The metathoracic scent gland system in Hydrocorisae (Heteroptera: Nepomorpha)

Abstract. The metathoracic scent gland system is a basic feature of the order Heteroptera. It occurs widely not only in the terrestrial forms (Geocorisae) and water-surface bugs (Amphibicorisae) but also in the totally aquatic bugs (Hydrocorisae) and their littoral relatives (Ochteridae, Gelastocoridae). In Hydrocorisae the metathoracic scent gland conforms to Carayon's (1971) omphalian type (orifice median and undivided or, if divided, orifices close together towards the mid-ventral line) but shows marked differences in structure and physiological function between species from different families. There is taxonomic interest in the distribution of the three distinctly different types of metathoracic occlusion apparatus. Naucoridae and Belostomatidae have a median lip-valve, Notonectidae and Gelastocoridae a pair of stop-valves, Corixidae a median flap-valve. The valve opener muscles are usually dorso-ventral but are ventral in Corixidae; the cuticular microsculpture in the metathoracic efferent system specifically in Hydrocorisae with stop-valves (Notonectidae, Gelastocoridae) is similar to that widely present in Geocorisae. Groupings of Hydrocorisae from variations in the metathoracic occlusion apparatus differ from others based upon variations in the chemical constitution of the secretions. It is considered that the facts now known on metathoracic scent gland structure and function accord well with the hypothesis that Hydrocorisae constitute a polyphyletic assemblage.     

Systematics and biogeography of Rhodniini (Heteroptera: Reduviidae: Triatominae) based on 16S mitochondrial rDNA sequences

Aim The tribe Rhodniini is one of six comprising the subfamily Triatominae (Heteroptera: Reduviidae), notorious as blood‐sucking household pests and vectors of Trypanosoma cruzi throughout Latin America. The human and economic cost of this disease in the American tropics is considerable, and these bugs are unquestionably of great importance to man. Studies of the evolution, phylogeny, biogeography, ecology, physiology and behaviour of the Rhodniini are needed to help improve existing Chagas’ disease control programmes. The objective of the study reported here was to propose biogeographical hypotheses to explain the modern geographical distribution of the species of Rhodniini. Location Neotropical region. Methods We employed mitochondrial rDNA sequences (16S) currently available in GenBank to align sequences of Rhodniini species using ClustalX. The analyses included 16S sequences from predatory reduviid subfamilies (Stenopodainae, Ectrichodiinae, Harpactorinae, Reduviinae and Salyavatinae) present in GenBank as an outgroup. Cladistic analysis used the program PAUP to derive trees based on maximum parsimony (MP) and maximum likelihood (ML). Known distribution data for Rhodniini species were obtained from reviews and plotted on maps of South and Central America using the program iMap. An area cladogram was derived from the cladistic result to show the historical connections among the studied taxa and the endemic areas. The program TreeMap (Jungle Edition) was used to deduce taxon–area associations where the optimal solutions to explain the biogeographical hypothesis of the Rhodniini in the Neotropics were those with lowest total cost. Results Parsimony and maximum‐likelihood analysis of 16S rDNA sequences included 14 species of Rhodniini, as well as five species of predatory Reduviidae representing five of the predatory subfamilies. Tanglegrams were used to show the relationship between the Neotropical areas of endemism and Rhodniini species. When TreeMap with codivergence (vicariance) events were weighted as 0 and duplication (sympatry), lineage losses (extinction) and host switching (dispersal) were all weighted as 1, 20 scenarios were found to explain the biogeographical history of Rhodniini in the Neotropical region. Twelve of the optimal solutions with the lowest total cost were used to explain the biogeography of the Rhodniini in the Neotropics. These optimal reconstructions require six vicariance events, 20 duplications (sympatry), at least three dispersals, and at least one extinction event. Main conclusions The Rhodniini have a complex biogeographical history that has involved vicariance, duplications (sympatry), dispersal and extinction events. The main geological events affecting the origin and diversification of the Rhodniini in the Neotropics were (1) uplift of the Central Andes in the Miocene or later, (2) break‐up of the Andes into three separate cordilleras (Eastern, Central and Western) in the Plio‐Pleistocene, (3) formation of a land corridor connecting South and North America in the Pliocene, and (4) uplift of the Serra do Mar and Serra da Mantiqueira mountain systems between the Oligocene and Pleistocene. The relationships and biogeographical history of the species of Rhodniini in the Neotropical region probably arose from the areas of endemism shown in our work.     

