Sugar Feeders Research Articles

Manipulated ants: inducing loyalty to sugar feeders with an alkaloid.

Wood ants are promising biocontrol agents in fruit plantations because they prey on pest insects and inhibit plant diseases. However, these ants also attend plant-feeding homopterans to harvest their honeydew secretions, thereby increasing their numbers. This problem can be solved by offering ants alternative sugar sources that are more attractive than honeydew. From natural interactions, it is known that some species manipulate mutualistic partners toward loyalty by adding alkaloids to the food they offer their mutualists. Inspired by this, the addition of alkaloids might be used to make ants loyal to artificial sugar feeders and thus used to reduce populations of ant-farmed homopterans in ant-mediated biological control. We aimed to explore whether wood ants (Formica polyctena) would develop a taste preference for morphine-containing sugar solutions in two-choice laboratory tests. After having fed on a morphine/sugar solution for 1 week, ants showed a significant preference for morphine solutions compared with equal concentration sugar solutions without morphine. Furthermore, ants lost this preference after 6-9 days on a morphine-free diet. The results show that wood ants react to morphine in their food, enabling chemical manipulation of their behavior, most likely through a taste preference. Thus, ants are susceptible to manipulation by mutualistic partners in natural interactions and furthermore may be manipulated artificially in biocontrol programs to avoid ant-mediated build-up of homopteran populations. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Sugar feeders reduce weaver ants’ drawbacks when used as biological control agents in mango orchards

The use of predatory arthropods in biological pest control in agriculture can generate resistance by farmers when these beneficials become noxious for them or their crops. The African weaver ant, Oecophylla longinoda (Hymenoptera: Formicidae), an effective biocontrol agent of pests, particularly Bactrocera dorsalis fruit flies in mango orchards in West Africa, is a good example of such inconveniences. We here explored whether manipulating their behavior by providing sugar feeders on trees would (i) alter their mutualistic relationships with scale insects, thereby reducing the incidence of this pest, (ii) decrease nest abundance often considered by farmers to reduce foliage development, and (iii) reduce their aggressiveness. To that end, a field monitoring was launched in an organic mango orchard in Senegal wherein three treatments were compared: (1) mango trees with ants and sugar feeder, (2) mango trees with ants but no sugar feeder, and (3) mango trees with neither ants nor sugar feeder. The population dynamics of scale insects and weaver ants as well as their behavior were monitored over two years. Sugar provisioning significantly reduced scale insect infestations, nest abundance, and ant aggressiveness over time. Such manipulation of ant behavior through sugar supplementation should help breaking down obstacles that hamper their wide-scale use for the biological control of fruit flies in mango orchards.

Alien vs. herbivore: ant-mediated plant defense as an option for biological control of leafcutter ants

Leafcutter ants are a major pest in vineyards in Argentina, but their damage to vine plants has not been sufficiently quantified. Biological control against leafcutter ants has not been successful so far. Sugary rewards can trigger ants to act as plant bodyguards against a wide range of herbivores. The Argentine ant Linepithema humile (Mayr) is a common invader of vineyards worldwide and has a strong preference for carbohydrates. In a first 10-week field experiment, we attracted L. humile ants to a group of plants using sugar feeders, while no feeders were used for a second group. Ant-excluded control plants were also deployed. We quantified the damage inflicted by the leafcutter ant Amoimyrmex bruchi (Forel) on potted vines with and without L. humile ants. In a second short field experiment, we evaluated the impact of L. humile on A. bruchi foraging through the quantification of foraging activity and the amount of transported material as a function of L. humile presence. We found that A. bruchi caused >90% leaf area reductions in plants without L. humile, while plants where the species was present were rarely attacked and leaves developed similar to those of ant-excluded controls. Active interaction with L. humile decreased A. bruchi’s foraging activity and the amount of material transported by it. This is the first report of A. bruchi as a vineyard pest and the first quantification of the damage inflicted by a leafcutter ant on organic grapevines. We demonstrate that L. humile defends vine plants against herbivore pests and artificial sugar sources boost can this defense service. The development of biological control strategies that include the ecological services of ants as natural enemies of herbivorous pests could become a useful tool in sustainable viticulture and horticulture.

