YANG, R. L.*; FUSHING, H.; HORNG, S. B.; National Taiwan University; Univ. of California, Davis; National Taiwan University: Evaluating discrimination performances of the seed beetle, Callosobruchus maculatus (F.)

Many parasitic and endophagous species are capable of discriminating the quality of their hosts. However, it is still difficult to evaluate an animal�s discrimination performance. In this study, we attempted to quantify egg- and size-discrimination performances of the seed beetle, Callosobruchus maculatus, in different stages of oviposition. In addition, the relative importance of the two types� discrimination and differences in performance when females searched patches with different resource heterogeneities were also explored. Prediction of the egg dispersion was made by combining time-dependant available resource quality defined by fitness (egg-discrimination) and host weight factors (size-discrimination). The Chi-square test was then used for goodness-of-fit testing, and thus the performances of egg- and size-discrimination by the seed beetle in environments with differing resource heterogeneities were compared. This may be the first study that provides a method to quantify an individual�s discrimination performance, and we found that size- rather than egg-discrimination played a more-important role in the oviposition process of most individual seed beetles, especially in the later parasitized phase. A coarse-grain setting (4-patch design) was more helpful at screening out individuals with discrimination deficiencies. This behavior-to-fitness computation model may greatly improve physiological and genetic studies, and it may be further applied to comparing performances when the target trait belongs to additive heredity.