Kairomones from Euschistus heros egg masses and their potential use for Telenomus podisi parasitism improvement.

Telenomus podisi Ashmead (Hymenoptera: Scelionidae) is the most important egg parasitoid of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), and its successful parasitism is related to their searching ability to find suitable hosts under a complex chemical environment using host-reliable cues. Thus, the objective of this study was to elucidate chemical substances on the external layer of E. heros eggs and report its potential kairomonal activity on T. podisi. We tested female wasps in olfactometer system to synthetic compounds obtained from a chemical identification of E. heros egg masses. The synthetic blend was also evaluated in parasitism tests under laboratory and semi-field conditions. We identified 31 substances from egg surface extracts, including monoterpenes, aldehydes and alkanes. Among those compounds, a synthetic solution including camphene, ß-pinene, limonene and benzaldehyde-induced chemotaxic behaviour on the wasps and increased the parasitism on E. heros eggs, either in laboratory or semi-field test, suggesting its potential use to T. podisi manipulation and parasitism improvement.

Faecal occult blood test-based screening programme with high compliance for colonoscopy has a strong clinical impact on colorectal cancer.

BACKGROUND: The results of a pilot colorectal cancer screening programme by biennial immunochemical faecal occult blood test (FOBT) are reported. METHODS: All residents aged between 50 and 69 years in the Italian province of Lecco were invited to have a FOBT. Those with a positive result were offered colonoscopy. FOBT uptake and compliance with colonoscopy were assessed. Detection rate and positive predictive value (PPV) for cancer and adenoma were calculated. Tumour stages were compared between screen-detected cancers and other colorectal cancers diagnosed within the target age group. RESULTS: Some 38,693 (49.6 per cent) of 78,083 individuals had a FOBT and 2392 (6.2 per cent) had a positive result. Colorectal cancer was diagnosed in 4.6 per cent and advanced adenoma in 32.7 per cent. PPVs were 4.0 per cent for cancer, 28.1 per cent for advanced adenoma and 36.6 per cent for any adenoma. There was a significant difference in incidence of stage III/IV disease between screened and non-screened cohorts. Compliance for colonoscopy was 92.0 per cent. Major determinants of compliance were age less than 59 years, female sex, high education level and non-manual work. CONCLUSION: These results justify extension of colorectal cancer screening to other regions of Italy.

Taxonomic Status and Population Oscillations of Aphidius colemani Species Group (Hymenoptera: Braconidae) in Southern Brazil.

Aphidius colemani (Viereck) was reported in Brazil before the Biological Control Program of Wheat Aphids (BCPWA) when Mediterranean genotypes were introduced from France and Israel. This species was re-described as a complex called A. colemani group composed of three species. Consequently, uncertainty remains about which parasitoid of the group is occurring in southern Brazil. This study has two main objectives: (i) re-examine the species status of A. colemani group collected during the introduction of parasitoids and from a 10-year (2009-2018) monitoring program in wheat fields in northern Rio Grande do Sul (RS), Brazil; (ii) describe the variation in the population density of parasitoids and its association with meteorological factors during this period. We examined 116 specimens from the Embrapa Wheat entomological collection, and those collected in Moericke traps in Coxilha, RS. All the parasitoids of the A. colemani group from the BCPWA period were identified as Aphidius platensis (Brèthes). In traps, 6541 cereal aphid parasitoids were collected, of which 61.9% (n = 4047) were from A. colemani group and all those were identified as A. platensis. Temperature was the factor that effected population density with the highest number of parasitoids recorded in the winter months. Sex ratio changed between years varying from 0.50 to 0.97. The parasitoid A. platensis was the only species in the A. colemani group sampled during 10 years of monitoring.

Spatial distribution of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) larvae in three scales.

The spatial distribution of larvae of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), the citrus leaf miner, in leaves, shoots, and tree crowns of Montenegrina tangerine (Citrus deliciosa Tenore) and Murcott tangor (Citrus sinensis L. Osbeck x Citrus reticulata Blanco) was determined. Fortnightly samplings from July/2001 to June/2003, in orchards located in Montenegro (29 degrees 68' S and 51 degrees 46' W), RS, Brazil, were carried out. At each sampling occasion eighth shoots randomly selected were collected. The spatial distribution pattern of P. citrella larvae between tree crowns and in the shoots was aggregated in most sampling occasions in both citrus species. Nevertheless, on the leaves, this pattern followed a random distribution, as indicated by the indices I, Idelta and k parameter.

