ABSTRACT
The objective of this research was to evaluate weed control in a successional soybean-sorghum system by using preemergent herbicides. Two trials were conducted in soybean and two in sorghum, in different soil types (sandy in Rio Verde city and clayey in Montividiu city). All trials were established in a completely randomized block design with five preemergent herbicides in soybean (rates in): diclosulam 35.3 g a.i.·ha1, chlorimuron 20 g a.i.·ha1, sulfentrazone 200 g a.i.·ha1, flumioxazin 50 g a.i.·ha1, S-metolachlor 1728 g a.i.·ha1, and two controls (hand weeded and untreated). Treatments in sorghum trials were the same to the soybean plus atrazine 1250 g a.i.·ha1 and atrazine 1250 g a.i.·ha1 + S-metolachlor 1728 g a.i.·ha1. All treatments had four replicates. Weed control was assessed at 7, 14, 21 and 28 days after planting (DAP) in both crops. In addition, yield was measured when grains reached physiological maturity. All preemergent herbicide treatments successfully controlled weeds, specially Commelina benghalensis, Cenchrus echinatus and Eleusine indica, in both soybean trials until 28 DAP. In some weeds of sorghum, sulfentrazone, diclosulam and chlorimuron sprayed at soybean preemergence performed better than atrazine sprayed at sorghum preemergence. All preemergent herbicides sprayed at soybean preemergence did not affect soybean and sorghum yield, showing similarity with the hand weeded treatment. The results of this research provide evidence that the mix of crop succession and preemergent herbicide applications can be a strong strategy for integrated weed management.
Subject(s)
Glycine max/parasitology , Crop Production , Sorghum/parasitology , Weed Control/methods , Herbicides/analysisABSTRACT
The aim of this study was to identify mite fauna associated with soybean crops and to report new species of the Monsoy 8349 IPRO variety in the municipality of Luís Eduardo Magalhães, western region of Bahia. Samplings were performed in an area with transgenic soybeans, subdivided into three treatments: T01, with no use of agricultural pesticides; T02, complete package of pesticides, except for acaricides; and T03, complete package of pesticides including acaricides. Twenty plants were selected per treatment at each sampling; one apical, one median, and one basal leaf were collected from each plant, totaling 60 leaves per treatment. A total of 1,292 mites were found, belonging to three families, five genera, and six species. The major phytophagous mite species found were Mononychellus planki McGregor and Tetranychus urticae Koch, while the major predatory mites found were Neoseiulus transversus Denmark & Muma and Euseius concordis Chant.
Subject(s)
Animals , Glycine max/parasitology , Pest Control, Biological/methods , Tetranychidae/classification , Mites/classification , BrazilABSTRACT
Abstract The use of GMO expressing Bt toxin in soybean production has increased significantly in the last years in Brazil in order to manage the damage caused by lepidopteran pests. In this study, we compared the richness and abundance of owlet moths (Noctuoidea) associated with Bt and non-Bt soybean. We determined the temporal variations as a function of phenology, and correlated the population variations of the most common species with meteorological variables. The research was conducted at the experimental area of Embrapa Cerrados. The collection method used was differentiated being suppressive and absolute. A total of 13 species were collected, of which eight occurred on Bt soybeans. The most representative taxa were Chrysodeixis includens (72.87%), Anticarsia gemmatalis (18.17%) and Spodoptera spp (5.22%). The number of larvae belonging to species targeted by the Bt technology was 10 times lower on Bt than on non-Bt soybeans. Utetheisa ornatrix and Elaphria deltoides were recorded on soybean for the first time, observing larvae of both species in non-Bt soybean and those of U. ornatrix also in Bt soybean. Only A. gemmatalis larvae correlated (p <0.05) negatively with precipitation. This study provided field information on the abundance and species richness of owlet moths on non-Bt soybeans, associated with the effects of Bt soybean. When considering the different levels of infestation between cultivars as a criterion, larvae monitoring is of substantial importance in order to develop the lost control program.
Resumo O uso de OGM que expressam toxina Bt na produção de soja tem aumentado significativamente nos últimos anos no Brasil e são utilizados para conter os danos causados pelos lepidópteros pragas. Neste estudo comparamos a riqueza e a abundância de Noctuoides (Noctuoidea) associados à soja Bt e não-Bt. Determinamos as variações temporais em função da fenologia e correlacionamos às variações populacionais das espécies mais comuns com variáveis meteorológicas. A pesquisa foi conduzida na área experimental da Embrapa Cerrados. O método de coleta utilizado foi diferenciado sendo supressivo e absoluto. Um total de 13 espécies foram coletadas, das quais oito ocorreram em soja Bt. Os taxa mais representativos foram Chrysodeixis includens, Anticarsia gemmatalis e Spodoptera spp. O número de larvas pertencentes às espécies alvo da tecnologia Bt foram 10 vezes menores na soja Bt do que em soja não-Bt . Utetheisa ornatrix e Elaphria deltoides foram registradas na soja pela primeira vez, observando-se larvas de ambas espécies na soja não-Bt e as de U. ornatrix também na soja Bt. Somente as larvas de A. gemmatalis se correlacionaram (p <0,05) negativamente com a precipitação. Este estudo forneceu informações em campo sobre a abundância e riqueza de espécies na soja não- Bt, associada aos efeitos da soja Bt. A importância do monitoramento das lagartas é substancial, a fim de tomar a melhor decisão de controle, considerando-se os diferentes níveis de infestação entre cultivares como critério.
