Interactions between Phaedrotoma scabriventris Nixon (Hymenoptera: Braconidae) and Zaeucoila unicarinata Ashmead (Hymenoptera: Figitidae), endoparasitoids of Liriomyza sativae Blanchard (Diptera: Agromyzidae)

Liriomyza sativae Blanchard is a key pest of melon (Cucumis melo L.) in Brazil and a target of biological control using parasitoids. Even though they share similar niches and competitive interactions can occur, Phaedrotoma scabriventris Nixon and Zaeucoila unicarinata Ashmead are potential candidates for controlling L. sativae in melon. Here, we investigated interactions between P. scabriventris (Ps) and Z. unicarinata (Zu) under laboratory conditions. We evaluated: (1) puparia to verify both parasitism and the interactions between parasitoid immature stages; and (2) emerged adults to verify host mortality due to parasitism, host stinging, host feeding, and parasitoid sex ratios. We observed in the dissected puparia that P. scabriventris predominated in all three forms of interaction evaluated. In addition, predation and physical combats were observed between immature stages of both parasitoids. When we consider the emerged adults, both species showed a similar parasitism rate in isolation (P. scabriventris, 19.40 +/- 3.57 % and Z. unicarinata, 17.60 +/- 4.54 %). The sequential interaction (Zu -* Ps) significantly decreased the parasitism by Z. unicarinata (4.92 +/- 0.14 %) compared to its parasitism rate in isolation. The greatest total parasitism rate was observed when both species simultaneously (Ps + Zu) parasitised the larvae (51.28 +/- 3.08 %). Phaedrotoma scabriventris and Z. unicarinata caused the greatest non-reproductive larvae mortality under the isolated exposure forms (35.90 +/- 2.55 % and 37.00 +/- 4.60 %, respectively). The sex ratio decreased significantly only in P. scabriventris (22.62 % of females) in the sequential interaction (Ps -* Zu). Our results indicate that both P. scabriventris and Z. unicarinata should be used in combination in the control of L. sativae in melon.