Discrimination of Spartocera dentiventris (Berg, 1884) (Hemiptera: Coreidae) eggs by Gryon gallardoi (Brèthes, 1913) (Hymenoptera: Scelionidae).

This paper aimed to evaluate the stimuli that orient Gryon gallardoi females to the eggs of Spartocera dentiventris and allow their discrimination. Using a four-arm olfactometer connected to four odor sources--S. dentiventris eggs; hexane washed eggs; tobacco leaves; and tobacco leaves with eggs--the arrestment of female parasitoids with previous oviposition experience and without was individually verified. The time of permanence in each odor field was registered for a period of 15 minutes. Host discrimination, regarding age and previous parasitism, was tested using arenas, where females were exposed for 30 minutes, individually, to egg groups with different treatments. To evaluate age discrimination, three groups of eggs, previously washed with hexane, were employed in the following conditions: one day-old eggs; one-day brushed with 12-days-old egg extract; 12-days-old eggs with extract of one day-old eggs; and control (washed eggs, one day-old). The same procedure was done using five and eight days-old eggs jointly with control. Age-dependent egg discrimination was verified exposing four egg groups in the following treatments: parasitized, parasitized and washed with hexane, not parasitized, and not parasitized with extract of parasitized eggs. Olfactometer tests showed that inexperienced females remained more time next to tobacco leaves when compared to experienced ones. Experienced females responded to odors that emanated from eggs. Egg extracts did not promote age discrimination; however, non parasitized eggs, with extract of parasitized eggs were partially avoided. The results obtained indicate that G. gallardoi females might modify their responses upon contact with host. This fact suggests learning occurs; however, the acceptance and discrimination of host may be influenced by a complex array of stimuli, difficult to evaluate in isolation.

Is It Possible to Manipulate Scelionidae Wasps' Preference to a Target Host?

Parasitoid host selection is mainly mediated by chemical cues, which can be adjusted by experience, changing their innate behavior. Therefore, this study evaluated if immature experience (pre-imaginal conditioning) on eggs and volatiles from different host eggs has influence on parasitism and chemotaxic behavior of Telenomus podisi Ashmead and/or Trissolcus basalis Wollaston (Hymenoptera: Scelionidae). Both wasp species were submitted to a multiple-choice parasitism test among Euschistus heros (Fabricius), Piezodorus guildinii (Westwood), and Nezara viridula L. (Hemiptera: Pentatomidae) (Hemiptera: Pentatomidae) egg masses. Eggs from these three stink bugs were equally offered to female parasitoids. After that, adults which emerged from each host were also exposed to parasitism in a multiple-choice test for up to an additional generation. Moreover, in olfactometer "Y," the behavior of innate and experienced T. podisi females to volatiles from hosts' egg extracts was tested, to study their learning and memory ability. The original host had influence on T. podisi parasitism; however, T. basalis always parasitized more N. viridula eggs independently of its last rearing host. Innate T. podisi females responded positively to E. heros and P. guildinii egg volatiles, but this behavior was not observed in N. viridula. When T. podisi females were experienced on egg volatiles from a new host, they showed significant learning and memory ability for the specific host volatile for, at least, 24 h. Experienced wasps responded positively to N. viridula and through this result we have evidences about the possibility to manipulate wasp's preferences to a specific target host.

Insect diversity in organic rice fields under two management systems of levees vegetation.

