Flutuação populacional de Anastrepha fraterculus (Wiedemann, 1830) (Diptera, Tephritidae) na Região Oeste de Santa Catarina, Brasil

Fruit flies are the major pests in fruit orchards and require a frequent insecticide aplication control, which increases production cost and chemical residues in fruits. Adults of Anastrepha fraterculus were sampled from twelve peach, plum, orange, tangerine and acid lime orchards in four counties in the Western Region of Santa Catarina. Modified McPhail plastic traps, baited with glucose 10%, were used to collect the flies from October 1998 to September 2000. Trap monitoring, bait replacement and fruit flies sorting by species and sex were done weekly. A total of 4,164 specimens of A. fraterculus was collected and highest population was registered in the county of Chapecó (64,8% of all sampled flies). Adults were collected all year long, with the highest population peaks occurring from December and January, although the fluctuation was different for each fruit species due to their particular phenology and in different years. Positive correlation among temperature, atmospheric humidity and population levels of adults of A. fraterculus was observed. According to the degree days obtained for each year, 4851.9, 4632.9 and 4983.7, respectively in 1998, 1999 and 2000, it was established that A. fraterculus could present an average of 11.2 generations a year.

A possible territorial or recognition behavior of Leptoglossus zonatus (Dallas) (Heteroptera, Coreidae)

The coreid Leptoglossus zonatus (Dallas, 1852) is commonly found in corn (Zea mays L.) fields in Brazil, and it has been observed flying and landing on objects or persons near these fields. During January, 1995, this behavior was studied in corn plantations. Results indicated that the bugs concentrated on objects (plastic cylinders traps) introduced into their habitat and that their number increased during the first 24 hs. However, as time passed (8 days), this possible territorial or recognition behavior gradually decreased, and tended to disappear.

Influence of male nutritional conditions on the performance and alimentary selection of wild females of Anastrepha obliqua (Macquart)(Diptera, Tephritidae)

Influence of male nutritional conditions on the performance and alimentary selection of wild females of Anastrepha obliqua (Macquart) (Diptera, Tephritidae). The behavior of A. obliqua females is regulated by endogenous and exogenous factors and among these the presence of males. Experiments were carried out to investigate whether the presence of males and their nutritional condition may affect the behavior of self-selection feeding and the performance of A. obliqua females. Females were sorted in groups containing yeast-deprived females and males, and non-yeast-deprived females and males. The females were maintained apart from the males by a transparent plastic screen. Several yeast and sucrose combinations were offered to the females in a single diet block or in separate blocks. Ingestion, egg production, longevity and diet efficiency were determined. The non-yeast-deprived males positively influenced the females performance when the latter were fed with yeast and sucrose in distinct diet blocks. Performance was better in the groups without males and with yeast-deprived males where the females could not select the nutrient proportions (yeast and sucrose in a single diet block).

Improvement of a test-chamber for behavioral studies on adult females of Aedes aegypti (Linnaeus) (Diptera, Culicidae)

A test-chamber (K&L-Chamber) made of cardboard and acrylic plastic, and consisting in four sections (A, B, C and D) was developed by Klowden & Lea (1978) for Aedes aegypti host-seeking behavior studies. Later, Foster & Lutes (1985) also used an identical chamber to successfully evaluate the efficacy of electronic repellers. It was described here a modified K&L-Chamber for behavioral studies of Ae. aegypti adults. The chamber was made in polystyrene, consisting of three sections (A, B and C) and using a human hand and a fluorescent lamp as stimulus to attract the mosquitoes. The suitability of the present test-chamber was validated assaying 80 replicates and releasing 10 Ae. aegypti females in each replicate. The females were released in the section A and allowed to fly to the section C. A mean of 96.0% (s.e. 0.213) Ae. aegypti females successfully reached section C. The present test-chamber is cheaper and easier to handle and as efficient as K&L-Chamber, when compared to Foster & Lutes (1978) that noticed 93.8% of Ae. aegypti reaching the trap section.

