Nutritional Value-Dependent and Nutritional Value-Independent Effects on Drosophila melanogaster Larval Behavior

Abstract

Gustatory stimuli allow an organism not only to orient in its environment toward energy-rich food sources to maintain nutrition but also to avoid unpleasant or even poisonous substrates. For both mammals and insects, sugars-perceived as "sweet"-potentially predict nutritional benefit. Interestingly, even Drosophila adult flies are attracted to most highpotency sweeteners preferred by humans. However, the gustatory information of a sugar may be misleading as some sugars, although perceived as "sweet," cannot be metabolized. Accordingly, in adult Drosophila, a postingestive system that additionally evaluates the nutritional benefit of an ingested sugar has been shown to exist. By using a set of seven different sugars, which either offer (fructose, sucrose, glucose, maltodextrin, and sorbitol) or lack (xylose and arabinose) nutritional benefit, we show that Drosophila, at the larval stage, can perceive and evaluate sugars based on both nutrition-dependent and-independent qualities. In detail, we find that larval survival and feeding mainly depend on the nutritional value of a particular sugar. In contrast, larval choice behavior and learning are regulated in a more complex way by nutrition valuedependent and nutrition value-independent information. The simplicity of the larval neuronal circuits and their accessibility to genetic manipulation may ultimately allow one to identify the neuronal and molecular basis of the larval sugar perception systems described here behaviorally.

Starvation stress during larval development facilitates an adaptive response in adult worker honey bees (Apis mellifera L.)

“…Indeed, we found that larval starvation impacted adult feeding behavior, measured as the gustatory perception of sugar. Gustatory perception is critical for animal survival, perhaps especially in a low-nutrient environment (Linford et al, 2015), as it helps an organism locate energy-rich food sources in order to maintain adequate nutrition (Drewnowski, 2000;Rohwedder et al, 2012). In our study, we observed reduced gustatory perception in the adult bees that experienced starvation as larvae.…”

The neuronal and molecular basis of quinine-dependent bitter taste signaling in Drosophila larvae

“…To address the effect of quinine in different larval behaviors, we assessed the naive behavior of wild type CantonS larvae for quinine-dependent choice behavior, quinine-dependent feeding, survival on quinine, and quinine-reinforced associative olfactory learning [a detailed description of the methods is also given in Rohwedder et al (2012)].…”

“…To test for quinine-dependent choice behavior, naive larvae were allowed for 5 min to choose between pure agarose and agarose containing quinine (El-Keredy et al, 2012; Rohwedder et al, 2012). Quinine concentrations ranged from 0 to 6 mM (Figure 1A), the latter being the highest soluble quinine concentration dissoluble in 2.5% agarose.…”

“…The neurons involved in the alternative quinine signaling pathways are yet unknown. However, several possibilities can be taken into consideration based on recent findings on sugar reward processing in larvae and flies (Inoshita and Tanimura, 2006; Burke and Waddell, 2011; Miyamoto et al, 2012; Rohwedder et al, 2012; Dus et al, 2013; Gruber et al, 2013; Mishra et al, 2013) These studies suggest that sugar reward is not due to a single-GRN-based signal, but on a more complex set of sensory inputs that integrate different types of sensory information. If negative inputs are similarly encoded, there are several possibilities that might signal punishing reinforcement in larval odor-quinine learning.…”

Appetitive Associative Olfactory Learning in <em>Drosophila</em> Larvae

“…Olfactory stimuli as well as light can be used as a conditioned stimulus to be associated with either reward or punishment (unconditioned stimulus). Rewarding stimuli include sugar and low concentrations of salt; punishing stimuli comprise high concentrations of salt, quinine, electric shock, heat, mechanical stimulation through vibration (buzz) and light 11,12,[17][18][19][20][21][22][23][24] . Click here to view larger figure.…”