A novel role for proline in plant floral nectars

Plants offer metabolically rich floral nectar to attract visiting pollinators. The composition of nectar includes not only sugars, but also amino acids. We have examined the amino acid content of the nectar of ornamental tobacco and found that it is extremely rich (2 mM) in proline. Because insect pollinators preferentially utilize proline during the initial phases of insect flight and can reportedly taste proline, we determined whether honeybees showed a preference for synthetic nectars rich in proline. We therefore established an insect preference test and found that honeybees indeed prefer nectars rich in the amino acid proline. To determine whether this was a general phenomenon, we also examined the nectars of two insect-pollinated wild perennial species of soybean. These species also showed high levels of proline in their nectars demonstrating that plants often produce proline-rich floral nectar. Because insects such as honeybees prefer proline-rich nectars, we hypothesize that some plants offer proline-rich nectars as a mechanism to attract visiting pollinators.     

Behavioral repeatability and personality in pit-building antlion larvae under differing environmental contexts

Over the last decades, there has been growing interest among behavioral ecologists in exploring animal personalities. However, while the foraging behavior of active foragers has been extensively studied, only little is known about that of sit-and-wait predators within the personality framework. We investigated the existence of repeatability and personality in pit-building antlion larvae in the context of foraging (pit construction) and habitat selection (relocation distance and direction) over time and under three environmental contexts: thermal conditions, sand depth, and soil type. Over time, repeatability was much stronger for relocation distance than for movement directionality. Additionally, we observed positive correlations across the two levels of sand depth and soil type but not between thermal conditions. Change in substrate type may induce faster decision-making in these sand-dwelling insects or could be perceived by such insects as a more drastic alteration in their habitat. We suggest that different individuals indeed possess distinct personalities. We also suggest that repeatability should be measured at two levels: the amount of energy expenditure (distances and pit construction) and the pattern of energy expenditure (directionality). Finally, our study illustrates how differing environmental conditions can result in differing levels of plasticity, while largely preserving individual personalities.