Simplified environments characterize agroecosystems, reducing the diversity of associated plants, which are not cultivated for economic purposes, causing unbalances that can promote the emergence of cultivated plants pests, as well as the reduction of their natural enemies. Management systems that increase diversity in agroecosystems can extend the action of natural enemies of pests. Studies to understand the diversity of insects associated with rice cultivation and determine their ecological guilds can provide information about the composition and structure of such ecosystems, which can be applied to integrated pest management. Therefore, the study aimed to describe and compare groups of insects in irrigated rice fields, with organic management using two different systems of levees vegetation management, and relate them to the phenological states of rice cultivation (seedling, vegetative, and reproductive). Samples were taken in a plantation located in Águas Claras district of Viamão, RS. The total area of 18 ha was divided into two. A subarea called not cut (NC), where wild vegetation of levees was maintained, and the subarea named cut (C), where monthly cuts were made to levees vegetation, from the beginning of soil preparation until the harvest. From October 2012 to March 2013 were held weekly collections in quadrats randomly located in both the rice fields and the levees. A total of 800 insects were collected, 429 in the C subarea and 371 in the NC. There were identified 97 morphospecies in the C and 108 in NC, being 54 shared between the subareas. The captured insects were grouped into guilds: saprophages (C = 38.2%; NC = 27.5%), phytophagous (C = 28.5%; NC = 33.2%), entomophagous (grouping parasitoids and predators) (C = 29.4%; NC = 35%) and finally other insects (C = 4 %; NC = 4.3%). The peak abundance of phytophagous and entomophagous was registered in the vegetative stage of rice. At the same stage the UPGMA analysis showed that similarity in species composition was greater than 90% in the groups obtained in the paddy fields of C and NC subareas. The vegetation of levees can positively influence the presence of entomophagous in the field. Although the abundance did not change clearly, the greatest diversity in the NC areas of all the groups, may contribute to the maintenance of ecological services expanding the system resilience.

A new electro-optical approach for conductance measurement: an assay for the study of drugs acting on ligand-gated ion channels.

Ligand gated ion channels are involved in many pathophysiological processes and represent a relevant, although challenging, target for drug discovery. We propose an innovative electro-optical approach to their analysis able to derive membrane conductance values from the local membrane potential changes imposed by test current pulses and measured by fast voltage-sensitive fluorescent dyes. We exploited the potential of this proprietary method by developing a drug testing system called "ionChannel Optical High-content Microscope" (ionChannelΩ). This automated platform was validated by testing the responses of reference drugs on cells expressing different ligand-gated ion channels. Furthermore, a double-blind comparison with FLIPR and automated patch-clamp was performed on molecules designed to act as antagonists of the P2RX7 receptor. ionChannelΩ proved highly reliable in all tests, resulting faster and more cost-effective than electrophysiological techniques. Overall, ionChannelΩ is amenable to the study of ligand gated ion channels that are receiving less attention due to limitations in current assays.

Internal reproductive organs of Cosmoclopius nigroannulatus (Hemiptera: Reduviidae).

The internal reproductive organs of Cosmoclopius nigroannulatus males and females are described, illustrated and measured. No significant difference was registered among immature and reproductive structures of males and their aspect was also similar. However, in females noteworthy differences both in size and aspect were found.

Dispersal of the egg parasitoid Gryon gallardoi (Brethes) (Hymenoptera: Scelionidae) in tobacco crops.

A mass marking-recapture experiment was carried out to study the dispersal of Gryon gallardoi (Brethes) (Hymenoptera: Scelionidae) in tobacco crops. Parasitoids emerged in the laboratory were marked with dye powder. Six separate field trials were conducted in Jan/Feb 2002 involving the simultaneous release of marked parasitoids. Dispersal was determined by the recapture of individuals in sets of sticky and Moericke traps arranged in three concentric circles arranged at 1.4 m intervals from the central point of release. Traps were checked 4, 8, 24, 28, 32 and 48 h after parasitoid release and weather data were recorded at 2-h intervals from 9 to 17 h at the site. Of the 699 marked parasitoids released, 91 were recaptured (13.02%). Fewer females were recaptured in the late afternoon, suggesting they are less active than males after dusk. G. gallardoi recaptures were not associated with average wind direction in any trials. After eight hours of release, recaptures occurred mostly in the traps farthest from the release point, suggesting that the experimental area was small in relation to the dispersal capacity of the parasitoid. Fitting a 4-h-after-release density-distance curve to a geometric model and considering a daily activity of 12 h, the female dispersal capacity was estimated to be at least 7.6 m/day. The values reported here must be considered as indicative of the potential for active dispersal under the particular experimental conditions of these trials. It is possible that G. gallardoi may disperse downwind much farther than the distance recorded in this study.

Reproductive parameters and longevity of Gryon gallardoi (Brethes) (Hymenoptera: Scelionidae) parasitizing Spartocera dentiventris (Berg) (Hemiptera: Coreidae) eggs.