Occurrence, biology and behavior of Liogenys fuscus Blanchard (Insecta, Coleoptera, Scarabaeidae) in Aquidauana, Mato Grosso do Sul, Brazil

Due to the importance of some Pleurosticti Scarabaeidae as agricultural pests allied to information absence on the species that occur in Brazilian Central-West region, on studies occurrence, biology and behavior on this group of scarabs were conducted. Biology and behavioral studies started with Liogenys fuscus Blanchard, 1850 (Melolonthinae), a very common species and were developed in Aquidauana, Mato Grosso do Sul. Adult beetles were collected from light traps from February 2005 to January 2007, at the experimental farm of the Universidade Estadual de Mato Grosso do Sul in Aquidauana (UEMS). In the laboratory adults were placed in plastic containers with soil with sprouts of Brachiaria decumbens Stapf (Poaceae). Eggs were transferred to a climatized chamber at 26 ± 1º C with a 12hourlight, 12hour darkness photoperiod cycle. Adult flight activity occurred in August and in September to December from 06:00 pm to 06:00 am, with the largest number of individuals flying from 07:00 to 10:00 pm. Eggs measured 1 x 1.5 mm and were laid individually or in groups in soil chambers; eggs were initially white and became yellow near hatching. The embryonic period lasted 14.3 days; first, second and third instars lasted 28.5, 48.8, and 68.2 days, respectively. The prepupal period lasted 120.2 days and the prepupa stayed inactive in soil. The mean duration of pupal stage was 27.5 days and the mean longevity of adults was 23.6 days. In laboratory the calling behavior between males and females was observed; copulation lasted, in mean, 25 minutes.

Occurrence of adults and biological aspects of Geniates borelli Camerano (Coleoptera, Scarabaeidae, Rutelinae) in Aquidauana, MS, Brazil

Occurrence of adults and biological aspects of Geniates borelli Camerano (Coleoptera, Scarabaeidae, Rutelinae) in Aquidauana, Mato Grosso do Sul, Brazil. Due to the importance of Geniates borelli Camerano as a pest in many crops, studies were developed at Universidade Estadual de Mato Grosso do Sul, Aquidauana campus, MS, Brazil. Adults were collected with a light trap from January 2006 to December 2007. 3,320 adults were collected, and the highest quantities were obtained in October 2006 and November 2007, with 1,548 and 802 adults recorded, respectively. Collected adults were kept in plastic containers with soil and Brachiaria decumbens seedlings for oviposition. 535 eggs measuring 2.30 × 1.60 mm were obtained. As the embryonic development progressed, eggs increased in size to 3.00 × 2.70 mm, and this change occurred between 6 and 10 days after oviposition. The embryonic period lasted 17.9 days. The first, second, and third instars lasted 37.6, 49.7, and 74 days, respectively. The prepupal stage lasted 65.9 days and the pupal stage lasted an average of 18.5 days. The biological cycle is completed in 315.8 days, which characterizes the species as univoltine. The average longevity of females was 35.4 days and 28.5 days for males.

New method for rearing Spodoptera frugiperda in laboratory shows that larval cannibalism is not obligatory

New method for rearing Spodoptera frugiperda in laboratory shows that larval cannibalism is not obligatory. Here we show, for the first time, that larvae of the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera, Noctuidae), can be successfully reared in a cohort-based manner with virtually no cannibalism. FAW larvae were reared since the second instar to pupation in rectangular plastic containers containing 40 individuals with a surprisingly ca. 90% larval survivorship. Adult females from the cohort-based method showed fecundity similar to that already reported on literature for larvae reared individually, and fertility higher than 99%, with the advantage of combining economy of time, space and material resources. These findings suggest that the factors affecting cannibalism of FAW larvae in laboratory rearings need to be reevaluated, whilst the new technique also show potential to increase the efficiency of both small and mass FAW rearings.

