Effects ofBathyplectes curculionis andBathyplectes anurus [Hym.: Ichneumonidae] on the growth and development ofHypera postica [Col.: Curculionidae]

Observations, linear measurements, dissections, and histological preparations were made of parasitized and nonparasitized larvae of the alfalfa weevil,Hypera postica (Gyllenhal), on a daily basis. The observed developmental period lasted from 24 h after oviposition byBathyplectes curculionis (Thomson) orBathyplectes anurus (Thomson) until parasite larvae emerged from their hosts. Adult and larval parasites significantly altered growth and development ofH. postica larvae.B. curculionis andB. anurus caused 24 and 29% greater premature mortality in young host larvae than that observed in the unparasitized controls. Rate of development for parasitized larvae during the 1st 12 days was essentially the same as for nonparasitized larvae. Nonparasitized larvae reached maximum size in 17–18 days, whereas larvae parasitized byB. curculionis andB. anurus required 14–21 and 19–22 days, respectively. Larvae parasitized byB. curculionis are smaller in overall lengths, widths and head capsule widths than nonparasitized larvae and those parasitized byB. anurus.