Effect of time of permanence of host fruits in the field on natural parasitism of Anastrepha spp. (Diptera: Tephritidae)

Abstract

The present work evaluated the influence of time of permanence of the fruit in the field after its abscission on natural parasitism of Anastrepha spp. In February 2000, three trees of Spanish prune (Spondias purpurea L.) and three guava tree (Psidium guajava L.) were selected in the Universidade Federal Rural do Rio de Janeiro, State of Rio de Janeiro, Brazil. Sampling consisted of 250 infested fruits collected per tree. Fifty of them were taken immediately to the laboratory in order to obtain Tephritidae pupae (0-day exposure). The remaining fruits were divided in four batches and placed in plastic trays on a layer of sand, underneath the tree canopy. Every other day, the fruits of one tray were transported to the laboratory (2, 4, 6 and 8 days exposure). A total of 1,123 flies of the genus Anastrepha [A. obliqua (Macquart) and A. fraterculus (Wiedemann)] and 1,880 Hymenopteran parasitoids (Braconidae, Figitidae and Pteromalidae) were recovered from Spanish prune. From guava, 4,714 adults of Anastrepha spp. (A. obliqua, A. fraterculus and A. sororcula Zucchi) and 383 Hymenopteran parasitoids (Braconidae, Figitidae and Pteromalidae) were obtained. The highest percent parasitism by Braconidae (67.2% in Spanish prune and 6.4% in guava) was recorded on fruits of 0-day, suggesting that they would prefer the larvae in the fruits while on the tree. For Figitidae the higher percent parasitism (2.8% in Spanish prune and 4.7% in guava) occurred on fruits present for six days in the field and for Pteromalidae in fruits present for eight days (2.4% in Spanish prune and 1.9% in guava).