Scholarly Literature

This is a database of scholarly literature that concentrates currently on natural and engineered selfish genetic elements (gene drives).  The latest are shown here.
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Diverse mating phenotypes impact the spread of wtf meiotic drivers in Schizosaccharomyces pombe

20396
J. F. L. Hernandez, R. M. Helston, J. J. Lange, R. B. Billmyre, S. H. Schaffner, M. T. Eickbush, S. McCroskey and S. E. Zanders,  Elife,  10:30. 2021-12-13 09:37:02.
Meiotic drivers are genetic elements that break Mendel's law of segregation to be transmitted into more than half of the offspring produced by a heterozygote. The success of a driver relies on outcrossing (mating between individuals from distinct lineages) because drivers gain their advantage in heterozygotes. It is, therefore, curious that Schizosaccharomyces pombe, a species reported to rarely outcross, harbors many meiotic drivers. To address this paradox, we measured mating phenotypes in S. pombe natural isolates. We found that the propensity for cells from distinct clonal lineages to mate varies between natural isolates and can be affected both by cell density and by the available sexual partners. Additionally, we found that the observed levels of preferential mating between cells from the same clonal lineage can slow, but not prevent, the spread of a wtf meiotic driver in the absence of additional fitness costs linked to the driver. These analyses reveal parameters critical to understanding the evolution of S. pombe and help explain the success of meiotic drivers in this species. eLife digest The fission yeast, Schizosaccharomyces pombe, is a haploid organism, meaning it has a single copy of each of its genes. S. pombe cells generally carry one copy of each chromosome and can reproduce clonally by duplicating these chromosomes and then dividing into two cells. However, when the yeast are starving, they can reproduce sexually. This involves two cells mating by fusing together to create a 'diploid zygote', which contains two copies of each gene. The zygote then undergoes 'meiosis', a special type of cell division in which the zygote first duplicates its genome and then divides twice. This results in four haploid spores which are analogous to sperm and eggs in humans that each contain one copy of the genome. The spores will grow and divide normally when conditions improve. The genes carried by each of the haploid spores depend on the cells that formed the zygote. If the two 'parent' yeast had the same version or 'allele' of a gene, all four spores will have it in their genome. However, if the two parents have different alleles, only 50% of the offspring will carry each version. Although this is usually the case, there are certain alleles, called meiotic drivers, that are transmitted to all offspring even in situations where it is only carried by one parent. Meiotic drivers can be found in many organisms, including mammals, but their behavior is easiest to study in yeast. Meiotic drivers known as killers achieve this by disposing of any 'sister' spores that do not inherit the same allele of this gene. This 'killing' can only happen when only one of the 'parents' carries the driver. This scenario is thought to rarely occur in species that inbreed, as inbreeding leads to both gene copies being the same. However, this does not appear to be the case for S. pombe, which contain a whole family of killer meiotic drivers, the wtf genes, despite also being reported to mainly inbreed. To investigate this contradiction, Lopez Hernandez et al. isolated several genetically distinct populations of S.pombe. These isolates were grown together to determine how often the each one would outcross (mate with an individual from a different population) or inbreed. The results found that levels of inbreeding varied between isolates. Next, Lopez Hernandez et al. used mathematical modelling and experimental evolution analyses to study how wtf drivers spread amongst these populations. This revealed that wtf genes spread faster in populations with more outcrossing. In some instances, the wtf driver was linked to a gene that could harm the population. In these cases, Lopez Hernandez et al. found than inbreeding could purge these drivers and stop them from spreading the dangerous alleles through the population. Lopez Hernandez et al. establish a simple experimental system to model driver evolution and experimentally demonstrate how key parameters, such as outcrossing rates, affect the spread of these genes. Understanding how meiotic drivers spread is important, as these systems could potentially be used to modify populations important to humans, such as crops or disease vectors.

