Induced volatiles in the interaction between soybean (Glycine max) and the Mexican soybean weevil (Rhyssomatus nigerrimus) / Voláteis induzidos na interação entre soja (Glycine max) e gorgulho da soja mexicana (Rhyssomatus nigerrimus)

Abstract The present study analyzed the volatile compounds emitted by Glycine max (cv. FT-Cristalina-RCH) soybean plants: healthy plants and plants damaged mechanically or by the Mexican soybean weevil Rhyssomatus nigerrimus. The SPME method was used to compare the volatile profile of soybean plants in four different conditions. The volatile profile of G. max plants infested by R. nigerrimus was qualitatively and quantitatively different from that of healthy and mechanically damaged plants. Emission of 59 compounds was detected in the four treatments. Of these compounds, 19 were identified by comparison of the Kovats index, mass spectrum and retention times with those of synthetic standards. An increase in concentration of the volatiles (Z)-3-hexenyl acetate and the compound 1-octen-3-ol was observed when the soybean plants were mechanically damaged. The compounds mostly produced by the soybean plant during infestation by male and female R. nigerrimus were 1-octen-3-ol, 6-methyl-5-hepten-2-one, (E)-β-ocimene, salicylaldehyde, unknown 10, linalool, methyl salicylate, (Z)-8-dodecenyl acetate (ester 5), ketone 2 and geranyl acetone. Behavioral effects of the identified compounds during the insect-plant interaction and their conspecifics are discussed.

Resumo O presente estudo analisou os compostos voláteis emitidos pelas plantas de soja Glycine max (cv. FT-Cristalina-RCH): plantas e plantas sadias danificadas mecanicamente ou pelo gorgulho da soja mexicana Rhyssomatus nigerrimus. O método SPME foi utilizado para comparar o perfil volátil de plantas de soja em quatro diferentes condições. O perfil volátil das plantas de G. max infestadas por R. nigerrimus foi qualitativa e quantitativamente diferente do das plantas saudáveis e danificadas mecanicamente. Foi detectada, nos quatro tratamentos, emissão de 59 compostos, dos quais 19 foram identificados por comparação do índice de Kovats, espectro de massa e tempos de retenção com aqueles de padrões sintéticos. Um aumento na concentração dos voláteis acetato de (Z)-3-hexil e do composto 1-octeno-3-ol foi observado quando as plantas de soja foram mecanicamente danificadas. Os compostos produzidos principalmente pela planta de soja durante a infestação por R. nigerrimus macho e fêmea foram 1-octeno-3-ol, 6-metil-5-hepteno-2-ona, (E)-β-ocimeno, salicilaldeído, desconhecido 10, linalol, salicilato de metila, acetato de (Z)-8-dodecenila (éster 5), cetona 2 e geranil acetona. Foram discutidos os efeitos comportamentais dos compostos identificados durante a interação inseto-planta e seus coespecíficos.

Induced volatiles in the interaction between soybean (Glycine max) and the Mexican soybean weevil (Rhyssomatus nigerrimus)

Abstract The present study analyzed the volatile compounds emitted by Glycine max (cv. FT-Cristalina-RCH) soybean plants: healthy plants and plants damaged mechanically or by the Mexican soybean weevil Rhyssomatus nigerrimus. The SPME method was used to compare the volatile profile of soybean plants in four different conditions. The volatile profile of G. max plants infested by R. nigerrimus was qualitatively and quantitatively different from that of healthy and mechanically damaged plants. Emission of 59 compounds was detected in the four treatments. Of these compounds, 19 were identified by comparison of the Kovats index, mass spectrum and retention times with those of synthetic standards. An increase in concentration of the volatiles (Z)-3-hexenyl acetate and the compound 1-octen-3-ol was observed when the soybean plants were mechanically damaged. The compounds mostly produced by the soybean plant during infestation by male and female R. nigerrimus were 1-octen-3-ol, 6-methyl-5-hepten-2-one, (E)--ocimene, salicylaldehyde, unknown 10, linalool, methyl salicylate, (Z)-8-dodecenyl acetate (ester 5), ketone 2 and geranyl acetone. Behavioral effects of the identified compounds during the insect-plant interaction and their conspecifics are discussed.

Resumo O presente estudo analisou os compostos voláteis emitidos pelas plantas de soja Glycine max (cv. FT-Cristalina-RCH): plantas e plantas sadias danificadas mecanicamente ou pelo gorgulho da soja mexicana Rhyssomatus nigerrimus. O método SPME foi utilizado para comparar o perfil volátil de plantas de soja em quatro diferentes condições. O perfil volátil das plantas de G. max infestadas por R. nigerrimus foi qualitativa e quantitativamente diferente do das plantas saudáveis e danificadas mecanicamente. Foi detectada, nos quatro tratamentos, emissão de 59 compostos, dos quais 19 foram identificados por comparação do índice de Kovats, espectro de massa e tempos de retenção com aqueles de padrões sintéticos. Um aumento na concentração dos voláteis acetato de (Z)-3-hexil e do composto 1-octeno-3-ol foi observado quando as plantas de soja foram mecanicamente danificadas. Os compostos produzidos principalmente pela planta de soja durante a infestação por R. nigerrimus macho e fêmea foram 1-octeno-3-ol, 6-metil-5-hepteno-2-ona, (E)--ocimeno, salicilaldeído, desconhecido 10, linalol, salicilato de metila, acetato de (Z)-8-dodecenila (éster 5), cetona 2 e geranil acetona. Foram discutidos os efeitos comportamentais dos compostos identificados durante a interação inseto-planta e seus coespecíficos.

El programa de control integral para la enfermedad de chagas en Tupiza: una experiencia al servicio del país / The comprehensive control program for Chagas disease in Tupiza: an experience to the service of the country

Entre los mayores problemas socioeconómicos que encara en la actualidad América Latina son los elevados índices de pobreza de los habitantes de áreas rurales y las condiciones que de ella emergen.

Chagas disease vector control in Tupiza, Southern Bolivia

Heavy domestic and peridomestic infestations of Triatoma infestans were controlled in two villages in southern Bolivia by the application of deltramethrin SC25 (2,5 per cent suspension concentrate) at a target dose of 25 mg a.i.m². Actual applied dose was monitored by HPLC analysis of filter papers placed at various heights on the house walls, and was shown to range from 0 to 59.6 about a mean of 28.5 mg a.i./m². Wall bioassays showed high mortality of T.infestans during the first month after the application of deltamethrin. Mortality declined to zero as summer temperatures increased, but reappeared with the onset of the following winter. In contrast, knockdown was apparent throughtout the trial, showing no discernible temperature dependence. House infestation rates, measured by manual sampling and use of paper sheets to collect bug faeces, declined from 79 per cent at the beginning of the trial to zero at the 6 month evalution. All but one of the houses were still free of T.infestans at the final evaluation 12 months after spraying, although a small number of bugs were found at this time in 5 of 355 peridomestic dependencies. Comparative cist studies endorse the recommendation of large-scale application of deltamethrin or pyrethroid of similar cost-effectiveness, as a means to eliminate domestic T.infestans populations in order to interrupt transmission of Chagas disease.