The fecundity, daily progeny and longevity of Gryon gallardoi (Brethes) (Hym.; Scelionidae) were determined under laboratory conditions, using Spartocera dentiventris (Berg) (Hem.; Coreidae) eggs as host. Nineteen G. gallardoi females and 34 males were reared at 25 +/- 1 degrees C, with a 12 h photophase, fed on a 10% aqueous honey solution and provided with 25-30 S. dentiventris eggs daily. The average pre-oviposition period was 1.3 +/- 0.35 days, although some females began laying from the day of emergence. On average, oviposition lasted for 10.1 +/- 1.74 days, reaching a peak on the second day, with 67.5 +/- 11.29 eggs laid. The post-oviposition period was short (2.4 +/- 0.48 days). G. gallardoi females lived significantly longer than males: 13.7 +/- 1.94 and 10.6 +/- 1.78 days, respectively. The overall sex ratio was 0.79. The results reported here on the reproductive capability of the species suggest it may have a good potential as an agent for the control of S. dentiventris.

Species composition and structure of Thysanoptera communities in different microhabitats at the Parque Estadual de Itapuã, Viamão, RS.

Although thrips are known as inhabitants of flowers, they are also abundant and diverse in other microhabitats. There is an information gap concerning them, especially related to the native fauna in southern Brazil. The structure and composition of the thysanopteran community in different microhabitats was studied at the "Parque Estadual de Itapuã" (30 degrees 22' S 51 degrees 02' W), RS, southern Brazil. Between June 1999 and May 2001, branches (n = 1,274), flowers (n = 774), grass tussocks (n = 596) and leaf litter (n = 603) were sampled systematically in 20 points of four trails (T1 - Pedreira beach, T2 - Araçá beach, T3 - Lagoinha, and T4 - Grota hill). We found 2,197 adult thrips determined in 73 species in 41 genera, of which 37 could be nominated. Four families are represented, Thripidae, Phlaeothripidae, Heterothripidae and Merothripidae, with the first the most abundant (N = 1,599) and with the highest species richness (S = 32). The highest thrips abundance occurred in flowers N = 1,224 and the highest number of exclusive species occurred in the leaf litter (27). Frankliniella rodeos Moulton, 1933, Frankliniella gemina Bagnall, 1919 and Smicrothrips particula Hood, 1952 comprise 49.4% of the total sampled. Regarding T2, we obtained the highest abundance (N = 935) and highest species richness (S = 43). The composition of the faunas in each kind of environment proved very particular.

Seasonal abundance and mortality of Oebalus poecilus (Dallas) (Hemiptera: Pentatomidae) in a hibernation refuge.

Oebalus poecilus (Dallas) is an important pest affecting irrigated rice in Rio Grande do Sul, Brazil. It hibernates during the coldest months of the year in refuges such as bamboo litter. This study examined O. poecilus hibernation to determine the causes of mortality during this period. The study was conducted in a 140 m(2) bamboo plantation located in a rice-growing area in Eldorado do Sul County (30 degrees 02 S and 51 degrees 23 W), RS. During June 2000 to April 2002, 63 samples of litter were taken in weekly or fortnightly intervals, and the number of bugs recorded in the laboratory. The arrival at the hibernation site (bamboo litter) began in the first fortnight of March, and was completed in the beginning of May. O. poecilus left this refuge from middle October to the end of December. Parasitism by tachinid flies and Beauveria bassiana (Bals.) Vuill. fungus were the most important mortality factors.

Influence of the vegetation management of the leeves in irrigated rice organic in diversity of Hymenoptera parasitoids.

Among the natural enemies of insect pests in rice fields, parasitoids are especially notable. To better understand the space-time dynamics of these insects, the objectives of this study were to describe and compare groups of parasitoids in organic irrigated rice fields using two management approaches for levee vegetation, and to relate them to the phenological stages of rice cultivation (the seedling, vegetative, and reproductive stages). The samples were taken in a plantation located in Viamão, RS, Brazil. The total area of 18 ha was divided into two parts: a no-cut (NC) subarea in which the wild vegetation of the levees was maintained, and a cut (C) subarea in which the levee vegetation was cut monthly. In each subarea, four Malaise traps considered as pseudo-replicas were installed and remained in the field for 24 hours at each sampling location. Collections occurred twice a month from the beginning of cultivation (October 2012) until harvest (March 2013). A total of 3,184 Hymenoptera parasitoids were collected: 2,038 individuals in the NC subarea and 1,146 in the C subarea. We identified 458 morphospecies distributed in 24 families. Mymaridae was the most abundant and Eulophidae was the richest in both subareas. A total of 198 morphospecies was shared between the subareas, including Platygastridae, Eulophidae, and Mymaridae, which were the families with the highest number of shared species. The richness and abundance of parasitoids varied according to their phenological developmental stages, with peak abundance registering during the vegetative period. The Morisita index identified three groupings, indicating a similarity that was related to the three phases of rice growth and development: seedling, vegetative and post-harvest.