Exploiting a Y chromosome-linked Cas9 for sex selection and gene drive

19623
S. Gamez, D. Chaverra-Rodriguez, A. Buchman, N. P. Kandul, S. C. Mendez-Sanchez, J. B. Bennett, C. H. Sánchez, T. Yang, I. Antoshechkin, J. E. Duque, P. A. Papathanos, J. M. Marshall and O. S. Akbari,  Nature Communications,  7202. 2021-12-10 21:34:38.
CRISPR-based genetic engineering tools aimed to bias sex ratios, or drive effector genes into animal populations, often integrate the transgenes into autosomal chromosomes. However, in species with heterogametic sex chromsomes (e.g. XY, ZW), sex linkage of endonucleases could be beneficial to drive the expression in a sex-specific manner to produce genetic sexing systems, sex ratio distorters, or even sex-specific gene drives, for example. To explore this possibility, here we develop a transgenic line of Drosophila melanogaster expressing Cas9 from the Y chromosome. We functionally characterize the utility of this strain for both sex selection and gene drive finding it to be quite effective. To explore its utility for population control, we built mathematical models illustrating its dynamics as compared to other state-of-the-art systems designed for both population modification and suppression. Taken together, our results contribute to the development of current CRISPR genetic control tools and demonstrate the utility of using sex-linked Cas9 strains for genetic control of animals.

Evolution of B Chromosomes: From Dispensable Parasitic Chromosomes to Essential Genomic Players

19731
M. Johnson Pokorná and R. Reifová,  Frontiers in Genetics,  12:727570. 2021-12-09 12:58:40.
B chromosomes represent additional chromosomes found in many eukaryotic organisms. Their origin is not completely understood but recent genomic studies suggest that they mostly arise through rearrangements and duplications from standard chromosomes. They can occur in single or multiple copies in a cell and are usually present only in a subset of individuals in the population. Because B chromosomes frequently show unstable inheritance, their maintenance in a population is often associated with meiotic drive or other mechanisms that increase the probability of their transmission to the next generation. For all these reasons, B chromosomes have been commonly considered to be nonessential, selfish, parasitic elements. Although it was originally believed that B chromosomes had little or no effect on an organism's biology and fitness, a growing number of studies have shown that B chromosomes can play a significant role in processes such as sex determination, pathogenicity and resistance to pathogens. In some cases, B chromosomes became an essential part of the genome, turning into new sex chromosomes or germline-restricted chromosomes with important roles in the organism's fertility. Here, we review such cases of "cellular domestication" of B chromosomes and show that B chromosomes can be important genomic players with significant evolutionary impact.

Genomic insertion locus and Cas9 expression in the germline affect CRISPR/Cas9-based gene drive performance in the yellow fever mosquito Aedes aegypti

19603
W. R. Reid, J. Lin, A. E. Williams, R. Juncu, K. E. Olson and A. W. E. Franz,  bioRxiv,  2021.12.08.471839. 2021-12-08 18:56:04.
The yellow fever mosquito Aedes aegypti is a major vector of arthropod-borne viruses, including dengue, chikungunya, and Zika. A novel approach to mitigate arboviral infections is to generate mosquitoes refractory to infection by overexpressing antiviral effector molecules. Such an approach requires a mechanism to spread these antiviral effectors through a population, for example, by using CRISPR/Cas9-based gene drive systems. Here we report an autonomous single-component gene drive system in Ae. aegypti that is designed for persistent population replacement. Critical to the design of a single-locus autonomous gene drive is that the selected genomic locus be amenable to both gene drive and the appropriate expression of the antiviral effector. In our study, we took a reverse engineering approach to target two genomic loci ideal for the expression of antiviral effectors and further investigated the use of three promoters for Cas9 expression (nanos, β2-tubulin, or zpg) for the gene drive. We found that both promoter selection and genomic target site strongly influenced the efficiency of the drive, resulting in 100% inheritance in some crosses. We also observed the formation of inheritable gene drive blocking indels (GDBI) in the genomic locus with the highest levels of gene drive. Overall, our drive system forms a platform for the further testing of driving antipathogen effector genes through Ae. aegypti populations.Competing Interest StatementThe authors have declared no competing interest.

Modeling impact and cost-effectiveness of driving-Y gene drives for malaria elimination in the Democratic Republic of the Congo

19594
N. Metchanun, C. Borgemeister, G. Amzati, J. von Braun, M. Nikolov, P. Selvaraj and J. Gerardin,  Evolutionary Applications,  2021-12-07 17:59:09.
Malaria elimination will be challenging in countries that currently continue to bear high malaria burden. Sex-ratio distorting gene drives, such as driving-Y, could play a role in an integrated elimination strategy if they can effectively suppress vector populations. Using a spatially explicit, agent-based model of malaria transmission in eight provinces spanning the range of transmission intensities across the Democratic Republic of the Congo, we predict the impact and cost-effectiveness of integrating driving-Y gene drive mosquitoes in malaria elimination strategies that include existing interventions such as insecticide-treated nets and case management of symptomatic malaria. Gene drive mosquitoes could eliminate malaria and were the most cost-effective intervention overall if the drive component was highly effective with at least 95% X-shredder efficiency at relatively low fertility cost, and associated cost of deployment below 7.17 $int per person per year. Suppression gene drive could be a cost-effective supplemental intervention for malaria elimination, but tight constraints on drive effectiveness and cost ceilings may limit its feasibility.

