Practical Experience in the Field Release of Transgenic Mosquitos

Transcription

1 April 2013 Practical Experience in the Field Release of Transgenic Mosquitos

2 structure Overview including field efficacy Separating males from females Longevity Gene and insect dispersal Gene penetrance Persistence Impact on non-target organisms

3 OX513A OX513A is the lead Aedes aegypti line for the control of Ae. aegypti (dengue vector) The only genetically engineered mosquito strain to have been released in the open Inserted gene for overexpression of a protein and a gene for fluorescence Bi-sex lethality/marker expressed in both sexes

4 our approach Oxitec male 1. Oxitec release males (males do not bite) 2. males mate with wild females 3. offspring do not survive 4. successive releases reduce, or eliminate, the mosquito population OX513A now approved for unrestricted release By CTNBio in Brazil

5 Oxitec GM differs from GM crops GM crops Competitive advantage over non-gm GM traits are self-perpetuating Genetic change to the food product Potential introgression with non-gm Complex monitoring Oxitec insects Oxitec genes confer major disadvantage Oxitec gene self-limiting: cannot persist No genetic change to the food product In-built biocontainment Simple monitoring

6 mosquitoes' field environment

7 completed field studies East End, Cayman Islands ~ 300 population / 16 ha Itaberaba, Juazeiro, Brazil ~ 1800 population / 11 ha Mandacaru, Juazeiro, Brazil ~ 2800 population / 40 ha Pedra Branca, Jacobina, Brazil ~ 1200 population / 23 ha

8 completed field studies East End Itaberaba 96% reduction 94% reduction Mandacaru Pedra Branca 99% reduction 92% reduction

9 sex sorting procedure Males and females separated by pupal size Typically around 50,000 pupae per batch Gap between wires is calibrated

10 sex sorting procedure QC done on every batch Samples of 1000 mechanically-sexed pupae are checked manually 2 females in 1000 pupae is our acceptable limit If more than 2 females the batch is re-sorted The system results in significantly less than 0.1% females

11 % females after sex separation sex sorting procedure Panama demonstration 2014 (ongoing) pupae manually checked during a 7 week period contained 6 females = %

12 Longevity - field No released Number recaptures over time (days) % recapture DSP -95%CI +95%CI ALE 10, % , % , % , % , % , % , % Mark-release-recapture data numbers of marked males recaptured over time and with total % recapture, Daily Survival Probability (DSP), and Average Life Expectance (ALE).

13 Tsuda 2001 ( ) MacDonald 1977 ( ) MacDonald 1977 ( ) Tsuda 2001 ( ) Getis 2003 ( ) Reuben 1975 ( ) Ordonez-Gonzalez 2001 ( ) Maciel-de-Freitas 2007a ( ) Muir 1998 ( ) Maciel-de-Freitas 2007b ( ) McKemey (Brazil) ( ) Tsuda 2001 ( ) Maciel-de-Freitas 2007a ( ) Maciel-de-Freitas 2007a ( ) McKemey (Brazil) ( ) Tsuda 2001 ( ) Lacroix 2012 ( ) Maciel-de-Freitas 2007b ( ) Muir 1997 ( ) McKemey (Brazil)( ) McKemey (Brazil) ( ) Russel 2005 ( ) Maciel-de-Freitas 2007a ( ) McKemey (Brazil)( ) Maciel-de-Freitas 2007b ( ) Maciel-de-Freitas 2007b ( ) Trpis 1986 ( ) Lacroix 2012 ( ) Trpis 1986 ( ) Reuben 1975 ( ) Reiter 1995 ( ) Reiter 1996 ( ) Reiter 1996 ( ) Maciel-de-Freitas 2009 ( ) transgene and insect dispersal Harrington Wild type 2005 ( ) McKemey OX513A (Brazil) ( ) McKemey OX513A Gene (Brazil)( ) Dissemination Mean dispersal distances (m) for wild type Aedes aegypti, OX513A, and OX513A genes following male release References: Getis et al., 2003; Harrington et al., 2005; Lacroix et al., 2012; MacDonald, 1977; Maciel- De-Freitas et al., 2007a; Maciel-De-Freitas et al., 2007b; Maciel-de-Freitas and Lourenco-de-Oliveira, 2009; Muir and Kay, 1998; Ordonez-Gonzalez et al., 2001; Reiter, 1996; Reiter et al., 1995; Reuben et al., 1975; Russell et al., 2005; Trpis and Häusermann, 1986; Tsuda et al., 2001

