Seasonal occurrence of the herbivore Trirhabda geminata (Coleoptera: Chrysomelidae) on Encelia farinosa in southern California

• Published in: Annals of the Entomological Society of America Vol. 89; no. 6; pp. 843 - 848
• Main Authors: Bethke, J.A. (University of California, Riverside, CA.), Redak, R.A
• Format: Journal Article
• Language: English
• Published: Lanham, MD Entomological Society of America 01-11-1996
• Subjects: AESTIVATION; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; CALIFORNIA; CALIFORNIE; CHAETONODEXODES VANDERWULPI; CHRYSOMELIDAE; CICLO VITAL; CYCLE DE DEVELOPPEMENT; Demecology; DESARROLLO ESTACIONAL; DEVELOPPEMENT SAISONNIER; Encelia farinosa; ESTIVACION; ESTIVATION; Fundamental and applied biological sciences. Psychology; LIFE CYCLE; LIFE HISTORY; LLUVIA; PARASITISM; PARASITISME; PARASITISMO; PLUIE; Protozoa. Invertebrata; RAIN; SEASONAL ABUNDANCE; SEASONAL DEVELOPMENT; TACHINIDAE; California; United States; North America; America; USA, California; Chrysomelidae; Coleoptera; Insecta; Diapause; Compositae; Quiescence; Phytophagous; Geographic distribution; Seasonal variation; Arthropoda; Dicotyledones; Angiospermae; Emergence; Development; Population dynamics; Spermatophyta; Parasitism; Invertebrata; Population density
• ISSN: 0013-8746; 1938-2901
• DOI: 10.1093/aesa/89.6.843

The seasonal distribution of Trirhabda geminata Horn, the dominant herbivore of brittle brush, Encelia farinosa Gray, was monitored in California coastal sage scrub. Larval emergence coincided with the 1st precipitation of the growing season and the development of young host-plant foliage. Larvae were present from December through April; 3 instars were detected. Pupation occurs in the upper 5 cm of the soil immediately underneath host plants. Adults were present from early March through mid-June. The number of adults exhibiting mating behaviors (mate selection, copulation, mate guarding) was at a maximum in April. Larval T. geminata are parasitized by the tachinid fly Chaetonodexodes vanderwulpi (Townsend) with parasitism rates ranging from 3.4 to 34.9% for the 2 yr of study. The presence of a summer quiescence period and the apparent lack of a diapause period is discussed for this species.