Genetic conversion of a split-drive into a full-drive element

19540
G. Terradas, J. B. Bennett, Z. Li, J. M. Marshall and E. Bier,  bioRxiv,  2021.12.05.471291. 2021-12-06 20:21:27.
Gene-drive systems offer an important new avenue for spreading beneficial traits into wild populations. Their core components, Cas9 and guide RNA (gRNA), can either be linked within a single cassette (full gene drive, fGD) or provided in two separate elements (split gene drive, sGD) wherein the gRNA-bearing element drives in the presence of an independent static source of Cas9. We previously designed a system engineered to turn split into full gene drives. Here, we provide experimental proof-of-principle for such a convertible system inserted at the spo11 locus, which is recoded to restore gene function. In multigenerational cage studies, the reconstituted spo11 fGD cassette initially drives with slower kinetics than the unlinked sGD element (using the same Mendelian vasa-Cas9 source), but eventually reaches a similar level of final introgression. Different kinetic behaviors may result from transient fitness costs associated with individuals co-inheriting Cas9 and gRNA transgenes during the drive process.

Nuclear transport genes recurrently duplicate by means of RNA intermediates in Drosophila but not in other insects

19591
A. Mirsalehi, D. N. Markova, M. Eslamieh and E. Betrán,  BMC Genomics,  22:876. 2021-12-06 17:52:07.
We find that most of the nuclear transport duplications in Drosophila are of a few classes of nuclear transport genes, RNA mediated and fast evolving. We also retrieve many pseudogenes for the Ran gene. Some of the duplicates are relatively young and likely contributing to the turnover expected for genes under strong but changing selective pressures. These duplications are potentially revealing what features of nuclear transport are under selection. Unlike in flies, we find only a few duplications when we study the Drosophila duplicated nuclear transport genes in dipteran species outside of Drosophila, and none in other insects.

The economic value of genetically engineered mosquitoes as a Malaria control strategy depends on local transmission rates

19788
K. Lacy, K. A. Schaefer, D. P. Scheitrum and E. Y. Klein,  Biotechnology Journal,  10. 2021-12-06 14:26:13.
This paper assesses the economic value of genetically engineered (GE) Anopheles gambiae mosquitoes as a malaria control strategy. We use an epidemiological-economic model of malaria transmission to evaluate this technology for a range of village-level transmission settings. In each setting, we evaluate public health outcomes following introduction of GE mosquitoes relative to a "status quo" baseline scenario. We also assess results both in contrast to-and in combination with-a Mass Drug Administration (MDA) strategy. We find that-in low transmission settings-the present value (PV) public health benefits of GE mosquito release are substantial, both relative to status quo dynamics and MDA. In contrast, in high transmission settings, the release of GE mosquitoes may increase steady-state infection rates. Our results indicate that there are substantial policy complementarities when GE mosquito release is combined with local MDA-the combined control strategy can lead to local eradication.

Towards Integrated Management of Dengue in Mumbai

19735
P. N. Paradkar, P. R. Sahasrabudhe, M. Ghag Sawant, S. Mukherjee and K. R. Blasdell,  Viruses,  13. 2021-12-04 13:10:23.
With increasing urbanisation, the dengue disease burden is on the rise in India, especially in large cities such as Mumbai. Current dengue surveillance in Mumbai includes municipal corporation carrying out specific activities to reduce mosquito breeding sites and the use of insecticides to suppress the adult mosquito populations. Clinical cases remain either underreported or misreported due to the restriction to government clinics, missing the large private health care sector. There is a need for an integrated approach to manage dengue outbreaks in Mumbai. There are various novel strategies available for use that can be utilised to improve disease detection, mosquito surveillance, and control of mosquito-borne diseases. These novel technologies are discussed in this manuscript. Given the complex ecosystem of mosquito-borne diseases in Mumbai, integrating data obtained from these technologies would support the ongoing mosquito control measures in Mumbai.