Top-down response to spatial variation in productivity and bottom-up response to temporal variation in productivity in a long-term study of desert ants.

Under the Ecosystem Exploitation Hypothesis ecosystem productivity predicts trophic complexity, but it is unclear if spatial and temporal drivers of productivity have similar impacts. Long-term studies are necessary to capture temporal impacts on trophic structure in variable ecosystems such as deserts. We sampled ants and measured plant resources in the Simpson Desert, central Australia over a 22-year period, during which rainfall varied 10-fold. We sampled dune swales (higher nutrient) and crests (lower nutrient) to account for spatial variation in productivity. We asked how temporal and spatial variation in productivity affects the abundance of ant trophic guilds. Precipitation increased vegetation cover, with the difference more pronounced on dune crests; seeding and flowering also increased with precipitation. Generalist activity increased over time, irrespective of productivity. Predators were more active in more productive (swale) habitat, i.e. spatial impacts of productivity were greatest at the highest trophic level. By contrast, herbivores (seed harvesters and sugar feeders) increased with long-term rainfall; seed harvesters also increased as seeding increased. Temporal impacts of productivity were therefore greatest for low trophic levels. Whether productivity variation leads to top-down or bottom-up structured ecosystems thus depends on the scale and dimension (spatial or temporal) of productivity.

Honey bees communicate distance via non-linear waggle duration functions.

Honey bees (genus Apis) can communicate the approximate location of a resource to their nestmates via the waggle dance. The distance to a goal is encoded by the duration of the waggle phase of the dance, but the precise shape of this distance-duration relationship is ambiguous: earlier studies (before the 1990s) proposed that it is non-linear, with the increase in waggle duration flattening with distance, while more recent studies suggested that it follows a simple linear function (i.e. a straight line). Strikingly, authors of earlier studies trained bees to much longer distances than authors of more recent studies, but unfortunately they usually measured the duration of dance circuits (waggle phase plus return phase of the dance), which is only a correlate of the bees’ distance signal. We trained honey bees (A. mellifera carnica) to visit sugar feeders over a relatively long array of distances between 0.1 and 1.7 km from the hive and measured the duration of both the waggle phase and the return phase of their dances from video recordings. The distance-related increase in waggle duration was better described by a non-linear model with a decreasing slope than by a simple linear model. The relationship was equally well captured by a model with two linear segments separated at a “break-point” at 1 km distance. In turn, the relationship between return phase duration and distance was sufficiently well described by a simple linear model. The data suggest that honey bees process flight distance differently before and beyond a certain threshold distance. While the physiological and evolutionary causes of this behavior remain to be explored, our results can be applied to improve the estimation of honey bee foraging distances based on the decoding of waggle dances.

Grazing and aridity have contrasting effects on the functional and taxonomic diversity of ants

Ants are one of the most abundant and ubiquitous organisms on Earth and play critical roles in multiple ecosystem services such as seed dispersal and nutrient cycling. Despite this, the effects of climatic and land use stressors on particular species or groups of ants are poorly known. We conducted a regional field survey across 108 locations in south-eastern Australia, using correlation network analysis and structural equation modelling to identify how ants respond to environmental stressors. We found contrasting relationships amongst ants, and aridity, and vertebrate grazing intensity and history. Increasing aridity was associated with reduced ant richness, whereas increasing grazing intensity was associated with greater ant richness directly, and indirectly, via reductions in litter depth and perennial grass density. However, these taxonomically diverse groups of ant species still shared contrasting responses to increasing aridity and grazing intensity. We found strong associations between grazing, aridity and the abundance of Seed Harvesters, weak indirect relationships with Generalist Foragers, but no relationships for Predators or Sugar Feeders. Taken together, our work identifies contrasting relationships amongst grazing, aridity and ants (ant ‘winners’ or ‘losers’) across contrasting ecological contexts. Given that increasing aridity is generally associated with lower grazing intensity, our results suggest that locations with more arid sites will have lower ant richness with fewer Seed Harvesters, whereas more mesic sites with high grazing intensity might increase ant richness, and the abundance of specific ant species. Such knowledge is important if we are to maintain critical ant-mediated functions as Earth becomes drier and grazing intensity increases.

