación y temporalidad de las poblaciones de las “moscas de la fruta”.

Evaluation of a pelleted diet for larval mass‐rearing of Anastrepha ludens and Anastrepha obliqua

AbstractMost artificial diets used for mass‐rearing of fruit fly larvae involve the purchase and independent weighing of each ingredient of the formulation, followed by mixing and diet preparation process. A ready‐to‐use formulation would avoid this time‐consuming task and simplify the preparation procedure, leading to a more standardized diet. In this work, we compared life‐history traits and survival and developmental parameters of Anastrepha ludens Loew and Anastrepha obliqua (Macquart) (Diptera: Tephritidae) reared on two formulations of an artificial diet. Two experiments were performed; first, a conventional non‐pelleted diet was compared to a newly developed pelleted diet, which was mixed with water before being given to the larvae. The second experiment consisted of a comparison between the pelleted diet which was stirred in a mixer with water and dissolved preservatives and a pelleted diet which was only soaked in water with dissolved preservatives. We found that the pelleted diet allowed the mass‐rearing of A. ludens and A. obliqua. Moreover, feeding larvae with pelleted diet led to increased weight of the larva by 7.4 and 11.8%, and of the pupa by 9.5 and 16.7% for A. ludens and A. obliqua, respectively, compared to conventional diet. For process evaluation, the number of activities, handling time, reception, storage, and larval diet preparation were recorded. The pelleted diet only needed soaking in water containing preservatives, thereby simplifying the mass‐rearing process and saving time, space, and labour. Pelletizing is a versatile technology that can be adjusted for better physicochemical quality and reduced microbiological risk. This diet should be of particular interest for the mass‐rearing process in ‘sterile insect technique’ applications.

Frugivorous flies and their parasitoids associated with native fruits in an urban area

This study aimed to know the species of frugivorous flies (Tephritidae and Lonchaeidae) and their parasitoids associated with fruits in home orchards. It was conducted in the Gurgueia Valley, municipality of Bom Jesus, Piauí, Brazil. Fruit collection was carried out from April to December 2016. A total of 959 fruits (12 kg) belonging to seven fruit species were sampled, such as acerola (Malpighia glabra), carambola (Averrhoa carambola), lime (Citrus aurantifolia), balsam pear (Momordica charantia), cherry of the Rio Grande (Eugenia involucrata), umbu-cajá (Spondias bahiensis), and purple mombin (Spondias purpurea). Only three among these species (acerola, umbu-cajá, and purple mombin) were host, with 2,770 frugivorous flies. Umbu-cajá hosted 316 specimens of Anastrepha obliqua, from which puparia have emerged 84 specimens of Opius bellus and four of Pachycrepoideus vindemmiae. Purple mombin hosted Ceratitis capitata (2,384 specimens), Neosilba pendula (69 specimens), and Anastrepha sp. (one male). Eleven specimens of Tetrastichus giffardianus emerged from the puparia of C. capitata. Acerola hosted only one female of C. capitata and six specimens of N. pendula. Ceratitis capitata and N. pendula were recorded for the first-time infesting fruits of purple mombin in Piauí. Tetrastichus giffardianus parasitizing C. capitata in purple mombin was first recorded in the state of Piauí. Pachycrepoideus vindemmiae is a new record in A. obliqua in umbu-cajá in Brazil.

Variations in the Bacterial Communities in Anastrepha obliqua (Diptera: Tephritidae) According to the Insect Life Stage and Host Plant

Insects have established close relationships with a wide variety of microorganisms, which play a key role in insect ecology and evolution. Fruit flies in the Tephritidae family have economic importance at the global level, including species such as Anastrepha obliqua, which is an important pest in the neotropical region. Although several studies have been performed on the microbiota associated with fruit flies, there are still large gaps in our knowledge about the bacterial communities on the genus Anastrepha. During this study, we used high-throughput sequencing to characterize the bacterial communities of the polyphagous fly A. obliqua, and we evaluated the effect of the life stage (larvae and adults) and host plant (three plant species) on the structure of these communities. Our results show that the bacterial communities in A. obliqua appears to bestructured according to the insect life stage and the host plant. The predominant genera belonging to the phylum Proteobacteria were Wolbachia and Enterobacter in both larvae and adults, and they displayed differences in abundance between them, with Wolbachia sp. being more abundant in larvae and Enterobacter sp. being more abundant in adults. Differences in the structures of the bacterial communities were also observed according to the host plant with higher abundance of Enterobacter and Acetobacter bacteria in mango and plum fruits. Based on our results, it can be hypothesized that the bacterial communities on A. obliqua reorganize according to the needs of these insects during their different life stages and could also play an important role in the establishment of this fly species on different host plants. This study represents the first approach to understanding microorganism-insect interactions in fruit flies in Colombia.

Does Size Matter? Mate Choice in Two Lekking Flies.

