Timing Is Everything. Temporal and Spatial Niche Segregation in Curculio spp. (Coleoptera: Curculionidae) Associated with Oak Trees

SIMPLE SUMMARY: Acorn weevils from the genus Curculio (Curculionini) represent a group of species developing in fructifications of plants. In Poland, three different species of those beetles develop on the same host plant and use the same resources, which can lead to increased competition. We tested preferences of weevil females towards acorn size chosen for oviposition as well as reproduction time and other characteristics of their breeding behavior. The results clearly indicate that particular species prefer acorns of different masses and breeds in different periods corresponding to different stages of fruit growth. In other words, this enables weevils to pass each other during reproduction. Furthermore, one of the studied species varies distinctly also in terms of the number of laid eggs and the manner of locating them within the acorn tissues. Our observations support the hypothesis that niche partitioning among the species appears to be occurring when the resources—acorns, are limited. The work helps to understand how multi-species communities of insects cope in order to survive in a shared habitat. ABSTRACT: Oak seed predatory weevils occurring in Poland are prone to increased interspecific competition due to the limited number of Quercus species, compared to southern Europe, in which they can develop. Therefore, analyses on the preferences of three weevil species for acorn sizes chosen for reproduction, as well as on reproductive period duration, were performed. Cafeteria-type experiments were set for females of three species associated with one oak species. Females were allowed to choose and oviposit in acorns of different sizes and growth stages. Research revealed statistically significant differences between the masses of acorns chosen for oviposition by females of Curculio glandium (the biggest), C. pellitus (medium), and C. venosus (the smallest). Studied weevils also differed in terms of the beginning of the reproductive period, which corresponded with the increasing mass of growing acorns. Moreover, C. glandium was observed to be the only species to perform radial egg galleries and lay a considerably higher and varied number of eggs. The results support the hypothesis of a strategy aimed at reducing interspecific competition between Curculio spp. in terms of limited host plant species number.