Abstract Asian soybean rust (Phakopsora pachyrhizi – ASR) is one of the major diseases that occur in soybean and causes great damage to commercial crops. Therefore, the goal of this work was to investigate the relationship between biochemical and photosyntetic parameters in soybean with ASR. Two experiments were performed in a randomized complete block with three treatments (water, Tween 20, and methyl jasmonate). The evaluated traits were: severity, chlorophyll pools, concentration of phenolic compounds content, enzyme activity, and photosyntetic parameters. Based on Pearson correlation, correlation network and path analysis it was verified that the severity had high correlation with almost all traits evaluated meanwhile photosynthesis is weakly related with almost all traits. Therefore, the occurrence of ASR affects directly the traits related to enzymatic activity and phenolic compounds content in soybean plants inoculated with ASR. The management of ASR is important to keep in normal levels the rates of photosynthesis carried out by the plant, and thus not affect the yield. Besides that, understanding the biochemical mechanisms and ecophysiological responses that occur during the soybean-P. pachyrhizi interaction has a great importance for breeding programs, as it will help for obtaining resistant cultivars or efficient methods in fungus control.

The flavonoid rutin is recognized as playing an important role in the protection of plants against lepidopterans. Bioassays with this compound are generally carried out using artificial diets. Proteins of high energy value, such as casein, are important ingredients of insect artificial diets as a source of essential amino acids. However, such proteins can generally increase the allelochemical activity. Our objective was to evaluate the effects of rutin on larvae of the velvetbean caterpillar Anticarsia gemmatalis Hübner by incorporating this allelochemical into diets with different concentrations of casein. Three casein concentrations (0, 7 g, or 14 g) combined with none, 0.65%, or 1.30% of rutin were added to the rearing diet and offered to the larvae from hatching to pupation. Rutin negatively affected larval development, the amount of food consumed, and pupal weight of A. gemmatalis. These negative effects were clearly seen in insects fed on diets with 7 g of casein to which any concentration of rutin was added. The effects of rutin when added to the diets without casein were stronger than in diets containing a suitable amount of casein (14 g). The greater negative effects of rutin in diets containing suboptimal concentrations of casein indicate that casein can increase the effects of rutin only when the diets are nutritionally unsuitable for insect development.

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.

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 padrão de distribuição temporal e vertical de Phyllophaga cuyabana (Moser) foi avaliado no perfil do solo para subsidiar amostragens da população do inseto visando ao seu manejo. Em levantamentos populacionais realizados durante três anos, em de Boa Esperança, PR, P. cuyabana foi univoltina, com baixa sobreposição de estádios de desenvolvimento. Houve um pico populacional no verão (dezembro a fevereiro) e um declínio nos meses frios, quando as larvas estavam em diapausa. O inseto, nos distintos estágios de desenvolvimento, explorou diferentes profundidades do solo. Ovos e larvas no início do primeiro instar concentraram-se entre 5 cm e 10 cm de profundidade e, ao se desenvolverem, atingiram 30 cm de profundidade. Adultos e ovos ocorreram na primavera (outubro a dezembro), quando começaram a ser observadas as larvas ativas em amostras realizadas entre zero e 15 cm de profundidade. Larvas em diapausa e pupas foram observadas em maior concentração entre 15 e 30 cm de profundidade, do inicio do outono ao início da primavera. O número de insetos no solo (até 40 cm de profundidade) mostrou relação funcional positiva com a temperatura do ar e com a evapotranspiração. Entretanto, a relação da distribuição percentual de larvas no perfil do solo com a temperatura do solo foi positiva apenas para profundidades de zero a 10 cm. Para estimar a população de corós de novembro a abril, as amostragens podem ser feitas até 20 cm de profundidade, porém de maio a outubro a profundidade das amostragens deve atingir 30 cm.

