Host-Acceptance Behavior of Dinocampus coccinellae (Hymenoptera: Braconidae)

Abstract

Dinocampus coccinellae (Schrank) spent >80% of a 300-s observation period in host-handling activities (orienting toward, pursuing, and attacking hosts) when exposed to individual adult Coleomegilla maculata (DeGeer) or Coccinella septempunctata (L.). When D. coccinellae was exposed to two populations of Hippodamia variegata (Goeze) from Canada or France and Propylea quatuordecimpunctata (L.) from Canada or Turkey, host-handling activities decreased to <70% of 300 s. D. coccinellae oriented toward and attacked C. maculata and C. septempunctata in 10–12 s, compared with 18–38 s for H. variegata and P. quatuordecimpunctata . Additionally, C. maculata and C. septempunctata were attacked more frequently (mean = 3.3 and 2.6 in 300 s, respectively) than H. variegata or P. quatuordecimpunctata (mean = 2 and 1.5 in 300 s, respectively). No differences in D. coccinellae behavior were observed in response to the two H. variegata and two P. quatuordecimpunctata populations. D. coccinellae successfully emerged from 58% of C. maculata , 47% of C. septempunctata , 7–15% of H. variegata , and 1% of P. quatuordecimpunctata . Total mortality of adults exposed to D. coccinellae was 80% for C. maculata , 76% for C. septempunctata , 50% for H. variegata (France), 38% for H. variegata (Canada), and 11% for both P. quatuordecimpunctata populations. Based upon our observations, we expanded the description of D. coccinellae selection behavior to include orientation, which precedes forward motion toward a host.