Subject(s)
Animals , Bacterial Proteins/genetics , Bacterial Proteins/pharmacology , Endotoxins/genetics , Endotoxins/pharmacology , Hemolysin Proteins/genetics , Hemolysin Proteins/pharmacology , Glycine max/genetics , Glycine max/parasitology , Brazil , Pest Control, Biological , Plants, Genetically Modified/genetics , Plants, Genetically Modified/parasitology , Larva/drug effects , Moths/drug effectsABSTRACT
In the present study, the essential oils from Eucalyptus globulus Labill., Citrus sinensis L. Osbeck and Citrus limon L. were analysed by GC-MS (gas chromatographymass spectrometry) and evaluated for their toxic effects on Sternechus subsignatus and Rhyssomatus subtilis, two important pest of soybean in South America. Contact toxicity assayed by impregnation on filter paper discs showed that these oils caused significant mortality of the test insects (100 percent of mortality at 5 uL/cm2). Eucalyptus oil (98.9 percent of 1,8-cineole) had the greatest contact toxicity (LD50 = 0.40 and 0.84 uL/cm2 for S. pinguis and R. subtilis, respectively), whereas orange (87.6 percent of limonene) and lemon oils (62.5 and 12.6 percent of limonenen and beta pinene, respectively) were less toxic (LD50 > 1 uL/cm2 for both insects). All the responses were found dose-dependent. Rhyssomatus subtilis was more resistant than Sternechus pinguis to the toxicity of the essential oils studied.
En el presente estudio se analizaron por CG-EM (cromatografía de gases-espectrometría de masas) los aceites esenciales de eucalipto (Eucalyptus globulus Labill.), naranja (Citrus sinensis L. Osbeck) y limón (Citrus limon L) y se evaluaron sus efectos tóxicos contra dos especies de plagas importantes para la soja en Sud América: Sternechus subsignatus y Rhyssomatus subtilis. La toxicidad por contacto, ensayada por discos de papel de filtro impregnados, mostró que estos aceites causaron una mortalidad significativa de los insectos testeados (100 por ciento de mortalidad a 5 uL/cm2). El aceite de eucalipto (98.9 por ciento de 1,8-cineol) presentó la mayor toxicidad por contacto (LD50 = 0.40 y 0.84 uL/cm2 para S. pinguis y R. subtilis, respectivamente), mientras que el aceite de naranja (87.6 por ciento de limoneno) y el de limón (62.5 y 12.6 por ciento de limoneno y beta pineno, respectivamente) fueron menos tóxicos (LD50 > 1 uL/cm2 para ambos insectos). Todas las respuestas fueron dosis dependiente. Rhyssomatus subtilis fue más resistente que Sternechus pinguis a la toxicidad de los aceites esenciales estudiados.
Subject(s)
Animals , Oils, Volatile/pharmacology , Citrus/chemistry , Eucalyptus/chemistry , Weevils , Insecticides/pharmacology , Glycine max/parasitology , Coleoptera , Gas Chromatography-Mass Spectrometry , Insect Control , Pesticides/pharmacologyABSTRACT
Laboratory studies were conducted to compare duration of feeding and superficial and in-depth damage to soybean (Glycine max) seeds by the Southern green stink bug, Nezara viridula (L.), the Neotropical brown stink bug, Euschistus heros (F.), the red-banded stink bug, Piezodorus guildinii (Westwood), and the green-belly stink bug, Dichelops melacanthus (Dallas). Results indicated that feeding time was significantly longer for N. viridula (≈ 133 min) compared to E. heros and D. melacanthus (≈ 70 min), but not different from P. guildinii (≈ 103 min). There was a positive correlation between feeding time and the resulting damage for E. heros, N. viridula and P. guildinii (R² > 0.80, P < 0.0001), but not for D. melacanthus (R² = 0.1011, P = 0.1493). The deepest seed damage (2.0 mm) was made by P. guildinii and the shallowest (0.5 mm) by D. melacanthus. The depth of the seed damage by E. heros and N. viridula (0.8, 1.2 mm, respectively) was intermediate in comparison to the other species studied. Feeding damage to the seed endosperm caused variable cell disruption and protein body dissolution, particularly when P. guildinii fed on seeds, suggesting that the deleterious action of salivary enzymes was greater for this bug compared to the others.
