Specificity of the Red Imported Fire Ant Phagostimulant Response to Carbohydrates
The red imported fire ant, Solenopsis invicta Buren, is considered an oil-loving feeder, however, carbohydrates are essential ingredients in the diet of the fire ant also. Comprehensive screening of mono-, di-, and tri-saccharides demonstrated that glucose, fructose, fucose, sucrose, maltose, turanose and raffinose were significant phagostimulants for fire ant workers. It was also found that while D-glucose and L-fucose, the naturally occurring isomers, were active, the opposite diastereomers were not. Any structural modification of the glucose molecule resulted in loss of activity. None of the sugar alcohols evaluated were active. The fire ant is an agricultural pest and the many reports of fire ant damage to food crops may be linked to their need for dietary carbohydrates. A knowledge of carbohydrate phagostimulants may help to understand specificity of fire ant /plant interactions.
The flow of food in colonies of the fire ant, Solenopsis invicta: a multifactorial study
ABSTRACT. A study was conducted to determine the interaction of several factors in the trophallactic distribution of food in colonies of Solenopsis invicta Buren. Radioactive iodine (125I) was used to quantify both the ingestion of test foods by foragers and the distribution of this food to nestmates. A multifactorial design tested the simultaneous effects of: (1) food‐type (sugar water, casein hydrolysate, or oil), (2) temperature during foraging and food‐sharing (25, 30 or 35°C), and (3) starvation period (colonies deprived for 0, 3, 7 or 14 days). The amount of food consumed by foragers was influenced by the interaction of food‐type and starvation. Foragers from severely starved colonies ingested more aqueous foods than did those from slightly starved colonies, but oil was always taken in smaller quantities and its ingestion was least affected by starvation. Ingestion was generally lowest at 35°C, probably because of mutual interference of workers while feeding. Within the colony, food sharing varied with food type and increased with starvation. The sugar solution was utilized primarily by workers. Amino acids were shared throughout the colony, but were directed preferentially to the growing larvae. Soy oil was equally shared among workers and larvae and reached more colony members per initial unit volume than did the other foods. The test factors also interacted in their influence on trophallaxis. Starvation stimulated the dispersal of labelled foods, but at different intensities for different foods. The probability of the queen's receiving food increased when the labelled food was widely exchanged among her nestmates. Casein hydrolysate reached the queen in more cases than did the other tested foods.
Food-Sharing Behaviour of the Ants Formica Sanguinea and Formica Fusca
[1. The basic distinction in food-sharing is between donor and acceptor responses, which are mutually inhibitory. 2. Whether the donor or acceptor initiates food-sharing depends on the relative strengths of the motivation of the two potential participants. A similar factor determines whether the donor or the acceptor will terminate food-sharing. 3. Food-sharing may be shown in widely different circumstances. It is not possible to locate normally essential sign stimuli specific to these responses, but various stimuli may be facilitatory. 4. Visual stimuli are not important as cues or releasers and blinding does not depress the amount of food-sharing shown. Removal of one antenna does not impede food-sharing, but removal of both (a) depresses the total food-sharing shown and (b) renders ants markedly less successful in attempts to feed. But, even the antennae are not essential. 5. The stimuli which facilitate food-sharing may be divided into those which: (a) Facilitate food-sharing in general, but are not specific to either donor or acceptor behaviour, e.g. the palpating movements, movement itself, colony odour, etc. (b) Facilitate either donor or acceptor responses in particular, e.g. internal stimuli from the crop and chemoreceptors, etc. Some external stimuli, e.g. licking by the other ant, play a minor role. 6. The two forms of palpation may be shown by either donors or acceptors. The hypothesis was advanced that the palpating movements reflect the relative strength of either tendency to donate or tendency to accept food. Antennal palpation is shown at lower levels of motivation than foreleg plus antennal palpation. 