The influence of competition between foragers on clutch size decisions in insect parasitoids

The effect of competition between ovipositing females on their clutch size decisions is studied in parasitoid insects. The effect of this competition depends on whether the competition between parasitoid larvae within a host is contest (solitary parasitoids) or scramble competition (gregarious parasitoids). For gregarious parasitoids, a decreasing clutch size with increasing competition between females is predicted while for solitary parasitoids an increase is predicted. These predictions mere tested using the gregarious parasitoid Aphaereta minuta (M. E. Visser, 1996, Behav. Ecol. 7, 109-114) and the solitary parasitoid Comperiella bifasciata (J. A. Rosenheim and D. Hongkham, 1996, Anim. Behav. 51, 841-852). Parasitoids were either kept alone or in groups before the experiments, in which they were introduced singly into a patch containing unparasitized hosts. In the experiment with A. minuta, females kept together before the experiment laid smaller clutches than females kept alone. In C. bifasciata, the clutch size laid by females kept together was larger than that of females kept alone. Thus, both predictions were supported. [KEYWORDS: parasitoids; clutch size; competition; Aphaereta minuta; Comperiella bifasciata Hymenoptera; superparasitism; patch; oviposition; braconidae; allocation; females; wasp

Model comparison tests to determine data information content

In the context of inverse or parameter estimation problems we demonstrate the use of statistically based model comparison tests in several examples of practical interest. In these examples we are interested in questions related to information content of a particular given data set and whether the data will support a more complicated model to describe it. In the first example we compare fits for several different models to describe simple decay in a size histogram for aggregates in amyloid fibril formation. In a second example we investigate whether the information content in data sets for the pest Lygus hesperus in cotton fields as it is currently collected is sufficient to support a model in which one distinguishes between nymphs and adults. Finally in a third example with data for patients having undergone an organ transplant, we question whether the data content is sufficient to estimate more than 5 of the fundamental parameters in a particular dynamic model