Influence of physical and chemical factors during foraging and culture of the symbiont fungus in Atta sexdens rubropilosa （Hymenoptera： Formicidae）

The aim of this paper is to investigate the influence of physical and chemical factors on transport and use of substrate for Atta sexdens rubropilosa workers. Three types of rectangular fragments were used to study the physical influence factors： filter paper with paraffin, filter paper without paraffin and polyester film. To study the chemical factors, some fragments were impregnated with organic extract of orange albedo, others were soaked with soybean oil and for the remaining ones nothing was applied. The fonowing parameters were evaluated： （i） attractiveness of substrate for transport and number of loading workers per treatment; （ii） foraged material incorporation; （iii） rejection by numbers of fragments deposited in the garbage or beside the fungus garden. All the polyester film fragments carried out to the fungus garden were subsequently rejected. We verified that chemical factors of the substrate were more quickly detected by the workers, whereas physical factors were used as a criterion in the decision-making to reject or accept the substrate collected.     

External and internal structure of Atta bisphaerica Forel (Hymenoptera: Formicidae) nests

Abstract:  This work was carried out to determine the internal and external structures of Atta bisphaerica (Forel) nests. Six nests were excavated and during excavation, all data referring to chambers and tunnels were recorded. Three nests had been internally cement-moulded, which enabled a better view of the chamber and tunnel structures. Atta bisphaerica nests presented a similar structural pattern, varying only in the number of chambers as a function of external mound area. Chambers were spherical with two communication tunnels. Internal tunnels had an elliptical section, sometimes circular, indirectly linked to chambers through ramifications and directly through short tunnels. Entrance holes were linked to the area of highest chamber concentration by tunnels from the elliptical section, which led to the nest in a radial manner. Knowledge of the colony's three-dimensional architecture permits successful application of chemical control processes, reduces the quantity of product applied, and consequently diminishes costs and environmental damage.     

Reproduction by virgin queen fire ants in queenless colonies: Comparative study of three taxa (Solenopsis richteri,hybridS. invicta/richteri,S. geminata) (Hymenoptera: Formicidae)

Summary In the fire ant,Solenopsis invicta, some winged virgin queens are known to shed their wings (dealate) upon removal of the mated mother queen. These virgin queens then develop their ovaries and begin to lay eggs, thereby foregoing the option of leaving on mating flights and attempting to found their own colonies. Such a response of virgin queens to queenlessness has not been reported for other ants. In order to determine if virgin queens of some other fire ants (subgenusSolenopsis) would respond in the same way, experiments were conducted onS. richteri, hybridS. invicta/richteri andS. geminata, a member of a species complex different from that of the other taxa. Just as inS. invicta, virgin queens ofS. richteri and the hybrid dealated and began to lay eggs within days of the removal of the queen. In addition, workers executed many of the reproductively active virgin queens, a phenomenon also found inS. invicta. In contrast, virgin queens ofS. geminata did not dealate or quickly begin to lay eggs upon separation from the queen. Reasons for the variability in the response of virgin queens of the different species may be 1) higher probability of reproductive success for unmated dealated queens compared to normal claustral founding inS. invicta andS. richteri linked to relatively frequent loss of the mother queen; or 2) phylogenetic constraint.     

Electroantennogram and behavioral responses of workers of the stingless bee Oxytrigona mediorufa to mandibular gland volatiles

Gas chromatography-mass spectrometric analysis showed that the mandibular gland secretion of workers of the stingless bee Oxytrigona mediorufa (Cockerell) (Hymenoptera: Apidae) is composed of 3-hepten-2,5-dione, 3-nonene-2,5-dione, 2-heptanone, hydrocarbons, tetradecyl, and hexadecyl acetates and minor compounds related to these. Behavioral and electroantennographic tests were carried out on conspecific workers to observe the effect of worker mandibular gland secretion, individual compounds (2-heptanone, 2-nonanone, and tetradecyl acetate), and a blend of these three. Bioassays showed that biting responses of O. mediorufa to the odor of the mandibular gland secretion were similar to that of 2-heptanone and to the three-component blend. Oxytrigona mediorufa workers exhibited antennal olfactory responses to the gland extract, 2-heptanone, and the synthetic mixture. The function of the mandibular gland secretion and 2-heptanone is discussed in terms of an alarm pheromone and defensive substances.     

