The Cimicidae (Hemiptera) are known to be blood ectoparasites primarily on birds and bats. Three species of the subfamily Haematosiphoninae are known from Argentina: Acanthocrios furnarii, Ornithocoris toledoi, and Psitticimex uritui; all feed on diverse avian hosts. The chromosome number and male meiosis of A. furnarii, and P. uritui from new Argentinean samples are analyzed and compared with previous data. The sample of A. furnarii described by Ueshima (1966) with 2n = 32 + XY (male), strikingly differs from the present results (2n = 10 + XY, male). The diploid number of P. uritui agree with the previously reported by Ueshima (1966), 2n = 28 + X 1 X 2 Y (male). Taxonomical implications about the identity of A. furnarii are discussed and the mechanisms of the karyotype evolution of species belonging to Haematosiphoninae are proposed.

Insects found in the nests of Anumbius annumbi (Vieillot) [Aves: Furnariidae] from the provinces of Buenos Aires, Santa Fe, Entre Ríos, and La Pampa (Argentina) were studied. A total of 20 nests was sampled every 21 days in Buenos Aires, together with the insects found under ritidome of Eucalyptus in the same area. Samples from nests were divided by seasons: end of summer [nest 1]; autumn [nests 2 to 6]; winter [nests 7 to 12]; spring [nests 13 to 16]; summer [nests 17 to 19], and beginning of autumn [nest 20]. A total of 92 species of insects was found, of which only 36 species had been previously reported in the literature from 1943 until 2005. Additional nests were sampled from Santa Fe (3 nests), Entre Ríos (1 nest), and La Pampa (4 nests). Species richness, abundance and diversity per nest are given and discussed. Insects in birds´nests are classified according to their functional guilds (predators; hematophages and parasitoids; detritivores; phytophages and fungivorous); degree of permanence in the nests (temporal inhabitants [hibernants]; permanent inhabitants; accidentals and/or occasionals). Mortality among the insect fauna inside the nests and other dead insects found inside nests, probably prey remains, are cited. The insect fauna under the ritidome of Eucalyptus permits establishment of a habitat gradient: species only found in the nests, species mainly found in the nests and rarely under the ritidome, species found both under the ritidome and in the nests, species mainly found under ritidome and seldom in the nests, and species only found under the ritidome. Comments and remarks are made on selected taxa lacking or with limited biological data. The microhabitat in the tunnels of Ctenomys [Rodentia] is compared with the birds’nests regarding its similar insect fauna. Inquiline birds and mammals are also mentioned.

Neotropical birds’ nests have received a great deal of attention because sylvatic species of Triatominae (Hemiptera: Reduviidae) and parasitic flies of the genus Philornis (Diptera: Muscidae) were discovered inside them. Those insects known in birds’ nests from Argentina, the chacoan region of Bolivia, and the southern portion of Brazil and Uruguay were extensively but not completely summarized by Turienzo & Di Iorio (2007). The present contribution summarizes all insects known to occur in birds’ nests from the Neotropical Region (except for Argentina and the Antarctic Region of adjacent countries), updating Hicks’ catalogues for this part of the world. Regarding birds, the list comprises 172 taxa identified to species (in 38 families), 8 to genus (in 6 families), 6 to family (in 4 families), and 27 birds´nests not identified. Regarding insects of the Neotropical region, 123 were identified to species (13 Blattaria; 5 Coleoptera; 26 Diptera; 34 Hemiptera; 15 Hymenoptera; 23 Psocoptera; 6 Siphonaptera; 1 Thysanura), 96 to genus (5 Blattaria; 8 Coleoptera; 48 Diptera; 4 Hemiptera; 6 Hymenoptera; 25 Psocoptera), 63 to superfamily, family or subfamily (1 Blattaria; 21 Coleoptera; 10 Diptera; 7 Hemiptera; 14 Hymenoptera; 1 Isoptera; 3 Orthoptera; 5 Psocoptera; 1 Thysanoptera), and 34 to order (6 Blattaria [including 1 Mantodea]; 6 Coleoptera; 3 Diptera; 3 Embioptera; 2 Hemiptera; 3 Hymenoptera; 1 Thysanoptera; 2 Isoptera; 4 Lepidoptera; 1 Orthoptera; 1 Phthiraptera; 2 Psocoptera). Associations of Neotropical insects with birds´nests were extracted from 392 references including original and posterior citations. Some North American species of insects that are neotropical immigrants are discussed, while a few other had been accidentally introduced in both directions. Synonymies, old combinations, misidentifications, original localities, amounts of insects, and repositories when they were stated, are provided.

A bibliographical review of the insects found in birds’ nests from Argentina is herein presented. The bird species are cited as they were originally recorded in the respective publications, but their nomenclature is updated. For each kind of nest, the data are ordered in the following manner: by insect order, family, subfamily and species (references, without locality) and by province: locality with specimens when stated (reference with locality data). Comments on nomenclature and some corrections are included under the respective notes. Three items that have received most attention were the hematophagous Reduviidae: Triatominae, Cimicidae, and the larvae of Philornis (Diptera: Muscidae). Identifications of other insects are scarce, and were explicitly mentioned in only three short works, and in an anecdotal manner in other papers. In general, insects found in birds’ nests may be grouped by ecological guilds (predators, hematophagous parasitoids, detritivores, phytophagous and some predator insect hibernants, and inquilines), permanency (temporal and permanent residents) inside the nests, and according to their direct relationship to the birds. A transmission mechanism is hypothesized for the hematophagous bugs of the family Cimicidae based upon data on birds that nidificate in nests of other birds. Some new records are included.

Members of the family Cimicidae (Heteroptera: Cimicomorpha) are temporary bloodsuckers on birds and bats as primary hosts and humans as secondary hosts. Acanthocrios furnarii (2n=12=10+XY, male) and Psitticimex uritui (2n=31=28+X1X2Y, male) are two monotypic genera of the subfamily Haematosiphoninae, which have achiasmatic male meiosis of collochore type. Here, we examined chromatin organization and constitution of cimicid holokinetic chromosomes by determining the amount, composition and distribution of constitutive heterochromatin, and number and location of nucleolus organizer regions (NORs) in both species. Results showed that these two bloodsucker bugs possess high heterochromatin content and have an achiasmatic male meiosis, in which three regions can be differentiated in each autosomal bivalent: (i) terminal heterochromatic regions in repulsion; (ii) a central region, where the homologous chromosomes are located parallel but without contact between them; and (iii) small areas within the central region, where collochores are detected. Acanthocrios furnarii presented a single NOR on an autosomal pair, whereas P. uritui presented two NORs, one on an autosomal pair and the other on a sex chromosome. All NORs were found to be associated with CMA3 bright bands, indicating that the whole rDNA repeating unit is rich in G+C base pairs. Based on the variations in the diploid autosomal number, the presence of simple and multiple sex chromosome systems, and the number and location of 18S rDNA loci in the two Cimicidae species studied, we might infer that rDNA clusters and genome are highly dynamic among the representatives of this family.