Subject(s)
Animals , Feeding Behavior , Heteroptera/physiology , Seeds/parasitology , Glycine max/parasitology , Time FactorsABSTRACT
Trichogramma spp. (Hymenoptera: Trichogrammatidae) parasitam ovos de Anticarsia gemmatalis (Lepidoptera: Noctuidae), o principal desfolhador de soja no Brasil. O objetivo deste trabalho foi avaliar o parasitismo de onze espécies/linhagens de Trichogramma em cartelas de cartolina com vinte ovos de A. gemmatalis por fêmea desse parasitoide durante 24 horas. A linhagem de Trichogramma atopovirilia (Hymenoptera: Trichogrammatidae) de Sete Lagoas, Minas Gerais, apresentou melhor desempenho com 19 ovos de A. gemmatalis parasitados por fêmea em 24 horas, viabilidade de 98% e razão sexual de 0,84. A linhagem de Trichogramma pretiosum de Cristalina, Goiás, parasitou 11,9 ovos de A. gemmatalis por fêmea com 98% de viabilidade e razão sexual de 0,65. Esse trabalho confirma a importância de se avaliar linhagens de Trichogramma antes de programas de controle biológico, pois diferentes linhagens de uma mesma espécie desse parasitoide apresentam resultados distintos.
Several Trichogramma (Hymenoptera: Trichogrammatidae) species parasitize Anticarsia gemmatalis (Lepidoptera: Noctuidae) eggs, the major soybean desfoliator in Brazil. The objective of this work was to evaluate the parasitism of eleven Trichogramma species/strains in cardboards with twenty eggs of A. gemmatalis by this parasitoid female for 24 hours. The strain trat - 2 Trichogramma atopovirilia (Hymenoptera: Trichogrammatidae) of Sete Lagoas, Minas Gerais, showed better performance with 19 A. gemmatalis eggs parasitized by female in 24 hours, 98% viability and sex ratio of 0.84. The strain Trichogramma pretiosum of Crystalline, Goiás, parasitized 11.9 A. gemmatalis eggs per female with 98% viability and sex ratio of 0.65. This work confirms the importance of evaluating Trichogramma strains before biological control programs, because different strains of the same species of parasitoid have distinct results.
Subject(s)
Glycine max/parasitology , Pest Control, Biological/methods , Hymenoptera , Lepidoptera/physiologyABSTRACT
The silverleaf whitefly Bemisia tabaci (Genn.) biotype B has become a serious problem for soybean cultivation because it can significantly reduce soybean productivity. The use of soybean cultivars resistant to whitefly attack is an important strategy in an integrated pest management (IPM) program. This study evaluated the preference for oviposition and colonization by B. tabaci biotype B on different soybean genotypes. In the free-choice test, the genotypes studied were 'IAC 17' and 'IAC 19' as the standards for resistance and 'IAC Holambra Stwart' as the standard for susceptibility, as well as BABR01-0492, BABR01-0173, BABR01-1259, BABR01-1576, BABR99-4021HC, BABR99-4021HP, 'Barreiras', 'Conquista', 'Corisco', 'BRS Gralha', PI274454, PI227687, and PI171451. In the no-choice test, the four best genotypes selected in the free-choice test, in addition to the susceptible and resistant standards were evaluated. Our data indicated 'Barreiras' as the most resistant genotype against B. tabaci biotype B. 'BRS Gralha', which was the least attractive to whitefly adults in the free-choice test, did not show resistance to insect attack when they were confined in cages in the no-choice test. Despite the high number of eggs observed, BABR01-1576 and BABR99-4021HC showed a reduced number of nymphs, indicating antibiosis. The genotypes with a high level of resistance can be used as a tool against B. tabaci in IPM or as a source of resistance in plant-breeding programs.