Chemical and behavioural studies of the trail-following pheromone in the leaf-cutting ant Atta opaciceps,Borgmeier (Hymenoptera: Formicidae)

To understand the significance of the trail pheromone used in chemical communication of the leaf-cutting ants Atta opaciceps we investigated, under laboratory conditions, the trail-following behaviour of different castes. We observed a clear behavioural discrimination of conspecific venom gland extract of foraging ants from those of other species. Additionally, we determined the pheromone composition of A. opaciceps venom gland secretion using a two-dimensional gas chromatography coupled with mass spectrometry. Chemical analyses revealed the presence of three nitrogen-containing compounds, identified as 2,5-dimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine and methyl 4-methylpyrrole-2-carboxylate (M4MPC). Four different bioassays performed with workers from different castes of A. opaciceps suggested that the trail pheromone elicits the trail-following behaviour in conspecifics of all castes, but the foragers respond more strongly to their own pheromone than to that of other castes (gardeners, generalists and soldiers). In addition, A. opaciceps foragers follow the trails made with the venom gland extracts of the unrelated Acromyrmex subterraneus subterraneus foragers as well as they follow the trails made with their own venom gland extract. M4MPC was identified to be the most abundant and the most behaviourally active component of the venom gland extract of A. opaciceps foragers.     

An organic bait based on Palicourea marcgravii (Rubiaceae) and Tephrosia candida (Fabaceae) does not control nests of Atta laevigata (Hymenoptera: Formicidae) in eucalyptus plantations

1. Leaf-cutting ants of the genus Atta (Myrmicinae: Attini) are the main forest pests in Brazil, due to their economic damage, social complexity and geographical distribution. Chemical control with baits is the most viable and successful method to control these insects; and products with low environmental impact have been researched.
2. The objective of this study was to evaluate the mortality of Atta laevigata (Hymenoptera: Formicidae) nests treated with Bioisca® bait, in different dosages, in eucalyptus plantations compared with those treated with sulfluramid and fipronil baits.
3. Seven treatments were used: Bioisca® (Palicourea marcgravii (Rubiaceae) + Tephrosia candida (Fabaceae)), with 5, 10, 15 and 20 g; Blitz® (fipronil), Atta Mex-S® (sulfluramid) baits with 6 g/m² of ant nest loose soil and the control, without ant baits.
4. It took 7 days for the first colony to have its activity stopped using the Blitz® treatment. It happened only at 30 days when treated with Bioisca® and Atta-Mex-S® .
5. The mortality of nests treated with Bioisca® was very low with only one controlled out of 20 that received this bait. Bioisca® does not control the nests of A. laevigata in eucalyptus plantations.

     

(1S,3S,7R)-3-methyl-alpha-himachalene from the male sandfly Lutzomyia longipalpis (Diptera: Psychodidae) induces neurophysiological responses and attracts both males and females

Lutzomyia longipalpis adult males form leks on or near hosts and release (1S,3S,7R)-3-methyl-alpha-himachalene from their tergal glands to lure females to the same site for mating and feeding. Here we have examined whether the male-produced attractant could also serve as a male aggregation stimulus. High resolution chiral capillary gas chromatography analysis of male tergal gland extracts, synthetic (1S,3S,7R)-3-methyl-alpha-himachalene, and a synthetic mixture of all isomers of 3-methyl-alpha-himachalene, was coupled to electrophysiological recordings from ascoid sensillum receptor cells in antennae of male and female sandflies. Receptor cells of both sexes responded only to the main component of the male tergal gland extract that eluted at the same retention time as (1S,3S,7R)-3-methyl-alpha-himachalene. Furthermore, of the eight 3-methyl-alpha-himachalene isomers in the synthetic mixture only the fraction containing (1S,3S,7R)-3-methyl-alpha-himachalene, co-eluting with an isomer of (1S*,3S*,7S*)-3-methyl-alpha-himachalene, elicited an electrophysiological response from male and female ascoid sensillum receptor cells. Both males and females flew upwind in a wind tunnel towards a filter paper disk treated with either 4-6 male equivalents of the tergal gland extract, pure (1S,3S,7R)-3-methyl-alpha-himachalene or the synthetic mixture of eight isomers. This indicates that (1S,3S,7R)-3-methyl-alpha-himachalene derived from L. longipalpis males may have a dual function in causing male aggregation as well as serving as a sex pheromone for females.     

