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PubMed2004

B chromosomes in Sternorrhyncha (Hemiptera, Insecta).

In the hemipteroid insects of the suborder Sternorrhyncha, B chromosomes are relatively common in comparison with other suborders of Hemiptera. However, the occurrence of supernumerary chromosomes is restricted, in most cases, to several genera or closely related species. At least in some species of Psylloidea with the XY sex determination system, a mitotically stable B chromosome integrated into an achiasmatic segregation system with the X, and became fixed as a Y chromosome. In some Aphidoidea with a multiple X system of sex determination, B chromosomes appear to be in fact non-functional X chromosomes. Supernumerary chromosomes thus probably play an important role in the evolution of sex determination systems in Sternorrhyncha.

Animals↗
PubMed1986

Persistence of hemoglobin allergenicity and antigenicity during metamorphosis of Chironomidae (Insecta: Diptera).

Chironomid hemoglobins are potent allergens. The allergenic and antigenic activities of these hemoglobins are studied with the help of RAST, RAST inhibition and double immunodiffusion. Human as well as rabbit antisera were used. It was shown that hemoglobins are the main antigenic/allergenic components in extracts of Camptochironomus tentans larvae. Furthermore, immunological cross-reactivity among larvae, pupae and adult midges of this species are shown to be due to the existence of hemoglobin antigenic determinants in all developmental stages of this insect.

Animals↗
PubMed2004

Differences in the effects of salinity on larval growth and developmental programs of a freshwater and a euryhaline mosquito species (Insecta: Diptera, Culicidae).

The effects of salinity on growth and development of the euryhaline Ochlerotatus taeniorhynchus and the freshwater Aedes aegypti are compared. O. taeniorhynchus grow larger, and have greater intrinsic growth rates, than A. aegypti. Females of each species attain greater mass, take longer to develop, and have greater growth rates than do males. In O. taeniorhynchus, pupal mass, larval stage duration and growth rates (dry mass) increase with salinity, whereas growth rates (wet mass) remain constant across salinities, reflecting a decrease in percent body water. The pupal mass (wet or dry) of O. taeniorhynchus is determined primarily by effects of salinity on the rate of assimilation of dry mass, because the latter contributes very strongly to final pupal mass in both species. In contrast, the duration of A. aegypti larval stage follows a upsilon-shaped curve, with most rapid development at intermediate salinities. Growth rates of A. aegypti decrease with increasing salinity, and percent body water is constant across salinities. As for O. taeniorhynchus, duration of A. aegypti larval stage increases at high salinity. However, this increase in larval stage duration cannot compensate for the decrease in growth rate at high salinity, resulting in an overall decrease in both wet and dry pupal mass at high salinity. Thus, salinity has fundamentally different effects on developmental programs and phenotypic plasticity in the two species investigated.

Aedes↗
PubMed2004

Ontogenesis of the attachment ability in the bug Coreus marginatus (Heteroptera, Insecta).

Each tarsus of Coreus marginatus L. (Coreidae) bears a pair of smooth flexible pulvilli adapted for attachment to relatively smooth surfaces, such as their host plant Rumex crispus L. (Polygonaceae). This account quantifies insect attachment abilities on smooth surfaces at various stages of ontogenesis. Friction (shear) force (FF) of adults and juvenile insects was measured by the use of a computer controlled centrifugal force tester equipped with a fibre optical sensor. Pad area, body size and body mass were determined individually for each experimental insect. Light microscopy revealed no difference in pulvilli area between different leg pairs. Pulvilli area demonstrated a stronger increase with increasing linear dimensions, as predicted by scaling laws. Since friction coefficient (relationship between FF and body weight) (FC) was always higher than 1, it was concluded that adhesion has strongly contributed to the measured friction. The frictional properties of pulvilli do not change during ontogenesis. Thus, only the growth of pulvilli and, therefore, the increased contact area, contribute to the increasing attachment ability in insects at later larval stages. Due to different scaling of the body mass and area of attachment organs, smaller insects attach relatively more strongly. Both FF and FC were higher in experiments in which higher angular acceleration (AC) was applied. Lateral tenacity determined individually for experimental insects and pooled for all animals and accelerations is 0.097 N m(-2). These data led us to suggest that viscosity of the pad secretion and/or visco-elastic properties of the foam-like material of pulvilli play an important role in the attachment ability of insects.

Animals↗
PubMed2000

Adhesion measured on the attachment pads of Tettigonia viridissima (Orthoptera, insecta).

The tarsi of the cricket Tettigonia viridissima bear flexible attachment pads that are able to deform, replicating the profile of a surface to which they are apposed. This attachment system is supplemented by a secretion produced by epidermal cells and transported onto the surface of the pad through the pore canals of the pad cuticle. This study shows that the secretion alone is necessary, but not sufficient, for adhesion. To account for the full adhesive force, the deformation of the pad and the resulting changes in contact area were considered. In two series of experiments, the adhesive properties of the secretion and the adhesion of the whole pad were measured using a force tester, the sensitivity of which ranged from micronewtons to centinewtons. The adhesive forces of the secretion measured between a smooth sapphire ball with a diameter of 1.47 mm and a flat silicon surface ranged from 0.1 to 0.6 mN. In a control experiment on the silicon surface without secretion, no adhesive force was measured. There was no dependence of the adhesive force on the applied compressive force. When an intact pad was pulled off a flat silicon surface, the adhesive force increased with increasing applied compressive force, but it did not increase further once the applied force exceeded a certain value. The saturated adhesive force, ranging from 0.7 to 1.2 mN, was obtained at applied forces of 0.7-1.5 mN. The hemispherical surface of the pad had a larger contact area and demonstrated greater adhesion under a larger applied force. Adhesion became saturated when a pad was deformed such that contact area was maximal. The tenacity (the adhesive force per unit area) was 1.7-2.2 mN mm(-)(2).

