Dataset Information

Improvement of the Mass-Rearing Protocols for the South American Fruit Fly for Application of the Sterile Insect Technique.

ABSTRACT: 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.

SUBMITTER: Mastrangelo T

PROVIDER: S-EPMC8304162 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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Improvement of the Mass-Rearing Protocols for the South American Fruit Fly for Application of the Sterile Insect Technique.

Mastrangelo Thiago T Kovaleski Adalecio A Maset Bruno B Costa Maria de Lourdes Zamboni MLZ Barros Claudio C Lopes Luis Anselmo LA Caceres Carlos C

Insects 20210709 7

The existing rearing protocols for <i>Anastrepha fraterculus</i> 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 <i>A. fraterculus</i> strain for the mass production of sterile flies. A series of b ...[more]

PMID: 34357284

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Project description:BackgroundInsect species have established sophisticated symbiotic associations with diverse groups of microorganisms including bacteria which have been shown to affect several aspects of their biology, physiology, ecology and evolution. In addition, recent studies have shown that insect symbionts, including those localized in the gastrointestinal tract, can be exploited for the enhancement of sterile insect technique (SIT) applications against major insect pests such as the Mediterranean fruit fly (medfly) Ceratitis capitata. We previously showed that Enterobacter sp. AA26 can be used as probiotic supplement in medfly larval diet improving the productivity and accelerating the development of the VIENNA 8 genetic sexing strain (GSS), which is currently used in large scale operational SIT programs worldwide.ResultsEnterobacter sp. AA26 was an adequate nutritional source for C. capitata larvae, comprising an effective substitute for brewer's yeast. Incorporating inactive bacterial cells in the larval diet conferred a number of substantial beneficial effects on medfly biology. The consumption of bacteria-based diet (either as full or partial yeast replacement) resulted in decreased immature stages mortality, accelerated immature development, increased pupal weight, and elongated the survival under stress conditions. Moreover, neither the partial nor the complete replacement of yeast with Enterobacter sp. AA26 had significant impact on adult sex ratio, females' fecundity, adults' flight ability and males' mating competitiveness. The absence of both yeast and Enterobacter sp. AA26 (deprivation of protein source and possible other important nutrients) from the larval diet detrimentally affected the larval development, survival and elongated the immature developmental duration.ConclusionsEnterobacter sp. AA26 dry biomass can fully replace the brewer's yeast as a protein source in medfly larval diet without any effect on the productivity and the biological quality of reared medfly of VIENNA 8 GSS as assessed by the FAO/IAEA/USDA standard quality control tests. We discuss this finding in the context of mass-rearing and SIT applications.

Project description:RNA interference (RNAi) technology has been used in the development of approaches for pest control. The presence of some essential genes, the so-called "core genes," in the RNAi machinery is crucial for its efficiency and robust response in gene silencing. Thus, our study was designed to examine whether the RNAi machinery is functional in the South American (SA) fruit fly Anastrepha fraterculus (Diptera: Tephritidae) and whether the sensitivity to the uptake of double-stranded RNA (dsRNA) could generate an RNAi response in this fruit fly species. To prepare a transcriptome database of the SA fruit fly, total RNA was extracted from all the life stages for later cDNA synthesis and Illumina sequencing. After the de novo transcriptome assembly and gene annotation, the transcriptome was screened for RNAi pathway genes, as well as the duplication or loss of genes and novel target genes to dsRNA delivery bioassays. The dsRNA delivery assay by soaking was performed in larvae to evaluate the gene-silencing of V-ATPase, and the upregulation of Dicer-2 and Argonaute-2 after dsRNA delivery was analyzed to verify the activation of siRNAi machinery. We tested the stability of dsRNA using dsGFP with an in vitro incubation of larvae body fluid (hemolymph). We identified 55 genes related to the RNAi machinery with duplication and loss for some genes and selected 143 different target genes related to biological processes involved in post-embryonic growth/development and reproduction of A. fraterculus. Larvae soaked in dsRNA (dsV-ATPase) solution showed a strong knockdown of V-ATPase after 48 h, and the expression of Dicer-2 and Argonaute-2 responded with an increase upon the exposure to dsRNA. Our data demonstrated the existence of a functional RNAi machinery in the SA fruit fly, and we present an easy and robust physiological bioassay with the larval stages that can further be used for screening of target genes at in vivo organisms' level for RNAi-based control of fruit fly pests. This is the first study that provides evidence of a functional siRNA machinery in the SA fruit fly.

Project description:Novel and alternative vector control approaches using a sterile male-based release to suppress Aedes aegypti mosquito vectors have recently been tested in the field in many countries. These approaches included the sterile insect technique (SIT), incompatible insect technique (IIT), and a combination of both techniques. In this study, we conducted a series of experiments to compare the quality between radiation-based and Wolbachia-induced sterile males in terms of flight ability, sterility, mating competitiveness, survival rate, and longevity. Aedes aegypti mosquitoes irradiated at 50 Gy (SIT) and those trans-infected with wAlbB Wolbachia (IIT) were used for quality comparison. Our results showed that irradiated and Wolbachia trans-infected males were not significantly different in flight ability (p > 0.05) and both could induce sterility in wild-type females. In addition, although irradiation at 50 Gy or Wolbachia trans-infection reduced male mating competitiveness, combined irradiation and Wolbachia wAlbB trans-infection increased male competitiveness at the one-to-one ratio. Increasing the number of sterile males released could compensate for reduced competitiveness but it does not make them more competitive. Irradiation did not affect the survival and longevity of irradiated males, but it showed significant negative impacts on females (p < 0.05); while the opposite was observed in the case of Wolbachia infection, i.e., with significant increase in the survival rate of Wolbachia trans-infected males (p < 0.05), but both survival and longevity were reduced in Wolbachia trans-infected females with no significant impacts (p > 0.05). In conclusion, neither irradiation nor Wolbachia trans-infection significantly affected the quality of sterile males except their mating competitiveness; but this could compensate by increasing the number of sterile males released. Sterility could be induced by either 50 Gy irradiation or wAlbB trans-infection. Mating competitiveness results showed that a higher number of sterile males produced by irradiation need to be released in comparison to those produced by Wolbachia trans-infection. Our results should be useful for planning SIT, IIT, or a combination for Ae. aegypti vector control.

Dataset Information

Improvement of the Mass-Rearing Protocols for the South American Fruit Fly for Application of the Sterile Insect Technique.

Publications

Improvement of the Mass-Rearing Protocols for the South American Fruit Fly for Application of the Sterile Insect Technique.

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