Nest Entrances, Spatial Fidelity, and Foraging Patterns in the Red Ant Myrmica rubra: A Field and Theoretical Study.

The nest architecture of social insects deeply impacts the spatial distribution of nestmates their interactions, information exchanges and collective responses. In particular, the number of nest entrances can influence the interactions taking place beyond the nest boundaries and the emergence of collective structures like foraging trails. Here, we investigated in the field how the number of nest entrances impacted the foraging dynamics of Myrmica rubra ant colonies. We located the nest entrances where recruitment occurred towards sugar feeders placed in their surroundings. The nests showed one or multiple entrance(s) aggregated in clusters spaced by at least 15 cm. Foragers from colonies with two clusters of entrances were distributed more homogeneously among the feeders than those of colonies with one cluster. In addition, foragers always returned to the first discovered feeder and demonstrated a high fidelity to their original entrance. Finally, a multi-agent model highlighted that additional entrances and clusters of entrances delayed the mobilisation of workers but favoured the simultaneous exploitation of several sources, which was further enhanced by the spatial fidelity of foragers. Multiple nest entrances seem to be a way for medium-sized colonies to benefit from advantages conferred by polydomy while avoiding associated costs to maintain social cohesion.

Attract and distract: Manipulation of a food-mediated protective mutualism enhances natural pest control

Abstract Ants can act simultaneously as predators and as protectors of honeydew producing pests. As a result, their impact on plants can be both positive and negative. By guarding honeydew producers against their natural enemies, ants can severely disrupt biological control programs and are often seen as important indirect pests. Chemical control, as well as physical ant-exclusion is employed to disrupt the mutualistic relationship between ants and honeydew producers. However, the exclusion or killing of ants also eliminates their services as biocontrol agents. Herein, we tested whether it is possible to use artificial sugar supplements to shift the balance in ant-pest interaction from pest guarding to pest control. Sugar feeders were supplied either on the ground near the tree trunk, or on the tree branches of citrus trees. Subsequently we assessed whether the provisioning of artificial sugar sources i) alters ant activity ii) disrupts the association between the ant Lasius grandis and the aphid Aphis spiraecola and iii) reduces the aphid populations over time. Compared to control trees (no sugars), ant activity within the tree was significantly reduced when the sugar feeders were placed on the ground and significantly increased when the feeders were placed on the tree branches. Ant tending of aphid colonies was reduced in all trees featuring sugar feeders. Similarly, aphid colony size was significantly reduced relative to control trees, both for trees with sugars on the ground or on the branches. However, the reduction was more pronounced when the sugars were offered on the tree branches. Finally, the abundance of natural enemies being associated with the aphid colony was significantly increased on trees with sugars on the branches. This shows that the provisioning of artificial sugar sources has practical potential as a sustainable strategy for ant management in programs aiming at the biological control of honeydew producing pests.

Restoration of trophic structure in an assemblage of omnivores, considering a revegetation chronosequence

