Biology subjects

Nicholls, E.

Publications and source records attributed to Nicholls, E..

4 recordsLinked to original sources

bioRxiv2024

Shifts in honeybee worker metabolism immediately post-eclosion

O_LIThe metabolic rate of an organism is intrinsically linked to key traits such as reproductive output and lifespan. While the drivers of individual differences in metabolic rate are poorly understood, previous research in insects has shown that metabolic rate can change substantially in the initial hours and days post-eclosion as adults. C_LIO_LIHere we repeatedly measured the resting and active metabolic rate of individual adult honeybees (Apis mellifera) for up to 48 hours from the time of eclosion. We combined flow-through respirometry with automated behaviour tracking, permitting us to obtain active (AMR) and true resting metabolic rate (RMR) from freely moving animals. We compared these recordings to the more conventional approach of obtaining resting metabolic rate by restraining animals. C_LIO_LIBoth active and resting metabolic rates and mass-specific metabolic rates increased significantly in the first 48-hours post-eclosion, whereas metabolic scope did not change. Mass-specific water loss was highest in active bees and changed non-linearly with time post-eclosion, increasing in the first 24 hours before decreasing again. A similar quadratic relationship with time was also observed for bees movement speed. Speed- and mass-specific metabolic rate and scope increased with time post-emergence, whereas speed- and mass-specific water loss did not. C_LIO_LIThe metabolic rate of restrained bees was consistently significantly higher than the true RMR at all time points, likely due to the stress associated with being restrained. Therefore, we recommend future studies of insect resting metabolic rates avoid restraining organisms to restrict movement and consider employing behaviour tracking as a means to extract metabolic rate data from periods of true rest. C_LIO_LIThis study provides important insights into the previously overlooked changes in metabolism exhibited by newly emerged honeybee workers. The high mortality rate beyond 48 hours, coupled with significant changes in metabolic rates, body mass, and water loss, underscores the importance of this early post-eclosion period for survival and metabolic stabilization. C_LI

physiology↗

bioRxiv2024

Gustatory sensitivity to amino acids in bumblebees

Bees rely on amino acids from nectar and pollen for essential physiological functions. While nectar typically contains low (<1 mM) amino acid concentrations, while their levels in pollen are higher, but vary widely (10-200 mM). Behavioural studies suggest bumblebees have preferences for specific amino acids but whether such preferences are mediated via gustatory mechanisms remains unclear. This study explores bumblebees (Bombus terrestris) gustatory sensitivity to two essential amino acids (EAAs), valine and lysine, using electrophysiological recordings from gustatory sensilla on their mouthparts. Valine elicited a concentration-dependent response from 0.1 mM, indicating that bumblebees could perceive valine at concentrations found naturally in nectar and pollen. In contrast, lysine failed to evoke a response across tested concentrations (0.1-500 mM). The absence of lysine detection raises questions about the specificity and diversity of amino acid-sensitive receptors in bumblebees. Bees responded to valine at lower concentrations than sucrose, suggesting comparatively higher sensitivity (EC50: 0.7 mM vs. 3.91 mM for sucrose). Our findings indicate that bumblebees can rapidly evaluate the amino acid content of pollen and nectar using pre-ingestive cues, rather than relying on post-ingestive cues or feedback from their nestmates. Such sensory capabilities likely impact foraging strategies, with implications for plant-bee interactions and pollination.

neuroscience↗

bioRxiv2024

Understanding pollination in urban food production: the importance of data validation and participant feedback for citizen science project design

O_LIThere is a significant knowledge gap regarding the pollination needs of urban farming, partly due to barriers for researchers in accessing these growing spaces. Involving growers in data collection offers a potential solution but presents other challenges in terms of data accuracy and participant retention. C_LIO_LIWe developed a citizen science methodology for monitoring plant-pollinator interactions in urban food systems and evaluated the accuracy of data collected by growers by comparison to data collected by a professionally trained researcher. We also collected feedback from participants at the mid- and endpoints of the project regarding their experiences of taking part. C_LIO_LIWhile there was some agreement between the datasets in terms of the crops most (raspberries and squash) and least attractive (tomatoes) to insects, relying only on the dataset collected by growers themselves (citizen scientists) would lead to an overestimation of the generality of relationships between crops and pollinating insects in urban food production. Possible reasons for discrepancies between the datasets include species misidentification and non-reporting of surveys where no insects were observed by citizen scientists. C_LIO_LICitizen scientists reported lack of time, concerns about data accuracy and too complex methods as barriers to participation. Implementation of their suggestions for improvements led to a 66% increase in participation in the following year, demonstrating the importance of maintaining a two-way dialogue between participants and project organisers. Citizen scientists also reported an increased appreciation and understanding of insect pollinations following participation, highlighting an additional benefit of involving urban growers in data collection. C_LI Social Impact StatementGrowing food in urban areas can contribute towards sustainable food production. We know little about urban crop pollination, and data collection can be challenging due to restricted access to growing spaces. We developed and tested the effectiveness of a method for urban growers themselves to collect data on insects visiting their crops. Comparing data to that collected by a professional researcher, we found similarities in terms of the most and least attractive crops to pollinators, but there were also large discrepancies in the datasets that mean there are limitations to relying on grower-collected data alone to understand urban plant-pollinator interactions.

ecology↗

bioRxiv2021

Larval nutrition impacts survival to adulthood, body size, and the allometric scaling of metabolic rate in adult honeybees

Resting metabolic rate (RMR) is a fundamental physiological measure linked to numerous aspects of organismal function, including lifespan. Although dietary restriction in insects during larval growth/development affects adult RMR, the impact of larval diet quality on adult RMR has not been studied. Using in vitro rearing to control larval diet quality, we determined the effect of dietary protein and carbohydrate on honeybee survival-to-adulthood, time-to-eclosion, body mass/size and adult RMR. High carbohydrate larval diets increased survival-to-adulthood and time-to-eclosion compared to both low carbohydrate and high protein diets. Upon emergence, bees reared on the high protein diet were smaller and lighter than those reared on other diets, whilst those raised on the high carbohydrate diet varied more in body mass. Newly emerged adult bees reared on the high carbohydrate diet showed a significantly steeper increase in allometric scaling of RMR compared to those reared on other diets. This suggests that diet quality influences survival-to-adulthood, time-to-eclosion, and the allometric scaling of RMR. Given that agricultural intensification and increasing urbanisation have led to a decrease in both forage availability and dietary diversity for bees, our results are critical to improving understanding of the impacts of poor developmental nutrition on bee growth/development and physiology. Summary statementWe show, for the first time, that the nutritional quality of insect larval diets affects the scaling of metabolic rate with body mass in newly emerged adult honeybees.

physiology↗