Mosquito (Diptera: Culicidae) Diversity of a Forest-Fragment Mosaic in the Amazon Rain Forest

To study the impact of Amazonian forest fragmentation on the mosquito fauna, an inventory of Culicidae was conducted in the upland forest research areas of the Biological Dynamics of Forest Fragments Project located 60 km north of Manaus, Amazonas, Brazil. The culicid community was sampled monthly between February 2002 and May 2003. CDC light traps, flight interception traps, manual aspiration, and net sweeping were used to capture adult specimens along the edges and within forest fragments of different sizes (1, 10, and 100 ha), in second-growth areas surrounding the fragments and around camps. We collected 5,204 specimens, distributed in 18 genera and 160 species level taxa. A list of mosquito taxa is presented with 145 species found in the survey, including seven new records for Brazil, 16 new records for the state of Amazonas, along with the 15 morphotypes that probably represent undescribed species. No exotic species [Aedes aegypti (L.) and Aedes albopictus (Skuse)] were found within the sampled areas. Several species collected are potential vectors of Plasmodium causing human malaria and of various arboviruses. The epidemiological and ecological implications of mosquito species found are discussed, and the results are compared with other mosquito inventories from the Amazon region.

Taxonomic and Phylogenetic Relationships Between Species of the Genus Culex (Diptera: Culicidae) From Brazil Inferred From the Cytochrome c Oxidase I Mitochondrial Gene

Species of the genus Culex Linnaeus have been incriminated as the main vectors of lymphatic filariases and are important vectors of arboviruses, including West Nile virus. Sequences corresponding to a fragment of 478 bp of the cytochrome c oxidase subunit I gene, which includes part of the barcode region, of 37 individuals of 17 species of genus Culex were generated to establish relationships among five subgenera, Culex, Phenacomyia, Melanoconion, Microculex, and Carrollia, and one species of the genus Lutzia that occurs in Brazil. Bayesian methods were employed for the phylogenetic analyses. Results of sequence comparisons showed that individuals identified as Culex dolosus, Culex mollis, and Culex imitator possess high intraspecific divergence (3.1, 2.3, and 3.5%, respectively) when using the Kimura two parameters model. These differences were associated either with distinct morphological characteristics of the male genitalia or larval and pupal stages, suggesting that these may represent species complexes. The Bayesian topology suggested that the genus and subgenus Culex are paraphyletic relative to Lutzia and Phenacomyia, respectively. The cytochrome c oxidase subunit I sequences may be a useful tool to both estimate phylogenetic relationships and identify morphologically similar species of the genus Culex.

Resurrection of Two Species From Synonymy of Anopheles (Nyssorhynchus) strodei Root, and Characterization of a Distinct Morphological Form From the Strodei Complex (Diptera: Culicidae)

Anopheles albertoi Unti and Anopheles arthuri Unti are revived from the synonymy with Anopheles strodei Root, and a distinct morphological form (designated in this study as Anopheles CP Form) from the Strodei Complex of Anopheles (Nyssorhynchus) is characterized. The male genitalia of An. arthuri and An. albertoi are described and illustrated for the first time. An. strodei, An. arthuri, and An. albertoi were first distinguished based on scanning electron microphotos of the eggs, and then each egg type was associated with diagnostic characters of the male genitalia. Identification of Anopheles CP Form was based on morphological characters of the male genitalia, characterized and illustrated in this study. Molecular phylogenetic analysis was most clear when an outgroup was not included, in which case using the nuclear white gene, or the white gene in combination with the mitochondrial cytochrome c oxidase subunit I (COI) gene, clearly separated these four taxa. When Anopheles quadrimaculatus Say and Anopheles stephensi Liston were included as an outgroup, combined white and COI data resolved An. strodei and An. albertoi, whereas An. arthuri was not well resolved. The single sequence of Anopheles CP Form was recovered well separated from other groups in all analyses.

