Non-target effects of the exotic generalist parasitoid wasp Fopius arisanus (Sonan) estimated via competition assays against Doryctobracon areolatus (Szepligeti) on both native and exotic fruit fly hosts

摘要

Biological control by the generalist egg parasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae) has been proposed against Bactrocera carambolae (Drew & Hancock) (Diptera: Tephritidae) in northern Brazil. This study assessed possible effects of F. arisanus on native parasitoids by focusing on competition with the native wasp Doryctobracon areolatus (Szepligeti) (Hymenoptera: Braconidae) on two hosts, Anastrepha fraterculus (Wiedemann), a native tephritid, and Ceratitis capitata (Wiedemann), an introduced pest tephritid. Laboratory and greenhouse cage studies showed that F. arisanus parasitized < 3% of the native host in competition or alone compared to 41-65% for C. capitata, while D. areolatus parasitized 12-42% of the native host and < 4% on C. capitata. The host origin of F. arisanus did not affect subsequent parasitism rates on native or exotic hosts. However, when reared on C. capitata, F. arisanus had higher parasitism on C. capitata than on A. fraterculus. Lab and greenhouse competition studies showed that F. arisanus had no measurable detrimental effect on the native parasitoid in either the native or introduced host, suggesting that F. arisanus interfered minimally with the native parasitoid. Based on these results and other relevant studies showing non-preference of F. arisanus for the native fruit fly species, as well as the non-preference of native parasitoids for exotic fruit flies, we infer that the release of F. arisanus against exotic tephritids such as C. capitata and B. carambolae in Brazil would not cause major disruption of the native populations of A. fraterculus parasitoids.