Dissemination of Lathrolestes ensator (Ichneumonidae), a larval parasite of the European Apple Sawfly, Hoplocampa testudinea (Tenthredinidae), in Eastern North America

• Lathrolestes ensator is a larval parasite of the apple sawfly Hoplocampa testudinea.
• From 2002 to 2015 L. ensator was disseminated in eastern North America.
• Random samples of these fruitlets were dissected to estimate % parasitized larvae.
• L. ensator established in three localities of Quebec and one locality in Ontario.
• L. ensator is the only known natural enemy of H. testudinea in North America.

The larval parasite Lathrolestes ensator Brauns (Hymenoptera: Ichneumonidae) has only one known host, Hoplocampa testudinea Klug (Hymenoptera: Tenthredinidae), a pest that attacks only one host: the apple tree. A classical biological program conducted from 1994 to 2001 successfully led to the establishment of L. ensator in Frelighsburg, QC, Canada. This paper reports on work conducted from 2002 to 2015 to disseminate L. ensator in eastern North America. Each year, fruitlets showing secondary damage of H. testudinea were collected in source orchards of Frelighsburg. Random samples of these fruitlets were dissected to estimate % parasitized larvae: the remaining fruitlets were used for releases in apple orchards located in Quebec, Ontario, Nova Scotia and New Hampshire. Collection of fruitlets with secondary damage in participating orchards showed that L. ensator successfully established in Quebec in Henryville, Saint-Hilaire, Magog and St-Georges de Windsor, and in Ontario in Hilton. L. ensator is the only known natural enemy of H. testudinea in North America.