Who's controlling alfalfa weevil in New Mexico? Evaluating the impact of three introduced parasitoids on biological control of alfalfa weevil

A study was conducted in 2002 -2009 to evaluate parasitism of alfalfa weevil, Hypera postica (Gyllenhal) in New Mexico. Multiple fields were sampled for parasitized weevils in seven counties. Results indicate wide variation in control levels. Parasitism rates were high in Dona Ana County with a season average of 45% parasitized weevils. Control was low in Valencia County with 5% parasitized weevils. Control in Eddy and Chaves counties were highly variable with 0-92% parasitized weevils. Two parasitoids, Bathypletes spp. (Thomson) and Oomyzus incertus (Ratzeburg), were recovered in all counties except Chaves and San Juan. Microctonus colesii (Drea) was only recovered in Eddy County and Dona Ana County. Results from a small number of fields indicated 2-11% parasitized weevils in San Juan, Soccoro and Rio Arriba Counties