Ghost Ant Research Articles

The previous concept of the cosmopolitan pest ant Tapinoma melanocephalum (Fabricius, 1793) includes two species (Hymenoptera: Formicidae: Tapinoma)

Tapinoma melanocephalum (Fabricius, 1793), known under the vernacular name Ghost Ant and being a widely distributed cosmopolitan tramp species with significant pest status, has been considered long-since to represent a single species. Yet, investigation of 83 worker samples from the whole globe provided evidence that the Ghost Ant consists of two species: 8.4 % of the samples belonged to the new species T. pithecorum sp. nov. whereas 91.6 % were classified as T. melanocephalum. Absence of mixed samples indicates that T. melanocephalum and T. pithecorum sp. nov. do not represent morphs of the same species. T. pithecorum sp. nov. is known from a greenhouse finding in Germany and outdoor populations from the south of the Arabian Peninsula, Pakistan, India, Malaysia and the Fiji and Christmas Islands. The phenotypical separation of the new species from other minute Tapinoma species of Orientalic, Indo-Australian and Australasian origin is very clear, allowing identification even by evaluation of z-stack photos. A detailed argumentation is presented that Tapinoma pellucida (Smith, 1857), T. coronatum (Forel, 1908), T. malesianum (Forel, 1913), T. australis (Santschi, 1928), T. australe (Santschi, 1928), T. luffae (Kurian, 1955), T. wallacei (Guerrero, 2018) and T. jerdoni nom. nov. should be considered as synonyms of T. melanocephalum. Synomymies of T. melanocephalum and T. pithecorum sp. nov. with T. indicum (Forel, 1895) and Tapinoma minutum (Mayr, 1862) are clearly excluded by morphometric data. Diagrams of principal component analyses, photos, a key as well as a morphometric table to separate these four species are presented. In a concluding section, is argued that the true number of species related to these four species is much larger than presently known and a warning is given regarding careless use of pigmentation characters in ant identification.

Ant–hemipteran association decreases parasitism of Phenacoccus solenopsis by endoparasitoid Aenasius bambawalei

1. Mutualism between ants and honeydew‐excreting hemipterans is ubiquitous in the ecosystem. It is widely accepted that ant tending facilitates the colony growth of hemipterans by protecting them from predators and parasitoids. However, few studies have explored how ant tending helps defend against natural enemies.2. Ghost ant Tapinoma melanocephalum and the invasive mealybug Phenacoccus solenopsis have a close mutual relationship. Previous studies have shown that ghost ant tending can definitely reduce parasitism and visit frequency of Aenasius bambawalei, the dominant endoparasitoid of P. solenopsis. However, the ghost ant workers seldom attack the parasitoids. It is still unclear how the ghost ant adversely affects parasitoids. This study explored the mechanism underlying the impacts of ants on natural enemies of the mealybugs.3. Honeydew produced by P. solenopsis was an attractant to A. bambawalei. Parasitoids exhibited less searching activity, shorter longevity and lower parasitism when supplied with less honeydew. Aenasius bambawalei showed significant avoidance of pygidial gland secretions and visual cues of ghost ants. Parasitism in plants treated with 6‐methyl‐5‐hepten‐2‐one, actinidine, and gland extracts was significantly lower than that in plants treated only with solvents (paraffin oil or double‐distilled water).4. It is concluded that honeydew consumption by ghost ants could negatively influence the performance of parasitoids. The pygidial gland secretions and visual cues of ghost ants also significantly inhibit the parasitism. These results may contribute to a better understanding of the regulation mechanism in ant–hemipteran–enemy interactions.

Temperature warming strengthens the mutualism between ghost ants and invasive mealybugs

Although the exogenous forces that directly affect the mutualisms between ants and honeydew-producing hemipterans have been well documented, few studies have been focused on the impacts of environmental warming on ant-hemipteran interactions. Here, we investigated how temperature warming affects the mutualism between ghost ant Tapinoma melanocephalum and invasive mealybug Phenacoccus solenopsis by experimental manipulation of temperature. We found that higher temperatures have significant direct effects on the growth rate of mealybug colony, and the positive effect of ant tending on mealybug colony growth is temperature-dependent. Honeydew excretion by mealybugs was affected by ant tending and temperature warming, and was significantly increased under higher temperature. The effect of ant tending on percentage parasitism was also influenced by temperature warming. Ant performance including tending level, aggression, activity, and honeydew consumption was enhanced by temperature warming, which may provide superior protection to the mealybugs. Our results show that ghost ant-mealybug mutualism is strengthened in a warmer environment. These findings may facilitate the prediction of how each partner in the ant-hemipteran-enemy interactions responds to increasing temperature.

