Eggload Dynamics and Oviposition Rate in a Wild Population of a Parasitic Wasp

• Published in: The Journal of animal ecology Vol. 69; no. 2; pp. 185 - 193
• Main Authors: Casas, Jerome, Nisbet, Roger M., Swarbrick, Sue, Murdoch, William W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK British Ecological Society 01.03.2000; Blackwell Science Ltd; Blackwell; Blackwell Scientific Publications; Blackwell Publishing Ltd
• Subjects: Animal and plant ecology; Animal ecology; Animal, plant and microbial ecology; Animals; Aondiniella aurantii; Aphelinidae; Aphytis; Aphytis melinus; Aves; Biological and medical sciences; Biological control; Control; Demecology; Ecological genetics; Eggs; Female animals; Foraging; Fundamental and applied biological sciences. Psychology; host–parasitoid population dynamics; Human ecology; Insect ecology; life‐history strategies; Oviposition; Parasite hosts; Parasitoids; Phytopathology. Animal pests. Plant and forest protection; Protozoa. Invertebrates; scale insects; Vertebrata; California; United States; North America; America; Host parasite relation; Citrus fruit; Insecta; Biological control; Rutaceae; Activity; Pest; Homoptera; Chalcidoidea; Dicotyledones; Angiospermae; Diaspididae; Aonidiella aurantii; Oocyte maturation; Load; Life history; Egg; Aphelinidae; Coccoidea; Clutch size; Citrus; Parasitoid; Arthropoda; Aphytis; Strategy; Spermatophyta; Population dynamics; Hymenoptera; Invertebrata
• DOI: 10.1046/j.1365-2656.2000.00376.x
• ISSN: 0021-8790

1. This paper develops and tests in the field a model that predicts the oviposition rate and the rate of egg maturation of a synovigenic parasitic wasp during a foraging period. The parasitoid is Aphytis melinus, the highly successful biological control agent of California redscale (Aondiniella aurantii), a pest of citrus worldwide. 2. Females were sampled in the interior canopy of grapefruit trees either just before and at the end of the foraging period over 2 days and were dissected to determine the starting and ending eggload distributions. A group of females was caught before the onset of activity and kept in vials in the field in trees with honey but without access to hosts during the foraging period. Their eggload at the end of the day was used to estimate the egg maturation rate during the foraging period. 3. Two stochastic models are used to predict the eggload distribution at the end of the day. Both use the observed starting eggload distribution, the observed length of the foraging period and the estimated rate of egg maturation. The model providing the better fit uses an oviposition rate which is an increasing function of the eggload. 4. The eggload does not attain a steady state distribution during a foraging period. One-third to one-half of the population is predicted to experience egg-limitation at some time during the foraging period. Five percent of the population will experience egg-limitation a second time within a single day. 5. The common occurrence of egg-limitation over a single day and the relatively high rate of change of states between egg- and time-limitation imply that the rate of nutrient acquisition and use are likely to be subject to strong evolutionary pressures.