" "Never kill more than about 75% of the existing pest population with a single pesticide at any time" -- to avoid resistance."

That is not a typo.  There was a good article on exactly this topic published in Science about two years ago.  I did not save the exact reference.  This also is not new news.  We have known a low kill rate was desirable to slow resistance development since the 1980s.  I am well aware that folk wisdom says trying for a 100% kill is the way to go.  But, folk wisdom is simply wrong.  Suppose you kill 9999 out of 10,000.  That one you left alive is resistant and the only breeding stock available.  It multiplies and for a year or two you do not have a problem due to the low population.  After that you have 100% resistant stock and are in trouble.  If you kill a lot fewer competition may well result in resistant individuals dying.  Resistance often results in individuals that have lower livability than wild type.  Also with more living individuals competing random deaths may eliminate resistant individuals.  Plus resistance may be recessive and with a low population of resistant individuals constantly out crossing to non-resistant stock you can greatly postpone development of a resistant population. Plus other reasons.

Dick

HL Mencken said: "The whole aim of practical politics is to keep the populace alarmed — and hence clamorous to be led to safety — by menacing it with an endless series of hobgoblins, all of them imaginary. "

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