ompetition or cooperation? – the concurrent development of grain weevil (Sitophilus granarius L.) and lesser grain borer (Rhyzopertha dominica F.)on barley grain

Abstract

This study consists of an evaluation of the development of two primary grain pests: lesser grain borer (Rhyzopertha dominica F.) and grain weevil (Sitophilus granarius L.) on barley grain. The research objective was to evaluate the concurrent development of these two species and to determine if there was a competition between them, and if so which species was winning it. Parameters of the populations of these pests were examined (abundance of the offspring generation, amount of dust and loss of grain mass) in variants where the pest species had identical conditions for development or when one had an advantage (in terms of their number or duration of being settled on the grain). The species developed under constant thermal and humidity conditions maintained in a climate chamber, for 8 weeks. When they develop independently, there was a linear relationship between the growth in the number of offspring and the dust mass and kernel mass loss. When developing together with the other species, the lesser grain borer had better conditions for the development, probably owing to greater availability of dust used by young larvae of R. dominica. The lesser grain borer formed larger progeny populations and had a more dynamic development as a species than the grain weevil did.