For insect pests controlled through the Sterile Insect Technique (SIT), which consists in the mass production, sterilization, and release of target insects into affected areas, sterile male mating success with wild females is the key that will reduce population levels in the next generation. Male size is assumed to be important for mating success, but often without any concrete evidence or confounded by other parameters. Here, we evaluated male size and its interaction with male origin (laboratory or wild) on female choice for two lekking species controlled through SIT, Anastrepha obliqua (Macquart) and Anastrepha ludens (Loew) (Diptera: Tephritidae). In field cages, we tested wild females mating with: large wild males competing against small wild males; large wild males against small laboratory-sterile males; and large laboratory-sterile males against small wild males. We found evidence of large male advantage for A. obliqua but no effect of male size on mating competitiveness for A. ludens. For A. obliqua large wild males had a greater mating success over small laboratory males, yet large laboratory males secured a similar amount of copulations than small wild males. For A. ludens, there was no effect of male size on mating success. We discuss why A. obliqua is sensitive to size and origin while no effect was seen in A. ludens. SIT programs should not assume that male mating success is dependent on a large size. Alternatively, when an advantage exists for large males, mass-rearing programs should stride to produce and release large males.

Interaction Between Beauveria bassiana (Hypocreales: Cordycipitaceae) and Coptera haywardi (Hymenoptera: Diapriidae) for the Management of Anastrepha obliqua (Diptera: Tephritidae).

The interaction between the entomopathogenic fungus Beauveria bassiana (Balsamo) and the parasitoid Coptera haywardi (Oglobin), as potential biological control agents for Anastrepha obliqua (Macquart) fruit flies, was evaluated under laboratory and semi-protected field cage conditions. The effects of the parasitoids and fungus were individually and jointly assessed in Plexiglas cages. Application of B. bassiana dry conidia to soil produced 40% mortality in A. obliqua adults. However, mortality was lower (21.2%) on evaluation under field cage conditions. According to the multiple decrement life table analysis, the probability of death of A. obliqua was 88% when C. haywardi parasitoids and B. bassiana conidia were used in conjunction, 89% when only C. haywardi parasitoids were released and 23% when only B. bassiana conidia were applied. These results demonstrate that no synergistic, additive or antagonistic interaction took place with the simultaneous use of these natural enemies, since the presence of B. bassiana had no effect on the C. haywardi parasitism. These results indicate that the parasitoid is a better natural enemy for the control of A. obliqua, and show that, although the two biological control agents can be used simultaneously, their joint application will not produce increased control.

Quality control and characterization of the testicles and ovaries of irradiated Anastrepha obliqua from Brazil

With the aim of making the application of the Sterile Insect Technique (SIT) feasible in the management of the West Indian fruit fly in Brazil, Anastrepha obliqua (Macquart) (Diptera: Tephritidae), a number of quality parameters required by the SIT were investigated in this study. The aim was to verify the influence of a range of doses of gamma radiation (40, 50, 60, 70 and 80 Gy) on the fertility of females and to evaluate several quality control parameters, such as fly emergence, sex ratio, flight ability and survival under stress, as well as the characterization of the morphology (measurement of length and width) of the ovaries and testicles of A. obliqua. Pupae with 24 h before adult emergence were irradiated at CENA/Universidade de Sao Paulo. The radiosterilization test showed no difference between treatments for the parameters of fly emergence, sex ratio and survival under stress. The radiation at doses above 40 Gy resulted in ovarian atrophy in females and the absence of egg production. In males, the radiation also affected testicular development. Considering the quality parameters assessed, the sterilization results obtained agreed with previous data in the literature for other A. obliqua strains, and the dose of 60 Gy could be considered as the best compromise between insect quality and full sterility for the Brazilian strain of A. obliqua evaluated.

The Past and Current Potential Distribution of the Fruit Fly Anastrepha obliqua (Diptera: Tephritidae) in South America.

Anastrepha obliqua (Macquart) is an agricultural pest of wide geographic distribution infesting a vast list of host species in America. However, little is known about the past geographic distribution of this species. In this study, we investigated the potential past and current distribution of species in South America. In this sense, the MaxEnt algorithm was used to model the ecological niche of the species in the past (Last Interglcial Maximum; Last Glacial Maximum) and current periods. The results suggested that under the current climatic conditions, A. obliqua showed high environmental suitability to become established in most South American countries, especially in Brazil. The lowest suitability indices were observed in Chile, Argentina, and Uruguay. The past analysis for Last Glacial Maximum revealed that there was no significant change in the distribution potential of the species when compared to the current model; however, in the Last Interglacial Maximum period, there was a large reduction in the areas of suitability for the species when compared to the current and Last Glacial Maximum distribution models. The analysis also revealed vast areas of refuges for the species mainly on the coast of Brazil, as well as Venezuela, Bolivia, Guyana, and Surinam. The results presented here may be useful for future phylogeographical studies in order to test if the refuge areas concentrate greater genetic diversity for this species. In addition, our study provides important information for understanding the current dynamics of A. obliqua, which may be useful for control programs in places where this species can become a pest.