No impact of Bt soybean that express Cry1Ac protein on biological traits of Euschistus heros (Hemiptera, Pentatomidae) and its egg parasitoid Telenomus podisi (Hymenoptera, Platygastridae)

No impact of Bt soybean that express Cry1Ac protein on biological traits of Euschistus heros (Hemiptera, Pentatomidae) and its egg parasitoid Telenomus podisi (Hymenoptera, Platygastridae). Biological traits of the stink bug Euschistus heros and its main biological control agent Telenomus podisi were evaluated under controlled environmental conditions (25 ± 2ºC; 60 ± 10% RH; and 14/10 h photoperiod) by placing first instar nymphs into Petri dishes with pods originating from two soybean isolines (Bt-soybean MON 87701 × MON 89788, which expresses the Cry1Ac protein, and its near non-Bt isoline A5547) where they remained until the adult stage. Due to gregarious behavior exhibited by first instar nymphs, they were individualized only when at the second instar. Adults were separated by sex and weighed, and pronotum width of each individual was subsequently measured. They were placed into plastic boxes containing soybean grains of the same soybean isoline as food source. Egg viability and female fecundity were assessed in adult individuals. Adult females of T. podisi (up to 24h old) were placed with eggs of E. heros from mothers reared on both soybean isolines. Nymphal development time, insect weight, pronotum width, sex ratio, female fecundity, and egg viability (% emergence) of Euschistus heros did not differ between treatments. Eggto-adult development time, female longevity, sex ratio, and percentage of parasitized eggs were not impacted by the Bt-soybean (expressing Cry1Ac protein). Results indicate that the Bt-soybean, MON 87701 × MON 89788, has no direct significant impact on the two studied species.

Response of Epidendrum Ibaguense (orchidaceae) to the application of lime rates to the pot

In the best cultivation methods of orchids, in particular of the genus Phalaenopsis, liming is a common practice. The objective of this study was to evaluate the influence of lime rates (0.0; 1.0; 2.0; 3.0; 4.0; and 5.0 g dm-3 of substrate) applied to the cultivation substrate (xaxim) on the growth of Epidendrum ibaguense seedlings. In a greenhouse, 1-L plastic pots filled with 0.8 dm³ of xaxim were irrigated such that no leachate was lost during the experiment. N, P, K, Ca, Mg, S, Fe, Zn, B, and Mn contents in roots, stems and leaves were measured. Leachate was collected by applying a sufficient water volume to obtain 25 mL from each pot. Fourteen days after lime application of 3 g dm-3, the pH of the collected leachate reached values above 7 and a value of 6.29 with the highest lime rate at the end of the experiment. The lime rate did not influence plant height, probably due to a Zn deficiency at high pH levels and a Ca deficiency in the control. Nevertheless, there was a large increase in leaf production, for number as well as for dry matter mass. There was no statistical difference between treatments in root dry matter production. Maximum dry matter production was obtained at a lime rate of 4.09 g dm-3. Zinc concentrations diminished linearly with increasing lime rates; the concentrations in all treatments were below the levels suggested as adequate in the literature (25-200 mg kg-1). Nutrient concentrations in leaves indicated deficiency of N, S, and B at the highest lime rates (4.0 and 5.0 g dm-3), and of Ca in the treatment without liming.

Growth of seedlings of pigeon pea (Cajanus cajan (l.) millsp), wand riverhemp (Sesbania virgata (cav.) pers.), and lead tree (Leucaena leucocephala (lam.) de wit) in an arsenic-contaminated soil

Phytoremediation strategies utilize plants to decontaminate or immobilize soil pollutants. Among soil pollutants, metalloid As is considered a primary concern as a toxic element to organisms. Arsenic concentrations in the soil result from anthropogenic activities such as: the use of pesticides (herbicides and fungicides); some fertilizers; Au, Pb, Cu and Ni mining; Fe and steel production; coal combustion; and as a bi-product during natural gas extraction. This study evaluated the potential of pigeon pea (Cajanus cajan), wand riverhemp (Sesbania virgata), and lead tree (Leucaena leucocephala) as phytoremediators of soils polluted by As. Soil samples were placed in plastic pots, incubated with different As doses (0; 50; 100 and 200 mg dm-3) and then sown with seeds of the three species. Thirty (pigeon pea) and 90 days after sowing, the plants were evaluated for height, collar diameter and dry matter of young, intermediate and basal leaves, stems and roots. Arsenic concentration was determined in different aged leaves, stems and roots to establish the translocation index (TI) between the plant root system and aerial plant components and the bioconcentration factors (BF). The evaluated species showed distinct characteristics regarding As tolerance, since the lead tree and wand riverhemp were significantly more tolerant than pigeon pea. The high As levels found in wand riverhemp roots suggest the existence of an efficient accumulation and compartmentalization mechanism in order to reduce As translocation to shoot tissues. Pigeon pea is a sensitive species and could serve as a potential bioindicator plant, whereas the other two species have potential for phytoremediation programs in As polluted areas. However, further studies are needed with longer exposure times in actual field conditions to reach definite conclusions on relative phytoremediation potentials.