Behavioral and olfactory antennal responses of Solenopsis geminata (Fabricius) (Hymenoptera: Formicidae) workers to their dufour gland secretion

Behavioral and electrophysiological tests were performed to evaluate the responses of workers of the ant Solenopsis geminata (Fabricius) from different size categories to Dufour gland extracts. Morphometric measures based in head widths across eyes were used to determine worker sizes. Trail following response of different worker sizes to Dufour gland extract from workers of different sizes was assessed. For each worker size category olfactory responses to Dufour gland extracts were determined using electroantennography (EAG). Gas chromatography and mass spectrometry (GC-MS) were used to determine the chromatographic profile of Dufour gland secretion for each worker size. Morphometric measures permitted to classify the workers of S. geminata as large, medium and small workers. Medium S. geminata workers displayed a significantly higher behavioral response to Dufour gland extracts produced by medium size workers. Similarly, medium workers showed a significantly higher EAG response to Dufour gland extracts produced by medium sized workers. Chromatographic profile of Dufour gland secretions produced by workers showed that each size category exhibited a characteristic profile of the three main components considered as potential trail pheromone constituents. This work showed that medium workers of S. geminata exhibited a high trail-following behavior as well as a high antennal response to Dufour gland secretion. This and their relative abundance in field foraging areas, suggest that medium-sized workers are specialized in foraging activities.     

Respective contributions of leader and trail during recruitment to food inTetramorium bicarinatum (Hymenoptera: Formicidae)

Summary This paper describes the food recruitment strategy of the antTetramorium bicarinatum, at both the individual and collective levels. The general organisation of recruitment used by this species during the exploitation of sucrose solutions shows similarities with group recruitment described for other species. However, our experiments demonstrate that inT. bicarinatum, the first trail laid by a recruiter during its return trip to the nest is more efficient than in other species using group recruitment, for exampleTetramorium impurum. Moreover, the efficiency of the first trail of aT. bicarinatum recruiter is comparable with that ofTapinoma erraticum, a species that uses mass recruitment. Despite the efficiency of the trail, choice experiments show that the recruited workers prefer to follow the leader rather than the first trail, suggesting the emission of a more attractive signal by the leader on its way back to the food. The function of the leader in this strategy is discussed in terms of collective decisions.     

Social selection and the evolution of a female weapon in queens of the ant Messor pergandei (Hymenoptera: Formicidae)

The evolution of weaponry occurs less frequently in females than in males and is most often important for protecting ecological resources or offspring rather than winning mates. The purpose of female weapons is often confounded by the presence of similar weapons in males, so cases where only females need weapons provide important tests of our understanding of how and why weapons evolve. In some populations of the ant, Messor pergandei (Mayr), newly mated queens initiate new nests in social groups that subsequently break down when queens engage in battles for control. The incipient social environment differs geographically, so that lethal fighting occurs in some populations but not others. Consistent with the hypothesis that queens in populations where lethal fighting occurs should show selection for weaponry (broad heads and strong mandibles), we found that heads of queens from sites where lethal fighting occurs were broader than those at sites with non‐fighting queens and a site with solitary queens. Evolution of weaponry is specific to queens, because regression results from workers often did not follow this pattern. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 1011–1020.     

Chemical and ethological studies of the trail pheromone of the ant Manica rubida (Hymenoptera: Formicidae)

ABSTRACT. The poison gland of Manica rubida contains nanogram quantities of four alkylpyrazines, methylpyrazine, 2,5-dimethylpyrazine, trimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine, of which only the last induces pronounced trail-following behaviour. Myrmica rubra and M. rubida workers follow each other's trails equally well when allowance is made for the much greater size of M. rubida workers. The cross activity in trail-following between M. rubida, M. rubra and Tetramorium caespitum is understandable in terms of the amounts and proportions of the different pyrazines present in their glands and their responses to the synthetic substances and appropriate mixtures of them.     

