Coccinellid host morphology dictates morphological diversity of the parasitoid wasp Dinocampus coccinellae

Abstract Pararsitoid-host interactions involving host species that are newly introduced into the range of a generalist parasitoid provide systems that can be examined for phenotypic plasticity and evolutionary changes in parasitoid-host dynamics. The solitary Braconid parasitoid wasp, Dinocampus coccinellae , has a cosmopolitan distribution and parasitizes approximately 50 species of predatory lady beetles (ladybirds) in the family Coccinellidae. In this study we quantified the effect of six (4 native North American and 2 non-native North American) host species on the morphometrics of D. coccinellae . Adult lady beetles were collected from 13 locations in the United States and reared in the laboratory until D. coccinellae exited from their adult beetle hosts. Eighty-nine individual D. coccinellae females and their associated host were weighed and morphometric measurements were taken. The smallest lady beetle host Hippodamia parenthesis produced the smallest adult wasps; the largest host species, Coccinella septempunctata , produced the largest female wasps. A directional cline in morphology of wasps and their coccinellid hosts was also observed in a dry-weight regression (R 2  = 0.4066, p-value  D. coccinellae is governed by phenotypic plasticity with the size of the emerging offspring contingent on the size of the coccinellid host, and/or (2) that morphometric variation in D. coccinellae is governed by genomic adaptation to coccinellid host populations.