Effects of Selection Logging on Birds in Northern Belize1

We compared bird diversity and frequency in selection logged and unlogged forest to determine the effects of recent selection logging on avian biodiversity in a subtropical, moist evergreen forest. We used a combination of mist netting and fixed-radius point counts to assess bird communities in February and March 1993 in northwestern Belize. Vegetation structure and composition was similar in logged and unlogged forest. The 66 most common species occurred with statistically similar frequency in logged and unlogged forest although 13 species were two times more frequent in intact forest. Numbers of total bird species were similar between logging gaps and the logged forest matrix, and between the logged forest matrix and unlogged forests. A comparison of numbers of species in 26 guilds based on migration strategy, diet, foraging substrate, and height strata also showed them to be similar regardless of logging history. Our results differed from previous studies that reported lower bird species richness and abundance of individual species in logged tropical forests than in unlogged forest. The differences might be explained by the lower logging intensity and/or greater levels of natural disturbance in our study area compared to previous studies.     

Taxonomic and Numerical Resolutions of Nepomorpha (Insecta: Heteroptera) in Cerrado Streams

Transformations of natural landscapes and their biodiversity have become increasingly dramatic and intense, creating a demand for rapid and inexpensive methods to assess and monitor ecosystems, especially the most vulnerable ones, such as aquatic systems. The speed with which surveys can collect, identify, and describe ecological patterns is much slower than that of the loss of biodiversity. Thus, there is a tendency for higher-level taxonomic identification to be used, a practice that is justified by factors such as the cost-benefit ratio, and the lack of taxonomists and reliable information on species distributions and diversity. However, most of these studies do not evaluate the degree of representativeness obtained by different taxonomic resolutions. Given this demand, the present study aims to investigate the congruence between species-level and genus-level data for the infraorder Nepomorpha, based on taxonomic and numerical resolutions. We collected specimens of aquatic Nepomorpha from five streams of first to fourth order of magnitude in the Pindaíba River Basin in the Cerrado of the state of Mato Grosso, Brazil, totaling 20 sites. A principal coordinates analysis (PCoA) applied to the data indicated that species-level and genus-level abundances were relatively similar (>80% similarity), although this similarity was reduced when compared with the presence/absence of genera (R = 0.77). The presence/absence ordinations of species and genera were similar to those recorded for their abundances (R = 0.95 and R = 0.74, respectively). The results indicate that analyses at the genus level may be used instead of species, given a loss of information of 11 to 19%, although congruence is higher when using abundance data instead of presence/absence. This analysis confirms that the use of the genus level data is a safe shortcut for environmental monitoring studies, although this approach must be treated with caution when the objectives include conservation actions, and faunal complementarity and/or inventories.     

中国蝽科新记录属种（半翅目：异翅亚目）

报道中国蝽科(Heteroptera: Pentatomidae)3个中国新记录属:库蝽属 Cuspicona Dallas、赫蝽属Hermolaus Distant、昂角蝽属 Oncinoproctus Breddin,以及6个新记录种:绿库蝽 Cuspicona antica Vollenhoven、赫蝽 Hermolaus typicus Distant、笑曼蝽 Menida atkinsoni Distant、昂角蝽 Oncinoproctus griseolus Breddin、斑卷蝽 Paterculus aberrans Distant 和短线鳖蝽 Rolstoniellus malacanicus (Yang)。并给出各种的虫体背腹面照片和生殖节结构图。除绿库蝽的观察标本保存在中国科学院动物所(IZCAS)以外,其余研究观察标本保存在南开大学昆虫研究所标本馆(NKUM)。     

Seven decades of monitoring the aquatic bug fauna of Lake Balaton (Heteroptera: Nepomorpha)

Detailed faunistic data originating from four sampling series of aquatic Heteroptera (Nepomorpha) in the Lake Balaton (the largest shallow lake of Central Europe) between 1928 and 2002 were analysed. A comparative analysis confirmed that the aquatic bug fauna of this great lake can be established with suitable accuracy if it is sampled by different but devoted collectors. So far 26 species of aquatic bugs have been reported from here. The fauna changed considerably during the seven decades. Species lists of the four basins of the lake established during the four sampling periods show characteristic differences. Not only the frequency of four Micronecta species (Micronecta griseola, M. pusilla, M. scholzi, M. minutissima) changed characteristically but there has been a distinct change in the ratio of rare species too. Rare species were present in significantly higher proportion in the period 1928–1930 than in any of the later samplings between 1984 and 2002. All these changes run parallel with the direction of anthropogenic influences.     