A flurry of sex-ratio distorters

19527
A. A. Vogan,  Nature Ecology and Evolution,  2021-12-03 19:49:56.
Two analyses of long-read sequencing show that the Winters sex-ratio distorter of Drosophila has been a part of a recent gene family expansion, coupled to the appearance of suppressors, in a genomic arms race driven by satellite DNA.

Rapid evolutionary dynamics of an expanding family of meiotic drive factors and their hpRNA suppressors

19515
J. Vedanayagam, C. J. Lin and E. C. Lai,  Nature Ecology and Evolution,  2021-12-03 17:20:42.
Meiotic drivers are a class of selfish genetic elements whose existence is frequently hidden due to concomitant suppressor systems. Accordingly, we know little of their evolutionary breadth and molecular mechanisms. Here, we trace the evolution of the Dox meiotic drive system in Drosophila simulans, which affects male-female balance (sex ratio). Dox emerged via stepwise mobilization and acquisition of multiple D. melanogaster gene segments including from protamine, which mediates compaction of sperm chromatin. Moreover, we reveal novel Dox homologs and massive amplification of Dox superfamily genes on X chromosomes of its closest sisters D. mauritiana and D. sechellia. Emergence of Dox loci is tightly associated with 359-class satellite repeats that flank de novo genomic copies. In concert, we find coordinated diversification of autosomal hairpin RNA-class siRNA loci that target subsets of Dox superfamily genes. Overall, we reveal fierce genetic arms races between meiotic drive factors and siRNA suppressors associated with recent speciation.

CRISPR-Cas9 effectors facilitate generation of single-sex litters and sex-specific phenotypes

19469
C. Douglas, V. Maciulyte, J. Zohren, D. M. Snell, S. K. Mahadevaiah, O. A. Ojarikre, P. J. I. Ellis and J. M. A. Turner,  Nature Communications,  12:6926. 2021-12-03 15:06:30.
Animals are essential genetic tools in scientific research and global resources in agriculture. In both arenas, a single sex is often required in surplus. The ethical and financial burden of producing and culling animals of the undesired sex is considerable. Using the mouse as a model, we develop a synthetic lethal, bicomponent CRISPR-Cas9 strategy that produces male- or female-only litters with one hundred percent efficiency. Strikingly, we observe a degree of litter size compensation relative to control matings, indicating that our system has the potential to increase the yield of the desired sex in comparison to standard breeding designs. The bicomponent system can also be repurposed to generate postnatal sex-specific phenotypes. Our approach, harnessing the technological applications of CRISPR-Cas9, may be applicable to other vertebrate species, and provides strides towards ethical improvements for laboratory research and agriculture.

Public Perceptions Regarding Genomic Technologies Applied to Breeding Farm Animals: A Qualitative Study

19920
F. Z. Naab, D. Coles, E. Goddard and L. J. Frewer,  BioTech,  10. 2021-12-03 09:13:38.
The societal acceptability of different applications of genomic technologies to animal production systems will determine whether their innovation trajectories will reach the commercialisation stage. Importantly, technological implementation and commercialisation trajectories, regulation, and policy development need to take account of public priorities and attitudes. More effective co-production practices will ensure the application of genomic technologies to animals aligns with public priorities and are acceptable to society. Consumer rejection of, and limited demand for, animal products developed using novel genomic technologies will determine whether they are integration into the food system. However, little is known about whether genomic technologies that accelerate breeding but do not introduce cross-species genetic changes are more acceptable to consumers than those that do. Five focus groups, held in the north east of England, were used to explore the perceptions of, and attitudes towards, the use of genomic technologies in breeding farm animals for the human food supply chain. Overall, study participants were more positive towards genomic technologies applied to promote animal welfare (e.g., improved disease resistance), environmental sustainability, and human health. Animal “disenhancement” was viewed negatively and increased food production alone was not perceived as a potential benefit. In comparison to gene editing, research participants were most negative about genetic modification and the application of gene drives, independent of the benefits delivered.

