The fruit fly parasitoid Fopius arisanus: reproductive attributes of pre‐released females and the use of added sugar as a potential food supplement in the field

Abstract

Abstract Fopius (= Biosteres) arisanus (Sonan) (=Opius oophilus Fullaway) (Hymenoptera: Braconidae) is an egg‐pupal parasitoid of tephritid fruit flies. Small scale releases of F. arisanus were undertaken in coffee, Coffea arabica L., on the island of Kauai, to evaluate its potential for suppression of fruit fly populations. In conjunction with field releases, assays were conducted to determine the quality of pre‐released parasitoids. In addition, the suitability of various sugars as potential food supplements in the field was evaluated. Spermathecal dissection showed that >70% of a total 1.7 million females released in 1998 and 1999 were successfully mated. Moreover, a sperm rating of 2.5–2.6 indicated that the spermathecae of inseminated females were 50% full. There were 85–137 matured eggs (mean = 101.7 ± 11.5) in the ovaries of mated or virgin females. When honey was replaced with ripe coffee and water, ripe coffee, or water alone, 10 days after emergence, females remained alive for another 5.5, 5.4, and 4.9 days, respectively. There was corresponding deterioration in the ovaries of gravid females. Mean eggs of honey‐deprived females declined from >100 to <70 shortly before their death. Suitability test of various sugars showed that females lived longer when fed with honey (26 days), maple syrup (25 days) or molasses (20 days). Moreover, females provided with these sugars produced mean cumulative progeny per female of 77.2 ± 19, 67 ± 7, and 81 ± 14, respectively, during a 2‐week egging period. Our findings provided a basis for development of field release strategy for F. arisanus.