Relationship between biochemical and photosynthetic traits with Asian soybean rust.

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 natural plant stress elicitor cis-jasmone causes cultivar-dependent reduction in growth of the stink bug, Euschistus heros and associated changes in flavonoid concentrations in soybean, Glycine max.

To test the hypothesis that the plant stress related elicitor cis-jasmone (cJ) provides protection in soybean pods against the seed-sucking stink bug pest, Euschistus heros, the growth of E. heros on cJ-treated pods was investigated using three soybean cultivars differing in insect susceptibility, i.e. BRS 134 (susceptible), IAC 100 (resistant) and Dowling (resistant). E. heros showed reduced weight gain when fed cJ-treated Dowling, whereas no effect on weight gain was observed when fed other treated cultivars. Using analysis of variance, a three factor (cultivar x treatment x time) interaction was observed with concentrations of the flavonoid glycosides daidzin and genistin, and their corresponding aglycones, daidzein and genistein. There were increases in genistein and genistin concentrations in cJ-treated Dowling at 144 and 120 h post treatment, respectively. Higher concentrations of malonyldaidzin and malonylgenistin in Dowling, compared to BRS 134 and IAC 100, were observed independently of time, the highest concentrations being observed in cJ-treated seeds. Levels of glycitin and malonylglycitin were higher in BRS 134 and IAC 100 compared to Dowling. Canonical variate analysis indicated daidzein (in the first two canonical variates) and genistein (in the first only) as important discriminatory variables. These results suggest that cJ treatment leads to an increase in the levels of potentially defensive isoflavonoids in immature soybean seeds, but the negative effect upon E. heros performance is cultivar-dependent.

Do different casein concentrations increase the adverse effect of rutin on the biology of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)?

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.

Do different casein concentrations increase the adverse effect of rutin on the biology of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)?

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 percent, or 1.30 percent 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.

Interactions among insect-resistant soybean genotypes extracts with populations of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) susceptible and resistant to its nucleopolyhedrovirus

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.

Seasonal and vertical distribution of Phyllophaga cuyabana (Moser)(Coleoptera: Melolonthidae) in the soil profile.

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 to 15 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.

Interactions among insect-resistant soybean genotypes extracts with populations of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) susceptible and resistant to its nucleopolyhedrovirus.

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.

Seasonal and vertical distribution of Phyllophaga cuyabana (Moser)(Coleoptera: Melolonthidae) in the soil profile / Distribuição estacional e vertical de Phyllophaga cuyabana (Moser) (Coleoptera: Melolonthidae) no perfil do solo

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.

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.

Feeding and oviposition preference of Phyllophaga cuyabana (Moser) (Coleoptera: Melolonthidae) on several crops.

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, without 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.

Feeding and oviposition preference of Phyllophaga cuyabana (Moser) (Coleoptera: Melolonthidae) on several crops

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.

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.

Nymphal development, lipid content, growth and weight gain of Nezara viridula (L. ) (Heteroptera: Pentatomidae) fed on soybean genotypes / Desenvolvimento de ninfas, conteúdo de lipídios, crescimento e ganho de peso de Nezara viridula (L. ) (Heteroptera: Pentatomidae) alimentada com genótipos de soja

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 percent and 27.5 percent. 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.

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 por cento e 27,5 por cento, 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.