CRISPR gene-drive systems based on Cas9 nickases promote super-Mendelian inheritance in Drosophila

19471
V. Lopez del Amo, S. Sanz Juste and V. M. Gantz,  bioRxiv,  2021.12.01.470847. 2021-12-02 15:07:14.
CRISPR-based gene drive systems can be used to modify entire wild populations due to their ability to bias their own inheritance towards super-Mendelian rates (>100%). Current gene drives contain a Cas9 and a gRNA gene inserted at the location targeted by the gRNA. These gene products are able to cut the opposing wildtype allele, and lead to its replacement with a copy of the gene drive through the homology-directed DNA repair pathway. When this allelic conversion occurs in the germline it leads to the preferential inheritance of the engineered allele; a property that has been proposed to disseminate engineered traits for managing disease-transmitting mosquito populations. Here, we report a novel gene-drive strategy relying on Cas9 nickases which operates by generating staggered paired-nicks in the DNA to promote propagation of the gene drive allele. We show that only when 5' overhangs are generated, the system efficiently leads to allelic conversion. Further, the nickase gene-drive arrangement produces large stereotyped deletions, providing potential advantages for targeting essential genes. Indeed, the nickase-gene-drive design should expand the options available for gene drive designs aimed at applications in mosquitoes and beyond.

Gene drive that results in addiction to a temperature-sensitive version of an essential gene triggers population collapse in Drosophila

19441
G. Oberhofer, T. Ivy and B. A. Hay,  Proceedings of the National Academy of Sciences,  118:e2107413118. 2021-12-01 20:58:01.
One strategy for population suppression seeks to use gene drive to spread genes that confer conditional lethality or sterility, providing a way of combining population modification with suppression. Stimuli of potential interest could be introduced by humans, such as an otherwise benign virus or chemical, or occur naturally on a seasonal basis, such as a change in temperature. Cleave and Rescue (ClvR) selfish genetic elements use Cas9 and guide RNAs (gRNAs) to disrupt endogenous versions of an essential gene while also including a Rescue version of the essential gene resistant to disruption. ClvR spreads by creating loss-of-function alleles of the essential gene that select against those lacking it, resulting in populations in which the Rescue provides the only source of essential gene function. As a consequence, if function of the Rescue, a kind of Trojan horse now omnipresent in a population, is condition dependent, so too will be the survival of that population. To test this idea, we created a ClvR in Drosophila in which Rescue activity of an essential gene, dribble, requires splicing of a temperature-sensitive intein (TS-ClvRdbe). This element spreads to transgene fixation at 23 °C, but when populations now dependent on Ts-ClvRdbe are shifted to 29 °C, death and sterility result in a rapid population crash. These results show that conditional population elimination can be achieved. A similar logic, in which Rescue activity is conditional, could also be used in homing-based drive and to bring about suppression and/or killing of specific individuals in response to other stimuli.

Applying functional genomics to the study of lamprey development and sea lamprey population control

19946
J. R. York, R. E. Thresher and D. W. McCauley,  Journal of Great Lakes Research,  47:S639-S649. 2021-12-01 09:30:24.
Lampreys are one of the few survivors of an ancient lineage of jawless vertebrates and have become an important study organism in numerous disciplines in the biological sciences, including evolutionary biology, embryology, ecology, physiology and biomedicine. At the same time, however, lampreys have created economic and ecological problems due, primarily, to the invasion of parasitic sea lamprey (Petromyzon marinus) into the North American Great Lakes and consequent negative impacts on local fish populations. Barriers, trapping and lampricide treatments have reduced these impacts, but concern for habitat restoration, non-target effects and possible evolution of resistance to lampricides suggests the need to develop additional strategies that supplement current control measures. The advent of functional genomics, and in particular CRISPR/Cas9 genome editing, offers a molecular approach to this on-going problem. Here, we review the successful application of functional genetic, transcriptomic, and CRISPR/Cas9 genome editing technologies in lampreys to address basic research questions in the fields of evolutionary and developmental biology. We then describe how these tools may be repurposed for use by fishery and conservation biologists to approach the problem of invasive sea lamprey from a molecular-genetic perspective.

New Arthropod Containment Recommendations Provide Essential Guidance for Safety of Gene Drive Research

19467
S. James and D. O’Brochta,  The American Journal of Tropical Medicine and Hygiene,  tpmd211148. 2021-11-30 14:49:53.
Gene drive technologies have not yet been field tested, however, there are no data on the possible environmental or health effects of releasing gene drive–modified organisms. For this reason, there have been widespread calls for additional guidance on risk assessment and management, and some have even proposed a moratorium on gene drive research until such guidance is in place. One immediate need has been for guidance on appropriate containment measures that researchers should follow when investigating gene drive–modified organisms, given that these are meant to spread their transgenes by inter breeding with compatible local species. For example, a 2020 survey of biosafety professionals revealed that the majority felt existing guidance was inadequate for making risk assessments and containment decisions regarding gene drive–modified arthropods. Lack of standard guidance can lead to uneven application of containment measures among institutions and decreased public confidence in the research. The American Committee of Medical Entomology (ACME)of the American Society of Tropical Medicine and Hygiene has responded to this need with the recent publication of an addendum to its widely influential Arthropod ContainmentGuidelines. The new addendum6provides specific recommendations on containment practices for arthropods modified with engineered transgenes capable of gene drive.

