Abstract
All animals depend on their taste or smell senses, as functionality for locating and choosing food – whether the foods are animal, plant or other compounds. This function is made possible by chemoreceptors, which are located at the taste buds of the tongue, especially, for humans. Inquiries into the functionality of these taste senses make use of insects, as they are easy to control and manipulate. They are also used, because; their sensory-reaction models are relatively simple, as compared to those of other animals. Insects are further, highly, sensitive as they are able to detect the tastes of food substances by walking over them.
This functionality is made possible by the hollow furs located at the proboscis, which have detector neurons, which help the insects distinguish between the tastes of sugar, salt, and water. During this inquiry, the researchers tested the capability of the blowfly Sarcophaga bullata, in perceiving the tastes of different sugar substitutes, sugars and saccharin. The major difference between the taste abilities of the blowfly Sarcophaga bullata and those of other animals, like humans, is that it can detect the sodium salt in saccharic acid, though this sugar may feel 300-500 times sweeter than sucrose. Previous studies have shown that these insects have five functional cells, which aid in the detection of sugar, salt, water, and oil. Through this identification of the different substances, they determine whether to reject or accept the food compounds.
The hypothesis of the study was that taste perception and detection of different sugars by these insects was similar to that of humans. The rationale of the study revolves around the significance of the extensive comprehension to be gained, on the behavioral patterns regarding the choice of foods, as a way of offering information to guide the control of insects and pests. The materials to be used for the study include the insects (subjects), posickle sticks, sticky wax, distilled water, the sugar compounds for the study, and open containers. The study will involve the sticking of the flies to the posickle sticks – through pressing their wings against the surface of the sticks. The second stage will involve exposing the flies to the different sugar compounds, where feeding will be signified by the lowering of proboscis.
Introduction
All animals depend on their taste or smell senses, towards locating and choosing suitable food – whether other animals, like insects or plant materials, for sustained survival. This function is played through the aid of Chemoreceptors, which are located at the taste buds of the tongues, especially for humans (Campbell 2008), for instance, when tasting food compounds, towards deciding whether it is eatable and fit for consumption.
In this line, some food compounds may be classified as – those supposed to go through refining, which may take the form of cooking. Inquiries into sensory functioning, often, make use of bugs and insects as the experimentation subjects. This is the case, because; such insect subjects can be controlled and manipulated easily as well as that their sensory-reaction structures are moderately simple (Campbell 2008; Dethier 1963).
For instance, these creatures are capable of tasting food substances through walking over it (Dethier 1963). This functionality is made possible by the hollow furs located at the proboscis. The tarsi areas also enclose detector neurons, which are capable of distinguishing the tastes of sugars, salts and waters. Further, these flies can perceive the difference between different forms and types of sugars (Dethier 1976). These characteristic functions allow such animals; to locate and make choice of the nutrition they require (Campbell and Reece 2008).
Discussion
During this study, the researchers tested the capability of the ‘blowfly Sarcophaga bullata,” in perceiving the tastes of various sugar substitute, sugars and saccharin. Based on the fact that sucrose, which is very sweet to the human tongue – the researchers supposed, that these flies would taste lesser sucrose concentrations, than they would perceive glucose and maltose, which are less tasty sugars to the human tongue. Also, due to the sweet nature of saccharin, which is highly sweet tasting to the human tongue, the researchers expected that the insects would react in a positive manner and consume it as well.
From scientific literatures like (Dethier1963; Robertson and Wanner 2006), it was argued that insects can detect the sodium salt in saccharic acid, even though it is approximately 300 – 500 times sweeter than sucrose, when perceived by the human tongue. The study used the technique of using different compounds, to comprehend the taste abilities and characteristics of these insects. The model used alcohol, sugar, water, oil and salt – which were to be classified as acceptable or not, after it was tested by the insects. From the findings, it was concluded that the tarsi membrane acted as the functional receptor, as its depolarization was useful in propagating the stimulus of the insect.
The study, also, showed that there are five functional cells, in addition to the mechanoreceptor – which detect the compounds: sugar, alcohol, salt, water and oil – to determine its rejection or acceptance as a food component. From the five varied cells, the stimulation of sugar and water cells induced eating, while the detection of oil, salt or alcohol receptors restrain feeding (Dethier 1963).
From previous studies in the area, for example (Ozaki and Tominaga 1999), the touch-chemoreceptor sensilla located at the labellum of the blowfly takes the shape of furs, which house five sense-detection neurons. These include a single mechanoreceptor center and four touch-chemoreceptor neurons. Of the four receptor neurons, three are noted as the water, sugar and salt receptor centers – based on the adequate stimuli. The fourth receptor neuron is simply referred as the fifth receptor cell, as it plays the function of receptivity to fatty acids (Dethier and Hanson 1968). The impulses registered at the salt receptor center as well as that at the fifth cell center are evoked by ion reactions, namely Cs+or Rb+ (Gillary1966).
