Stoichiometric niche, nutrient partitioning and resource allocation in a solitary bee are sex-specific and phosphorous is allocated mainly to the cocoon

Abstract

Life histories of species may be shaped by nutritional limitations posed on populations. Yet, populations contain individuals that differ according to sex and life stage, each of which having different nutritional demands and experiencing specific limitations. We studied patterns of resource assimilation, allocation and excretion during the growth of the solitary bee Osmia bicornis (two sexes) under natural conditions. Adopting an ecological perspective, we assert that organisms ingest mutable organic molecules that are transformed during physiological processes and that the immutable atoms of the chemical elements composing these molecules may be allocated to specific functions, thereby influencing organismal fitness and life history. Therefore, using the framework of ecological stoichiometry, we investigated the multielemental (C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, Cu) compositions of six components of the bee elemental budget: food (pollen), eggs, pupae, adults, cocoons and excreta. The sexes differed fundamentally in the assimilation and allocation of acquired atoms, elemental phenotypes, and stoichiometric niches for all six components. Phosphorus, which supports larval growth, was allocated mainly (55–75%) to the cocoon after larval development was complete. Additionally, the majority (60–99%) of the Mn, Ca, Mg and Zn acquired during larval development was allocated to the cocoon, probably influencing bee fitness by conferring protection. We conclude that for holometabolous insects, considering only the chemical composition of the adult body within the context of nutritional ecology does not provide a complete picture. Low ratios of C to other nutrients, low N:P and high Na concentrations in excreta and cocoons may be important for local-scale nutrient cycling. Limited access to specific nutritional elements may hinder bee development in a sex-dependent manner, and N and P limitations, commonly considered elsewhere, may not play important roles in O. bicornis. Sexual dimorphism in nutritional limitations due to nutrient scarcity during the larval stage may influence bee population function and should be considered in bee conservation efforts.

Unravelling the dependence of a wild bee on floral diversity and composition using a feeding experiment

“…For the -KP diet (scarce in K and P), we observed signi cant improvement of cocoon development as well as a slight increase in male cocoon mass after supplementation with de cient nutrients, indicating that the elements scarce in this diet are important mainly for cocoon formation. The obtained results are in accordance with our previous study showing that the majority of P acquired during larval development is allocated to the cocoon and that a high proportion of K intake is used to build cocoons (Filipiak et al, 2021). The lack of improvement after supplementation that occurred in some cases might have been caused by additional (not studied) factors, e.g., the scarcity of colimiting nutrients (other than K, Na and P) (Bryś et al, 2021;Moerman et al, 2017;Vanderplanck et al, 2014;Vaudo et al, 2020;Zu et al, 2021) or the presence of poisonous substances (Eckhardt et al, 2013;Sedivy et al, 2011), various secondary metabolites (Palmer-Young et al, 2019) or the lack of an adequate microbial community (Dharampal et al, 2019(Dharampal et al, , 2020Steffan et al, 2019).…”

“…Our previous studies suggested that mismatches between the nutritional supply of pollen and the nutritional demands for building O. bicornis bodies and cocoons particularly concern sodium (Na), potassium (K), phosphorous (P), copper (Cu), and zinc (Zn) (Filipiak, 2019;Filipiak et al, 2021;Filipiak and Filipiak, 2020). Therefore, we used the concentrations and proportions of K, Na, P, Cu and Zn in the feeding experiment.…”

Assessing pollen nutrient content: a unifying approach for the study of bee nutritional ecology

“…Fe, Zn, Mn)—might affect bee health. However, new insights are beginning to emerge, for both wild bees [98–100] and honeybees [101]. Importantly, two aspects make an elemental approach particularly attractive.…”

Physiological stress and higher reproductive success in bumblebees are both associated with intensive agriculture

“…In pollinator research, ecological stoichiometry has been used to study relationships between the chemical content and quality of bee food, and the consequences these may cause on the individual development of bees and the diversity of local pollinator communities ( Filipiak & Weiner, 2017 ; Filipiak et al, 2017 ). The maintenance of stoichiometric balance is important because inconsistency between the chemical composition of an organism’s tissues and that of its food sources strongly affects the organism’s life history traits, including fitness ( Filipiak, 2018 ; Filipiak, Woyciechowski & Czarnoleski, 2021 ). This suggests that the availability of suitable food and its elemental composition may influence the stoichiometric balance of individual pollinators ( Simanonok & Burkle, 2020 ).…”