Adhesiveness↗
PubMedDate not supplied

4-methyl-l-hepten-3-one, the defensive compound from Agathemera elegans (Philippi) (Phasmatidae) Insecta.

Insects of the genus Agathemera (Phasmatidae) live in the Chilean Andes over 1500 m above sea level. On disturbing, the insects release a spray that can cause temporary blindness in humans. Very little is known on the composition of chemicals used for defense by South American phasmids. Here we show that both female and male defensive secretion of Agathemera elegans is made up of 4-methyl-1-hepten-3-one. The compound is reported for the first time as a natural product.

Animals↗
PubMed2002

Activity of tabanids (Insecta: Diptera: Tabanidae) attacking the reptiles Caiman crocodilus (Linn.) (Alligatoridae) and Eunectes murinus (Linn.) (Boidae), in the central Amazon, Brazil.

Tabanid females are better known as hematophagous on man and other mammals, and linked to mechanical transmission of parasites. The association between tabanids and reptiles is poorly known, but has been gaining more corroboration through experiments and occasional observation in the tropics. The present study was conducted at a military base (CIGS/BI-2), situated 54 km from Manaus, Amazonas, in a small stream in a clearing (02 degrees 45'33"S; 59 degrees 51'03"W). Observations were made monthly, from April 1997 to March 1998, during two consecutive days. At the same time, other vertebrate animals were offered, including humans. However in this paper only data obtained on a common caiman, Caiman crocodilus (Linn.), and an anaconda, Eunectes murinus (Linn.), in diurnal observations from 05:30 a.m. to 18:30 p.m., will be discussed. A total of 254 tabanid specimens were collected, 40 from the anaconda and 214 from the caiman. Four tabanid species were recorded on these two reptiles: Stenotabanus cretatus Fairchild, S. bequaerti Rafael et al., Phaeotabanus nigriflavus (Kröber) and Tabanus occidentalis Linn. Diurnal activities showed species-specific patterns. The first three species occurred only in the dry season. T. occidentalis occurred during the whole observation period, and with increased frequency at the end of the dry season. We observed preferences for body area and related behavior of the host. Observations on the attack of tabanids on one dead caiman are also presented.

Alligators and Crocodiles↗
PubMed2003

The type specimens of chewing lice (Insecta, Mallophaga) deposited in the entomological collection of Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.

This paper presents a list of 131 Mallophaga type specimens deposited in the Werneck Collection of Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil. It includes 69 holotypes, 62 allotypes, 683 paratypes, 1 syntype and 2 neoparatypes, distributed among 6 families and 35 genera. The types are listed with their respective data and literature.

Animals↗
PubMed2003

Feeding habits of chironomid larvae (Insecta: Diptera) from a stream in the Floresta da Tijuca, Rio de Janeiro, Brazil.

Chironomids larvae are frequently one of the most abundant and diverse groups of insects in several kinds of aquatic environments. Also, they play a major role in the aquatic food webs, representing a major link among producers and secondary consumers. This work investigates the feeding behavior of the chironomid larvae present in the Rio da Fazenda, situated in the Parque Nacional da Tijuca, Rio de Janeiro, Brazil, between August 1994 and May 1995. Algae, fungi, pollen, leaf and wood fragments, animal remains, detritus and silt were the main gut contents found in the larvae studied. The main food item ingested by the larvae was detritus, except for the Stenochironomus whose main food source was leaf and wood fragments. Tanypodinae exhibited a large quantity of animal remains of several kinds in the diet. During the period studied it was observed that the diet of 16 genera (out of 24 studied) varied. Tanypodinae had mainly coarse particulate organic matter (> 1 mm) in the gut contents, while Chironominae and Orthocladiinae had fine particulate organic matter (< 1 mm).

Animals↗
PubMed2001

A new species of sucking louse (Insecta, Anoplura) parasitic on Auliscomys (Mammalia, Rodentia) in Argentina.

Hoplopleura auliscomydis n. sp. is described based on specimens collected from Auliscomys micropus (Waterhouse 1837), from Collń Curá, Neuquén Province, Argentina. Descriptions are provided for the holotype male, female, first nymphal instar, external architecture of eggs (by scanning electron microscopy), and sites of oviposition, providing differences from its close relative Hoplopleura neotomydis Castro, González, and Cicchino, 1995. The geographical ranges of these 2 species are restricted to the Neuquén Province in Argentina. A key to the 9 species of the Hoplopleura travassosi species-group recorded in Argentina is also given.

Animals↗
PubMed2002

Strelkovimermis rubtsovi n. sp. and Strelkovimermis ozawindibi n. sp. (Nematoda: Mermithidae) parasitizing chironomid (Insecta: Diptera) adults eclosing from northern Minnesota glacial lakes.

Two new species of Strelkovimermis are described from chironomid imagoes eclosing from northern Minnesota glacial lakes. The 2 species are distinguished from the other 12 species in the genus by terminal mouths, rounded or nippled posterior ends, short buccal funnels, short terminal limbs of the S-shaped vagina, and presence of a bursal sleeve. Strelkovimermis rubtsovi n. sp. is distinguished from S. ozawindibi n. sp. by the presence of a dorsal protractor. Procladius (Psilotanypus) bellus (Loew) is the host of S. rubtsovi. The chironomid host of S. ozawindibi has not been determined. An artificial key is provided to distinguish the 14 species of the genus.

Animals↗