Survival, Population Size, and Gonotrophic Cycle Duration of Nyssomyia neivai (Diptera: Psychodidae) at an Endemic Area of American Cutaneous Leishmaniasis in Southeastern Brazil

The survival, absolute population size, gonotrophic cycle duration, and temporal and spatial abundance of Nyssomyia neivai (Pinto) were studied in a rural area endemic for American cutaneous leishmaniasis (ACL) in Conchal, Sao Paulo State, southeastern Brazil, using mark-release-recapture techniques and by monitoring population fluctuation. The monthly abundance exhibited a unimodal pattern, with forest and domicile habitats having the highest relative abundances. A total of 1,873 males and 3,557 females were marked and released during the six experiments, of which 4.1-13.0% of males and 4.1-11.8% of females were recaptured. Daily survivorship estimated from the decline in recaptures per day was 0.681 for males and 0.667 for females. Gonotrophic cycle duration was estimated to be 4.0 d. Absolute population size was calculated using the Lincoln Index and ranged from 861 to 4,612 males and from 2,187 to 19,739 females. The low proportion of females that reach the age when they are potentially infective suggests that N. neivai has a low biological capacity to serve as a vector and that factors such as high biting rates and opportunistic feeding behavior would be needed to enable Leishmania (Viannia) braziliensis Vianna transmission. This agreed with the epidemiological pattern of ACL in southeastern Brazil that is characterized by low incidence, with isolated cases acquired principally within domiciliary habitats.

Insight into Anopheles (Nyssorhynchus) (Diptera: Culicidae) Species from Brazil

Anopheles (Nyssorhynchus) benarrochi s.l., Anopheles (Nyssorhynchus) oswaldoi s.l., and Anopheles (Nyssorhynchus) konderi s.l. collected in Acrelandia, state of Acre, Brazil, were identified based on morphological characters of the male genitalia, fourth-instar larvae, and pupae. Morphological variation was observed in the male genitalia of these species in comparison with specimens from other localities in Brazil. DNA sequence from the nuclear ribosomal second internal transcribed spacer of individuals identified as An. benarrochi s.l. by using male genitalia characteristics showed that the various morphological forms are conspecific but are distinct from An. benarrochi B from Colombia. Anopheles konderi s.l. and An. oswaldoi s.l. both misidentified as An. oswaldoi s.s. (Peryassu) throughout Brazil, may actually comprise at least two undescribed species. Diagnostic morphological characteristics of the male genitalia are provided to distinguish Anopheles benarrochi s.l., Anopheles oswaldoi s.l., and Anopheles konderi s.l. from morphologically similar species. Incrimination of An. oswaldoi s.s. in malaria transmission in Brazil needs further investigation because other undescribed species from Acre may have been confounded with this taxon.

Ecological aspects of mosquitoes (Diptera: Culicidae) in an Atlantic forest area on the north coast of Rio Grande do Sul State, Brazil

Mosquito diversity was determined in an area located on the southern limit of the Atlantic Forest on the north coast of Rio Grande of Sul State. Our major objective was to verify the composition, diversity, and temporal distribution of the mosquito fauna, and the influence of temperature and rainfall. Samplings were performed monthly between December, 2006 and December, 2008, in three biotopes: forest, urban area, and transition area, using CDC light traps and a Nasci vacuum. A total of 2,376 specimens was collected, from which 1,766 (74.32%) were identified as 55 different species belonging to ten genera. Culex lygrus, Aedes serratus, and Aedes nubilus were dominant (eudominant) and constant throughout samplings. The forest environment presented the highest species dominance (D(S) = 0.20), while the transition area showed the highest values of diversity (H` = 2.55) and evenness (J` = 0.85). These two environments were the most similar, according to the Morisita-Horn Index (I(M-H) = 0.35). Bootstrap estimates showed that 87.3% of the species occurring in the region were detected. The seasonal pattern showed a greater abundance of mosquitoes between May and October, indicating the period to intensify entomological surveillance in that area. Journal of Vector Ecology 36 (1): 175-186. 2011.