7. Experiments were designed to test the hypothesis using both Formica sanguinea and F. fusca. These included study of situations where a high tendency to feed was induced by a period of desiccation and of returned foragers, where the tendency to regurgitate was high. Evidence from behaviour sequences was also used. 8. It was found that the amount of feeding with foreleg palpation increases with increase in the tendency to feed. Antennal palpation accompanying feeding shows a peak at a lower level of this tendency, and is shown at a time when feeding with no palpation or even regurgitation may be shown. Analysis of sequential behaviour in general gives support to the hypothesis. Scrutiny of results for fusca brings out further points of interest and suggests that differences exist in the relations between regurgitation, regurgitation with antennal palpation, and regurgitation with foreleg plus antennal palpation in the two species. Circumstantial evidence is, thus, fairly strong in support of the hypothesis. The expected sequence, moving from a high tendency to feed to a high tendency to regurgitate, would be:- FP →FA → F → R → RA →RF ∥ ←OFFER→ When: FP = foreleg plus antennal palpation associated with feeding FA = antennal palpation associated with feeding F = feeding with no palpation R = regurgitation with no palpation RA = antennal palpation associated with regurgitation RF = foreleg plus antennal palpation associated with regurgitation Offer = offering. There is good evidence to associate offering with regurgitation motivated at the RA level. 9. The function of palpation as a form of facilitatory behaviour is discussed, and the importance of the two types of palpation in feeding and regurgitation is compared. A diagram attempts to summarize the conclusions relating motivation to the different forms of palpation, etc., 1. The basic distinction in food-sharing is between donor and acceptor responses, which are mutually inhibitory. 2. Whether the donor or acceptor initiates food-sharing depends on the relative strengths of the motivation of the two potential participants. A similar factor determines whether the donor or the acceptor will terminate food-sharing. 3. Food-sharing may be shown in widely different circumstances. It is not possible to locate normally essential sign stimuli specific to these responses, but various stimuli may be facilitatory. 4. Visual stimuli are not important as cues or releasers and blinding does not depress the amount of food-sharing shown. Removal of one antenna does not impede food-sharing, but removal of both (a) depresses the total food-sharing shown and (b) renders ants markedly less successful in attempts to feed. But, even the antennae are not essential. 5. The stimuli which facilitate food-sharing may be divided into those which: (a) Facilitate food-sharing in general, but are not specific to either donor or acceptor behaviour, e.g. the palpating movements, movement itself, colony odour, etc. (b) Facilitate either donor or acceptor responses in particular, e.g. internal stimuli from the crop and chemoreceptors, etc. Some external stimuli, e.g. licking by the other ant, play a minor role. 6. The two forms of palpation may be shown by either donors or acceptors. The hypothesis was advanced that the palpating movements reflect the relative strength of either tendency to donate or tendency to accept food. Antennal palpation is shown at lower levels of motivation than foreleg plus antennal palpation. 7. Experiments were designed to test the hypothesis using both Formica sanguinea and F. fusca. These included study of situations where a high tendency to feed was induced by a period of desiccation and of returned foragers, where the tendency to regurgitate was high. Evidence from behaviour sequences was also used. 8. It was found that the amount of feeding with foreleg palpation increases with increase in the tendency to feed. Antennal palpation accompanying feeding shows a peak at a lower level of this tendency, and is shown at a time when feeding with no palpation or even regurgitation may be shown. Analysis of sequential behaviour in general gives support to the hypothesis. Scrutiny of results for fusca brings out further points of interest and suggests that differences exist in the relations between regurgitation, regurgitation with antennal palpation, and regurgitation with foreleg plus antennal palpation in the two species. Circumstantial evidence is, thus, fairly strong in support of the hypothesis. The expected sequence, moving from a high tendency to feed to a high tendency to regurgitate, would be:- FP →FA → F → R → RA →RF ∥ ←OFFER→ When: FP = foreleg plus antennal palpation associated with feeding FA = antennal palpation associated with feeding F = feeding with no palpation R = regurgitation with no palpation RA = antennal palpation associated with regurgitation RF = foreleg plus antennal palpation associated with regurgitation Offer = offering. There is good evidence to associate offering with regurgitation motivated at the RA level. 9. The function of palpation as a form of facilitatory behaviour is discussed, and the importance of the two types of palpation in feeding and regurgitation is compared. A diagram attempts to summarize the conclusions relating motivation to the different forms of palpation, etc.]