Effects of Host Plant and Larval Density on Intraspecific Competition in Larvae of the Emerald Ash Borer (Coleoptera: Buprestidae)

• Published in: Environmental entomology 2013-12, Vol.42 (6), p.1193-1200
• Main Authors: Duan, Jian J, Larson, Kristi, Watt, Tim, Gould, Juli, Lelito, Jonathan P
• Format: Article
• Language: English
• Subjects: Agrilus planipennis; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Biomass; cannibalism; Coleoptera - physiology; competition; Competitive Behavior; Demecology; density dependence; eggs; Female; fitness; Fraxinus; Fraxinus pennsylvanica; Fraxinus uhdei; Fundamental and applied biological sciences. Psychology; host plants; insects; intraspecific competition; Larva - physiology; larvae; larval density; pests; phloem; Phytopathology. Animal pests. Plant and forest protection; Population Density; population dynamics; POPULATION ECOLOGY; Protozoa. Invertebrata; Protozoa. Invertebrates; Records, symptoms, damages, economic importance, population surveys; sapwood; serpentine; Species Specificity; starvation; surface area; survival rate; trees
• ISSN: 0046-225X; 1938-2936; 0046-225X
• DOI: 10.1603/EN13209

Competition for food, mates, and space among different individuals of the same insect species can affect density-dependent regulation of insect abundance or population dynamics. The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious invasive pest of North American ash (Fraxinus spp.) trees, with its larvae feeding in serpentine galleries between the interface of sapwood and phloem tissues of ash trees. Using artificial infestation of freshly cut logs of green ash (Fraxinus pennsylvanica Marshall) and tropical ash (Fraxinus uhdei [Wenzig] Lingelsh) with a series of egg densities, we evaluated the mechanism and outcome of intraspecific competition in larvae of A. planipennis in relation to larval density and host plant species. Results from our study showed that as the egg densities on each log (1.5–6.5cmin diameter and 22–25cmin length) increased from 200 to 1,600 eggs per square meter of surface area, larval survivorship declined from ≈68 to 10% for the green ash logs, and 86 to 55% for tropical ash logs. Accordingly, larval mortality resulting from cannibalism, starvation, or both, significantly increased as egg density increased, and the biomass of surviving larvae significantly decreased on both ash species. When larval density was adjusted to the same level, however, larval mortality from intraspecific competition was significantly higher and mean biomasses of surviving larvae was significantly lower in green ash than in tropical ash. The role of intraspecific competition of A. planipennis larvae in density-dependent regulation of its natural population dynamics is discussed.