Density and survival rate of Culex quinquefasciatus at Parque Ecologico do Tiete, Sao Paulo, Brazil

Parity rate, gonotrophic cycle length, and density of a Culex quinquefasciatus female population was estimated at the Parque Ecologico do Tiete (PET), Sao Paulo, Brazil. Adult Cx. quinquefasciatus females were collected from vegetation along the edges of a polluted drainage canal with the use of a battery-powered backpack aspirator from September to November 2005 and from February to April 2006. We examined 255 Cx. quinquefasciatus ovaries to establish the parity rate of 0.22 and determined the gonotrophic cycle length under laboratory conditions to be 3 and 4 days. From these data, we calculated the Cx. quinquefasciatus survival rate to be 0.60 and 0.68 per day. Density of the Cx. quinquefasciatus female (5.71 females per m(2)) was estimated based on a population size of 28,810 individuals divided by the sampled area of 5,040 m(2). Results of all experiments indicate medium survivorship and high density of the Cx. quinquefasciatus female population. This species is epidemiologically relevant in the PET area and should be a target of the vector control program of Sao Paulo municipality.

Misidentification of two Brazilian triatomes, Triatoma arthurneivai and Triatoma wygodzinskyi, revealed by geometric morphometrics

Triatoma arthurneivai Lent & Martins and Triatoma wygodzinskyi Lent (Hemiptera: Reduviidae) are two Brazilian species found in the sylvatic environment. Several authors may have misidentified T. arthurneivai and consequently published erroneous information. This work reports the use of geometric morphometric analysis on wings in order to differentiate T. arthurneivai and T. wygodzinskyi, and thus to detect possible misidentifications. Triatomines collected from the field in the states of Minas Gerais and Sao Paulo, and from laboratory colonies, were used. Analyses show a clear differentiation between specimens of T. arthurneivai and T. wygodzinskyi. This indicates that T. arthurneivai populations from Sao Paulo state were misidentified and should be considered as T. wygodzinskyi. This study also suggests that T. arthurneivai is an endemic species from Serra do Cipo, Minas Gerais state.

Redescription of Anopheles (Nyssorhynchus) lutzii, and Resurrection of Anopheles guarani From Synonymy With An. lutzii (Diptera: Culicidae)

Anopheles lutzii Cruz (Diptera: Culicidae) is redescribed using specimens collected in Pariquera-Acu, Vale do Ribeira, state of Sao Paulo, southeastern Mata Atlantica, Brazil. Specimens of An. lutzii from Vale do Ribeira and two females from Nova Friburgo, Rio de Janeiro, are compared with three syntypes of An. lutzii, deposited in the Instituto Oswaldo Cruz, Rio de Janeiro. Comparisons of external morphology of specimens from the type locality of Anopheles guarani Shannon demonstrate it is a valid species, and that Anopheles niger Theobald is conspecific with Anopheles guarani stat. rev. The adult male, male terminalia, fourth-instar larva, and pupa of An. guarani stat. rev. are described for the first time. Diagnostic characters of the male and female, male terminalia, fourth-instar larva and pupa of An. lutzii and An. guarani stat. rev. are illustrated. An. guarani stat. rev. is herein resurrected from the synonymy with An. lutzii, and Anopheles niger comb. nov. is transferred from the synonymy with An. lutzii to the synonymy of An. guarani stat. rev.

Selective preying of the sphecid wasp Trachypus boharti on the meliponine bee Scaptotrigona postica: potential involvement of caste-specific cuticular hydrocarbons

The specialist digger wasp Trachypus boharti Rubio-Espina preys exclusively on males of the stingless bee Scaptotrigona postica Latreille 1807, although the hunting attacks involve both male and worker bees of S. postica and members of its own species. To understand the mechanism of prey selection, the cuticular hydrocarbon patterns of workers and males of S. postica are analyzed in detail, and the mandibular secretion of males is examined. The cuticular profiles of males and workers are distinctively different. The major group of cuticular compounds, heptacosene isomers, is twice as abundant in workers as in males. There is no clear distinction between worker and male mandibular secretions. Such a distinct and straightforward caste-specific difference in cuticular hydrocarbons could function as a recognition cue by which T. boharti distinguishes between workers and males of S. postica.