GPR133 (ADGRD1), an adhesion G-protein-coupled receptor, is necessary for glioblastoma growth.

Glioblastoma (GBM) is a deadly primary brain malignancy with extensive intratumoral hypoxia. Hypoxic regions of GBM contain stem-like cells and are associated with tumor growth and angiogenesis. The molecular mechanisms that regulate tumor growth in hypoxic conditions are incompletely understood. Here, we use primary human tumor biospecimens and cultures to identify GPR133 (ADGRD1), an orphan member of the adhesion family of G-protein-coupled receptors, as a critical regulator of the response to hypoxia and tumor growth in GBM. GPR133 is selectively expressed in CD133+ GBM stem cells (GSCs) and within the hypoxic areas of PPN in human biospecimens. GPR133 mRNA is transcriptionally upregulated by hypoxia in hypoxia-inducible factor 1α (Hif1α)-dependent manner. Genetic inhibition of GPR133 with short hairpin RNA reduces the prevalence of CD133+ GSCs, tumor cell proliferation and tumorsphere formation in vitro. Forskolin rescues the GPR133 knockdown phenotype, suggesting that GPR133 signaling is mediated by cAMP. Implantation of GBM cells with short hairpin RNA-mediated knockdown of GPR133 in the mouse brain markedly reduces tumor xenograft formation and increases host survival. Analysis of the TCGA data shows that GPR133 expression levels are inversely correlated with patient survival. These findings indicate that GPR133 is an important mediator of the hypoxic response in GBM and has significant protumorigenic functions. We propose that GPR133 represents a novel molecular target in GBM and possibly other malignancies where hypoxia is fundamental to pathogenesis.

Effect of temperature on the development and viability of Gryon gallardoi (Brethes) (Hymenoptera: Scelionidae) parasitizing Spartocera dentiventris (Berg) (Hemiptera: Coreidae) eggs.

The development and viability of Gryon gallardoi (Brethes) (Hym.: Scelionidae) in Spartocera dentiventris (Berg) (Hem.: Coreidae) eggs were studied under four temperatures: 15, 20, 25, and 30 +/- 1 degree C, with a 12-h photophase. No parasitoid developed at 15 degrees C. Otherwise, viability reached 98.8% without varying significantly over the temperature range tested. The duration of development for males and females was inversely proportional to the temperature increase, varying respectively from 46.2 +/- 0.13 and 47.1 +/- 0.11 days (20 degrees C) to 13.3 +/- 0.07 and 13.4 +/- 0.06 days (30 degrees C). Males developed faster than females. The values estimated for the lowest thermic thresholds of development and the thermic constants were 15.5 degrees C and 185.19 DD for males and 15.6 degrees C and 192.31 DD for females, respectively. Given the average weather conditions in Porto Alegre, RS (30 degrees 01' S and 51 degrees 13' W), Brazil, G. gallardoi could annually produce 8.54 and 8.07 generations of males and females, respectively. The low rates of parasitism observed in the field during the first generation of its host may be due to the small number of G. gallardoi generations in this period.

Spontaneous uterine rupture with amniotic sac protrusion at 28 weeks subsequent to previous hysteroscopic metroplasty.

BACKGROUND: Hysteroscopic metroplasty improves pregnancy outcome in case of uterine septum. Uterine rupture during a pregnancy following this procedure may occur. CASE: A patient with a history of hysteroscopic resection of a uterine septum complicated by fundal perforation, presented at 28 weeks a spontaneous uterine rupture with amniotic sac protrusion through the uterine wall disruption. CONCLUSION: Uterine rupture during pregnancy following a hysteroscopic metroplasty may occur even though it appears to be a very uncommon event. Patients who have had this procedure should be aware of this potential risk in case of future pregnancies. How to avoid such complication is still unclear.

