Description of the Immatures of the Ant, Myrmelachista catharinae

The Neotropical ant genus Myrmelachista Roger comprises 69 described species and subspecies, and still is a poorly studied group. Larvae play a paramount role in colony nutrition in social hymenopterans and bear considerable value in the reconstruction of group phylogenies, however, they are generally neglected. Larvae of different instars of Myrmelachista catharinae Mayr (Hymenoptera: Formicidae) are herein described in detail by light and scanning electron microscopy. The number of larval instars was estimated as three based on the frequency distribution of maximum head capsule widths. The described larvae confirmed some traits typical of the genus: general shape of body and mandibles, general aspect and distribution of body hairs, and the number of sensilla on the palps and galea. Differently from other Myrmelachista larvae previously described, M. catharinae presented two distinct kinds of second instars, some additional types of body hairs, different number of antennal sensilla, and a distinct labrum shape. M. catharinae presented ten pairs of spiracles, which is the first record for this genus

Biologia, morfologia e bioquímica de veneno da formiga lava-pés Solenopsis saevissima Smith (Insecta, Hymenoptera, Formicidae)

A formiga lava-pés Solenopsis saevissima Smith está entre os insetos que mais causam acidentes no Brasil, e é uma espécie pouco estudada. A presente série de investigações tenta suprir um pouco da necessidade de estudos com esta importante espécie no Brasil. Primeiramente são relatados detalhes da biologia de S. saevissima em comparação com outras espécies de formigas lava-pés: pela primeira vez é mostrada uma lista de artrópodes associados a estes formigueiros no Brasil, incluindo uma série de novos táxons, dos quais um é aqui descrito; as larvas desta espécie são descritas e comparadas com o que se sabe sobre as larvas de outras lava-pés, sendo visto que as semelhanças encontradas são extensas demais para permitir a utilização de caracteres larvais para filogenia e taxonomia em nível de espécie. Ainda na morfologia, são apresentados resultados de análise ultraestrutural do aparato de veneno por meio de microscopia ótica e eletrônica, onde é mostrado que as diferentes regiões do órgão apresentam especializações para a produção de cada um dos compostos do veneno. A composição do veneno desta espécie foi analisada pela primeira vez, onde verificou-se que acima de 90% do veneno de S. saevissima é composto de isômeros cis e tras de um mesmo alcalóide piperidinico oleoso, sendo o restante uma solução aquosa de toxinas protéicas, incluindo neurotoxinas, fosfolipases, e alérgenos. De uma forma geral, o veneno de S. saevissima tem uma diversidade menor de compostos que o de Solenopsis invicta, podendo figurar entre os motivos que explicam porque a espécie S. invicta é uma espécie invasora e S. saevissima não. São apresentados pela primeira vez evidências químicas da existência de espécies crítpticas dentro de S. saevissima. Tomados em conjunto, os resultados suprem um pouco da carência de estudos com as formigas lava-pés...The fire ant Solenopsis saevissima Smith is one of the insects most frequently involved in accidents in Brazil, yet being a poorly studied species. The series of studies presented here aimed at filling some of this gap in knowledge about this common and important ant species. Some aspects of the field biology of S. saevissima are shown in comparison with other fire ants: a unique list of associated arthropods collected from field inspections in Southern Brazil is given, which includes several new taxa, one of which is herein described for the first time. The larvae of S. saevissima are described for the first time and compared with larvae from close species, culminating with the demonstration that larval characters within this group cannot be feasibly employed in species-level phylogenetic and taxonomic analyses. In terms of internal anatomy, a detailed ultrastructural description of the venom apparatus of S. saevissima is given, wherein special emphasis was given to the particular organisation of each region of the apparatus, suggesting there are specialised areas for the production of each venom compound. The venom of this species was subject of biochemical analyses for the first time, generally illustrating that the venom of S. saevissima is >90% made of a simple mixture of cis- and trasundecil- pyperidinic alkaloids, being the remainder an aqueous solution of toxic proteins, comprising neurotoxins, and traces of phospholipases and allergens. The venom of S. saevissima proved being less diverse in toxins than the venom of Solenopsis invicta, possibly explaining why S. invicta is a successful invasive species while S. saevissima apparently is not. Moreover, herein is included the first record of intraspecific variation in the nature of venom alkaloids, providing biochemical evidence for the existence of cryptic species in S. saevissima. Taken together, the obtained... (Complete abstract click electronic access below

