Mosquitoes

BBC reports that scientists have bred mosquitoes that crank out 95% males.

Flooding cages of normal mosquitoes with the new strain caused a shortage of females and a population crash.

The system works by shredding the X chromosome during sperm production, leaving very few X-carrying sperm to produce female embryos.

In the wild it could slash numbers of malaria-spreading mosquitoes, reports the journal Nature Communications.

From the paper: "Resistance in female mosquitoes was often swiftly selected for, indicating the prevalence of natural resistance alleles." Surprise! In other words, the crash didn't work for long.

If you can achieve this sort of thing with sprays (without unintended side effects), you might get a short-term crash, but you can't exactly release these into the wild and expect them to outbreed the natives...