Summary Habitat loss is considered the single greatest driver of species extinctions and amelioration of this threat through habitat restoration is increasingly important in maintaining biodiversity and ecosystem functions. Success of restoration depends largely on the ability of species of a diversity of functional types to recolonize a restored site. We used a restoration chronosequence to investigate the success of revegetation efforts (direct‐seeding and tube stock methods) in returning species and trophic functions of trophically diverse ant assemblages to land formerly used for livestock grazing in south‐eastern Australia. We examined assemblages based on: (i) species composition; (ii) trophic position and diversity, measured using stable isotopes of nitrogen; and (iii) species richness of trophic guilds based on δ15N isotopes (‘δ15N guilds’) and prior knowledge of diet (‘traditional trophic groups’). Responses for δ15N trophic guilds were more distinct than for those based on traditional trophic groups. Assemblage trophic position (mean species δ15N enrichment) decreased and trophic diversity (variance among species in δ15N enrichment) increased along the chronosequence from pastures to remnants. These patterns resulted from an increase in the richness of species with low δ15N enrichment (i.e. more ‘herbivorous’ species) along the chronosequence, which was also reflected in increases in the species richness of sugar feeders. Recovery of direct‐seeded sites lagged behind tube stock sites of the same age, suggesting a role for habitat structure. Species composition followed a trajectory suggestive of partial recovery, with revegetated sites supporting assemblages intermediate to pastures and remnants, but distinct from both. Synthesis and applications. Tree planting promotes recovery of species composition and trophic function. Planting method affects the speed of functional recovery, although minimally. Species on the herbivorous end of the spectrum of omnivory were slower to recover than more predaceous species and may require deliberate restoration of features associated with mature trees. Trophic guilds based on objective measures of diet respond more clearly to restoration than do those based on subjective observations and offer a more insightful method.

Behavior of red wood ants (Hymenoptera, Formicidae) during interaction with different symbiont partners

A comparative analysis of the behavior of Formica polyctena Forst during interaction with different symbionts (free-living aphids Aphis grossulariae Kalt. and hidden larvae of the sawfly Blasticotoma filiceti Klug) was carried out. Red wood ants demonstrate different levels of functional differentiation in relatively constant groups of foragers collecting honeydew. A deep “professional” specialization with clear division of a number of tasks among foragers was studied in groups of ants tending aphids. Four professional groups of foragers with different tasks were revealed: “shepherds,” “guards,” “transporters,” and “scouts” (or “coordinators”). The groups of foragers caring for sawfly larvae mainly consist of unspecialized ants. Only few ants (about 5%) remain on duty on the fern plant near B. filiceti larvae and protect the food resource from competitors, especially from other ants. In addition, the ants demonstrate simpler behavior while collecting the larval excretion, resembling that at the sugar feeders. On the whole, the behavior of red wood ants is rather flexible. The level of functional differentiation in groups of foragers collecting honeydew is determined not only by the colony size and requirements but by the nature of their interaction with trophobionts, particularly, by the possibility of direct contact.

Complex memories in honeybees: can there be more than two?

Foraging honeybees are likely to learn visual and chemical cues associated with many different food sources. Here, we explore how many such sources can be memorized and recalled. Marked bees were trained to visit two (or three) sugar feeders, each placed at a different outdoor location and carrying a different scent. We then tested the ability of the bees to recall these locations and fly to them, when the training scents were blown into the hive, and the scents and food at the feeders were removed. When trained on two feeder locations, each associated with a different scent, the bees could correctly recall the location associated with each scent. However, this ability broke down when the number of scents and feeder locations was increased to three. Performance was partially restored when each of the three training feeders was endowed with an additional cue, namely, a distinct colour. Our results suggest that bees can recall a maximum of two locations when each is associated with a different scent. However, this number can be increased if the scent cues are augmented by visual cues. These findings have implications for the ways in which associations are established and laid down in honeybee memory.

Olfaction: scent-triggered navigation in honeybees.

The honeybee, Apis mellifera, navigates rapidly and accurately to food sources that are often kilometres away. They achieve this by learning visual cues, such as the location and colour of nectar-bearing flowers, and chemical cues, such as the scent and the taste of the nectar. Here we train bees to visit differently scented sugar feeders placed at specific outdoor locations and find that they can be induced to visit the same locations simply by having the corresponding scent blown into the hive, even when the destinations no longer have the food or carry the scent. A familiar nectar scent can trigger specific memories of a route and therefore expedite navigation to the food source.

