Engineered expression of the invertebrate-specific scorpion toxin AaHIT reduces adult longevity and female fecundity in the diamondback moth Plutella xylostella

Harvey-Samuel, T.; Xu, X.; Lovett, E.; Dafa'alla, T.; Walker, A. S.; Norman, V. C.; Carter, R.; Teal, J.; Akilan, L.; Leftwich, P. T.; Alphey, L.

doi:10.1101/2020.09.10.291187

bioRxiv · 10.1101/2020.09.10.291187

Engineered expression of the invertebrate-specific scorpion toxin AaHIT reduces adult longevity and female fecundity in the diamondback moth Plutella xylostella

Harvey-Samuel, T.·Xu, X.·Lovett, E.·Dafa'alla, T.·Walker, A. S.·Norman, V. C.·Carter, R.·Teal, J.·Akilan, L.·Leftwich, P. T.·Alphey, L.

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Abstract

BACKGROUNDPrevious Genetic Pest Management (GPM) systems in diamondback moth (DBM) have relied on expressing lethal proteins ( effectors) that are cell-autonomous i.e. do not leave the cell they are expressed in. To increase the flexibility of future GPM systems in DBM, we aimed to assess the use of a non cell-autonomous, invertebrate-specific, neurotoxic effector - the scorpion toxin AaHIT. This AaHIT effector was designed to be secreted by expressing cells, potentially leading to effects on distant cells, specifically neuromuscular junctions. RESULTSExpression of AaHIT caused a shaking/quivering phenotype which could be repressed by provision of an antidote (tetracycline); a phenotype consistent with the AaHIT mode-of-action. This effect was more pronounced when AaHIT expression was driven by the Hr5/ie1 promoter (82.44% of males, 65.14% of females) rather than Op/ie2 (57.35% of males, 48.39% of females). Contrary to expectations, the shaking phenotype and observed fitness costs were limited to adults where they caused severe reductions in mean longevity (-81%) and median female fecundity (-93%). qPCR of AaHIT expression patterns and analysis of piggyBac-mediated transgene insertion sites suggest that restriction of observed effects to the adult stages may be due to influence of local genomic environment on the tetO-AaHIT transgene. CONCLUSIONWe have demonstrated the feasibility of using non cell-autonomous effectors within a GPM context for the first time in the Lepidoptera, one of the most economically damaging orders of insects. These findings provide a framework for extending this system to other pest Lepidoptera and to other secreted effectors.

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Harvey-Samuel, T., Xu, X., Lovett, E., Dafa'alla, T., Walker, A. S., Norman, V. C., Carter, R., Teal, J., Akilan, L., Leftwich, P. T., Alphey, L.. 2020-09-11. Engineered expression of the invertebrate-specific scorpion toxin AaHIT reduces adult longevity and female fecundity in the diamondback moth Plutella xylostella. https://doi.org/10.1101/2020.09.10.291187

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