Ampulex compressa Fabricius

Ampulex compressa (Fabricius) Last larval instar Body: General body form as illustrated for Sphex tepanecus Saussure in Stehr (1987). Pale yellow, length ranging from 0.9 cm (penetrating larva) to 2.5 cm (fully fed mature larva), dorsoventrally compressed and rather flattened ventrally and rounded dorsally; more tapered anteriorly than posteriorly. Its maximum width ranged from 0.2 cm (penetrating larva) to 0.9 cm (fully fed mature larva) at fifth and sixth abdominal segments. Pleural lobes prominent. Most body segments divided into two annulets dorsally, integument slightly granulose. All spiracles brown and located inside pronounced depressions (Fig. 1 A). Spiracular atrium apparently unornamented; peritreme with five valve­like projections (Fig. 1 A). Anus terminal. Head capsule: Subcircular; measuring 1.1 mm long and 1.0 mm in maximum width with distinct depressions in antennal and coronal regions (Fig. 1 B). Anterior tentorial arms and pleurostoma unpigmented and discrete, hypostoma dark brown, parietal bands feeble (Fig. 1 C). Depressions in clypeal region; metopic suture strongly pronounced and continuous with the frontal suture (Fig. 1 B). Antennal orbits discrete and circular (diameter = 40 μm), with 3 sensilla apically. Cephalic surface with few punctures, mainly concentrated in clypeal region and with a distinct group of 6 punctures in subgenal area (not shown). Mouthparts: Labrum 562.6 ± 253.9 m (n= 5) wide, strongly bilobed (Fig. 1 C, 1 D), pigmented mesally and with 30–32 surface punctures, setae (8 m long) and basiconic sensilla (10 m diameter) (Fig. 1 D). Epipharynx densely spinulose mesally with 4 m spines directed apically, shorter spines present at the lobes’ extremities, but these are absent on the sensory area, which contains 8–10 scattered basiconic sensilla (7–8 m in diameter) (Fig. 1 E). Mandible is 418.2 ± 204.4 (n= 4) m long, brown, darker at apex and articulations, bearing 4–5 teeth, with neither punctures nor setae (Fig. 1 C). Maxilla with few setae (about 12 m); its inner basal portion with flattened papillae margined with short spikes; lacinial area with 3–5 m­long spines (Fig. 1 F). Pigmented maxillary palpus stout, 60 m long x 55 m wide, with three basiconic sensillae apically; galea pigmented, 30 m long x 30 m wide (not shown). Salivary lips with a deep medial groove just above a transverse spinneret with prominent raised lips, margined with spoon­like papillae on the upper lip which also bears short spikes internally (Fig. 2 A). Labium about 329 m wide, and pigmented at the sides; bearing weakly pigmented, cone­shaped, 47 m long x 61 m wide labial palpi (Fig. 1 C), culminating in three basiconic sensilla (not shown). Labiobase with few 9 m long setaceous sensilla (Fig. 2 A). Examined material: Two entire larvae and three head capsules, two analysed with a light microscope and one by scanning electronic microscopy. Second larval instar Body: light yellow, measuring 6.5 mm in maximum length and 3.0 mm in width, dorsoventrally compressed and with evident segmentation (Fig. 2 B). Pleural lobes pronounced, spiracular depressions present. Integument wholly covered with short spines (not shown). Head capsule: Mainly unpigmented; 2.0 mm long x 1.9 mm in maximum width. Coronal suture continuous with frontal suture (Fig. 2 C). Antennal orbits very inconspicuous with three sensilla (not shown). A distinct group of 6 punctures on subgenal area; parietal bands indistinguishable; hypostoma, pleurostoma and anterior tentorial arms pigmented, epistoma well defined and also pigmented (Fig. 2 C). Mouthparts: Labrum about 500 m wide, with 18–20 punctures (Fig. 2 C). Spines at middle of epipharynx, directed apically. Maxilla unpigmented, lacking setae. Mandible about 263 m long, bearing 3 teeth and various spine­like denticles; labium unpigmented and very simple, 230 m wide (Fig. 2 C). First larval instar Body: white and cylindrical, 3.0 mm long x 0.8 mm wide, with evident segmentation (Fig 2 D). Pleural lobes slightly pronounced in thoracic region, spiracles brown (not shown). Body covered with 1–2 μm spines, more densely so at posterior portion and intersegmental areas (Fig. 2 D—detail). Head capsule: Mostly unpigmented, except for brown maxillary scleromes, epistoma and pleurostoma. Mouthparts greatly reduced: labrum about 100 m wide with 9–10 punctures, mandible pigmented (172 m long) with 3 teeth, maxilla with no setae; labium unpigmented and very reduced (Fig. 2 D). Cocoon Wall composed of two distinct layers: a silky outer one and a sturdy dark brown internal one. Inner surface shiny black and smooth (not shown). Walls apparently composed of spherical grains embedded in some kind of secreted matrix (Fig. 2 E). Egg White, cylindrical, not curved, with rounded extremities; 2.5 mm length x 0.7 mm width. Micropyle appears as a punctured area on the anterior extremity (Fig. 2 F).Published as part of Fox, Eduardo Gonçalves Paterson, Buys, Sandor Cristiano, Mallet, Jace- Nir Reis Dos Santos & Bressan-Nascimento, Suzete, 2006, On the morphology of the juvenile stages of Ampulex compressa (Fabricius 1781) (Hymenoptera, Ampulicidae), pp. 43-51 in Zootaxa 1279 on pages 45-49, DOI: 10.5281/zenodo.27351

