The discrepancy between fire ant recruitment to and performance on rodent carrion

Ants have not been considered important in the process of vertebrate carrion decomposition, but a recent literature review reported over 150 carrion-visiting ant species. Though many ant species have been observed to remove carrion tissue and consume carrion-exuded liquids, the significance of ant recruitment to vertebrate carrion is poorly understood. We conducted a combination of field and laboratory experiments to quantify red imported fire ant recruitment to rodent carrion and determine whether consuming rodent carrion is beneficial to ant colony performance. In the field, 100% of rat carcasses were rapidly colonized by fire ants at high abundances. In our laboratory experiment, the performance of mice-fed fire ant colonies was poor when compared to colonies that were fed mice and insects or insects only. Our results suggest that there is a discrepancy between high levels of fire ant recruitment to vertebrate carrion and the poor colony performance when fed carrion. We hypothesize that fire ants are attracted to vertebrate carrion not because it is a high-quality food, but rather because it hosts large numbers of other invertebrates that can serve as prey for fire ants, potentially showcasing an interesting case of tritrophic interaction in carrion ecology.

Clinical and Laboratory Profile of Patients With Anaphylaxis to Fire Ant Venom (Solenopsis Sp) Under Specific Subcutaneous Immunotherapy.

Anaphylaxis to fire ant venoms (Solenopsis sp) is a significant cause of systemic allergic reaction caused by Hymenoptera stings in children. There are only a few reports about the safety and efficacy of specific immunotherapy. We aim evaluate clinical characteristics, IgE and IgG4 specific responses of patients undergoing immunotherapy with a whole-body extract of Solenopsis sp after one year of the maintenance phase. Thirty-three patients were enrolled due to anaphylaxis by fire ant venom (Solenopsis sp) and underwent specific venom immunotherapy. They were assessed at baseline and one year after the beginning of the maintenance phase for skin test; specific IgE and IgG4 antibodies to fire ant venom; tryptase. All patients included presented a severe anaphylactic reaction. Although two patients (6.25%) presented a tryptase level higher than 11.4 ug/ml, systemic mastocytosis was ruled out. There was no relationship between the severity of the reaction with gender, tryptase level, atopy, previous reactions, concentration of the allergen in the skin test or specific IgE level. There was an increase of the specific IgG4/IgE ratio between the two time points. Reactions were local, with only two mild systemic reactions during the build-up phase. Twenty patients had accidental stings during immunotherapy, with 3 presenting only urticaria. This study is unprecedented in evaluating clinical and laboratory data in the fire ant immunotherapy. Our results show that after one year of the maintenance phase, patients did not develop any severe reaction with only a few mild reactions and presented a significant production of specific IgG4.

Male fire ant neurotransmitter precursors trigger reproductive development in females after mating

Social insect queens have evolved mechanisms to prevent competition from their sexual daughters. For Solenopsis invicta, the fire ant, queens have evolved a primer pheromone that retards reproductive development in their winged reproductive daughters. If these daughters are removed from the influence of the queen, it takes about a week to start reproductive development; however, it starts almost immediately after mating. This dichotomy has been unsuccessfully investigated for several decades. Here we show that male fire ants produce tyramides, derivatives of the biogenic amine tyramine, in their reproductive system. Males transfer tyramides to winged females during mating, where the now newly mated queens enzymatically convert tyramides to tyramine. Tyramine floods the hemolymph, rapidly activating physiological processes associated with reproductive development. Tyramides have been found only in the large Myrmicinae ant sub-family (6,800 species), We suggest that the complex inhibition/disinhibition of reproductive development described here will be applicable to other members of this ant sub-family.

Intranest mutualisms between the forest fire ant Solenopsis virulens (Fr. Smith) (Hymenoptera; Formicidae) and two families of Hemiptera (Membracidae, Monophlebidae) in Brazilian Atlantic Forest

Hemipterans and ants are frequently recorded in trophobiotic associations, generally mutualism. Nests of the fire-ant Solenopsis virulens (Smith) found at the base of trees in the Atlantic Forest biome, Brazil, were investigated for their commensal fauna. The present study provides new information about the mutualism between the fire-ant with hemipterans Membracidae and Monophlebidae found in their nests, this report is the first mention of this kind of relationships in South America. Such associations are very common between ants and treehoppers but have seldom been reported with the family Monophlebidae.