Behavioral suites mediate group-level foraging dynamics in communities of tropical stingless bees

Competition for floral resources is a key force shaping pollinator communities, particularly among social bees. The ability of social bees to recruit nestmates for group foraging is hypothesized to be a major factor in their ability to dominate rich resources such as mass-flowering trees. We tested the role of group foraging in attaining dominance by stingless bees, eusocial tropical pollinators that exhibit high diversity in foraging strategies. We provide the first experimental evidence that meliponine group foraging strategies, large colony sizes and aggressive behavior form a suite of traits that enable colonies to improve dominance of rich resources. Using a diverse assemblage of Brazilian stingless bee species and an array of artificial ""flowers"" that provided a sucrose reward, we compared species` dominance and visitation under unrestricted foraging conditions and with experimental removal of group-foraging species. Dominance does not vary with individual body size, but rather with foraging group size. Species that recruit larger numbers of nestmates (Scaptotrigona aff. depilis, Trigona hyalinata, Trigona spinipes) dominated both numerically (high local abundance) and behaviorally (controlling feeders). Removal of group-foraging species increased feeding opportunities for solitary foragers (Frieseomelitta varia, Melipona quadrifasciata and Nannotrigona testaceicornis). Trigona hyalinata always dominated under unrestricted conditions. When this species was removed, T. spinipes or S. aff. depilis controlled feeders and limited visitation by solitary-foraging species. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines.

Chemical Communication in the Gregarious Psocid Cerastipsocus sivorii (Psocoptera: Psocidae)

The objectives of this study were: (1) to test the existence of an aggregation pheromone in the gregarious psocid Cerastipsocus sivorii; (2) to compare the attractiveness of odors from different aggregations; (3) to test whether nymphs are able to chemically recognize damage-released alarm signals. In a choice experiment conducted in the laboratory, we showed that psocids are able to detect chemical cues from groups of conspecifics. Laboratory experiments also showed that nymphs are capable of chemically recognizing the aggregations where they came from. Finally, in a field experiment, most aggregations dispersed when exposed to the body fluids of a crushed conspecific, but no aggregations dispersed upon exposure to a crushed termite. The implications of these results for the evolution of sociality in psocopterans are discussed.

Trophallaxis in Dehydrated Leaf Cutting Colonies of Atta sexdens rubropilosa (Hymenoptera: Formicidae)

Trophallaxis, the transfer of liquid among individuals by oral regurgitation or anal deposition, occurs in many insect groups including ants. The first indication that trophallaxis could occur in leaf cutting ants (Atta sexdens rubropilosa) was made by Autuori in 1942. He reported water collection by this ant species, and highlighted what in those days was an undescribed behavior for this species. In 2005, Da-Silva and Ribeiro presented preliminary results suggesting the existence of trophallaxis in A. sexdens rubropilosa. Here we report on a formal test of the hypothesis of trophallaxis in that species. Our approach was to test ant pairs in which only one individual (Group I) had access to blue-dyed water and the other individual (Group II), a nest-mate, came from a colony dehydrated by offering dry crushed corn for fungal growth. Positive results for trophallaxis were obtained in ants from four colonies and accounted for 33%-46% of all tests in which ants from Group I drank dyed water. These results indicate that trophallaxis occurs in this species.

Colony dehydration and water collection by specialized caste in the leaf-cutting ant Atta sexdens rubropilosa

Social organization enables leaf-cutting ants to keep appropriate micro-ecological nest conditions for the fungus garden (their main food), eggs, larvae and adults. To maintain stability while facing changing conditions, individual ants must perceive destabilising factors and produce a proper behavioral response. We investigated behavioral responses to experimental dehydration in leaf-cutting ants to verify if task specialization exists, and to quantify the ability of ant sub-colonies for water management. Our setup consisted of fourteen sub-colonies, ten of which were randomly assigned to different levels of experimental dehydration with silica gel, whereas the remaining four were controls. The ten experimental sub-colonies were split into two groups, so that five of them had access to water. Diverse ant morphs searched for water in dehydrated colonies, but mainly a caste of small ants collected water after sources had been discovered. Size specialization for water collection was replicable in shorter experiments with three additional colonies. Ants of dehydrated colonies accumulated leaf-fragments on the nest entrance, and covering the fungus garden. Behaviors that may enhance humidity within the nests were common to all dehydration treatments. Water availability increased the life span of dehydrated colonies.