Subject(s)
Animals , Hemiptera , Glycine max/genetics , Glycine max/parasitology , Genotype , Hemiptera/classification , Hemiptera/physiology , Immunity, Innate , Glycine max/immunologyABSTRACT
O estudo do impacto de inseticidas sobre a reprodução de predadores naturais ou introduzidos tem crescido, incluindo aqueles expostos durante a fase ninfal. Foi estudado o impacto da exposição à deltametrina durante a fase ninfal sobre a reprodução de machos e fêmeas do predador Brontocoris tabidus (Heteroptera: Pentatomidae) em planta de Eucalyptus urophylla ou soja Glycine max (L) Merrill, no campo e laboratório, em adultos de diferentes intervalosde emergência, e seu reflexo nas duas gerações, através de morfologia, morfometria, histologia, parâmetros da tabela de vida e fertilidade e duração dos estádios. Este inseticida não teve impacto na morfologia, morfometria e histologia de ambos os sexos de B. tabidus em ambas as plantas, ambientes e idades desse predador. Os parâmetros reprodutivos mostraram impacto da deltametrina apenas na geração (...), mas sem reflexo nas gerações seguintes. A fecundidade não variou no campo e foi menor no laboratório, assim como os números de ovos/fêmea e de ninfas na geração (...). A longevidade de B. tabidus foi semelhante no campoe laboratório, indicando que o tempo de atividade predatória em programas de controle biológico no campo pode ser obtida de indivíduos oriundos de criação massal no laboratório. A deltametrina afetou os números de ovos / fêmea, ovos / fêmea /dia e ovos / postura da geração (..) soja no laboratório, provavelmente devido à criação massal em eucalipto e às condições de teste no laboratório. As semelhanças morfológica e anatômica desse predador nas plantas,ambientes e gerações pesquisados mostraram que estes parâmetros não foram afetados pela deltametrina. A maior duração do estádio N3 da geração (...) foi devida a exposição aopiretróide, mas a semelhança da duração do N4 desta geração com o controle nas plantas e ambientes e o N5 semelhante ao controle na maioria dos parâmetros soja no campo
mostraram a recuperação do predador. Os estádios ninfais de B. tabidus não expostos a deltametrina foram mais curtos. A aplicação do inseticida nas culturas de eucalipto e soja pode ser compatível com o predador B. tabidus.
Subject(s)
Animals , Eucalyptus/parasitology , Glycine max/parasitology , Insecticides/administration & dosage , Insecticides/analysis , Insecta/metabolism , Pest Control, Biological , Permissible Limit of Occupational HazardsABSTRACT
Os percevejos fitófagos são importantes insetos-pragas na cultura da soja, causando danos desde a formação das vagens até o final do desenvolvimento dos grãos. O trabalho objetivou avaliar o controle desses insetos-pragas (complexo de percevejos) após o tratamento com inseticidas sob duas velocidades da assistência de ar junto à barra de pulverização combinadas a duas pontas de pulverização. Dois experimentos foram conduzidos na Faculdade de Ciências Agronômicas/UNESP Campus de Botucatu, safra 2006/2007 na cultura da soja, var. Conquista, no delineamento experimental em blocos ao acaso, com esquema fatorial 2 x 2 + 1 (dois níveis de ar, 0 e 100%; duas pontas de pulverização, JA-2 e AXI 11002, mais testemunha). No estádio de desenvolvimento R6 foi realizada uma pulverização com os inseticidas tiametoxam associado com lambda-cialotrina (experimento 1) na dosagem de 25,38 + 19,08 g i.a. ha-1 e endosulfan (experimento 2) na dosagem de 437,5 g.i.a. ha-1. A aplicação foi feita com um pulverizador Advanced Vortex 2000 conferindo um volume de calda de 200 L ha-1. As avaliações antes (prévia) e com 1, 3, 6, 10 e 14 dias após a aplicação foram realizadas pelo método do pano-de-batidas. O número médio de percevejos foi significativamente menor nas parcelas tratadas em relação àquelas não tratadas. De modo geral, não houve diferença estatística entre as tecnologias de aplicação em ambos os experimentos.
Stink bugs are an important pest in the soybean crop. The aim of this research was to evaluate the control of this pest with pesticides applied at two air speeds using an air assisted sleeve boom sprayer arranged with two nozzles. Two experiments were carried out at FCA/UNESP Botucatu, SP (Brazil), using soybean plants of the Conquista variety (season 2006/2007). The experimental design was randomized blocks with 5 treatments and 4 repetitions in a 2 x 2 + 1 factorial scheme (two levels of air speed, 0 and 100%, two nozzles: flat fan nozzle AXI 11002 and hollow cone nozzle JA-2, plus nontreated plots). The insecticide tiametoxam associated with lambdacialotrina (experiment 1) at 25.38 + 19.08 g i.a. ha-1 and endosulfan (experiment 2) at 437.5 g.i.a. per hectare were applied in the growth stage V6 with support of the spray Advanced Vortex 2000 using a volume rates of 200 L ha-1 for both treatments and experiments. The evaluations before (0) and 1, 3, 6, 10 and 14 days after applications were made by the method of hits on the cloth. The average numbers of stink bugs were significantly lower in treated plots in relation to nontreated plots. In general, there was no statistical difference between the application technologies in both experiments.
