Effects of plant availability on population size and dynamics of an insect community: diamondback moth and two of its parasitoids

• Published in: Bulletin of entomological research Vol. 104; no. 4; pp. 418 - 431
• Main Authors: Soufbaf, M., Fathipour, Y., Karimzadeh, J., Zalucki, M.P.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.08.2014
• Subjects: Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Animals; Bioavailability; Biological and medical sciences; Brassica napus - growth & development; Brassica napus - parasitology; Butterflies & moths; Cotesia; Diadegma; Flowers & plants; Fundamental and applied biological sciences. Psychology; Herbivory - physiology; Insects; Iran; Models, Biological; Moths - parasitology; Moths - physiology; Parasitology; Phytopathology. Animal pests. Plant and forest protection; Plant resources; Plutella xylostella; Population Density; Population Dynamics; Population number; Protozoa. Invertebrates; Records, symptoms, damages, economic importance, population surveys; Research Paper; Species extinction; Synecology; Terrestrial ecosystems; Wasps - physiology; Iran; plant structure; Plutella xylostella; community structure; parasitoid competition; Availability; Community structure; Insecta; Plutellidae; Pest; Parasitoid; Entomophagous; Animal community; Arthropoda; Host plant; Lepidoptera; Interspecific competition; Population dynamics; Ichneumonidae; Braconidae; Hymenoptera; Invertebrata
• ISSN: 0007-4853; 1475-2670
• DOI: 10.1017/S0007485314000054

To understand the effect of plant availability/structure on the population size and dynamics of insects, a specialist herbivore in the presence of two of its parasitoids was studied in four replicated time-series experiments with high and low plant availabilities; under the latter condition, the herbivore suffered from some periods of resource limitation (starvation) and little plant-related structural refuges. Population dynamics of the parasitoid Cotesia vestalis was governed mainly by the delayed density-dependent process under both plant setups. The parasitoid, Diadegma semiclausum, under different plant availabilities and different coexistence situations (either +competitor or –competitor) showed dynamics patterns that were governed mainly by the delayed density process (significant lags at weeks 2–4). Both the competing parasitoids did not experience beneficial or costly interferences from each other in terms of their own population size when the plant resource was limited. Variation in the Plutella xylostella population under limited plant availability is higher than that under the other plant setup. For both parasitoids, under limited plant setup, the extinction risk was lower when parasitoids were engaged in competition, while under the unlimited plant setup, the mentioned risk was higher when parasitoids competed. In this situation, parasitoids suffered from two forces, competition and higher escaped hosts.