As a result, the fifth cell is also referred as the second salt cell, which makes the insect vey sensitive to salts, for example those contained in sugars like the sodium salt in saccharic acid, which is noted as being 300 – 500 times sweeter than sucrose, when tasted by the human tongue. Further, the fifth cell of this fly is speculated as having another functional characteristic, that it is responsible for the detection and response-triggering, after it detects some vapors, which is believed to induce vigorous impulses at the cell (Dethier 1972).
The hypothesis of the study was that taste perception and detection of different sugars by these insects were similar to that of humans and that the insects have similar abilities for taste perception, as humans. The rationale of the study was that understanding the taste perception abilities of insects would be helpful in creating more understanding, on how insects could be controlled, using the tastes that they prefer (William, Goldstein, Von and Bernard 1971, p 370-371).
From the findings of this study, more understanding on the feeding patterns and behaviors of insects will be comprehended, which may be useful in inhibiting their harmful behaviors, as well as capitalize on their helpful ones. Further, the comprehension of the feeding patterns, sugar perceptions and taste preferences of these insects would be helpful in guiding breakthroughs in pest control, especially, selective pest control, where some insects are targeted while others are not (Campbell and Reece 2008). From this study, the blowfly study will offer information on correlative studies, with reference to gustatory reaction and the chemical structure of flies.
From the study, the inferences collected will aid, towards substantiating the conclusion that sugar complexes interacting with a putative glucose center – should take the pyranose model – where the structure of the C-4 and C-3 hydroxyl models influence the responsiveness. The study will also help shed more light on the speculation, based on behavioral reactions, that there is only a single variety of sweet-taste receptor cell center, though it may possess numerous receptor sites (William, Goldstein, Von and Bernard 1971, p 370-371).
Methods
The materials to be used for the study include the flies, which were collected three days before, placed under controlled feeding – then starved for 5 hours, prior to the administration of the experiment. The second material will be the posickle sticks, which are to be used for the sticking of the flies, prior to the study. The third material to be used during the experiment is sticky wax, which is to be applied onto the surface of the posickle sticks, so that they can allow for the sticking of the insects – onto the surface of the posickle sticks (Kwon, Dahanukar, Weiss and Carlson 2007).
The fourth material is distilled water, which will be used for the rinsing of the insects – during transition of administration from one sugar/ food compound to the next. The water will also be administered to the insects, prior to the exposure to the next study compound, as this will help clear the tastes registered from the previous study compound. Other materials include the open containers, inside which the different sugar compounds are to be poured – so as to administer the exposure in an easier manner. The sugar/ food compounds to be used during the study include diluted sucrose, glucose, and maltose – which are to be used during the different sugar compound exposure steps (Kwon, Dahanukar, Weiss and Carlson 2007).
The study will involve the sticking of flies to posickle sticks, which is affected by pressing their wings against a sticky wax applied at the surface of the sticks. The second step is the making of a dilution compound of sucrose, glucose and maltose in single-half log molar levels, from the different 1M solutions of the sugars availed for the study. The sensory of the flies is determined through offering each fly the opportunity to consume each of the sugar compounds. The exposure to the sugars starts from the lowest concentration to the highest levels. After exposing the fly to one sugar compound, it is rinsed – through swishing their feet into a container with distilled water.
During the exposure, a positive response is registered, when a fly lowers its proboscis. Towards ensuring that the positive responses were registered when exposed to sugars and not the water compound, the insects were allowed to drink the distilled water, prior to exposure at the next test compound. While placing the flies at the different sugar compounds, the flies are expected to lower their proboscis – as a signal of wanting to feed on the compound (Nelson, Hoon, Chandrashekar, Zhang, Ryba and Zuker 2001).
The choice of the testing technique was based on the scientific understanding that sugars are crucial dietary compounds for a wide range of insects, including the blowfly Sarcophaga. Further, the functionality of trehalose receptor traits is characteristic with the molecular genetic makeup of insects, with regard to the perception of sugars among these flies. Further, the taste receptors of the flies used for the study are similar to Co2 receptors and insect olfactory, though dissimilar to those of mammals, which use T1R2/T1R3for the detection of all sugar compounds.
The highly sensitive nature of the insects used for the study was also based on the scientific characteristics – that they use more than a single set of; discrete combinations of GRs towards the detection of the different sugar compounds (Robertson and Wanner 2006).
Conclusion
The appropriate nature of the study technique may also be proved on the basis of the facts that the responses of the sugar receptors located at the tarsal D furs of the blowfly – phormia regina, have been evaluated electrophysiologically. The capability of these receptor centers, in coding sugar/ food information – on sucrose concentration has been investigated and proven the methods and the concepts of information theory (Nelson, Hoon, Chandrashekar, Zhang, Ryba and Zuker 2001).
From such studies, it has been proven that the stimulus-reaction function is linearly related to the logarithm of the concentration of sucrose compounds range between 0.01 and 1.0 M. From the account of the proven nature of the interrelation between the receptor abilities of blowfly Sarcophaga, this mode of study is highly effective, as it offers exactitude information on the sugar-concentration and compound choices of the insects (Vaillant and Derridj 1992, p. 773 -775).
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