Subject(s)
Glycine max/parasitology , Pest Control, Biological/methods , Agricultural Pests , HeteropteraABSTRACT
O objetivo do trabalho foi avaliar o efeito de produtos fitossanitários sobre pupas de Trichogramma pretiosum. Foram conduzidos três bioensaios em delineamento inteiramente casualizado com 11 tratamentos e cinco repetições. Em cada repetição, ovos de Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) foram utilizados como hospedeiro alternativo, sendo aderidos em cartelas de cartolina de 1 cm2 com solução de goma arábica à 40% e oferecidos para o parasitismo por 24h. Após 168-192h do parasitismo, quando os parasitoides estavam na fase de pupa, as cartelas foram mergulhadas por cinco segundos nos tratamentos testados. Avaliou-se a sobrevivência dos indivíduos tratados e a redução na emergência dos parasitoides foi classificada segundo as normas da IOBC. Os inseticidas flufenoxurom (Cascade®) 10, diflubenzurom (Dimilin®) 20 e metoxifenozide (Intrepid 240SC®) 21,6 e 36 g i.a. ha-1 foram classificados como inócuos. Permetrina (Valon 384 CE®) 49,92; betaciflutrina 12,5 + imidacloprido 100 (Connect®) e gama-cialotrina (Stallion 150SC®) 3,75 g i.a. ha-1 foram levemente nocivos. Clorpirifós (Lorban 480BR®) 384 e espinosade (Tracer®) 24 g i.a. ha-1 foram moderadamente nocivos. Os herbicidas glifosato 720 + imazetapir 90 (Alteza®); s-metolacloro (Dual Gold®) 1920; flumioxazina (Flumyzin 500®) 60; clomazona (Gamit®) 1000; glifosato 2880 (Gliz 480SL®); dicloreto de paraquate 600 + diurom 300 (Gramocil®); glifosato 1200 (Roundup Ready®); foram classificados como inócuos e os herbicidas 2,4-D (DMA 806BR®) 1209; dicloreto de paraquate (Gramoxone®) 600; glifosato (Roundup Transorb®) 2592 g i.a. ha-1 classificados como levemente nocivos. Os fungicidas tiofanato-metílico (Cercobin 500 SC®) 400; flutriafol 60 + tiofanato-metílico 300 (Celeiro®); carbendazin (Derosal 500SC®) 250; tebuconazole (Folicur EC®) 150; flutriafol (Impact®) 125; tebuconazole 120 + trifloxistrobina 60 (Nativo®); epoxiconazole 30 + piraclostrobina 79,8 (Opera®); epoxiconazole (Opus SC®) 12,5; azoxistrobina (Priori®) 50; azoxistrobina 60 + ciproconazole 24 (Priori Xtra®) g i.a. ha-1 foram classificados como inócuos aT. pretiosumna fase de desenvolvimento avaliada (pupa). Dentre os produtos avaliados, aqueles classificados como inócuos devem ser priorizados no manejo integrado de pragas (MIP) por compatibilizar o uso do controle químico sem prejudicar o controle biológico. Do mesmo modo, os produtos classificados como moderadamente nocivos devem ser evitados sempre que possível ou substituídos por outro de menor impacto.
This study aimed to evaluate the effect of different pesticides onTrichogramma pretiosumpupae. Three tests were carried out with 11 treatments and 5 replications. Eggs ofAnagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) were used as a factitious host affixed on 1cm2 pieces of cardboard using a non-noxious glue solution (40% gum arabic) and then offered to parasitism for 24 h. After 168192 h from the parasitism, when the parasitoids were at the pupae stage, the pieces of cardboard were dipped for five seconds in the treatments. The parasitoid survival was evaluated and the emergence was classified accordingly to the IOBC guidelines. The insecticides flufenoxuron (Cascade®) 10, diflubenzuron (Dimilin®) 20 and methoxyfenozide (Intrepid 240SC®) 21.6 and 36 g a.i. ha-1 were classified as harmless. Permethrin (Valon 384CE®) 49.92, beta-cyfluthrin 12.5 + imidacloprid 100 (Connect®) and gammacyhalothrin (Stallion 150SC®) 3.75 g a.i. ha-1 were slightly harmful. Chlorpyriphos (Lorsban 480BR®) 384 and spinosad (Tracer®) 24 g a.i. ha-1 were moderately harmful. The herbicides glyphosate 720 + imazetapyr 90 (Alteza®), s-metolachlor (Dual Gold®) 1920, flumyoxazin (Flumyzin 500®) 60, clomazone (Gamite®) 1000, glyphosate (Gliz®) 2880, paraquat dichloride 600 + diuron 300 (Gramocil®), glyphosate 1200 (Roundup Ready®) were classified as harmless, and the herbicides 2.4-D (DMA®) 1209, paraquat dichloride (Gramoxone®) 600 and glyphosate (Roundup Transorb®) 2592 g a.i. ha-1 were classified as slightly harmful. The fungicides metil tiofanate (Cercobin 500SC®) 400, flutriafol 60 + metil tiofanate 300 (Celeiro®), carbendazin (Derosal 500SC®) 250, tebuconazol (Folicur EC®) 150, flutriafol (Impact®) 125, tebuconazol 120 + trifloxystrobin 60 (Nativo®), epoxiconazol 30 + piraclostrobin 79.8 (Opera®), epoxiconazol (Opus SC®) 12.5, azoxystrobin (Priori®) 50, azoxystrobin 60 + ciproconazol 24 (Priori Xtra®) g a.i. ha-1 were harmless toT. pretiosum pupae. Among the tested products, the harmless ones should be chosen in a program of integrated pest management (IPM) since it allows the use of pesticides without harm to the biological control. On the other hand, the moderately harmful pesticides should be avoided or replaced by another product with less impact whenever it is possible.
