Adaptation to a Novel Host by a Seed Beetle (Coleoptera: Chrysomelidae: Bruchinae): Effect of Source Population

• Published in: Environmental entomology Vol. 42; no. 4; pp. 733 - 742
• Main Authors: Messina, Frank J, Durham, Susan L
• Format: Journal Article
• Language: English
• Published: Lanham, MD Entomological Society of America 01-08-2013
• Subjects: adaptation; Adaptation, Biological; adults; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; biotypes; Burkina Faso; Chrysomelidae; Coleoptera - genetics; Coleoptera - growth & development; Coleoptera - physiology; Diet; experimental evolution; Fabaceae - physiology; Female; Fundamental and applied biological sciences. Psychology; Genetic Variation; Geography; grain legume; Herbivory; host range; host shift; hosts; India; insects; international trade; Larva - genetics; Larva - growth & development; Larva - physiology; larvae; legumes; Male; oviposition; PLANT-INSECT INTERACTIONS; population; Protozoa. Invertebrata; races; selection experiment; Vigna angularis; Asia; Africa; Chrysomelidae; experimental evolution; Coleoptera; Insecta; Geographical origin; Experimental study; Grain legume; Pest; Animal plant relation; Arthropoda; Host plant; host shift; Bruchidae; Invertebrata; selection experiment; Animal population; Adaptation
• ISSN: 0046-225X; 1938-2936
• DOI: 10.1603/EN13066

Geographic populations of a widespread species can differ in their ability to adapt to a novel environment because they possess different amounts of the requisite genetic variation. We compared responses to the same novel host in ecologically and genetically divergent populations of the seed beetle Cattosobruchus maculatus (F.). Populations from Africa and Asia had been derived from and maintained on different legume hosts. In preselection assays, both populations exhibited lower survival, slower development, and smaller size on a third host (adzuki bean), and the difference in performance between the ancestral and novel hosts was especially high for the African population. Replicate lines of each population were switched to adzuki bean or maintained on the ancestral host, and beetle performance was measured on both hosts after 12 generations. Survival on adzuki bean increased substantially in the adzuki-bean lines of the African population, but improved only slightly in the Asian lines. Similarly, only the African adzuki-bean lines exhibited significantly faster development on adzuki bean. Improved performance on adzuki bean did not simultaneously reduce performance on the ancestral host. Together with previous studies, these results confirm that populations of C. maculatus often possess sufficient standing genetic variation for rapid adaptation to a novel host, but the magnitude of the response may depend on the source population. Although international trade in grain legumes can expand beetle host ranges and produce unusual biotypes, the consistent absence of strong genetic trade-offs in larval performance or adult oviposition across hosts makes it unlikely that this insect would form distinct host races.