Functional response and parasitism of <i>Doryctobracon brasiliensis</i> (Hymenoptera: Braconidae) on <i>Anastrepha fraterculus</i> (Diptera: Tephritidae)

The biological control for fruit flies in Brazil has been extended with the introduction of the parasitoid Diachasmimorpha longicaudata (Ashmead, 1905) (Hymenoptera: Braconidae) and native parasitoids, such as Doryctobracon brasiliensis (Szepligeti, 1911) (Hymenoptera: Braconidae), which show great potential for control. Among the main pest species of fruit flies, Anastrepha fraterculus (Wiedemann, 1830) (Diptera: Tephritidae) and Ceratitis capitata (Wiedemann, 1830) (Diptera: Tephritidae) have a wide geographic distribution in the South American continent. The objectives of this study were to evaluate the functional response of D. brasiliensis to the density of A. fraterculus larvae and to model the parasitism rates of D. longicaudata and D. brasiliensis on A. fraterculus and that of D. longicaudata when exposed to C. capitata. The experiments were conducted to evaluate the parasitism rate, and the data were subjected to statistical analysis, verifying the probability distribution. The parasitism rate of D. brasiliensis ranged from 82.2% to 35% when 5 and 30 larvae were offered to each female, respectively. The results revealed a type II functional response, indicating that the parasitism rate reached a saturation point as the larval density increased. In A. fraterculus, the average number of larvae parasitized by D. longicaudata females was higher than that of C. capitata at nearly all host densities. The highest percentage of parasitism (55%) was observed at the density of 3 larvae per parasitoid, similar to what was recorded for C. capitata. The results obtained support the biological control program for fruit flies in Brazil, optimizing laboratory rearing and field release.