14 Soper 1938 ( ) McKemey (Brazil) ( ) Tsuda 2001 ( ) Tsuda 2001 ( ) Sheppard 1969 ( ) Tsuda 2001 ( ) Tsuda 2001 ( ) Harrington 2001 ( ) Sheppard 1969 ( ) Maciel-de-Freitas 2007b ( ) Takagi 1995 ( ) Maciel-de-Freitas 2007a ( ) Trpis 1986 ( ) Ordonez-Gonzalez 2001 ( ) Trpis 1995 ( ) Maciel-de-Freitas 2007a ( ) Maciel-de-Freitas 2007a ( ) Maciel-de-Freitas 2007b ( ) Trpis 1986 ( ) Muir 1998 ( ) Muir 1997 ( ) McKemey (Brazil) ( ) McKemey (Brazil)( ) McKemey (Brazil) ( ) Russel 2005 ( ) Maciel-de-Freitas 2007a ( ) Reuben 1975 ( ) Lacroix 2012 ( ) Reiter 1996 ( ) Lacroix 2012 ( ) McKemey (Brazil)( ) Maciel-de-Freitas 2007b ( ) Reuben 1975 ( ) Maciel-de-Freitas 2007b ( ) Harrington 2005 ( ) Reiter 1995 ( ) Hausermann 1971 ( ) Hausermann 1971 ( ) Bond 1970 ( ) Liew 2004 ( ) Maciel-de-Freitas 2009 ( ) MacDonald 1977 ( ) MacDonald 1977 ( ) Honorio 2003 ( ) Teesdale 1955 ( ) Reiter 1995 ( ) Shannon 1930 ( ) transgene and insect dispersal Soper Wild 1938 type ( ) McKemey OX513A (Brazil) ( ) McKemey OX513A Gene (Brazil)( ) Dissemination Maximum dispersal distances (m) for wild type Aedes aegypti, OX513A, and OX513A genes following male release References: Bond et al., 1970; Getis et al., 2003; Harrington et al., 2005; Harrington et al., 2001; Hausermann et al., 1971; Honorio et al., 2003; Lacroix et al., 2012; Liew and Curtis, 2004; MacDonald, 1977; Maciel-De-Freitas et al., 2007a; Maciel-De-Freitas et al., 2007b; Maciel-de-Freitas and Lourencode-Oliveira, 2009; Muir and Kay, 1998; Ordonez-Gonzalez et al., 2001; Reiter, 1996; Reiter et al., 1995; Reuben et al., 1975; Russell et al., 2005; Shannon and Davis, 1930; Sheppard et al., 1969; Soper, 1938; Takagi et al., 1995; Teesdale, 1955; Trpis and Häusermann, 1986; Trpis et al., 1995; Tsuda et al., 2001

15 transgene dispersal

16 transgene dispersal

17 insect dispersal migration UNTREATED TREATED Border Migration zone (200m)

18 penetrance (laboratory) Median survival of OX513A males and females was 2 days, as compared to corresponding wildtype males and females with median survival of 60 and 68 days respectively Survival curves for heterozygous OX513A-wild type progeny in the absence of tetracycline

19 penetrance / persistence (field) 145 OX513A males and 41 wild males, no heterozygotes found Lack of heterozygous adults indicates stability of the transgene No evidence of resistance in the field population. Field survival of heterozygotes is no higher than in lab no. WT no. RIDL Analysis of samples after last release date Daily BG-Sentinel catch was analysed by PCR. Only wild type (red bars) and homozygous OX513A (blue bars) were found i.e. no heterozygous individuals.

20 effects on non-target species No direct effects 100% species-specific Indirect effects Urban environment limited fauna Smallest possible ecological hole No wholly dependent predators or parasitoids Ae. aegypti is an invasive species Restoring native biodiversity Post release monitoring

21 summary Technology is novel not akin to GM crops It works consistently in all environments Dispersal (insect or transgene) is limited to 200 metres Persistence after releases is negligible Phenotype is sustained, and not prone to resistance 100% targeted at an invader with no known adverse effects on human or the environment

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