Rice grown in nutrient solution with doses of manganese and silicon

Although silicon is not recognized as a nutrient, it may benefit rice plants and may alleviate the Mn toxicity in some plant species. The dry matter yield (root, leaf, sheaths and leaf blade) and plant architecture (angle of leaf insertion and leaf arc) were evaluated in rice plants grown in nutrient solutions with three Mn doses, with and without Si addition. The treatments were arranged in a 2 x 3 factorial [with and without (2 mmol L-1) Si; three Mn doses (0.5; 2.5 and 10 µmol L-1)], in a randomized block design with 4 replications. The experimental unit was a 4 L plastic vase with 4 rice (Metica-1 cultivar) plants. Thirty nine days after keeping the seedlings in the nutrient solution the plant dry matter yield was determined; the angle of leaf insertion in the sheath and the leaf arc were measured; and the Si and Mn concentrations in roots, sheaths and leaves were determined. The analysis of variance (F test at 5 and 1 % levels) and the regression analysis (for testing plant response to Mn with the Si treatments) were performed. The Si added to the nutrient solution increased the dry matter yield of roots, sheaths and leaf blades and also decreased the angle of leaf blade insertion into the sheath and the foliar arc in the rice plant. Additionally, it ameliorated the rice plant architecture which allowed an increase in the dry matter yield. Similarly, the addition of Mn to the solution improved the architecture of the rice plants with gain in dry matter yield. As Si was added to the nutrient solution, the concentration of Mn in leaves decreased and in roots increased thus alleviating the toxic effects of Mn on the plants.

Temporal variability of soil water content under different surface conditions in the semiarid region of the Pernambuco state

Rainfall in the semiarid region of Pernambuco is characterized by irregular distribution in time and space, which significantly hinders the rainfed agriculture in the region. This work aims to evaluate the temporal profile of soil moisture in the semiarid region of the Pernambuco State (Brazil) and the effect of different soil surface conditions on soil water content variation and the yield of rainfed beans. To monitor soil water content, five plots 4.5 m wide by 11 m long were installed in a Yellow Argisol (Ultisol). The following treatments were adopted in the experimental plots: natural vegetation, bean intercropped with cactus, beans planted down the slope, beans planted along contour lines with mulch and rock barriers, and bare soil. In each plot, eight PVC access tubes were installed for monitoring the soil water content profile at depths of 0.20 and 0.40 m using a neutron probe device. The surface condition significantly influenced the soil water content variation, both in the dry and rainy seasons. The use of mulch, associated with rock barriers, provided higher soil water content levels than the other treatments and increased the rainfed beans production.

Tillage systems and nutrient sources affecting soil cover, temperature and moisture in a clayey oxisol under corn

Tillage affects soil physical properties, e.g., porosity, and leads to different amounts of mulch on the soil surface. Consequently, tillage is related to the soil temperature and moisture regime. Soil cover, temperature and moisture were measured under corn (Zea mays) in the tenth year of five tillage systems (NT = no-tillage; CP = chisel plow and single secondary disking; CT = primary and double secondary disking; CTb = CT with crop residues burned; and CTr = CT with crop residues removed). The tillage systems were combined with five nutrient sources (C = control; MF = mineral fertilizer; PL = poultry litter; CS = cattle slurry; and SS = swine slurry). Soil cover after sowing was greatest in NT (88 %), medium in CP (38 %) and lowest in CT treatments (< 10 %), but differences decreased after corn emergence. Soil temperature was related with soil cover, and significant differences among tillage were observed at the beginning of the growing season and at corn maturity. Differences in soil temperature and moisture in the surface layer of the tilled treatments were greater during the corn cycle than in untilled treatments, due to differences in intensity of soil mobilization and mulch remaining after soil management. Nutrient sources affected soil temperature and moisture in the most intense part of the corn growth period, and were related to the variation of the corn leaf area index among treatments