[Endometrial carcinoma: prognostic significance of cellular ploidy]. / Carcinoma endometriale: significato prognostico della ploidia cellulare.

BACKGROUND: The aim of the paper is to compare ploidy status with the traditional prognostic factors (grading, myometrial invasion, cytology of peritoneal fluid and node invasion) in 118 women affected by endometrial carcinoma and treated by hysterectomy in our department in order to evaluate a relationship between these parameters. METHODS: Since January 1988 and August 1996 127 women (average age: 61) affected by endometrial carcinoma and not previously treated have been submitted to abdominal or vaginal hysterectomy. A retrospective study was carried out on 118 of these women evaluating DNA ploidy on fixed neoplastic samples through flow cytometry (Coulter Elite with Argon Laser). Aneuploidy was defined as cell population containing at the same time two or more moderate peaks in G0/G1. Histology of neoplastic tissues could evaluate grading and myometrial invasion in all cases. Cytology of peritoneal fluids and nodal state were evaluated respectively in 99 and 56 patients. The results obtained have been compared by Fisher's statistical test. RESULTS: 70.3% of evaluated neoplasias were diploid, while 29.7% were aneuploid. No statistical difference was observed comparing ploidy status with every considered parameter. CONCLUSIONS: The results obtained show that DNA ploidy doesn't seem to be positively correlated with any traditional histopathological factors. The literature about this matter is questionable. Histopathological analysis is the only prognostic factor and it is the only parameter to personalize treatment.

Functional response of Cosmoclopius nigroannulatus (Hem.: Reduviidae) to different densities of Spartocera dentiventris (Hem.: Coreidae) nymphae.

This study evaluated the functional response of the predator Cosmoclopius nigroannulatus on first instar nymphae of Spartocera dentiventris, both species associated with Nicotina tabacum. The experiment was carried out in laboratory conditions: 27 +/- 1 degree C; 80 +/- 5%, RH; 12 h, photophase. Ten newly emerged adults of each sex of C. nigroannulatus were used in each of five densities (5, 15, 25, 35, and 45 individuals) of S. dentiventris nymphae. The predators were observed every 24 h for five days, when the number of dead and/or consumed nymphae was recorded. The results showed a positive correlation between the number of ingested nymphae and the increase in prey density. Females ingested more nymphae than the males. The estimated handling time per prey (Th) was higher in males (3.07 h) than in females (1.93 h), with total handling time (Th x Na) increased with density. Other components of the functional response, such as attack rate (a'), searching time (Ts), and search efficiency (E) showed, in neither males nor females, a negative correlation regarding density. The results indicated a higher predatory efficiency in the females. The components of the functional response fitted significantly the randomic model of the Holling discs equation (Na = N [1 - exp[- a'(T - ThNa)]]), evidencing a functional response of type II.

Population dynamics of Cosmoclopius nigroannulatus Stal (Hemiptera, Reduviidae) in tobacco culture.

The role of predators influencing populations of insects considered as pests is extremely important for agroecosystems. The population ecology of Cosmoclopius nigroannulatus, a predatory reduvid associated with the tobacco culture was investigated aiming to study the population dynamics of adults, along the culture cycle. In an experimental plot of approximately 300 m2, in Porto Alegre (30 degrees 0'S; 51 degrees 13'W), RS, Brazil, 270 tobacco plants were grown; each plant identified by alphanumeric coordinates. Using the mark-release-recapture method, daily samplings were done from August to December 1999, and three times a week from this date until April 2000. The adults were captured by hand, marked, sexed and released on the same plant they were captured. The individual number and plant coordinate were registered. Population estimates were analyzed by the Fisher-Ford method. In 107 sampling occasions, 604 individuals were marked, 273 males and 331 females. Three generations of C. nigroannulatus were registered during the culture cycle. The colonizing generation was represented by 14 males and 15 females (a sex ratio of 0.48), the first by 109 males and 137 females (0.44) and the second by 150 males and 179 females (0.46). The estimated daily survival rate varied between generations decreasing from 98% in the colonizing generation to 87% in the second. The observed longevity or permanence time in the experimental area varied significantly among generations, being at about 40 days in the colonizing generation, 13 days in the first and 5 days in the second. It was observed that as the population increases, the survival and/or permanence time in the area decreases, suggesting a relation between this and a decline in the available resources probably with an associated increase in intra-specific competition.