Resource Partitioning among Competing Individuals: an Experiment with Bean Weevil Acanthoscelides obtectus (Say, 1831) (Coleoptera: Chrysomelidae)

The aim of this study is to proof that intraspecific competition leads to unequal resource partitioning. Bean weevil Acanthoscelides obtectus larvae were used in the experiment. They foraged inside bean seeds drilling corridors. Different numbers of larvae can live together in one seed. The corridors were filled with a dentistic material. Following variables were measured in the experiment: weight of bean seed before and after the experiment, the number of larvae living in each seed, weights of filling which is a measure of the amount of resource consumed by a larva and the weight of adult individual emerging from each marked corridor of known size. Weights of fillings and weights of adult individuals are variable even when they are taken from seeds with only one larva living inside. However, in this case there are no other relations between variables measured in the experiment. When many larvae are living together in one seed, the variability of weights of fillings is greater and the distribution of weight of adult individuals is positively skewed. Additionally there is statistically significant positive relationship between weight of fillings and weight of adult individuals and negative relationship between the length of larval period and weight of adult individual together with weight of filling.