Morphological Studies on the Mature Worker Larvae of Paratrechina fulva (Hymenoptera, Formicidae)

Paper originally published with the extinct Sociobiology Journal at: http://www.csuchico.edu/biol/Sociobiology/volume/sociobiologyv55n32010.html<div>Original contains no link nor DOI number. </div><div>I have retained copyrights.</div><div>Abstract: The ant <em>Paratrechina fulva</em> is native to Brazil, but has spread to other countries where it has become a serious pest. Their larvae are known from a preliminary description made without the aid of scanning electron microscopy. The present investigation aimed at describing the mature worker larvae of this species in deeper detail, while identifying useful morphological characters for taxonomy and cladistics. General morphological traits typical of <em>Paratrechina</em> larvae described so far were also confirmed with this species, particularly regarding body shape, types of hairs, and distribution pattern of head sensilla, but <em>P. fulva</em> presented unusually shaped mandibles.</div><br>KEY WORDS: larval characters; scanning electron microscopy; taxonom

Comparative immature morphology of Brazilian fire ants (Hymenoptera: Formicidae: Solenopsis)

Although common in Brazil, the biology of the fire ant Solenopsis saevissima (Smith) is still poorly studied. Larval descriptions are useful to genus-level ant systematics and sometimes to species-level taxonomy. This study presents a detailed description of juveniles of S. saevissima from Brazil, which were compared with Brazilian specimens of Solenopsis invicta Buren, Solenopsis geminata (Fabricius), and Solenopsis altipunctata Pitts. Different larval instars were separated by diagnostic morphological traits which were confirmed by observing moults. Reproductive larvae could be easily sorted by their distinctive body dimensions and shape. Contrary to previous reports on this species, the larvae of S. saevissima proved to be generally identical to those of S. invicta, while a few specimens resembled those of other close species, such as Solenopsis megergates Trager. Mature larvae thus presented considerable intraspecific variation in some characters recently proposed to aid fire ant species separation (morphology of head hairs). © 2012 Eduardo Gonalves Paterson Fox et al

Intraspecific and Intracolonial Variation in the Profile of Venom Alkaloids and Cuticular Hydrocarbons of the Fire Ant Solenopsis saevissima Smith (Hymenoptera: Formicidae)

Fire ants are aggressive Neotropical ants that are extensively similar in general biology and morphology, making species identification difficult. Some fire ant species are top-rated pests spreading throughout the world by trade vessels. Many researchers attempted to sort between invasive and native species by using chemical characters, including patterns of venom alkaloids. The present study is the first to report intraspecific variation in some chemical characters, namely, cuticular hydrocarbons and venom alkaloids, within the Brazilian fire ant species Solenopsis saevissima and also reports on within-nest variations among members of different castes. Two different haplotypes (cryptic species) of S. saevissima were clearly identified, one presenting a predominant combination of the venom alkaloids cis- and trans-2-methyl-6-undecylpiperidine with the cuticular hydrocarbons C23, 3-Me-C23, 10-C25 : 1, C25, and 3-Me-C25, and the other a predominant combination of cis- and trans-2-methyl-6-tridecenylpiperidine with predominance of 12-C25 : 1, C25, 11-Me-C25, 3-Me-C25, 13-C27 : 1, C27, and 13-Me-C27. Intranest variations revealed that the proportions among these compounds varied sensibly among workers of different sizes, gynes, and males (no alkaloids were detected in the latter). Larva contained vestiges of the same compounds. The recorded chemical profiles are quite different from previous reports with S. saevissima samples from São Paulo. The finds thus support other recent claims that S. saevissima includes cryptic species; the study, moreover, adds the find that they can occur in the same geographical location