RESUMO

The existing rearing protocols for Anastrepha fraterculus must be reviewed to make economically viable the production of sterile flies for their area-wide application. Additionally, evidence of sexual incompatibility between a long-term mass-reared Brazilian strain and wild populations has been found. To address these issues, this study aimed to refine rearing protocols and to assess the suitability of an A. fraterculus strain for the mass production of sterile flies. A series of bioassays were carried out to evaluate incubation times for eggs in a bubbling bath and to assess the temporal variation of egg production from ovipositing cages at different adult densities. A novel larval diet containing carrageenan was also evaluated. Egg incubation times higher than 48 h in water at 25 °C showed reduced larval and pupal yields. Based on egg production and hatchability, the density of 0.3 flies/cm2 can be recommended for adult cages. The diet with carrageenan was suitable for mass production at egg-seeding densities between 1.0 and 1.5 mL of eggs/kg of diet, providing higher insect yields than a corn-based diet from Embrapa. Even after two years of being reared under the new rearing protocols, no sexual isolation was found between the bisexual strain and wild flies.

RESUMO

The Sterile Insect Technique (SIT) is an autocidal control method that relies on inundative releases of sterilized mass-reared insects. This technology has been used in several area-wide programmes for the suppression/eradication of fruit fly populations. Choosing the optimum sterilizing dose and the sterile release density is an essential step of the SIT. Considering unsolved issues related to the application of this technique against Anastrepha fraterculus (Wiedemann), this study aimed to define accurately the central target dose for both sexes of this species and to verify the induction of sterility in fertile flies at different sterile:fertile ratios. The results from the regression analyses proved that the sterilization process for the A. fraterculus Brazilian-1 morphotype (the most common in southern Brazil and Argentina) could consist of irradiating pupae 72 h before adult emergence at 40 Gy, with no detrimental effects to standard quality control parameters. The ovarian development in irradiated females was characterized, demonstrating that doses equal to or higher than 25 Gy cause complete and irreversible ovarian atrophy. The laboratory and field cage tests showed that the sterility induction increased with the proportion of sterile flies, and a sterile:fertile ratio of 50:1 should be appropriate in SIT field trials. The sterile females apparently did not distract the sterile males, despite of the slightly higher reductions in pupal yield for all ratios in their absence. The data generated in this study have a great practical value and will help decision-makers in planning field trials to evaluate the efficacy of the SIT against A. fraterculus populations.

Assuntos

RESUMO

The availability of accurate techniques to discriminate between marked laboratory-reared flies and unmarked wild flies captured in monitoring traps is essential for programs that integrate the Sterile Insect Technique (SIT) to manage fruit flies. In this study, the feasibility of using a stable isotope marking technique for the South American fruit fly, Anastrepha fraterculus (Wiedemann), was assessed. Wild flies were collected from apple orchards, which are a target of a SIT project in southern Brazil. To verify if adult flies could be labelled by the stable isotopes from larval diets, larvae were reared on two different C4-based diets and fruits in laboratory. To evaluate the influence of the two most common attractants applied to capture A. fraterculus (grape juice and CeraTrapTM) and the most common preservation method in fruit fly collections (ethanol), laboratory-reared flies were immersed in McPhail traps containing the respective treatments for two periods of time. Samples were analyzed in an elemental analyzer coupled to a Continuous Flow Isotope Ratio Mass Spectrometer (CF-IRMS) at CENA/USP. The δ13C signatures of flies reared on artificial diets differed significantly from the δ13C of flies whose larvae were reared on fruits and from wild flies. In contrast, the δ15N values were less conclusive and the technique could not rely solely on them. In all cases considered, the δ13C and δ15N signatures from males did not differ from females. Despite the alterations caused by the attractants tested and ethanol, laboratory-flies could be distinguished from the wild ones based on δ13C signatures. This is the first comprehensive study to demonstrate that it is possible to distinguish wild A. fraterculus from flies reared on larval diets containing C4 sugar. The first experimentally derived trophic discrimination factors were also obtained for this species. Thus, intrinsic isotope labelling can serve as a backup to conventional dye marking.

Assuntos

RESUMO

Some species of the genus Anastrepha (Diptera: Tephritidae) are successfully managed by matching the sterile insect technique with parasitoid releases. Such strategies used in integrated pest management can be implemented only where insect mass-rearing programs are feasible. In this study, we show the process of domestication, rearing technology and quality control data obtained from 54 generations of Anastrepha sp.1 aff. fraterculus (Wiedemann, 1830) kept under fully artificial conditions. Eggs were collected by an artificial oviposition panel consisting of one side of the cage made of blue voile fabric externally covered with a thin layer of silicon rubber. They were then air-bubbled in water at 25 ºC for 48 h before seeding. Larvae were reared on the regular laboratory artificial diet with 66 % of agar reduction turning over a semi-liquid diet, which reduced costs and improved insect quality. The adult and larval diets were composed of local ingredients including hydrolyzed yeast. When large-scale production of this fly is contemplated, the critical stage is larval development. This system of artificial rearing for A. fraterculus sp.1 developed in Brazil, allows for the production of a large number of insects of excellent quality using local ingredients and less agar in diet composition than the original medium used for this species. By reducing the interval of egg collection, the system might be optimized in terms of insect yield and, therefore, meet the demands of A. fraterculus sp.1 with regard to integrated pest management purposes.

Assuntos

RESUMO

Some species of the genus Anastrepha (Diptera: Tephritidae) are successfully managed by matching the sterile insect technique with parasitoid releases. Such strategies used in integrated pest management can be implemented only where insect mass-rearing programs are feasible. In this study, we show the process of domestication, rearing technology and quality control data obtained from 54 generations of Anastrepha sp.1 aff. fraterculus (Wiedemann, 1830) kept under fully artificial conditions. Eggs were collected by an artificial oviposition panel consisting of one side of the cage made of blue voile fabric externally covered with a thin layer of silicon rubber. They were then air-bubbled in water at 25 ºC for 48 h before seeding. Larvae were reared on the regular laboratory artificial diet with 66 % of agar reduction turning over a semi-liquid diet, which reduced costs and improved insect quality. The adult and larval diets were composed of local ingredients including hydrolyzed yeast. When large-scale production of this fly is contemplated, the critical stage is larval development. This system of artificial rearing for A. fraterculus sp.1 developed in Brazil, allows for the production of a large number of insects of excellent quality using local ingredients and less agar in diet composition than the original medium used for this species. By reducing the interval of egg collection, the system might be optimized in terms of insect yield and, therefore, meet the demands of A. fraterculus sp.1 with regard to integrated pest management purposes.(AU)

Assuntos

RESUMO

The aim of this study was to find alternatives to reduce the cost of mass production of the South American fruit fly (A. fraterculus) by looking for locally available products as protein source in the diet of adults to replace the imported product without changing the quality parameters. Two yeast from a Brazilian company were evaluated. The quality parameters showed that the imported hydrolyzed yeast used in the adult diet could be perfectly replaced by the local products tested, with a reduction of over 80% of the cost of the diet. The quality of the produced insects remained the same and there were improvements in some quality parameters such as the volume of eggs produced, number of adults flying and longevity under the stress.