Subject(s)
Pesticides/analysis , Pupa , Glycine max/parasitology , Insect Control/methods , Hymenoptera , Agricultural PestsABSTRACT
Three soybean experiments, one for each maturation group (early, semi-early, and medium), were installed in the field in Assis, State of São Paulo, during the 2003/2004 growing season to evaluate damage caused by Anticarsia gemmatalis (Hubn.) and by the soybean stink bug complex, Euschistus heros (F.), Piezodorus guildinii (West.), and Nezara viridula (L.). The experiments were installed again in 2004/2005, with the exception of the early cycle group. Defoliation caused by A. gemmatalis was evaluated by the percentage estimate of leaf area cut in the first year only, due to low caterpillar infestations in 2004/2005. All three stink bug species were present in both growing seasons. In 2003/2004, E. heros was predominant over the other two; in the following year, all three species occurred in similar numbers. The productivity criterion was adopted to evaluate stink bug damage. Based on both growing seasons and mainly considering productivity, a few lines could be selected within each maturation group for new field studies or for hybridizations in breeding programs. Among the early germplasm varieties, lines IAC 98-4540, IAC 98-4576, and IAC 98-3123 can be highlighted as promising; the latter also showed little defoliation by A. gemmatalis; in the semi-early group, IAC 98-4017, IAC 98-2663, and IAC 98-4250 were prominent, with steady productivity in both years; in the medium group, IAC 98-4136, the most productive, as well as IAC 98-4140 and IAC 98-4133, all with little defoliation, can be pointed out as promising.
Subject(s)
Animals , Heteroptera , Lepidoptera , Glycine max/genetics , Glycine max/parasitology , Genotype , Glycine max/growth & developmentABSTRACT
Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) is being used in Brazil as a biological insecticide. Host plant resistance of soybean to insects is been searched for and some authors have mentioned the interference of plant chemistry in virus efficiency. Interactions among soybean extracts of genotypes used as a source of resistance (PI 274454 and PI 227687) with different AgMNPV concentrations in populations of A. geatalis susceptible (S) and resistant (R) to the virus were studied at laboratory condition. Higher mortality was observed when larvae fed on diets with extracts of the soybean genotypes compared with those fed on a plain diet (control). The mean lethal concentration (LC50) was reduced about 10 ties in the S-population fed on diets containing PI 274454 extracts and different concentrations of AgMNPV, compared to control diet. Additive effect was predominantly observed when larvae fed on diets with extracts of soybean genotypes (PI 274454 and PI 227687) and AgMNPV for both larval populations. The pupal weight was negatively influenced by the extracts incorporated to the diets compared to control, for both larval populations, notably for R-population. The results suggest that, in general, leaf extracts of soybean resistant genotype did not cause any harmful effect on virus efficiency.
O nucleopoliedrovirus de Anticarsia gemmatalis (AgMNPV) tem sido utilizado como um inseticida biológico no Brasil. A resistência de plantas de soja a insetos tem sido pesquisada e alguns autores têm mencionado a interferência de substâncias químicas de plantas sobre a eficiência de vírus. As interações entre extratos de genótipos de soja utilizados como fontes de resistência (PI 274454 e PI 227687) com diferentes concentrações do AgMNPV em populações de A. gemmatalis suscetível (S) e resistente (R) ao vírus foram estudadas em condições de laboratório. Mortalidades elevadas foram observadas quando as larvas foram alimentadas com dietas contendo extratos dos genótipos de soja, em relação às larvas alimentadas com dieta artificial sem a presença de extratos (testemunha). A concentração letal média (CL50) foi reduzida em aproximadamente 10 vezes, na população s alimentada com dieta contendo extratos da PI 274454 e diferentes concentrações do AgMNPV, comparada à dieta testemunha. Um efeito aditivo foi predominantemente observado quando as larvas se alimentaram em dietas com extratos dos genótipos de soja (PI 274454 e PI 227687) e o AgMNPV, para ambas as populações (S e R). O peso de pupa foi negativamente influenciado pela dieta contendo os extratos em relação à dieta testemunha, para ambas as populações, com destaque para a população R. Os resultados indicam que, no geral, os extratos de folhas de genótipos de soja resistentes não causam efeitos negativos na eficiência do vírus.