Phyllophaga cuyabana (Moser) temporal and vertical distribution patterns were evaluated in the soil profile, in order to subsidize methodology for population sampling, aiming at its management. In insect surveys carried out during three years, in Boa Esperança County, State of Parana, Brazil, Phyllophaga cuyabana was univoltine, with little overlap of the larval stages. Population peaked during December-February, but declined during the colder months, when larvae were in diapause. Different developmental stages exploited distinct soil depths. Eggs and early first instars tended to concentrate between 5 cm and 10 cm deep, but they spread more uniformly through the soil profile, reaching depths up to 30 cm, as they developed. Adults and eggs occurred in the spring (October to December) when active larvae also started to be observed; feeding larvae occurred up to late-April between 0 to15 cm deep. Diapausing larvae and pupae were observed from early fall to early spring, mostly from 15 cm to 30 cm deep. Throughout the year, the number of insects in the soil (up to 40 cm deep) showed a positive functional relationship with air temperature and evapotranspiration. The relationship of percent distribution of larvae in the soil profile and soil temperature, however, was positive only above 10 cm. To estimate the insect population from November to April, samples can be collected until 20 cm deep; from May to October, however, samplings should be deeper, up to 30 cm.

Estudos em laboratório e em casa-de-vegetação foram conduzidos para estudar a preferência de Phyllophaga cuyabana (Moser) em se alimentar e ovipositar nas espécies de plantas: Cajanus cajan L. (guandu), Crotalaria juncea L. (crotalária), Crotalaria spectabilis Roth (crotalária), Crotalaria ochroleuca G. Don (crotalária), Glycine max [L.] Merrill (soja), Gossypium hirsutum L. (algodão), Helianthus annuus L. (girassol), Stizolobium aterrimum [Mucuna aterrima] Piper & Tracey (mucuna preta) e Zea mays L. (milho). O maior número de ovos foi observado em girassol, C. juncea e soja e o menor em algodão, em situação de confinamento. Em testes de multipla-escolha, os adultos não fizeram discriminação entre as plantas. Entretanto, em teste de dupla-escolha, a proporção de ovos e do consumo foliar em soja foi significativamente maior do que em C. spectabilis. Em situação de múltipla escolha, a distribuição das larvas ocorreu ao acaso, não sendo observada nenhuma tendência de preferência, mas em situação de dupla-escolha, usando-se soja como padrão, as larvas sempre preferiram se alimentar nas raízes de soja. Os adultos de P. cuyabana preferiram os hospedeiros mais adequados à sobrevivência de sua prole. Esse comportamento pode ser explorado em um programa de manejo integrado dessa praga.

Laboratory and greenhouse experiments were carried out to study food and oviposition preference by Phyllophaga cuyabana (Moser) on different plant species as Cajanus cajan L. (pigeon pea), Crotalaria juncea L. (sun hemp), Crotalaria spectabilis Roth (showy crotalaria), Crotalaria ochroleuca G. Don (slenderleaf rattlebox), Glycine max [L.] Merrill (soybean), Gossypium hirsutum L. (cotton), Helianthus annuus L. (sunflower), Stizolobium aterrimum [Mucuna aterrima] Piper & Tracey (velvetbean) and Zea mays L. (mayze). In no-choice experiments, the number of eggs layed in sunflower, C. juncea and soybean was larger compared to cotton. Despite the fact that the adults did not discriminate among plants, in dual-choice test, the proportion of eggs layed and leaf consumption by P. cuyabana adults in soybean were significantly higher than in C. spectabilis. The larval distribution in the soil was at random in multiple-choice, withouth any trend of preference, but in dual-choice, when soybean was the control, larvae always preferred to feed on its roots. P. cuyabana adults had preference for more suitable hosts and that could stand their offspring survival. This behaviour can be usefully exploited in an integrated management program for this pest.

Os efeitos de cinco genótipos de soja [Glycine max (L.) Merrill] ('BR-16', 'IAC-100,' PI 227687, PI 229358, PI 274454) no desenvolvimento ninfal, peso de adulto e quantidade de lipídio em Nezara viridula (L.) foram avaliados em laboratório. Quando as ninfas se alimentaram de vagens de PI 227687 (resistente) e 'BR-16' (suscetível), sua mortalidade foi de 66,2% e 27,5%, respectivamente. Ninfas de segundo ínstar, mantidas desde a eclosão em placas de Petri contendo vagens de PI 274454 e 'BR-16', pesaram 1,1 mg e 1,0 mg, respectivamente; sendo mais pesadas que aquelas alimentadas com vagens da PI 227687 (0,7 mg) e 'IAC-100' (0,7 mg). O peso fresco de adulto foi 146,9 mg quando as ninfas se alimentaram em 'BR-16,' 127,0 mg em PI 227687 e 125,5 mg em 'IAC-100'. Os dois últimos genótipos também afetaram negativamente o ganho de peso do percevejo. Fêmeas acumularam menos lipídio quando se alimentaram em 'IAC-100' (4,8 mg) e PI 227687 (4,3 mg), em comparação com aquelas alimentadas em outros genótipos. Por seus efeitos deletérios, PI 227687 confirma-se como alimento inadequado para N. viridula e como o genótipo mais promissor para ser usado em programas de melhoramento como fonte de resistência a percevejos.

