William P. Mackay

Absorption of copper(II) by creosote bush (Larrea tridentata): Use of atomic and x-ray absorption spectroscopy

Larrea tridentata (creosote bush), a common North American native desert shrub, exhibits the ability to take up copper(II) ions rapidly from solution. Following hydroponic studies, U.S. Environmental Protection Agency method 200.3 was used to digest the plant samples, and flame atomic absorption spectroscopy (FAAS) was used to determine the amount of copper taken up in different parts of the plant. The amount of copper(II) found within the roots, stems, and leaves was 13.8, 1.1, and 0.6 mg/g, respectively, after the creosote bush was exposed to a 63.5-ppm copper(II) solution for 48 h. When the plant was exposed to a 635-ppm copper(II) solution, the roots, stems, and leaves contained 35.0, 10.5, and 3.8 mg/g, respectively. In addition to FAAS analysis, x-ray microfluorescence (XRMF) analysis of the plant samples provided further confirmation of copper absorption by the various plant parts. X-ray absorption spectroscopy (XAS) elucidated the oxidation state of the copper absorbed by the plants. The copper(II) absorbed from solution remained as copper(II) bound to oxygen-containing ligands within the plant samples. The results of this study indicate that creosote bush may provide a useful and novel method of removing copper(II) from contaminated soils in an environmentally friendly manner.

Nectar secretion on fern fronds associated with lower levels of herbivore damage: field experiments with a widespread epiphyte of Mexican cloud forest remnants.

BACKGROUND AND AIMSnThe oldest group of plants in which nectar secretions have been observed are the Polypodiopsida (ferns sensu lato). Nectaries have been reported in a dozen extant genera. The function of these nectaries has been investigated in several fern species, and in some circumstances has been demonstrated to have an antiherbivore role, attracting and maintaining biotic defence (ants and/or other predatory arthropods). This study documents foliar nectaries in Pleopeltis crassinervata, a widespread Central American epiphyte growing on a variety of trees in cloud forest areas of Veracruz, Mexico. This is a new record for this genus and species.nnnMETHODSnAs previous experimental work on epiphytic species of Polypodium has demonstrated a protective role of ants for developing fronds, we conducted similar experiments (using nylon nail polish to cover nectaries rather than excluding ants with bands of sticky resin as in earlier work). The fronds of Pl. crassinervata developed over 6 weeks, at which time damage was assessed. The experiment was simultaneously conducted on a sympatric species lacking nectaries, Polypodium furfuraceum. Herbivore placement experiments were conducted with large and small caterpillars on both of these ferns.nnnKEY RESULTSnFronds with nectaries covered suffered greater damage from herbivores over the course of their development, compared with fronds that had uncovered nectaries functioning normally. The parallel experiment on Po. furfuraceum showed no difference between manipulated and control fronds. Six species of ants (Brachymyrmex minutus, Crematogaster formosa, Paratrechina longicornis, Solenopsis geminata, S. picea and Wasmannia auropunctata) were observed visiting nectaries of Pl. crassinervata; most were effective in removing herbivore larvae placed on the fronds.nnnCONCLUSIONSnThe long evolutionary history of ferns may explain why some previous studies of fern nectaries have shown little or no benefit to ferns from nectary visitors, as any coevolved herbivores are those resistant to ant defence. The results suggest that ants protect Pl. crassinervata fronds against herbivory. The presence of nectaries, and the relationship with ants, may contribute to this ferns widespread occurrence and persistence in the face of disturbance, though many other factors also play a role. Ant defence may be more likely to benefit a widespread species of disturbed habitats that encounters a wide range of non-adapted herbivores.

A descriptive morphology of the ant genus Procryptocerus (Hymenoptera: Formicidae)

Abstract Morphology is the most direct approach biologists have to recognize uniqueness of insect species as compared to close relatives. Ants of the genus Procryptocerus possess important morphologic characters yet have not been explored for use in a taxonomic revision. The genus is characterized by the protrusion of the clypeus forming a broad nasus and antennal scrobes over the eyes. The toruli are located right posterior to the flanks of the nasus opposite to each other. The vertex is deflexed posteriorly in most species. An in-group comparison of the external morphology is presented focusing on the workers. A general morphology for gynes and males is also presented. Previously mentioned characters as well as new ones are presented, and their character states in different species are clarified. For the metasoma a new system of ant metasomal somite nomenclature is presented that is applicable to Aculeata in general. Finally, a Glossary of morphological terms is offered for the genus (View glossary). Most of the terminology can be used in other members of the Formicidae and Aculeata.

A New Species of Afrotropical Ants in the Genus Bothroponera (Hymenoptera: Formicidae: Ponerinae)

We describe a new species of Afrotropical Bothroponera from Whittlesea City, Eastern Cape Province, South Africa. This species is unique among the African Bothroponera as it is the only species with a horizontal propodeal spiracle. It is also the largest species of African Bothroponera (total length 14.80–15.65). The clypeus lacks a medial longitudinal carina, the head is subquadrate, the sculpture is mostly foveolate, and the second gastral segment nearly lacks sculpturing. We compare the new species to the similar B. cavernosa and B. cavernosa var. montivaga. We also compare the new species to all of the other 10 taxa that belong to the cavernosa complex. A key to the cavernosa complex species of the Afrotropical Bothroponera is provided along with diagnosis, comparison, distribution, habitat, biology, and etymology for the new species.

Weaving through a cryptic species: Comparing the Neotropical ants Camponotus senex and Camponotus textor (Hymenoptera: Formicidae)

Camponotus senex (Fr. Smith 1858) and Camponotus textor Forel, 1899 are commonly confused species in the New World tropics. We provide morphological characteristics based on the larvae and adults, behavioural differences, together with evidence from molecular markers (cuticular hydrocarbon profiles, venom differences, nuclear ribosomal ITS-1, and mtDNA COI sequence comparisons) to separate the two species, demonstrating they are not immediately closely related. In conclusion we suggest new reliable morphological characters which can benefit from deeper phenetic analysis, and support the contextual usefulness of non-morphological tools in resolving sibling ant species.

A New Shield-Faced Ant of the Genus Pheidole (Hymenoptera: Formicidae: aberrans Group) From Argentina

ABSTRACT We describe Pheidole acutiloba Mackay, based on the majors, minors, females and males, with the head of the major formed into a shield. This species is similar to P. aberrans and P. obscurifrons, and we discuss the similarities and differences between the majors of the three species. We provide an amendment to the key in Wilsons monograph to accommodate the new species.

Urban ants of the city of Buenos Aires, Argentina: species survey and practical control

ABSTRACT Ants are among the most diverse, abundant and ecologically significant organisms on earth. They have colonized almost all existing habitats, including urban areas, where they may pose serious problems for human activities. Here, we present different aspects of our studies on urban ants in the city of Buenos Aires aimed at collecting information on the species present in the city and at improving bait control strategies via laboratory assays. The use of these baits represents a control strategy that is environment-friendly as it avoids indiscriminate pesticide release. Moreover, we show that our baits exhibit higher efficiency when compared to a commercial bait, as it is optimized in terms of the ants’ feeding behavior even when both have the same active compound and at the same concentration. This work represents the first integrative study on urban ants in the city of Buenos Aires and indicates that the control of invasive species in urban settings may be improved by increasing the scientific knowledge of the biology of the target species.