Phylogeny and diversification of the true water bugs (Insecta: Hemiptera: Heteroptera: Nepomorpha)

Climate fluctuations and tectonic reconfigurations associated with environmental changes play large roles in determining patterns of adaptation and diversification, but studies documenting how such drivers have shaped the evolutionary history and diversification dynamics of limnic organisms during the Mesozoic are scarce. Members of the heteropteran infraorder Nepomorpha, or aquatic bugs, are ideal for testing the effects of these determinants on their diversification pulses because most species are confined to aquatic environments during their entire life. The group has a relatively mature taxonomy and is well represented in the fossil record. We investigated the evolution of Nepomorpha based on phylogenetic analyses of morphological and molecular characters sampled from 115 taxa representing all 13 families and approximately 40% of recognized genera. Our results were largely congruent with the phylogenetic relationships inferred from morphology. A divergence dating analysis indicated that Nepomorpha began to diversify in the late Permian (approximately 263 Ma), and diversification analyses suggested that palaeoecological opportunities probably promoted lineage diversification in this group.     

Ehrendorferiana, a new genus of Neotropical jumping plant lice (Insecta: Hemiptera: Psylloidea) associated with conifers (Cupressaceae)

Ehrendorferiana and its two included new species, E. austrocedri (the type species) and E. fitzroyae, are diagnosed. The new genus is a member of the predominantly temperate Neotropical subfamily Aphalaroidinae (Psyllidae). Based on the absence of metabasitarsal spurs it forms a likely monophyletic group with Baccharopelma, Panisopelma and Russelliana. The absence or paucity of long dorsal or marginal setae on the wing pads and caudal plate suggests a probable sister-taxon relationship with Russelliana. Apart from two species of Triozidae from New Zealand on Podocarpaceae, Ehrendorferiana is unique within Psylloidea in its host association with conifers, viz. Austrocedrus and Fitzroya (both Cupressaceae).

See also Electronic Supplement at: http://www.senckenberg.de/odes/05-12.htm     

Differences in distress: Variance and production of American Crocodile (Crocodylus acutus) distress calls in Belize

Acoustic communication of American Crocodiles (Crocodylus acutus) is relatively understudied. Our overall aim was to determine the acoustic structure of wild American Crocodile distress calls, distinguish call differences among size classes (hatchling, juvenile, sub‐adult, and adult), and investigate call production on a gradient of human disturbance. American Crocodile distress calls have strong frequency modulation and are comprised of multiple harmonics in a downsweeping pattern. Measured parameters (total duration, first quartile duration, maximal frequency, first quartile frequency, end frequency, slope of first quartile, slope of last quartiles) differed significantly among size classes (p < .05). Hatchling distress calls are higher in frequency and strongly modulated, whereas calls produced by sub‐adults and adults showed little modulation, are lower in frequency, and have greater overall duration. Proportion of crocodiles that produced distress calls during capture differed by size class and sampling location, particularly adult distress calls which are reported here to be produced with undocumented frequency. We determined that American Crocodiles of all size classes produce distress calls at varying rates among study sites. Our results demonstrate that American crocodiles produce distress call more frequently at sites with higher anthropogenic activity. Measured call parameters of juveniles and hatchling American crocodiles also varied among sites in relation to human disturbance. Calls recorded at sites of high anthropogenic impact have increased duration and less modulation which may adversely affect response to emitted distress calls. Proportional and call parameter variances suggest anthropogenic activity as a driver for increased call production and alteration of call parameters at high human‐impacted sites.     

