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Effects of Floral Scents and Their Dietary Experiences on the Feeding Preference in the Blowfly, Phormia regina.

Maeda T, Tamotsu M, Yamaoka R, Ozaki M - Front Integr Neurosci (2015)

Bottom Line: After feeding on sucrose solutions flavored with floral scents for 5 days, the scents did not consistently show the previously observed effects.The results suggested that olfactory inputs through these organs play different roles in forming or modifying feeding preferences.Thus, our study contributes to an understanding of underlying mechanisms associated with the convergent processing of olfactory inputs with taste information, which affects feeding preference or appetite.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Graduate School of Science, Kobe University Kobe, Japan.

ABSTRACT
The flowers of different plant species have diverse scents with varied chemical compositions. Hence, every floral scent does not uniformly affect insect feeding preferences. The blowfly, Phormia regina, is a nectar feeder, and when a fly feeds on flower nectar, its olfactory organs, antennae, and maxillary palps are exposed to the scent. Generally, feeding preference is influenced by food flavor, which relies on both taste and odor. Therefore, the flies perceive the sweet taste of nectar and the particular scent of the flower simultaneously, and this olfactory information affects their feeding preference. Here, we show that the floral scents of 50 plant species have various effects on their sucrose feeding motivation, which was evaluated using the proboscis extension reflex (PER). Those floral scents were first categorized into three groups, based on their effects on the PER threshold sucrose concentration, which indicates whether a fly innately dislikes, ignores, or likes the target scent. Moreover, memory of olfactory experience with those floral scents during sugar feeding influenced the PER threshold. After feeding on sucrose solutions flavored with floral scents for 5 days, the scents did not consistently show the previously observed effects. Considering such empirical effects of scents on the PER threshold, we categorized the effects of the 50 tested floral scents on feeding preference into 16 of all possible 27 theoretical types. We then conducted the same experiments with flies whose antennae or maxillary palps were ablated prior to PER test in a fly group naïve to floral scents and prior to the olfactory experience during sugar feeding in the other fly group in order to test how these organs were involved in the effect of the floral scent. The results suggested that olfactory inputs through these organs play different roles in forming or modifying feeding preferences. Thus, our study contributes to an understanding of underlying mechanisms associated with the convergent processing of olfactory inputs with taste information, which affects feeding preference or appetite.

No MeSH data available.


Related in: MedlinePlus

The sucrose concentration-PER curves modified by Narcissus tazetta floral scent and its major component. (I) The curves in the absence (black circles) and presence (red circles) of the N. tazetta scent in non-experienced (open circles) and experienced flies (closed circles). (II) The curves in the absence (black circles) and presence of the D-limonene odor (red circles) in non-experienced (open circles) and experienced flies (closed circles). The red and black arrowheads indicate the mean PER threshold sucrose concentrations in the absence and presence of odor; the open and closed arrowhead in non-experienced and experienced flies, respectively. Broken lines indicate the concentration-PER curves in the absence of scent in non-experienced flies.
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Figure 5: The sucrose concentration-PER curves modified by Narcissus tazetta floral scent and its major component. (I) The curves in the absence (black circles) and presence (red circles) of the N. tazetta scent in non-experienced (open circles) and experienced flies (closed circles). (II) The curves in the absence (black circles) and presence of the D-limonene odor (red circles) in non-experienced (open circles) and experienced flies (closed circles). The red and black arrowheads indicate the mean PER threshold sucrose concentrations in the absence and presence of odor; the open and closed arrowhead in non-experienced and experienced flies, respectively. Broken lines indicate the concentration-PER curves in the absence of scent in non-experienced flies.

