Even though most plant-pollinator relationships are mutually beneficial the plant rewarding the pollinator's help with food their interests are conflicting.
"Speaking in evolutionary terms, the flower wants to be visited by a pollinator, but it doesn't want to invest too much because sacrificing resources and energy to make nectar is expensive," von Arx explained. "Often, plants are dishonest in their advertising, by presenting attractive flowers with no nectar."
But under certain circumstances, especially in desert environments, where water is scarce, it is beneficial for a flower to be honest, the researchers believe.
"If you're one of only a few flowers and there are lots of pollinators out there, you don't have to be honest about how much nectar you have because they'll visit anyway," von Arx said. "But if you want the attention of just a few, you really have to go all out. So by saying, 'Hey, come here, I have lots of nectar,' you're giving a faithful signal about an actual benefit that the pollinators can perceive and evaluate."
"I think in this case we showed that honesty makes sense in this system, because plants pollinated by hawkmoths are often pollinator-limited, and this signal, especially in the desert environment, is very potent."
According to von Arx, relative humidity plays an important role in the insect world and has been associated with choosing a suitable habitat but never was studied in the context of foraging for nectar. For example, neurobiological experiments revealed that cockroaches are able to detect humidity changes of a fraction of a percent.
"As creatures who use vision and olfaction, humans think in odors and shape, and color," von Arx said. "We are biased by what we can perceive. We know that moths have hygroreceptors on the tips of their antennae, but they remain a mystery for the most part. We know a lot about olfactory receptors, mechanoreceptors an
|Contact: Daniel Stolte|
University of Arizona