Pesticide-resistant flies 'rubbish at courting' - study
A single genetic change which enables male fruit flies to resist insecticides also leaves them struggling to procreate, scientists have observed.
Researchers from the University of Exeter also found male flies with the genetic difference to be smaller, less aggressive than normal and "rubbish" at courting females.
Furthermore, DDT-resistant males were also found to "decamp" more often, the technical term for giving up midway through a mating attempt.
Researchers said they were "surprised" that a single allele - a different version of the same gene - could have such a dramatic effect.
The single genetic change protects flies from the pesticide DDT, which is otherwise fatal to them.
"We bred the flies ourselves so we could create one group with, and another without, the resistance allele whilst ensuring they had the same genetic background," Professor Nina Wedell, one of the scientists behind the study, told Sky News.
"We were surprised that a fairly trivial genetic change could cause such a massive behavioural change."
She said: "It is amazing that even if all the genes are exactly the same, having this one gene expressed at a higher level has all these effects.
"The expression level of one gene responsible for detoxifying DDT also makes males smaller, less aggressive and rubbish at courting.
"We don't yet know how this comes about."
The research comes as scientists grow increasingly concerned about the detrimental effects of insecticides on beneficial insects such as pollinators, as well as the greater environment.
Insects are rapidly evolving resistance to existing agricultural pesticides. Researchers are scrambling to figure out how to counter the resistance and protect crops.
"If in general it is costly to male insects of carrying resistance genes, then this will have an impact on the spread and persistence of resistance alleles in nature," said Professor Wedell.
"If we can figure out why resistant males have become reproductively less competitive, we could use this knowledge to develop methods to suppress insect pest populations."
The study was published in the journal Behavior Genetics.
