MICROCTONUS STELLERI (HYMENOPTERA: BRACONIDAE, EUPHORINAE), A NEW PARASITE OF THE ALFALFA WEEVIL INTRODUCED INTO THE UNITED STATES

Microctonus stelleri Loan is described as a new species. This euphorine braconid occurs in France, Germany, Sweden, and Russia. It is umvoltine and its only known host is the alfalfa weevil, Hypera postica (Gyllenhal). In the spring the mature parasite larva issues from the overwintered adult host and forms a white cocoon in the ground litter. In about 2 weeks the adult parasite emerges, mates, and oviposits in larva of the alfalfa weevil. The parasite egg hatches and the first-instar larva remains within the host until the following spring. In northern France M. stelleri was the dominant parasite in overwintering adults of H. postica. Parasitism ranged from 0 to 13% though it was usually less than 6%. Laboratory studies showed that M. stelleri females live longer, have a higher rate of oviposition, and parasitize more hosts than females of M. colesi Drea, a parasite of the weevil in the United Slates. A technique is described for the recovery of M. stelleri from adult alfalfa weevils. From 1966 to 1970, 4387 parasites were imported from France and released at 24 localities in the United States.