The effects of five soybean [Glycine max (L.) Merrill] genotypes ('BR-16', 'IAC-100', PI 227687, PI 229358, PI 274454) on nymphal development, adult weight and lipid content of the stink bug Nezara viridula (L.), were evaluated in the laboratory. When fed on the pods of PI 227687 (resistant) and of 'BR-16' (susceptible) nymph mortalities were respectively 66.2% and 27.5%. Second instar nymphs, maintained since hatching in petri dishes containing PI 274454 and 'BR-16' pods, weighed 1.1 mg and 1.0 mg, respectively; they were heavier than those fed with PI 227687 (0.7 mg) and 'IAC-100' (0.7 mg) pods. Adult fresh weights were 146.9 mg when fed on 'BR-16', 127.0 mg with PI 227687 and 125.5 mg with 'IAC-100'. The later two genotypes also negatively affected stink bug weight gain. Females accumulated less lipid when fed on 'IAC-100' (4.8 mg) and PI 227687 (4.3 mg) than those fed on the other genotypes. By their deleterious effects, PI 227687 is confirmed as an inadequate food to N. viridula and as the most promising genotype for use in soybean breeding programs as sources of resistance to stink bug.

Estudou-se a localização e a distribuição de ovos, larvas e adultos de Sternechus subsignatus Boheman (Coleoptera: Curculionidae) em plantas de soja [(Glycine max (L.) Merrill] e no solo, em diferentes horários do dia, em lavouras comerciais no sistema plantio direto, entre as safras agrícolas de 1990/91 a 1996/97, em Cruz Alta e Júlio de Castilhos (RS). Ovos e larvas foram encontrados na haste principal, nos ramos laterais e nos pecíolos, nas partes superior, mediana e inferior das plantas. Não se verificou movimento das larvas para as partes mais altas ou mais baixas das planta à medida que se desenvolveram. Ovos (90%) e a maioria das larvas (87%) foram encontrados na haste principal e na parte mediana das plantas (79% e 78%, respectivamente). Adultos foram encontrados no terço superior, médio e inferior das plantas e no solo, em todos os horários de coleta. Verificou-se movimentação dos adultos para as partes mais altas das plantas durante a noite, e para as partes mais baixas das plantas e para o solo, durante o dia. Esses resultados evidenciam que a maioria dos ovos e das larvas fica protegida no interior da haste principal e na parte mediana das plantas, sob a folhagem. Adultos, durante o dia, ficam escondidos nas partes mais baixas das plantas, entre as folhas e no solo.

Soybean [(Glycine max (L.) Merrill] commercial fields, maintained under a no-till system, were sampled during the crop seasons 1990/91 and 1996/97, in Cruz Alta and Júlio de Castilhos, Rio Grande do Sul State, to determine the distribution of eggs, larvae and adults of Sternechus subsignatus Boheman (Coleoptera : Curculionidae). Soybean plants and soil were examined at different time schedules. Eggs and larvae were recorded in main stems, lateral branches and leaf petioles, divided into the upper third, medium and lower third of soybean plants. Eggs (87%), and larvae (79%) were mainly observed in the main stem and in the medium plant sections (87% and 78%, respectively). Larval movement was not observed because larvae remained inside the galls, in the same area where the eggs were laid. Adults were located in different places depending on the sampling time. At night, adults were observed to move to the upper third of the plant and, during the day, down to the lower third of the plant and to the soil. The insects are normally concealed during their pre- and post- embryonic stage throughout most of the day.