红火蚁工蚁对跟踪信息素的触角电位和行为反应

【目的】测定红火蚁Solenopsis invicta Buren工蚁对其跟踪信息素的触角电位（EAG）及行为反应。【方法】解剖红火蚁工蚁的杜氏腺, 用正己烷溶剂提取其分泌的跟踪信息素进行气相色谱-质谱（GC-MS）分析, 并测定了红火蚁工蚁对杜氏腺提取物、 工蚁提取物和合成的法尼烯混合物的EAG和招募行为反应。【结果】通过与合成的法尼烯混合物的气相色谱（GC）保留时间和质谱图比对, 发现杜氏腺提取物的主要成分并不是Z, E-α-法尼烯。EAG测定结果表明, 红火蚁工蚁对杜氏腺提取物、 工蚁提取物及100 μg的法尼烯混合物均有较强的EAG反应, 其次为10 μg和1 μg的法尼烯混合物。在招募行为测定中, 杜氏腺提取物和工蚁提取物招募作用明显, 而10, 1, 0.1和0.01 μg法尼烯混合物的作用均不显著。【结论】Z, E-α-法尼烯不是红火蚁跟踪信息素的主要成分; 红火蚁工蚁对杜氏腺提取物、 工蚁提取物有较强的EAG反应和明显的招募行为反应。     

Effect of gland extracts on digging and residing preferences of red imported fire ant workers (Hymenoptera: Formicidae)

There is evidence that ant‐derived chemical stimuli are involved in regulating the digging behavior in Solenopsis invicta Buren. However, the source gland(s) and chemistry of such stimuli have never been revealed. In this study, extracts of mandibular, Dufour's, postpharyngeal, and poison glands were evaluated for their effect on ant digging and residing preferences of S. invicta workers from three colonies. In the intracolonial bioassays, workers showed significant digging preferences to mandibular gland extracts in 2 of 3 colonies and significant residing preferences in 1 of 3 colonies; significant digging preferences to Dufour's gland extracts in 1 of 3 colonies and significant residing preferences in 2 of 3 colonies. No digging and residing preferences were found for postpharyngeal and poison gland extracts. In intercolonial bioassays, significant digging and residing preferences were found for mandibular gland extracts in 3 of 6 colony combinations. Significant digging preferences to Dufour's gland extracts were found in 4 of 6 colony combinations and significant residing preferences in all 6 colony combinations. For postpharyngeal gland extracts, significant digging preferences were found only in 1 of 6 colonial combinations and no significant residing preferences were found. For poison gland extracts, no significant digging preferences were found; significant residing preferences were found in 1 of 6 colony combinations. However, a significant residing deterrence (negative residing preference index) was found for 2 of 6 colony combinations. Statistical analyses using data pooled from all colonies showed that mandibular and Dufour's gland extracts caused significant digging and residing preferences in both intracolonial and intercolonial bioassays but not postpharyngeal and poison gland extracts. By analyzing the data pooled from the same three colonies used for gland extract bioassays, it was found that, in no cases, workers showed significant digging and residing preferences to 2‐ethyl‐3,6‐dimethylpyrazine, an alarm pheromone component from mandibular gland.     

Response of fire ants (Formicidae: Solenopsis invicta and S.gerninata) to artificial nectars with amino acids

Abstract.

• 1 The role that amino acids in extrafloral nectars play in attracting ants to plants was investigated. Workers from laboratory colonies of Solenopsis invicta Buren and S.geminafa (F). (Formicidae) fed from artificial nectaries containing mimics of the extrafloral nectar of Passiflora menispermifoh and P.caerulea; P.menispermifoh nectar contains higher levels of amino acids (1347.3 pdml) than does the nectar of P.currulea (125.2 μm /ml).
• 2 When sugar-only and sugar—amino acid nectar mimics were presented simultaneously, more S.invicta workers were counted at sugar—amino acid nectar mimics than at sugar-only nectars. S.geminatu did not discriminate between the two nectars.
• 3 When the two Pamiflora L. nectar mimics were presented simultaneously, S.invicta and S.geminata workers were more abundant at the nectaries containing high levels of amino acids (P.menispermifolia HBK mimic) than at the nectaries containing low levels of amino acids (P.cuerulea L. mimic).
• 4 The behaviour shown by S.invicta and S.gerninata suggests that plants with high levels of amino acids in their extrafloral nectars attract more ant protectors and might suffer less herbivory than plants producing nectars with low levels of amino acids. If so, ants may favour, over evolutionary time, plants that produce nectars with high levels of amino acids.
• 5 Day-to-day variability in ant behaviour was considerable even among laboratory colonies maintained on the same diet in similar environmental conditions. This variability will reduce the selective impact that ants have on plants and may help to explain why most ant-plant interactions are facultative.

