Pest e-alerts, 01/18/2012, v.11 no.2

              Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
405.744.5527
Vol. 11, No. 2
http://entoplp.okstate.edu/Pddl/
Jan 18, 2012
Alfalfa Weevil Egg Populations 2012
Kelly Seuhs and Phil Mulder,
OSU Extension Associate and Extension Entomologist
Alfalfa weevil egg populations for January are located in the attached table. In addition, degree days through January 16, 2012 are presented in the last column. Unfortunately, no data was collected for egg populations over the past three seasons. However, for the purposes of comparison, January egg populations and viability of those eggs for the previous collection years are also depicted in the table. Viability measurements for this year’s samples are still being processed; with four locations (Payne, Kingfisher, Grant and Washita Counties) having sufficient egg numbers for testing. Compared to previous sample years (2004-2007), relatively low numbers of eggs were recovered. In 2012, degree days through January 16 are averaging 59.5 across the ten sample sites.
In an attempt to identity what may be having an effect on alfalfa weevil populations over the last couple of years, we looked at the percentage of normal precipitation in each of the ten counties sampled this year. From the fall of 2010 through most of 2011, a large portion of the state was in an exceptional drought. As much as two thirds of the state didn’t receive any measurable rainfall until late summer or early fall of 2011.Currently, even with the moisture received last fall and thus far this year, most of the counties in the central to western parts of the state are still in an extreme drought with 40-80 percent below average rainfall. While those deficits may not totally account for the reduced numbers of alfalfa weevil eggs recovered this year, if you look at the impact from the extreme temperatures last summer (50+ days over 100 degrees), the combination of persistent drought with extremely high temperatures during the summer months of 2011, may have resulted in increased mortality of summer diapausing adult weevils. However we must remain vigilant, early2011 was a perfect storm for insect