Mentions: Using N. tazetta typed as Ag, we examined the effects of floral scent on appetite change in groups of non-experienced and experienced flies when either the antennae or maxillary palps were ablated. The reason why we used N. tazetta was that the major component of its scent was found to be limonene, which has reported as an oral toxic compound to be repelled for P. regina (Ozaki et al., 2003; Nisimura et al., 2005). As the control experiments and in order to confirm the type of effects of its scent (Table 1, Figures 2–4), we repeatedly performed five PER tests with the intact fly groups of 20 individuals each, in which both olfactory organs were preserved. In the presence of the N. tazetta scent, the non-experienced flies significantly increased individual PER threshold sucrose concentrations by the presence of the floral scent (p < 0.001, Mann-Whitney U test; n = 100) (Figure 5I Top). The mean PER threshold in the presence of the floral scent (average ± standard error of means (SEM): 0.625 ± 0.216 M; n = 5) increased approximately three-fold compared to that in the absence of scent (0.213 ± 0.120 M; n = 5). There was a significant difference between these mean PER thresholds (p < 0.05, Mann-Whitney U test; n =5). When the flies had an olfactory experience with the N. tazetta floral scent during sugar feeding for 5 days (Figure 5I Bottom), the individual PER threshold in the absence of scent significantly decreased (p < 0.05, Mann-Whitney U test; n = 100). On the other hand, the individual PER threshold in the presence of scent significantly increased (p < 0.05, Mann-Whitney U test; n = 100). Thus, the mean PER threshold in the absence of scent (0.106 ± 0.027 M; n = 5) significantly decreased to half of that observed in the non-experienced flies tested in the absence of scent (0.213 ± 0.120 M; n = 5). However, the mean PER threshold in the presence of scent (0.781 ± 0.297 M; n = 5) increased approximately four-fold compared to that of the non-experienced flies tested in the absence of scent (0.213 ± 0.120 M; n = 5) (p < 0.01, Mann-Whitney U test; n = 5). In conclusion, the appetite change induced by the N. tazetta floral scent was then determined to be the Ag type in accordance with our classification (Figure 1). As the major components of the scent of N. tazetta was limonene (Table 1), we compared this Ag type of data on the scent of N. tazetta (Figure 5I) with that on D-limonene odor (Figure 5II), which was found to be classified into the Aa type.


Effects of Floral Scents and Their Dietary Experiences on the Feeding Preference in the Blowfly, Phormia regina.

Maeda T, Tamotsu M, Yamaoka R, Ozaki M - Front Integr Neurosci (2015)

The sucrose concentration-PER curves modified by Narcissus tazetta floral scent and its major component. (I) The curves in the absence (black circles) and presence (red circles) of the N. tazetta scent in non-experienced (open circles) and experienced flies (closed circles). (II) The curves in the absence (black circles) and presence of the D-limonene odor (red circles) in non-experienced (open circles) and experienced flies (closed circles). The red and black arrowheads indicate the mean PER threshold sucrose concentrations in the absence and presence of odor; the open and closed arrowhead in non-experienced and experienced flies, respectively. Broken lines indicate the concentration-PER curves in the absence of scent in non-experienced flies.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664696&req=5