Individual differences in sugar consumption predict amphetamine-induced dopamine overflow in nucleus accumbens

Rats exhibit individual differences in their consumption of sugar and in their response to amphetamine treatments. Intrinsic variation in the functioning of the mesolimbic dopamine system is one potential mechanism underlying the expression of these individual differences. The present experiment examined the relationship between sugar consumption and the dopaminergic response to amphetamine. In vivo microdialysis was used to assess amphetamine-stimulated dopamine overflow in the posterior-medial nucleus accumbens in LOW and HIGH sugar feeders. Sugar consumption correlated significantly with amphetamine-stimulated accumbens-dopamine overflow. HIGH rats exhibited significantly higher levels of amphetamine-stimulated accumbens-dopamine overflow than LOW rats. These results suggest that the propensity to ingest sugar is a predictor of the nucleus accumbens dopaminergic response to amphetamine treatment.

Foraging Behaviour of Trigona Carbonaria (Hymenoptera: Apidae) at Multiple-Choice Feeding Stations

To examine the foraging behaviour of the stingless bee Trigona carbonaria Sm., a full-size colony was placed at the centre of a grid of multiple-choice feeding stations with feeders containing water and three sugar solutions at 10, 20 and 40% concentration. The feeding of workers at feeders was monitored during consecutive days under these variable resource conditions. Scouts marked all the sugar-solution feeders with a visible fluid, and the degree of marking and nestmate recruitment was positively correlated with sugar concentration. Workers exhibited characteristics of the group-foraging behaviour termed 'opportunism', whereby many foragers search independently in the field, until one of them finds an exceptional sugar-solution resource and then rapidly recruits nestmates. Overall, workers preferred the 40% sugar feeders, visitation rates decreased with increasing distance from the nest, and visits at the 20 and 10% feeders increased in that sequence when replenishment with sugar solution was interrupted and sugar concentrations declined progressively in the 40 and 20% feeders. These results show that workers have the physiological ability to identify the richest sugar solutions, but indicate that food choice will vary with resource variability. The evidence suggests that the primary strategy involved in the foraging behaviour of this species is to optimise the feeding intake of the colony.

Individual differences in sugar intake predict the locomotor response to acute and repeated amphetamine administration.

Rats exhibit profound individual differences in their propensity to ingest sugar and in their locomotor response to AMP. Intrinsic variation in the responsiveness of mesolimbic dopamine mechanisms has been suggested to account for these individual differences. In light of this overlap, it might be expected that individual differences in one behavior would predict individual differences in the other. The present study determined whether individual differences in sugar intake would predict individual differences in the locomotor response to AMP. Male Wistar rats were divided into low and high feeders based on a median split of their sugar intake in response to saline administration and were subsequently tested for their locomotor response to either 1.0 or 1.75 mg/kg AMP in experiment 1. High sugar feeders exhibited significantly more locomotion than low sugar feeders in response to 1.75 mg/kg AMP. This difference was observed immediately after injection and continued for approximately 90 min. There was no difference between the two groups in their locomotor response to 1.0 mg/kg AMP. In experiment 2, rats receiving 1.0 mg/kg AMP in experiment 1 were tested for the development of behavioral sensitization with repeated AMP administrations. Rats were administered 1.0 mg/kg AMP across 5 test days, interspersed with days in which they received AMP treatment in their home cages to minimize conditioning effects. High sugar feeders exhibited greater behavioral sensitization than low sugar feeders with repeated AMP administration. Starting on test day 3, high sugar feeders exhibited significantly greater AMP-induced locomotor activity than low sugar feeders.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological changes in the overwintering females of Anopheles freeborni (Diptera: Culicidae) in California.

A greater proportion of Anopheles freeborni females reared under long-day condition took a blood meal and developed mature eggs than did those reared under the short-day condition. Blood feeding does not appear to be essential to overwintering females. There appears to be little or no differences between diapausing females which do and do not take blood meals. Diapausing sugar feeders developed slightly greater lipid content than the diapausing blood feeders, but no detectable differences were observed in the survival rate of the 2 populations.