     

Trail following and stowaway behaviour of the myrmecophilous staphylinid beetle,Homoeusa acuminata,during foraging trips of its hostLasius fuliginosus (Hymenoptera: Formicidae)

Summary The behaviour of adultHomoeusa acuminata on trails of its hostLasius fuliginosus was investigated both in the field and in the laboratory. The beetles were active from May to September, accurately following the foraging trails of their hosts up to 20 metres from the nest. Most of the time, they were ignored by the ants, but if attacked they raised their abdomen as a possible appeasement or defensive behaviour. On trails the beetles most probably act as food robbers, feeding on prey collected by ants. The following method, called stowaway behaviour, was used by the beetles: when a beetle encountered an ant carrying a prey back to the nest it jumped on the prey, probably feeding on it while being transported.Laboratory experiments on circular artificial trails demonstrated thatH. acuminata follows a water extract of hindguts of the ants, the source of the trail pheromone. Both beetles and ants responded to an artificial trail of 0.03 hindgut equivalent per cm, but the mean distance followed by the beetles was about twelve times higher than that covered by the ants themselves. In contrast, experiments with solutions of the six fatty acids reported as the active components of the trail pheromone showed that the beetles did not respond at all, and that the ants only respond to the fatty acids at a very high concentration.     

红火蚁工蚁对棉蚜诱导的棉花挥发物的嗅觉和行为反应

【目的】红火蚁 Solenopsis invicta 与棉蚜 Aphis gossypii 存在兼性共生关系,红火蚁可能利用棉蚜危害诱导棉花释放的挥发物定位棉蚜。本研究将测试红火蚁工蚁对棉花挥发物的嗅觉和行为反应。【方法】使用Y型管实验测试红火蚁工蚁对棉花气味的行为反应;以红火蚁告警信息素2-乙基-3,5(6)-二甲基吡嗪为阳性对照,测试红火蚁工蚁对不同剂量(100, 10, 1 和0.1 μg)的9种棉花挥发物组分[α-蒎烯、β-蒎烯、β-石竹烯、( E, E )-4,8,12-三甲基-1,3,7,11-十三碳四烯(TMTT)、( E )-4,8-二甲基-1,3,7-壬三烯(DMNT)、辛醛、6-甲基-5-庚烯-2-酮、顺-3-己烯基乙酸酯和水杨酸甲酯]的触角电位反应;再利用Y型嗅觉仪测试这些挥发物对红火蚁工蚁的行为选择影响。【结果】结果表明,受棉蚜为害的棉花较健康棉花对红火蚁工蚁具有极显著的引诱效果。红火蚁对9种挥发物组分的EAG反应随着剂量升高而升高。各化合物在100 μg剂量时EAG反应值最大,其中,工蚁对水杨酸甲酯和6-甲基-5-庚烯-2-酮这两个化合物反应最强。在行为选择实验中,化合物水杨酸甲酯、6-甲基-5-庚烯-2-酮和DMNT对红火蚁工蚁均具有显著的引诱效果。【结论】棉蚜诱导的棉花挥发物中水杨酸甲酯和6-甲基-5-庚烯-2-酮对红火蚁有显著的引诱效果,这2种化合物可能在红火蚁定位棉蚜、建立共生关系中起着关键的作用。     

Antennal sensitivity to female sex pheromone compounds of Spodoptera frugiperda males (Lepidoptera: Noctuidae) and associated field behaviour

