Optimization of the sterilizing doses and overflooding ratios for the South American fruit fly

Abstract

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.

Egg Sterilisation of Irradiated Nezara viridula (Hemiptera: Pentatomidae)

“…A rigorous estimate of the ideal overflooding ratio of sterile-wild insects is crucial prior to the implementation of any SIT programme because the chance of a wild insect mating with a sterile insect increases with an increasing number of the latter in relation to the former [ 52 , 66 ]. Overflooding ratios are often estimated through population modelling, based on the percent sterility and biological parameters of the target pest that are relevant to population size over time [ 52 , 67 ].…”

Can stable isotope markers be used to distinguish wild and mass-reared Anastrepha fraterculus flies?

“…g . females cannot be easily distinguished on the basis of ovary development when they are younger than 7 days) [64], the SIA could be used to determine if the flies are wild, resolving the doubts of farmers and SIT managers. In addition to the already raised issues that should be further investigated, the next step of our research will be to determine isotopic turnover rates and the persistence of the stable isotopes of C and N during the life of A .…”

Multispectral imaging for quality control of laboratory‐reared Anastrepha fraterculus (Diptera: Tephritidae) pupae

“…300 million sterile flies per week for suppressing Anastrepha species in Mexico (Orozco‐Dávila et al, ). Likewise, in Brazil, the South American fruit fly, Anastrepha fraterculus Wiedemann (Diptera: Tephritidae), a major economic pest of temperate fruits, has been considered as a candidate pest species for its suppression by SIT application (Mastrangelo et al, ). A mass‐rearing facility under the umbrella of MOSCASUL is being built in southern Brazil that aims at producing millions of sterile A. fraterculus for suppressing wild populations of this pest from commercial apple orchards.…”

“…The sterile insect technique (SIT) has been reported to suppress/ eradicate several fruit fly species (Dyck, Hendrichs, & Robinson, 2005;Mastrangelo, Kovaleski, Botteon, Scopel, & Costa, 2018). The SIT application requires the production of millions of sterile flies in mass-rearing facilities and their inundative releases in the target areas.…”