Control of pest ants by pathogenic fungi: state of the art.

Pest ants are known for their damage to biodiversity, harm to agriculture, and negative impact on human welfare. Ants thrive when environmental opportunities arise, becoming pests and/or invading non-native areas. As social insects, they are extremely difficult to control using sustainable methods like biological control.

Entomopathogenic Strains of the Fungus Purpureocillium lilacinum Damage the Fungus Cultivar of Pest Leaf-Cutter Ants.

Purpureocillium lilacinum (Hypocreales: Ophiocordycipitaceae) is a cosmopolitan fungus not only pathogenic to insect and nematode hosts but also to other fungi. Although having one organism with multiple effects would be desirable in a biocontrol strategy, few studies have looked at the multiple roles one strain could play. This work shows how three strains of P.

Conidiobolus lunulus, a newly discovered entomophthoralean species, pathogenic and specific to leaf-cutter ants.

Conidiobolus lunulus is a recently described entomophthoralean species isolated from leaf-cutter ants. This fungus discharges not only primary but also secondary conidia and microconidia of different shapes. Because nothing was known about the biology of the fungus, and its interactions with hosts, we first evaluated if its pathogenicity against leaf-cutter ants changes with the fungal age (time grown in vitro), and if it is related to the conidial structures produced.

Ritualized aggressive behavior reveals distinct social structures in native and introduced range tawny crazy ants.

How workers within an ant colony perceive and enforce colony boundaries is a defining biological feature of an ant species. Ants fall along a spectrum of social organizations ranging from single-queen, single nest societies to species with multi-queen societies in which workers exhibit colony-specific, altruistic behaviors towards non-nestmate workers from distant locations. Defining where an ant species falls along this spectrum is critical for understanding its basic ecology.

Pseudacteon notocaudatus and Pseudacteon obtusitus (Diptera: Phoridae), two new species of fire ant parasitoids from South America.

Ongoing studies in South America of phorid flies of the genus Pseudacteon Coquillett 1907 have revealed two further new species in this genus that are described here: P. obtusitus and P. notocaudatus.

Natural enemies of Atta vollenweideri (Hymenoptera: Formicidae) leaf-cutter ants negatively affected by synthetic pesticides, chlorpyrifos and fipronil.

In southern South America, Ada vollenweideri Forel (Hymenoptera: Formicidae) is a significant pest of several crops and forestry, also considered to reduce the carrying capacity of pastures. The most usual control method used in Latin America is the application of synthetic pesticides, mainly chlorpyrifos and fipronil. However, no studies have assessed the effects of these agrochemicals on natural enemies of ants.

Optimal conditions to rear phorid parasitoids (Diptera: Phoridae) of Atta vollenweideri and Acromyrmex lundii (Hymenoptera: Formicidae).

Phorid flies have been considered viable options for biological control of leaf-cutter ants because they are highly specific to these hosts, producing direct mortality and also affecting the normal functioning of colonies. Designing protocols for mass rearing of these insects requires knowing the temperature and humidity conditions that optimize their development in terms of duration, survivorship and longevity of adults. We reared Apocephalus setitarsus Brown, Eibesfeldtphora trilobata Disney, and Myrmosicarius brandaoi Disney, which are specific leaf-cutter ant parasitoids of Atta vollenweideri Forel, and Apocephalus neivai Borgmeier and Myrmosicarius catharinensis Borgmeier, which are parasitoids of Acromyrmex lundii Guérin-Méneville.

Behavioral strategies of phorid parasitoids and responses of their hosts, the leaf-cutting ants.

Host-searching and oviposition behaviors of parasitoids, and defensive responses of the hosts, are fundamental in shaping the ecology of host-parasitoid interactions. In order to uncover key behavioral features for the little known interactions between phorid parasitoids (Diptera: Phoridae) and their leaf-cutting ant hosts (Formicidae: Attini), host-related behavioral strategies (i.e.

Pseudacteon tricuspis: its behavior and development according to the social form of its host and the role of interference competition among females.