Subject(s)
Animals , Moths/virology , Nucleopolyhedroviruses/physiology , Pest Control, Biological/methods , Plant Extracts/pharmacology , Glycine max/chemistry , Genotype , Host-Parasite Interactions , Larva/virology , Glycine max/genetics , Glycine max/parasitologyABSTRACT
The biology of the pentatomid Dichelops melacanthus (Dallas) feeding on cultivated and non-cultivated plants was studied in the laboratory. Nymph mortality varied from ≈ 60 on corn (seed mature) to 77 percent on wheat (ear immature); no nymphs survived on seedlings of corn or wheat. Nymph developmental time on soybean, corn or wheat (seed, pod or ear) varied from 25.5 to 32.8 days. Body weight at adult emergence was similar and greater on most foods than on wheat ear. Nymphs fed preferentially on soybean (pod immature). On non-cultivated hosts, nymphs showed high mortality (73 percent) on crotalaria (pod immature); on tropical spiderwort (stem) all nymphs died. Nymphs took longer time to develop on crotalaria and/or on spiderwort than on soybean. Body weight at adult emergence did not differ on crotalaria or soybean. Survivorship decreased with time on most foods, with ≈50 percent of adults alive at day 30. On corn and wheat seedlings ≈80 percent of adults were dead on day 20. Adult longevity ranged 31-43 days, except on corn and wheat seedlings < 15 days. Females percent ovipositing peaked (≈76 percent) on soybean (pod or seed immature), and was minimum (≈9 percent) on wheat ear (immature); no females reproduced on seedlings of corn or wheat. Preoviposition period was shorter (≈12 days) on soybean (immature pod or seed) and longer (≈37 days) on wheat (ear immature). Fecundity was similar and higher on all foods than on wheat (ear immature). Body weigh gain occurred on all foods, but on corn and wheat seedlings. Adults fed preferably on soybean (pod immature and seed mature); wheat (seedling) was the least preferred food.
A biologia do pentatomídeo Dichelops melacanthus (Dallas) em plantas cultivadas e não-cultivadas foi estudada em laboratório. A mortalidade ninfal variou de ≈ 60 por cento em milho (semente madura) a 77 por cento em trigo (espiga imatura); nenhuma ninfa sobreviveu em plântulas de milho ou trigo. O desenvolvimento ninfal em soja, milho ou trigo (semente, vagem ou espiga) variou de 25,5 a 32,8 dias. O peso dos adultos na emergência foi menor em espiga de trigo. As ninfas alimentaram-se preferencialmente de soja (vagem imatura). Nas plantas não-cultivadas, as ninfas tiveram mortalidade de 73 por cento em crotalária (vagem imatura); e 100 por cento em trapoeraba (ramo). O desenvolvimento ninfal foi mais lento em crotalária ou trapoeraba do que em soja. A sobrevivência dos adultos decresceu com o tempo na maioria dos alimentos, com ≈50 por cento dos adultos vivos no 30º dia. Em plântulas de milho e trigo ≈80 por cento dos adultos estavam mortos no 20º dia. A longevidade total dos adultos variou de 31-43 dias, exceto em plântulas de milho e trigo (< 15 dias). A por cento de fêmeas que ovipositou foi maior (≈76 por cento) em soja (vagem ou semente imatura) e menor (≈9 por cento) em espiga imatura de trigo; as fêmeas não reproduziram em plântulas de milho ou trigo. O período de pré-oviposição foi menor (≈12 dias) em soja (vagem ou semente imatura) e maior (≈37 dias) em trigo (espiga imatura). A fecundidade foi semelhante e maior em todos os alimentos do que em trigo (espiga imatura). O ganho de peso ocorreu em todos os alimentos, menos plântulas de milho e trigo. Os adultos alimentaram-se preferencialmente em soja (vagem imatura e semente madura); plântula de trigo foi o alimento menos preferido.
Subject(s)
Animals , Female , Heteroptera/growth & development , Glycine max/parasitology , Triticum/parasitology , Zea mays/parasitology , Body Weight , Fertility/physiology , Heteroptera/anatomy & histology , Longevity , Nymph/growth & development , Oviposition/physiologyABSTRACT
Nas últimas safras agrícolas, foram observadas severas infestações de ácaros fitófagos em diversos municípios do Rio Grande do Sul, demandando a utilização de pesticidas para seu controle. Este trabalho teve como objetivo identificar as espécies de ácaros fitófagos e predadores associados à soja em dez municípios daquele estado, nas safras de 2002/03 e 2003/04, em cinco cultivares de soja (A 6001 RG, A 7001 RG, A 8000 RG, A 8100 RG, Anta 82), todas geneticamente modificadas. Em amostras de folhas foram encontradas quatro espécies de ácaros fitófagos (Mononychellus planki (McGregor), Polyphagotarsonemus latus (Banks), Tetranychus desertorum Banks e Tetranychus gigas Pritchard & Baker) e duas espécies de ácaros predadores (Phytoseiulus fragariae Denmark & Schicha e Typhlodromalus aripo De Leon). Tetranychus desertorum foi registrada pela primeira vez, associada à soja, no país. P. fragariae e T. aripo foram registradas pela primeira vez em soja. O potencial dos ácaros fitoseídeos como agentes de controle biológico na cultura da soja foi discutido. Dentre as hipóteses para o crescimento das infestações de culturas de soja com ácaros fitófagos estão a expansão progressiva da área cultivada, os veranicos observados nos últimos anos durante a estação de plantio, as modificações no sistema de cultivo da soja que levaram ao aumento no uso de pesticidas e a utilização de novas cultivares com características morfológicas ou bioquímicas que favorecem o desenvolvimento de populações desses ácaros.
