Occurrence of sibling species of Lutzomyia longipalpis (Diptera : Psychodidae) in Venezuela: First evidence from reproductively isolated sympatric populations

The delimitation of cryptic species within the main vector of the American visceral leishmaniasis, Lutzomyia longipalpis, remains a topic of controversy. An analysis of generic variability based on 8 enzymatic loci revealed fixed differences in 2 diagnostic loci, adenylate kinase (Ak) and hexokinase (Hk), between sympatric and allopatric populations at 4 localities in Venezuela. The absence of heterozygotes for these 2 loci within 1 locality indicates, for the first time, the presence of 2 sympatric reproductively isolated populations or cryptic species within L. longipalpis. Significant differences were also detected between these cryptic species in the allele frequencies of glucose-6-phosphate isomerase (Gpi) and malate dehydrogenase, decarboxylating (Me). One species showed mean heterozygosities that ranged between 6.6% and 6.7%, with 1.6-1.9 alleles detected per locus, while the other had mean heterozygosities that ranged from 4.3% to 6.3%, with 1.3-1.6 alleles per locus. Comparisons of isozyme profiles with published data suggests that 1 species is similar to the L. longipalpis described in Colombian and Brazilian populations, whereas the other has not been previously reported.

Effect of biotic and abiotic factors on the tunneling behavior of Coptotermes gestroi and Heterotermes tenuis (Isoptera : Rhinotermitidae)

Using bidimensional arenas, the construction and spatial dispersion of tunnels constructed by Coptotermes gestroi and Heterotermes tenuis (Rhinotermitidae) was determined under different laboratory conditions. Workers of both species showed an increase of the tunneled area with the rise in temperature. The activity of workers of C gestroi also increased with the rise in soil moisture. Primary tunnels showed a high degree of dispersion in the arenas for all treatments. The presence of food did not influence the tunneling pattern of C. gestroi; but for H. tenuis there was a significant decrease in the number of tunnels. In addition, the type of substrate affected the tunneling pattern in both species. The understanding of food searching strategies of subterranean termites could contribute in the improvement of pest management programs based on the use of toxic baits. (c) 2005 Elsevier B.V. All rights reserved.

Neotenic formation in laboratory colonies of the termite Coptotermes gestroi after orphaning

The termite Coptotermes gestroi (Wasmann 1896) ( Rhinotermitidae: Coptotermitinae) is an exotic species in Brazil and information concerning its reproductive developmental biology is scarce. We induced the formation of neotenics in laboratory colonies through orphaning experiments. Orphaning experiments were conducted in three-year old colonies of C. gestroi kept under laboratory conditions. After three months, eight nymphoid neotenics were observed in one colony after queen removal. Histological analysis showed that these neotenics were non-functional. The results suggest that these individuals may have arisen from the first nymphal instar (N1) or from an early N1 instar after one or two larval moults. Neotenics also were recorded on two incipient colonies of C. gestroi that lost the queen naturally.

Soldiers initiate foraging activities in the subterranean termite, Heterotermes tenuis

Caste polyethism has been recorded in some termite species, however the foraging behavior of subterranean termites remains poorly known. Heterotermes tenuis Hagen (Isoptera: Rhinotermitidae) is a subterranean termite that is native to Brazil and is an agricultural and urban pest. The aim of this study was to investigate which caste acts as scouts when searching for food sources and determinate the percentages of each caste present in the foraging territories of field colonies of H. tenuis. Our results showed no significant differences among the caste proportions present in the foraging territories of the three colonies studied in the field. Laboratory experiments showed that minor soldiers were the most frequent initiators of foraging activities. This result suggests that the exploratory phase of the foraging behavior may be regulated by the number of soldiers present in the foraging territories of each colony.

Functional ultrastructure of the midgut of the fire ant Solenopsis saevissima Forel 1904 (Formicidae : Myrmicinae)

Solenopsis saevissima has a midgut composed of columnar, regenerative, and goblet cells. The midgut epithelium was covered by a basal lamina. Outside the basal lamina, layers of inner oblique, circular, and outer longitudinal muscles were present. Columnar cells showed a basal plasma membrane containing numerous folds, mitochondria, and the nucleus. Rough endoplasmic reticulum, Golgi bodies, membrane bounded vacuoles, and spherocrystals were found in this region. The apical plasma membrane was constituted by microvilli, which were above a region rich in mitochondria. Regenerative cells were found in groups lying by the basal lamina. Goblet cells were associated with an ion-transporting mechanism between the haemolymph and the midgut epithelium. These cells were lying by the midgut lumen and large microvilli were evident, but the cytoplasmic features were similar to the columnar cells.

