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Comparison of life history characteristics of the genetically modified OX513A line and a wild type strain of Aedes aegypti.

Bargielowski I, Nimmo D, Alphey L, Koella JC - PLoS ONE (2011)

Bottom Line: The genetically modified OX513A line overall showed 5% lower larval survival as well as reduced adult longevity (20 vs 24 days mean lifespan) compared to the unmodified line.Furthermore, the OX513A line pupated about one day sooner, which could be advantageous in mass-rearing, but produced somewhat smaller adults than the unmodified line; this effect was more pronounced in females than in males.Increasing the larval rearing density delayed pupation, decreased adult longevity and reduced adult size in both lines.

View Article: PubMed Central - PubMed

Affiliation: Division of Biology, Imperial College London, London, United Kingdom. irka.bargielowski06@imperial.ac.uk

ABSTRACT
The idea of implementing genetics-based insect control strategies modelled on the traditional SIT (Sterile Insect Technique), such as RIDL (Release of Insects carrying a Dominant Lethal), is becoming increasingly popular. In this paper, we compare a genetically modified line of Aedes aegypti carrying a tetracycline repressible, lethal positive feedback system (OX513A) with a genetically similar, unmodified counterpart and their respective responses to increasing larval rearing density using a constant amount of food per larva. The parameters that we examined were larval mortality, developmental rate (i.e., time to pupation), adult size and longevity. Analysis revealed some statistically significant differences between the life history traits we examined. The genetically modified OX513A line overall showed 5% lower larval survival as well as reduced adult longevity (20 vs 24 days mean lifespan) compared to the unmodified line. Furthermore, the OX513A line pupated about one day sooner, which could be advantageous in mass-rearing, but produced somewhat smaller adults than the unmodified line; this effect was more pronounced in females than in males. Increasing the larval rearing density delayed pupation, decreased adult longevity and reduced adult size in both lines. While the delay in pupation and the decrease in longevity were similar between the two lines, the decrease in adult size was more pronounced for OX513A males.Our study shows that in a controlled laboratory situation the transgenic sterile OX513A line may have somewhat reduced performance compared to its unmodified counterpart and that high rearing densities may further reduce performance. Laboratory-based cage trials as well as field trials are necessary to assess how the differences in life history traits documented here impact the males' success upon release. Furthermore, this paper highlights the potential value of optimisation of mass-rearing systems as optimised rearing methods may be able to alleviate performance issues associated with specific lines or with lab-adapted lines in general.

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Wing length.Comparisons of average wing length of WT and OX513A mosquitoes reared at different densities in 100 ml pots; error bars showing 95% CI.
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pone-0020699-g002: Wing length.Comparisons of average wing length of WT and OX513A mosquitoes reared at different densities in 100 ml pots; error bars showing 95% CI.

Mentions: Females of both lines were generally larger than the males (F1, 22.12 = 3975.57, p<0.001) and showed a greater decrease in wing length with increasing rearing density than the males (F2, 0.93 = 83.59, p<0.001). Both male and female unmodified mosquitoes were larger than their OX513A counterparts reared at the same density (F1, 0.26 = 46.8, p<0.001). Increased larval rearing density decreased adult wing length for both lines (F2, 2.32 = 208.22, p<0.001), but the OX513A line showed a greater response to increasing rearing density (difference 0.204 mm) than the unmodified line (difference 0.155 mm) (F2, 0.09 = 8.045, p<0.001), producing increasingly smaller adults. This effect is mainly due to the stronger reaction of OX513A males compared to their unmodified counterparts rather than the females (F2, 0.08 = 6.787, p = 0.0013) (Table 1, Figure 2).


Comparison of life history characteristics of the genetically modified OX513A line and a wild type strain of Aedes aegypti.

Bargielowski I, Nimmo D, Alphey L, Koella JC - PLoS ONE (2011)

Wing length.Comparisons of average wing length of WT and OX513A mosquitoes reared at different densities in 100 ml pots; error bars showing 95% CI.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3117796&req=5

pone-0020699-g002: Wing length.Comparisons of average wing length of WT and OX513A mosquitoes reared at different densities in 100 ml pots; error bars showing 95% CI.
Mentions: Females of both lines were generally larger than the males (F1, 22.12 = 3975.57, p<0.001) and showed a greater decrease in wing length with increasing rearing density than the males (F2, 0.93 = 83.59, p<0.001). Both male and female unmodified mosquitoes were larger than their OX513A counterparts reared at the same density (F1, 0.26 = 46.8, p<0.001). Increased larval rearing density decreased adult wing length for both lines (F2, 2.32 = 208.22, p<0.001), but the OX513A line showed a greater response to increasing rearing density (difference 0.204 mm) than the unmodified line (difference 0.155 mm) (F2, 0.09 = 8.045, p<0.001), producing increasingly smaller adults. This effect is mainly due to the stronger reaction of OX513A males compared to their unmodified counterparts rather than the females (F2, 0.08 = 6.787, p = 0.0013) (Table 1, Figure 2).

Bottom Line: The genetically modified OX513A line overall showed 5% lower larval survival as well as reduced adult longevity (20 vs 24 days mean lifespan) compared to the unmodified line.Furthermore, the OX513A line pupated about one day sooner, which could be advantageous in mass-rearing, but produced somewhat smaller adults than the unmodified line; this effect was more pronounced in females than in males.Increasing the larval rearing density delayed pupation, decreased adult longevity and reduced adult size in both lines.

View Article: PubMed Central - PubMed

Affiliation: Division of Biology, Imperial College London, London, United Kingdom. irka.bargielowski06@imperial.ac.uk

ABSTRACT
The idea of implementing genetics-based insect control strategies modelled on the traditional SIT (Sterile Insect Technique), such as RIDL (Release of Insects carrying a Dominant Lethal), is becoming increasingly popular. In this paper, we compare a genetically modified line of Aedes aegypti carrying a tetracycline repressible, lethal positive feedback system (OX513A) with a genetically similar, unmodified counterpart and their respective responses to increasing larval rearing density using a constant amount of food per larva. The parameters that we examined were larval mortality, developmental rate (i.e., time to pupation), adult size and longevity. Analysis revealed some statistically significant differences between the life history traits we examined. The genetically modified OX513A line overall showed 5% lower larval survival as well as reduced adult longevity (20 vs 24 days mean lifespan) compared to the unmodified line. Furthermore, the OX513A line pupated about one day sooner, which could be advantageous in mass-rearing, but produced somewhat smaller adults than the unmodified line; this effect was more pronounced in females than in males. Increasing the larval rearing density delayed pupation, decreased adult longevity and reduced adult size in both lines. While the delay in pupation and the decrease in longevity were similar between the two lines, the decrease in adult size was more pronounced for OX513A males.Our study shows that in a controlled laboratory situation the transgenic sterile OX513A line may have somewhat reduced performance compared to its unmodified counterpart and that high rearing densities may further reduce performance. Laboratory-based cage trials as well as field trials are necessary to assess how the differences in life history traits documented here impact the males' success upon release. Furthermore, this paper highlights the potential value of optimisation of mass-rearing systems as optimised rearing methods may be able to alleviate performance issues associated with specific lines or with lab-adapted lines in general.

Show MeSH
Related in: MedlinePlus