During the last growing seasons, high infestations of phytophagous mites were observed in the State of Rio Grande do Sul, Brazil, becoming necessary to apply pesticides for their control. The objective of this study was to identify phytophagous and predatory mite species associated with soybean in ten counties of that state, during the 2002/03 and 2003/04 growing seasons, in five soybean cultivars (A 6001 RG, A 7001 RG, A 8000 RG, A 8100 RG, Anta 82), all genetically modified. In samples of soybean leaves four phytophagous mite species (Mononychellus planki (McGregor), Polyphagotarsonemus latus (Banks), Tetranychus desertorum Banks and Tetranychus gigas Pritchard & Baker) and two predatory mite species (Phytoseiulus fragariae Denmark & Schicha and Typhlodromalus aripo De Leon) were found. T. desertorum was found for the first time associated with soybean in the country. Phytoseiulus fragariae and T. aripo are reported for the first time on soybean. The potential of phytoseid mites as biological control agents in soybean crop was discussed. Among the hypotheses to explain the increasing infestation of soybean fields with phytophagous mites area are the progressively larger cultivated area, the dry spells observed in the last few years in the growing season, changes in soybean cropping system that led to increased use of pesticides and utilization of new soybean cultivars with morphological or biochemicals characteristics that favour the development of these mite populations.
Subject(s)
Animals , Mites/physiology , Glycine max/parasitology , BrazilABSTRACT
A species of Neomegalotomus is an occasional pest of soybean [Glycine max (L.) Merrill] in the neotropics, including in Brazil. It was known as Neomegalotomus parvus (Westwood); but the discovery of the type specimen of a species described earlier requires that the name be changed to Neomegalotomus simplex (Westwood), which becomes the correct name for the soybean pest.
Uma espécie de Neomegalotomus é praga ocasional de soja [Glycine max (L.) Merrill] na Região Neotropical, incluindo o Brasil. Essa espécie era conhecida como Neomegalotomus parvus (Westwood); entretanto, a descoberta da espécie tipo de uma outra espécie, descrita anteriormente, requer que o nome seja trocado para Neomegalotomus simplex (Westwood), o que o torna o nome correto para essa praga da soja.
Subject(s)
Animals , Hemiptera , Glycine max/parasitology , Terminology as TopicABSTRACT
Se determinó en la ciudad de Santa Fe y su zona de influencia, la capacidad toxicogénica, mediante la aplicación de ensayos biológicos rápidos, a hongos contaminantes de cereales y productos alimenticios elaborados con ellos. Los alimentos estudiados fueron: soja, maíz, trigo y sus derivados: los géneros frecuentes aislados fueron: aspergillus, penicillium y fusarium, identificandose las especies de aquellos que resultaron toxicogénicos. Las acciones citotóxicas detectadas mediante los ensayos aplicados fueron: capacidad mutagénica, hemólisis de glóbulos rojos humanos y elongación e inhibición de células de bacillus thuringiensis
Subject(s)
Aspergillus/isolation & purification , Fusarium/isolation & purification , Mycotoxins/toxicity , Penicillium/isolation & purification , Food Contamination/analysis , Edible Grain/parasitology , Zea mays/parasitology , Glycine max/parasitology , Triticum/parasitologyABSTRACT
Pest Control is treated as a economic problem. The social and the private perspectives differ due to the consideration of the environmental and social impacts as well as technical aspects such as resistance, resurgence and secondary pests. A mathematical model is developed to determine and compare the social and the private optimum control strategies (which define the Economic Thereshold Levels) for the velvetbean caterpillar on soybeans in Brazil. The crop/pest system incorporates effects of predators and parasites, the soybean natural capacity to compensate for injury and the pesticide effects on both pests and its natural enemies; in the social case, the environmental and social impacts and the effects of pest resistance to the pesticide are incorporated. Consideration of density dependence, weather effects, randomnes of pest attack and risk aversion are discussed. The results can be compared with current control practices and IPM programme recomendations.