Effect of compaction on microbial activity and carbon and nitrogen transformations in two oxisols with different mineralogy

The use of machinery in agricultural and forest management activities frequently increases soil compaction, resulting in greater soil density and microporosity, which in turn reduces hydraulic conductivity and O2 and CO2 diffusion rates, among other negative effects. Thus, soil compaction has the potential to affect soil microbial activity and the processes involved in organic matter decomposition and nutrient cycling. This study was carried out under controlled conditions to evaluate the effect of soil compaction on microbial activity and carbon (C) and nitrogen (N) mineralization. Two Oxisols with different mineralogy were utilized: a clayey oxidic-gibbsitic Typic Acrustox and a clayey kaolinitic Xantic Haplustox (Latossolo Vermelho-Amarelo ácrico - LVA, and Latossolo Amarelo distrófico - LA, respectively, in the Brazil Soil Classification System). Eight treatments (compaction levels) were assessed for each soil type in a complete block design, with six repetitions. The experimental unit consisted of PVC rings (height 6 cm, internal diameter 4.55 cm, volume 97.6 cm³). The PVC rings were filled with enough soil mass to reach a final density of 1.05 and 1.10 kg dm-3, respectively, in the LVA and LA. Then the soil samples were wetted (0.20 kg kg-1 = 80 % of field capacity) and compacted by a hydraulic press at pressures of 0, 60, 120, 240, 360, 540, 720 and 900 kPa. After soil compression the new bulk density was calculated according to the new volume occupied by the soil. Subsequently each PVC ring was placed within a 1 L plastic pot which was then tightly closed. The soils were incubated under aerobic conditions for 35 days and the basal respiration rate (CO2-C production) was estimated in the last two weeks. After the incubation period, the following soil chemical and microbiological properties were detremined: soil microbial biomass C (C MIC), total soil organic C (TOC), total N, and mineral N (NH4+-N and NO3--N). After that, mineral N, organic N and the rate of net N mineralization was calculated. Soil compaction increased NH4+-N and net N mineralization in both, LVA and LA, and NO3--N in the LVA; diminished the rate of TOC loss in both soils and the concentration of NO3--N in the LA and CO2-C in the LVA. It also decreased the C MIC at higher compaction levels in the LA. Thus, soil compaction decreases the TOC turnover probably due to increased physical protection of soil organic matter and lower aerobic microbial activity. Therefore, it is possible to conclude that under controlled conditions, the oxidic-gibbsitic Oxisol (LVA) was more susceptible to the effects of high compaction than the kaolinitic (LA) as far as organic matter cycling is concerned; and compaction pressures above 540 kPa reduced the total and organic nitrogen in the kaolinitic soil (LA), which was attributed to gaseous N losses.

Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis

The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of soil samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, medium-textured and clay samples, and for 68 % of the results for heavy clay samples, indicating satisfactory repeatability of measurements with the RSh. Medium variability was frequently associated with silt, followed by the fine sand fraction. The sensitivity analyses indicated an accuracy of 100 % for the three main separates (total sand, silt and clay), in all 52 samples of the textural classes heavy clay, clay and medium. For the nine sand soil samples, the average accuracy was 85.2 %; highest deviations were observed for the silt fraction. In relation to the linear adjustments, the correlation coefficients of 0.93 (silt) or > 0.93 (total sand and clay), as well as the differences between the angular coefficients and the unit < 0.16, indicated a high correlation between the reference data (Prolab/IAC) and results obtained with the RSh. In conclusion, the mechanical dispersion by the reciprocal shaker of soil samples of different textural classes was satisfactory. The results allowed recommending the use of the equipment at low agitation for particle size- analysis. The advantages of this Brazilian apparatus are its low cost, the possibility to simultaneously analyze a great number of samples using ordinary, easily replaceable glass or plastic bottles.