New Hybrid Swarm Combines Deadly Agricultural Pests Into Mega-Pests
It was discovered in 2013 that the cotton bollworm had managed to somehow spread to Brazil in South America. The exact manner of how it accomplished this remains a mystery, but it has been devastating for the agricultural sector of the country. Now, it appears things might get even worse.
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The Hybrid Mega-Pest
There appears to have been significant hybridization occurring between the two moths. The scientists ran a whole genome resequencing on all of the eight specimens they had collected in Brazil and compared their genomes to the already sequenced genomes of the several dozen other samples from the two species they had gathered over the years. After that, they also ran a phylogenetic analysis of the single nucleotide differences in the observed genomes, along with matching them to the population structure of the species.
The first thing they revealed is that the cotton bollworm as a whole appears to have a population with incredibly high genetic diversity among its members. This might explain why it is so adaptive across multiple climes and can develop resistances so quickly so that it can invade new territory. But the big news is that it appears that the cotton bollworm is part of an ongoing, multigenerational hybridization with the corn earworm and it isn’t the sort of joining that just makes it easier to deal with both of them at the same time. Oh no, it’s much more complicated than that.
Every single one of the hybrids among the 8 samples were unique, with each of them having apparently hybridized on their own and forming a separate combination of genes from the two species. This sort of event is referred to scientifically as a “hybrid swarm”, where multiple generations past the initial event have happened, allowing the hybrids to genetically differentiate themselves from each other.
The worst part is that the hybrids seem to share resistance genes from both species, giving them a weapon against any chemical method agricultural researchers and farmers try to employ. The CSIRO scientists were able to estimate that around 65% of the US’ agricultural output is at risk if this hybrid spreads northward and things will likely be worse for other countries in the Americas that have even more reliance on crops like corn and cotton.
...http://bioscriptionblog.com/2018/04/06/hybrid-swarm-combines-mega-pests/
