Effectiveness of native parasites against Agromyza frontella (Rondani) (Diptera: Agromyzidae), an introduced pest of alfalfa.
The results are presented of a survey for native parasites of the introduced European agromyzid Agromyza frontella (Rond.), collections being carried out on lucerne in Delaware, Pennsylvania and New Jersey in 1975-77. Over 2000 parasites representing 14 species are recorded from 13 351 agromyzids. Two other species of parasites are reported from Canada (Ontario and Quebec). The complex of native parasites was poorly synchronised with the first 2 generations of the host, which could therefore reach economic injury levels, but it gave satisfactory control of the next 3 generations produced in a year. Season-long parasitism averaged 36%, but only 2% of the host puparia were parasitised. Rates of parasitisation are also given for 7 species in over 33 000 puparia of A. frontella collected in 6 countries in Europe in 1976-77 and shipped to Delaware; all of these have been released in the USA.