Segmental specializations in the Malpighian tubules of the fire ant Solenopsis saevissima Forel 1904 (Myrmicinae): an electron microscopical study

The Malpighian tubules of workers of the fire ant Solenopsis saevissima (Myrmicinae) were analyzed by scanning and transmission electron microscopy in order to determine their functional organization and association with the hindgut epithelium. The ants showed six Malpighian tubules with three segments morphologically and structurally different. The proximal segment was long and its cells showed abundant smooth endoplasmic reticulum and lipid droplets, which suggest their role in lipid secretion. The mid segment was long and undulated and it was composed by the cells that showed the typical features of ion transporting epithelia. The distal segment, short and flattened, adheres to the rectum wall. The cells of this segment showed the basal lamina fused to that of the rectum, it is probable that this part of the tubule may play a role in ion and water uptake from the feces. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Interferentes eritrocitários e ambientais na anemia falciforme

Erythrocytes and environmental interferences on sickle cell anaemia Sickle cell anaemia runs na extremely variable clinical course At one end of spectrum, it is characterized by a crippling haemolitic anaemia, interspersed with severe exacerbations, or crises, yet it may be an extremely mild disorder, which is found only by chance on rotine haematological examination. The reasons are only partly understood for these remarkable differences in phenotypic expression of what appears to be the same genetic defect: they include the level of Hb Fetal, coinheritance of the alpha thalassaemia and of other genetic variantsthat has influence as genetic modulation in sickle cell anaemia. However, other genetics abnormalities of erythrocytes: G-6PD deficiency, spherocytosis and deficiencies of anti-oxidant enzymes(SOD, GPx and Catalase) probably interfereon the clinical course of sickle cell anaemia. The haplotypes of the chromosome (Bantu, Benin, Camaroon and Arab-Indian) bearing the sickle gene is associated with assorted haematological and clinical features that are likely, at least in part, to be mediated throgh effects on Hb Fetal concentration. Beyond these factors characterizes as erythrocytes interferents, there are the environmental interferents. Between environmental interferents become detached the socio-economic and cultural situation of each patient. These aspects have influence on the life of affected individuals including social interactions, family relations, peer interaction, intimate relationships, education, enployment, violence, spiritual attitudes and navigating complexities of the health care system, providers and their ancillary functions. As a result of this article it is proposed a protocol of laboratorial management of sickle cell syndrome with detach to sickle cell anaemia.

Preliminary studies on agonistic behavior between colonies of Coptotermes havilandi (Isoptera, Rhinotermitidae) in laboratory bioassays

Intercolonial aggression is being used to delimit foraging territory in termite species of subterranean termites. The advance of the introduced pest termite Coptotermes havilandi Holmgren in the interior of São Paulo State is increasing its economic impact as well as its interspecific and intraspecific competition in Brazil. In order to evaluate the intraspecific agonism among different colonies collected in urban areas of Sȧo Paulo State were set up a series of preliminary bioassays. Different combination of nestmates from field colonies of C. havilandi of Rio Claro city showed lack of agonistic behavior. Nevertheless, encounters among individuals from São Paulo and Rio Claro cities showed agonistic behaviors. These preliminary results suggest that caution should be taken in using intercolonial aggression to delimit the foraging territory of C. havilandi colonies in São Paulo State.

Influence of the labial gland's semiochemicals on the feeding behavior of Coptotermes havilandi (Isoptera: Rhinotermitidae)

In termites, food search is mediated by semiochemicals that are liberated by exocrine glands. In the present work we investigated the effect of the secretion of the labial glands of workers on the feeding behavior of Coptotermes havilandi. The secretion of the labial glands exhibited phagostimulant effect on the workers of this species. The soldiers showed a low activity in response to the labial gland extracts suggesting that this gland's secretion might inhibit the recruitment of soldiers. Behavioral evidence for the regulation of food consumption by workers was observed.