Figure 5: The sucrose concentration-PER curves modified by Narcissus tazetta floral scent and its major component. (I) The curves in the absence (black circles) and presence (red circles) of the N. tazetta scent in non-experienced (open circles) and experienced flies (closed circles). (II) The curves in the absence (black circles) and presence of the D-limonene odor (red circles) in non-experienced (open circles) and experienced flies (closed circles). The red and black arrowheads indicate the mean PER threshold sucrose concentrations in the absence and presence of odor; the open and closed arrowhead in non-experienced and experienced flies, respectively. Broken lines indicate the concentration-PER curves in the absence of scent in non-experienced flies.
Mentions: Using N. tazetta typed as Ag, we examined the effects of floral scent on appetite change in groups of non-experienced and experienced flies when either the antennae or maxillary palps were ablated. The reason why we used N. tazetta was that the major component of its scent was found to be limonene, which has reported as an oral toxic compound to be repelled for P. regina (Ozaki et al., 2003; Nisimura et al., 2005). As the control experiments and in order to confirm the type of effects of its scent (Table 1, Figures 2–4), we repeatedly performed five PER tests with the intact fly groups of 20 individuals each, in which both olfactory organs were preserved. In the presence of the N. tazetta scent, the non-experienced flies significantly increased individual PER threshold sucrose concentrations by the presence of the floral scent (p < 0.001, Mann-Whitney U test; n = 100) (Figure 5I Top). The mean PER threshold in the presence of the floral scent (average ± standard error of means (SEM): 0.625 ± 0.216 M; n = 5) increased approximately three-fold compared to that in the absence of scent (0.213 ± 0.120 M; n = 5). There was a significant difference between these mean PER thresholds (p < 0.05, Mann-Whitney U test; n =5). When the flies had an olfactory experience with the N. tazetta floral scent during sugar feeding for 5 days (Figure 5I Bottom), the individual PER threshold in the absence of scent significantly decreased (p < 0.05, Mann-Whitney U test; n = 100). On the other hand, the individual PER threshold in the presence of scent significantly increased (p < 0.05, Mann-Whitney U test; n = 100). Thus, the mean PER threshold in the absence of scent (0.106 ± 0.027 M; n = 5) significantly decreased to half of that observed in the non-experienced flies tested in the absence of scent (0.213 ± 0.120 M; n = 5). However, the mean PER threshold in the presence of scent (0.781 ± 0.297 M; n = 5) increased approximately four-fold compared to that of the non-experienced flies tested in the absence of scent (0.213 ± 0.120 M; n = 5) (p < 0.01, Mann-Whitney U test; n = 5). In conclusion, the appetite change induced by the N. tazetta floral scent was then determined to be the Ag type in accordance with our classification (Figure 1). As the major components of the scent of N. tazetta was limonene (Table 1), we compared this Ag type of data on the scent of N. tazetta (Figure 5I) with that on D-limonene odor (Figure 5II), which was found to be classified into the Aa type.

Bottom Line: After feeding on sucrose solutions flavored with floral scents for 5 days, the scents did not consistently show the previously observed effects.The results suggested that olfactory inputs through these organs play different roles in forming or modifying feeding preferences.Thus, our study contributes to an understanding of underlying mechanisms associated with the convergent processing of olfactory inputs with taste information, which affects feeding preference or appetite.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Graduate School of Science, Kobe University Kobe, Japan.

ABSTRACT
The flowers of different plant species have diverse scents with varied chemical compositions. Hence, every floral scent does not uniformly affect insect feeding preferences. The blowfly, Phormia regina, is a nectar feeder, and when a fly feeds on flower nectar, its olfactory organs, antennae, and maxillary palps are exposed to the scent. Generally, feeding preference is influenced by food flavor, which relies on both taste and odor. Therefore, the flies perceive the sweet taste of nectar and the particular scent of the flower simultaneously, and this olfactory information affects their feeding preference. Here, we show that the floral scents of 50 plant species have various effects on their sucrose feeding motivation, which was evaluated using the proboscis extension reflex (PER). Those floral scents were first categorized into three groups, based on their effects on the PER threshold sucrose concentration, which indicates whether a fly innately dislikes, ignores, or likes the target scent. Moreover, memory of olfactory experience with those floral scents during sugar feeding influenced the PER threshold. After feeding on sucrose solutions flavored with floral scents for 5 days, the scents did not consistently show the previously observed effects. Considering such empirical effects of scents on the PER threshold, we categorized the effects of the 50 tested floral scents on feeding preference into 16 of all possible 27 theoretical types. We then conducted the same experiments with flies whose antennae or maxillary palps were ablated prior to PER test in a fly group naïve to floral scents and prior to the olfactory experience during sugar feeding in the other fly group in order to test how these organs were involved in the effect of the floral scent. The results suggested that olfactory inputs through these organs play different roles in forming or modifying feeding preferences. Thus, our study contributes to an understanding of underlying mechanisms associated with the convergent processing of olfactory inputs with taste information, which affects feeding preference or appetite.

No MeSH data available.


Related in: MedlinePlus