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is one of the most important insect pests of corn, sorghum, rice, and grasses. The sex pheromone produced by S. frugiperda is composed of a mixture of esters. In this study, I determined the antennal responses of FAW males from 22 populations in Mexico to the components of the sex pheromone of this species: (Z)-7-dodecenyl acetate (Z7-12:OAc), (Z)-9-tetradecenyl acetate (Z9-14:OAc), and (Z)-11-hexadecenyl acetate (Z11-16:OAc) at four doses (0.01, 0.1, 1, and 10 μg). In addition, I evaluated the behavioural activity of single compounds in the field. The largest antennal responses of FAW males from all the sampled regions were elicited by Z9-14:OAc (all doses evaluated) and Z7-12:OAc (0.01, 0.1, and 1 μg). The male antennal responses evoked by Z11-16:OAc were smaller but similar to responses to Z7-12:OAc at lower doses (0.01 and 0.1 μg). In the field test, Z9-14:OAc produced significantly higher captures of S. frugiperda males compared to Z7-12:AOc and Z11-16:OAc. Antennal responses were related to captures obtained in the field, supported by the positive correlation of these variables [electroantennography (EAG) response and behaviour], with the exception of Z7-12:OAc, which elicited relatively large EAG responses but did not produce high captures of S. frugiperda. These results are of importance to agriculture, enabling the implementation of better methods of monitoring and controlling this pest, and support the suggestion that a mixture of Z9-14:OAc and Z7-12:OAc could represent an effective attractant for all evaluated populations of S. frugiperda in Mexico.     

Phylogenetic relationships between the slave‐making ants Rossomyrmex and their Proformica hosts in relation to other genera of the ant tribe Formicini (Hymenoptera: Formicidae)

The ant genus Proformica is very common to Eurasian semi‐deserts, and a few species are parasitized by the slave‐making ants Rossomyrmex. However, the phylogenetic relationship between Proformica (host) and Rossomyrmex (parasite) remains unclear as another closely related genus (Cataglyphis) could be a sister group of Rossomyrmex. This work has two main goals: (i) to study the phylogenetic relationships among Proformica, Rossomyrmex, and other genera of the tribe Formicini, with a special focus on the highly diverse genus Cataglyphis; and (ii) to reconstruct the biogeographical distribution of parasite and host genera. We perform a phylogenetic study for the first time including several species of the genera Rossomyrmex, Proformica, and Cataglyphis. Our results indicate that Proformica and Rossomyrmex are reciprocally monophyletic and that Rossomyrmex is nested within Cataglyphis, rendering the latter paraphyletic. Finally, the ancestral distribution range of the host genus could be situated in Central Asia and subsequently dispersed to Western Europe, whereas additional studies are required to clarify the range of the parasite.     

Responses of Two Potential Host Species (Formica gnava and Formica occulta) to Pupae of the Obligatory Slave-Making Ant, Polyergus breviceps (Hymenoptera: Formicidae)

Queens of the slave-making ant, Polyergus breviceps, take over nests of adult Formica workers when establishing new colonies. Although naïve to slave-maker brood, the usurped Formica rear Polyergus offspring and nests containing both host and parasite species forms. Host worker acceptance of parasite brood has been attributed to the similarity of brood tending signals between these closely related taxa and/or the presence of an attractive pheromone in the slave-maker brood. By presenting single-species groups of Formica occulta and Formica gnava (two host species of P. breviceps) with a choice of Formica pupae of both species or with a choice of P. breviceps pupae from both types of mixed-species nests, it seems that neither close phylogenetic relatedness nor an attractive brood odor alone can account for the propensity of host workers to adopt slave-maker pupae. Significantly greater numbers of P. breviceps pupae were adopted by enslaved workers than by free-living workers, and within the enslaved groups and the free-living F. gnava group, greater numbers of P. breviceps pupae were adopted if they were from nests where the host species was conspecific to workers used in tests. When presented with F. gnava and F. occulta pupae, Formica workers adopted conspecific pupae almost exclusively and ignored or consumed pupae of the other host species. Taken together, these results imply that P. breviceps pupae have both a species-specific odor and a general brood-tending pheromone, upon which a host odor may be imposed. The disparate requirements of immatures at different stages of development for cue specificity or generality in maintaining nest exclusivity and maximizing inclusive fitness are discussed.