Habitat use,abundance, and persistence of Neotropical migrant birds in a habitat matrix in northeast Belize

ABSTRACT To ensure adequate protection of nonbreeding habitats used by Neotropical migratory landbirds, we must first address questions about habitat use and quality. On the Yucatan peninsula, migrants use many habitats, several of which remain unstudied, and methodological differences preclude interhabitat comparisons based on studies to date. We used distance sampling along line transects in six habitats in northeast Belize to examine use of previously unstudied habitats (e.g., salt marsh) by Neotropical migrants and to permit comparison across habitats. We calculated unadjusted and adjusted (for detectability) density estimates for individual migrant species and for all species combined to generate hypotheses about habitat quality based on the assumption that density and quality are positively correlated. Adjusted density estimates for all migrants were highest in black mangrove habitat (1799 ± 110 ind/km²), intermediate in three forest types and milpa (range 598–802 ind/km²), and lowest in salt marsh (207 ± 32.3 ind/km²). By combining density estimates with habitat availability in our study region, we estimated that evergreen forest and black mangrove supported 70% and 9% of the region's migrant population, respectively. At the species level, five of the 10 most common species had habitat preferences (>50% detections in one habitat). Given the diversity of habitat preferences among species and apparent seasonal movements, our results indicate that Neotropical migrants in northeast Belize are dependent on a matrix of interconnected habitats.     

Polymorphism of spermatozoa in Largus rufipennis Laporte 1832 (Heteroptera: Pyrrhocoroidea: Largidae)

The production of polymorphic spermatozoa has been registered in various insect orders such as Diptera, Lepidoptera, and Hemiptera. In this work, morphology of two types of spermatozoa produced by Largus rufipennis was reported for the first time in the Largidae family. For this, techniques including optical and transmission electron microscopy were used. Spermatozoa measured, on the average, 260 and 200 μm, and both types possessed a nucleus measuring on the average 65 μm. No ultrastructural differences were observed between the two spermatozoa types from L. rufipennis. The head region is composed of an acrosome, a nucleus, and part of the centriolar adjunct. The centriolar adjunct is in parallel with the nucleus and followed by mitochondrial derivates. The flagellum consists of an axoneme (9 + 9 + 2 microtubules) and two mitochondrial derivatives; no other accessory bodies were observed. The mitochondrial derivatives are symmetric in size and diameter. A similar quantity of the two spermatozoa types was observed in the seminal vesicle (57% of the large type and 43% of the small type), while in the spermatheca of the female, the larger spermatozoa were preferentially stored (87%). These results permit discussions concerning of the species biology reproduction, most specifically sperm competition strategies.     

Testicular,spermatogenesis and sperm morphology in Martarega bentoi (Heteroptera: Notonectidae)

The testicular, spermatogenesis and sperm morphology of the backswimmer Martarega bentoi was described using light and transmission electron microscopy. In this species, a pair of testes, two deferent ducts, two different pairs of accessory glands, and an ejaculatory duct form the male reproductive system. Each testis consists of two testicular follicles, which are arranged side by side in snail shape. The follicles are filled with cysts at different stages of spermatogenesis, but in the same cyst the germ cells (up to 64) are in the same stage. At the end of spermatogenesis, the sperm cells are very long, with the flagellum measuring approximately 2500 μm in length, the nucleus only 19 μm, and the acrosome, with two distinct regions, 300 μm. The flagellum is composed of an axoneme, with a 9 + 9 + 2 microtubular pattern, and 2 asymmetric mitochondrial derivatives (MDs). These have the anterior ends inserted into two cavities at the nucleus base, exhibit two paracrystalline inclusions, and have bridges linking them to the axoneme. Few spermatozoa per cyst, asymmetry in size and shape of the MDs, as well as their insertion at the nuclear base are characteristics considered derived, and that differentiate the sperm of M. bentoi from those of the Nepomorpha, Belostomatidae and Nepidae.     

The Human Ecology of Mayan Cacao Farming in Belize

This paper describes the expansion of cacao farming among Mayan farmers in the Toledo District, Belize, during the 1980s and why the expansion took place. Land planted with cacao increased from 237 acres in 1983 to 1014 acres in 1990. The number of cacao farmers increased from 70 to 365 and beans sold to Hershey Foods Corporation increased from 1086 to almost 32,000 pounds. This paper describes the distribution of cacao farming in space and time and it uses a holistic approach to explain land-use/cover change. An ecologic model is proposed that explains the cacao expansion that involves the interaction of several forces. During the 1980s, Hershey Foods Corporation provided an unlimited market for cacao beans, agricultural loans and technical assistance were provided by international development agencies, and Mayan farmers planted cacao to gain usufruct rights to reservation and national land. During the 1990s a British organic food company became the new market for cacao beans.     