Key to the nests of Brazilian Epiponini wasps (Vespidae: Polistinae)

Brazil possesses the richest diversity of Epiponini wasps in the world. However, field identification of genera of these wasps, based on morphological features, is difficult without optical equipment. Therefore, this work presents a key to the Brazilian Epiponini genera based on the structural features of the nests.

Cuticular Hydrocarbons of Heterotermes tenuis (Isoptera: Rhinotermitidae): Analyses and Electrophysiological Studies

Termites have become an important pest of Eucalyptus and Pinus reforestations, sugarcane and other cultures. An alternative for the control of this pest would be the use of attractive traps that take in account the social behavior of these insects. Diverse factors are important for the insects in the localization of the habitat and the choice of the food and specific odors can facilitate this. Studies referring to Heterotermes tenuis (Isoptera: Rhinotermitidae) are scarce. The objective of this work was to analyze the tergal cuticular extract of H. tenuis and determine the selectivity and sensitivity of its antennae to the components of this extract by electroantennography (EAG). The composition of the cuticular extract was determined by GC-MS analysis. The hydrocarbons found were restricted to linear alkanes, being most abundant C24 to C27 that comprises ca. 65% of the total. Olefins were not detected. EAG and behavioral test responses to the cuticular hydrocarbons were greater and significantly different from the control and the high selectivity of the antennae to the extract indicates its potential as chemical messenger. Cuticular hydrocarbons mixture is species-specific and can be used to identify a given taxon without the diagnostic castes, soldiers or imagoes. Difference in the composition appears to relate with the type of habitat of specie.

Trail-Pheromone Specificity of Two Sympatric Termites (Rhinotermitidae) from Southeastern Brazil

Studies on pheromone specificity are of ecological interest in termite biology where different species share the same habitat. In this work we evaluated the role of the trail pheromones as a mechanism for the isolation of sympatric populations of Coptotermes gestroi and Heterotermes tenuis (Rhinotermitidae) in Brazil. Based on our results, we conclude that trail pheromones are potentially capable of separating sympatric colonies of these species. Furthermore, the trail-pheromone specificity found in these species could be explained by quantitative differences of the common component of the trail pheromone. However, secondary components on the trail pheromone may neutralize the quantitative differences of a common component. Activity bioassays showed that synthetic (Z,Z,E) 3,6,8-dodecatrien-1-ol may act as the common component of the trail pheromone of these species. Further studies should focus on the chemical identification of the trails laid by the termites.

Reproductive strategy of Coptotermes gestroi (Isoptera: Rhinotermitidae) in Brazil

The termite Coptotermes gestroi (Wasmann) (Rhinotermitidae) is an exotic species in Brazil. This species forms colonies headed by primary reproductives, however, non-functional neotenics are commonly found even in the presence of the imaginai pair. The presence of non-functional neotenics in C. gestroi colonies may correspond to a strategy of this termite species for rapid colonization in foreign areas, instead of a response to chemical control methods.

Note about the first swarming in a laboratory colony of Coptotermes gestroi (Isoptera: Rhinotermitidae)

A laboratory rearing of Coptotermes gestroi which swarmed from the reared colony is described.

Enzymatic variability among venoms from different subspecies of Apis mellifera (Hymenoptera: Apidae)

The enzymatic variability was analyzed in venom extracts from bees reared in different colonies of the Africanized, A. m. ligustica and A. m. carnica subspecies. The implications of this variation focused on the biochemistry differentiation and immunogenicity of these venoms. The results showed the existence of a huge variability among the subspecies as well as among the colonies for three out of the six tested components - hyaluronidase, acid phosphatase and proteases - suggesting the utilization of these features as possible biochemical markers. Furthermore, although not statistically significant, it was found that the Africanized bee venom presented slightly higher levels of protein content and esterase activity, when compared to the other subspecies. If the esterase plays a role in the pain intensity caused by the sting, as suggested elsewhere, this might suggest a reason for a bigger algogenicity of this venom in relation to that of European bees. On the other hand, A. m. ligustica bees presented the highest levels of proteolytic and acid phosphatase activities, whose functions are not enlightened in Hymenoptera venoms. The A. m. carnica workers presented the highest hyaluronidase and the lowest acid phosphatase activity levels. The extremely variable results among colonies of the same subspecies and among subspecies, for the tested venom components, justify the absence of correlation between allergic reactions and tests with pooled venom.