Invasive ant Tapinoma melanocephalum (Hymenoptera: Formicidae): A rare guest or increasingly common indoor pest in Europe?

The ghost ant (GA), Tapinoma melanocephalum (Fabricius, 1793), is one of the most common invasive species of ants (Hymenoptera: Formicidae) in the world. While in its native tropical region it is both an ordinary indoor and outdoor pest, it occurs only indoors in the temperate zone, where increasingly more records of this species have been published since 1887. In this study, the current distribution of GA in Europe, including the new records published since Wetterer (2009), is reviewed. Furthermore, we report the first record of GA in the Czech Republic, where a large colony of GA was discovered in a block of flats in Ceske Budějovice in 2014, and present a case study of its eradication. The revised distribution of GA shows that despite previous concerns about the threats posed by this new pest only three other European countries (including Czech Republic) reported the presence of this species after 2009. Although GA is currently documented as occurring in 18 European countries, which were invaded mainly after 1990, there is only a single (or dubious) record for ten of these countries. Abundance of workers was monitored in two flats in an infested building using traps baited with yolk-honey and GA were subsequently eradicated with imidacloprid (0.01% w/w). The pre-treatment revealed abundances that ranged up to 524 workers per trap (mean = 99, S.D. = 142, 80% of baits occupied). Despite the initial success of the treatment (no ants observed after 3 weeks), monitoring of the building a year later revealed it was still infested with GA and in a similar rate. We suggest alternative methods of eradicating GA in the temperate zone based on studies carried out in the tropics. Our study indicates the difficulty of eradicating the species from buildings when its colony is already established. Furthermore, it highlights the bias in the discovery-probability of GA as a household pest probably due to the species cryptic appearance and lack of attention to it outside of the scientific community.

Does the host plant affect the benefits from mutualisms?The invasive mealybug and ghost ant association

1. The benefits to trophobionte hemipterans are affected by the ant tending level, which is a widely accepted statement. The ant tending level is closely related to multiple factors. It is clear that the ant tending level can be affected by the temporal factor, age‐specific, the density of the hemipterans, and quantity and quality of honeydew produced by hemipterans.2. Few studies of ant–hemipteran mutualisms have reported the patterns of host plants‐dependent effects, and whether host plants influence the ant tending level that is also unclear. As such, laboratory experiments were conducted to test whether the colony growth rate of an invasive mealybugPhenacoccus solenopsisTinsley, parasitism ofAenasius bambawaleiHayat, an dominant parasitoid ofP. solenopsis, are affected by tending by ghost ants (Tapinoma melanocephalum(Fabricius)], host plants (tomato and cotton), and interactions between the two factors. The difference in the ant tending level between the host plants was also determined.3. The results showed that mealybug colony growth and parasitism were significantly affected by ant tending and host plant separately. There were significant interactions between the independent factors on the mealybug colony growth rate and percentage parasitism. These results suggest that benefits to mealybugs are host plant‐dependent.

Strategies for controlling the ghost ant, Tapinoma melanocephalum (Hymenoptera: Formicidae) with liquid bait

The ghost ant, Tapinoma melanocephalum (F.), is a household pest and a considerable nuisance. The aim of this study is to demonstrate the toxicity and control efficacy of boric acid in liquid bait against queen and worker ghost ants. The LT50 values for workers fed with 0.5%–2.5% boric acid and 2% chicken peptone in 20% sucrose water solutions were 4.3–2.4days. The lethal times (LT50=5.2–7.6days) for queen ghost ants fed with various concentrations of a boric acid solution depended on the feeding behavior of the queens. The high boric acid (4%) content solutions were not repellent to the ghost ant workers. The liquid bait formulation of 1% boric acid, which caused a 100% worker, brood, and queen population reduction in 4, 4, and 5weeks, respectively, was significantly more effective than the solid bait formulation containing the same concentration (p≦0.05). The simulation tests involved using chicken peptone and sucrose as the attractant, and colonies were provided an alternate food source (20% sucrose solution and dog food) to achieve a more accurate assessment of bait acceptability in screening for the efficacy of the liquid boric acid bait. The control efficiency attained 99.9% in week 4. The results demonstrated that liquid bait, containing 2% chicken peptone, 20% sucrose as a food attractant, and 1% boric acid as the toxin, is efficient and highly recommended for ghost ant control.

Ghost Ant, Tapinoma melanocephalum (Fabricius) (Insecta: Hymenoptera: Formicidae)

This document is EENY-310 (originally published as DPI Entomology Circular 307), one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: October 2003.
 EENY310/IN532: Ghost Ant, Tapinoma melanocephalum (Fabricius) (Insecta: Hymenoptera: Formicidae) (ufl.edu)