The annual bluegrass weevil (ABW) is a pest which, unfortunately, can develop resistance to commonly applied insecticides if and when they are applied too often or incorrectly. Some turf care specialists call this “making them angry”…and you won’t like them when they’re angry. Turning the tide on insecticide resistance can be very difficult, they best thing to do is to not get them angry in the first place, once the population has become resistant there may be no way to make them susceptible once again.
Turf that has been intensively managed for ABW for a minimum of five years is bound to have some level of insecticide resistance. In this situation intensive management refers to large areas of turfgrass being treated with multiple applications every year for five years. Insecticide resistance may appear to sneak up on the turf manager; first signs may be excused by poorly timed applications, bad weather conditions, portions of lawn may have been missed by the applicator, etc. And it may even seem that more applications would be curative. Rutgers Entomology Department states “Seeing a lot adult ABW all over an area just days after an adulticide application should be an eye opener. Unfortunately, at this point the ABW should be already pretty resistant.”
Insecticide resistance is caused by repeated, excessive pesticide use within time and space while exercising poor insecticide resistance management. While only 1% or less of an ABW population will exhibit the genetic mutation allowing insecticide resistance these individuals will have better survival ratios when insecticides are applied excessively. Therefore, resistant individuals will contribute greatly to the genetic makeup of following generations. With more frequent pesticide applications, exposure reaches a larger proportion of the population and resistance will develop faster.
To decrease the chances of insecticide resistance developing on your property work with your arborist and lawn care specialist to assure pesticide applications are correctly timed, used when and where necessary and closely monitor adult and larval ABW populations.