New molecular genetic techniques: regulatory and societal considerations

19403
Nielsen, K. M.,  AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application,  2021-11-29 18:07:46.
A rapidly expanding toolbox of techniques available for genome editing provides the basis for a new continuum in types of modifications that can be introduced into a genome and blur the bimodal GMO vs. non-GMO (genetically modified organism) divide. Site-directed nucleases (SDN) are now used to modify existing nucleotides within genomes instead of adding recombined DNA as transgenes. Moreover, new gene drive approaches are in development based on SDNs. A number of potential drive applications have been reported, but uncertainties in trait stability and limitations in knowledge of the affected system at various temporal and spatial levels slow down their current uses. Adoption of new genome targeted technology takes place in a social context. The context will vary between countries and cultures, expressed in values, ethics, politics and priorities - that are translated into different regulatory approaches. Some developed products using new genome editing techniques clearly fall under internationally negotiated regulations of GMOs. However, other product outcomes of editing techniques challenge our current understanding and definition of GMOs. There is an urgent need for further research, for building international consensus and harmonizing regulatory approaches to facilitate categorization, predictability, transparency, trust and trade.

Genome editing and its applications for insect pest control: Curse or blessing?

19401
Hacker, I. , and Schetelig, M. F,  AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application,  2021-11-29 18:00:39.
Gene and genome editing are described as cutting-edge research tools with the potential to tackle urgent global challenges in the management of agricultural pests and human disease vectors such as mosquitoes. The field is defined by the chances and challenges to interlink the disciplines of insect genomics, molecular biology, and pest control together with the need for clear risk assessment, policy development and public approval of the application of such novel technologies. The goal is to generate innovative and sustainable pest control solutions applied in the best interest for the environment and human society. Here, starting from available genome editing technologies, the current strategies and applications for insect pest control are discussed, including approaches to overcome the evolution of resistance alleles and other potential pitfalls to be expected from selective pressures resulting from gene drive applications. They are supplemented by views on regulatory, policy and ethical considerations that in our opinion will be necessary to define how the different tools can be used in the future in a safe and responsible way.

Area-wide management of fruit flies in a tropical mango growing area integrating the sterile insect technique and biological control: From a research to an operational programme

19391
Liedo, P., Montoya, P. , and Toledo, J.,  AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application,  2021-11-29 17:29:33.
The Sterile Insect Technique (SIT) has been successfully used for the control of fruit flies in a number of places in the world. One requirement for its successful application is that wild populations should be at low densities to achieve effective sterile to wild fly overflooding ratios. This has been an important reason that has limited its integration in fruit fly management in tropical fruit growing areas, where climate conditions and the availability of hosts all year-round results in high population densities. Here we report the results of a project where SIT integration into fruit fly management was evaluated under the tropical conditions of the mango growing area in the Soconusco region of Chiapas, Mexico. The basis for the area-wide integrated pest management (AW-IPM) approach was the knowledge of the population dynamics of the pest fruit flies in the region and of the fruit phenology. The main commercial mango growing areas are in the lowlands, where fruit fly populations are very low outside of the mango production season. Population densities are higher in the midlands and highlands, where alternate hosts are common in backyards and as part of the natural vegetation. We call these refuge areas, and the AW-IPM approach aimed at establishing a biological barrier with releases of parasitoids and sterile male fruit flies to suppress the fruit fly populations and prevent or minimize the dispersal of wild flies from the refuge areas to the mango orchards. In 2014, after two years of releases, fruit fly population densities were suppressed more than 70% in the release area and 65% in the entire area, including the lowlands with the mango orchards. With the support of fruit growers, state and federal governments, this project was continued and established as an operational AW-IPM programme. In 2016, after 4 years of programme implementation, the detection of wild flies was significantly reduced, and the number of batches of fruit that were rejected at the packing houses due to the detection of infested fruits was the lowest in the past 12 years, since the recording of these data was initiated. These indicators declined even further in 2017. The results obtained demonstrate that AW-IPM integrating the SIT can be applied successfully against fruit flies under tropical conditions with naturally high pest densities, providing there is adequate knowledge on the population dynamics of the fruit fly species present in the region.

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