Microstructure of pretarsal pulvilli in shield bug Acanthosoma spinicolle (Heteroptera: Acanthosomatidae)

Shield bugs effectively attach themselves on both rough and smooth surfaces, but their advanced biological attachment devices have not been studied closely. Our fine structural examination of the attachment devices in the shield bug A. spinicolle reveals a unique system to achieve extraordinary adhesion that allows vertical climbing. Each appendage has a pair of tarsal claws that attach to rough substrates and a pair of pretarsal pulvilli that attach to smooth surfaces. Similar to other heteropteran insects, the pulvilli of this bug are categorized as a wet adhesion system, which makes use of an adhesive fluid from the pad secretion. However, this deformable pad creates a regular pattern of contact with the mating surface with a compact array of microfolds and setae with filamentous distal protrusions. To date, this distinctive microstructure in pulvilli pads has never been reported. These microstructural characteristics should be further studied to understand biological adhesion as well as create biomimetic applications.     

Immature stages of three species of Blissidae from Mexico (Heteroptera: Lygaeoideae)

Chinch bugs are associated with several species of monocots, and species of Gramineae are the principal plants utilized. In Mexico, 24 species of Blissidae have been recorded. The immature stages of Ischnodemus sallei (Signoret), Toonglasa munda (Slater & Wilcox), and T. tumorosis (Slater & Wilcox) are described and illustrated. These species have been recorded from several species of bamboo. Distributional records in Mexico and the host plants of these chinch bugs are also included.     

Documentation of brochosomes within Hemiptera, with emphasis on Heteroptera (Insecta)

Brochosomes, small secretory particles often found in abundance on the integument of leafhoppers, are currently considered a unique feature of the family Cicadellidae. The present work documents, for the first time, brochosomes in two other groups of Hemiptera, i.e. Psylloidea and Heteroptera. In Heteroptera the occurrence of relatively large amounts of brochosomes on various body parts is documented in several species of different families. Morphological structures of the legs and the setation are illustrated in detail and compared to those of Cicadellidae. The results are based on scanning electron microscopy (SEM) examination of museum specimens. The possible function of brochosomes within Hemiptera is briefly discussed.     

Copepods of the genus Halicyclops (Cyclopidae) from Belize

Halicyclops tetracanthus sp.n. and H. venezuelaensis Lindberg were found in the Sittee River Estuary, Belize. The new species is distinguished from all its congeners by having a distal spine and two spiniform heterogeneously ornamented setae on the inner margin of the terminal endopodal segment of legs 2 and 3. Halicyclops venezuelaensis, previously known only from Venezuela is redescribed based on specimens of both sexes. Differences in the ornamentation as well as in the relative length of some setae of the maxilla and maxilliped are pointed out as additional useful characters in the taxonomy of Halicyclops. This is the first record of Halicyclops in Belize.     

线粒体DNA序列在半翅目异翅亚目昆虫分子系统学上的应用

随着PCR技术的发展以及大量DNA序列的累积,昆虫分子系统学近年来快速发展。线粒体DNA(mtDNA)序列相对于核内DNA序列进化速率较快,常被用于昆虫的系统发育研究。本文综述了国内外学者利用各种线粒体DNA序列来研究半翅目异翅亚目昆虫系统发育的研究概况。总结发现,COⅠ、COⅡ、12S rDNA、16S rDNA、Cytb、ND1、ND2和ND5等线粒体区段被用于半翅目异翅亚目系统发育的研究,其中以COI、COⅡ、16S rDNA和Cytb应用最广泛,但目前尚缺乏不同分子标记间的联合分析。进一步的研究最好在选定半翅目异翅亚目昆虫的分类阶元(如科间、亚科间、科内属间、种间或种内)后,集中测定线粒体某几个区段的DNA序列,然后进行单一分析和联合分析,并与传统形态学研究结果进行比较,可望全面分析半翅目异翅亚目昆虫的系统发育关系。