We studied how the behavior and performance of Pseudacteon tricuspis Borgmeier varies with the social form of its host Solenopsis invicta Buren, in its native range in Argentina where monogyne colonies are more abundant than polygynes (approximately 75 vs. 25%). Female, P.

Life-history traits and parasitism rates of four phorid species (Diptera: Phoridae), parasitoids of Atta vollenweideri (Hymenoptera: Formicidae) in Argentina.

Leaf-cutting ants in the genus Atta F. (Formicidae, Attini) are among the most important pest arthropods in Central and South America, consuming more vegetation than any other animal group. Among the organisms attacking ants in nature, flies of the family Phoridae have been proposed as the most promising biocontrol agents for pest ants.

Distributional patterns of Pseudacteon associated with the Solenopsis saevissima complex in South America.

Classical biological control efforts against imported fire ants have largely involved the use of Pseudacteon parasitoids. To facilitate further exploration for species and population biotypes a database of collection records for Pseudacteon species was organized, including those from the literature and other sources. These data were then used to map the geographical ranges of species associated with the imported fire ants in their native range in South America.

Behavior and development of Pseudacteon curvatus (Diptera: Phoridae) varies according to the social form of its host Solenopsis invicta (Hymenoptera: Formicidae) in its native range.

We assessed the performance of Pseudacteon curvatus Borgmeier with respect to the social form of Solenopsis invicta Buren in Argentina In the field, we studied the effect the parasitoid on size and proportion of ant foragers. In the laboratory, we evaluated P. curvatus oviposition preferences; host size elected; developmental periods; and sexual size dimorphism, sex ratio, and parasitoid survivorship.

Cytogenetic analysis of three species of Pseudacteon (Diptera, Phoridae) parasitoids of the fire ants using standard and molecular techniques.

Pseudacteon flies, parasitoids of worker ants, are being intensively studied as potentially effective agents in the biological control of the invasive pest fire ant genus Solenopsis (Hymenoptera: Formicidae). This is the first attempt to describe the karyotype of P. curvatus Borgmeier, P.

Associations of fire ant phorids and microhabitats.

We examined flight activity patterns for a guild of fire ant parasitoids in western Argentina in relationship to their host's location (mound/foraging trail) and light condition (full sun/partial sun/full shade) at different scales, from the individually sampled mound to the full day's summation for each species. We asked first whether taxa showed preferences among these conditions, and second, whether certain species and sexes might be found together more frequently than expected to by chance. All species, except the P.

Development of Pseudacteon nocens (Diptera: Phoridae) on Solenopsis invicta and Solenopsis richteri fire ants (Hymenoptera: Formicidae).

We studied the developmental performance of the large morph of Pseudacteon nocens Borgmeier (Diptera: Phoridae), a prospective biological control agent of imported fire ants (Hymenoptera: Formicidae). We measured selected life history traits of this parasitoid as a function of 1) host species (Solenopsis invicta Buren versus Solenopsis richteri Forel), 2) temperature (22 versus 28 degrees C), 3) source population of the fly (Corrientes and Santiago del Estero, Argentina), and 4) varied size distributions of offered host ants. Developmental periods were influenced by host species, although the populations responded in opposing manners.

Developmental rates and host specificity for Pseudacteon parasitoids (Diptera: Phoridae) of fire ants (Hymenoptera: Formicidae) in Argentina.

This study extends our comparative knowledge of Pseudacteon interactions with Solenopsis fire ant workers. Reported in this work are development times for seven Argentinean parasitoid species reared on two hosts, Solenopsis richteri Forel and Solenopsis invicta Buren, under laboratory temperature regimes comparable with those of the climatic zones occupied by these host species. Developmental times spanned 31-66 d across phorid species, and in general did not differ between genders or host species, but were longer at lower temperatures.

Myrmecophytic Cecropia: antiherbivore defenses under different nutrient treatments.

In greenhouse experiments, we compared putative biotic, chemical, physical and phenological defenses of six myrmecophytic Cecropia species cultivated under high and low nutrient regimes. We tested the intraspecific predictions of the C:N balance hypothesis for a broader range of defenses than included in other studies to date. Treatment effects on defenses appear to depend on the nutrient constituents of those defenses.