RESUMO
The aim of this study was to evaluate and select entomopathogenic fungi that produces insecticidal compounds for the control of adults of Anastrepha obliqua Macquart (Diptera: tephritidae) that are the main pest of mango (Mangifera indica L. Bark) in Colombia. Nine entomopathogenic fungi isolates were evaluated, five belonging to the genus Metarhizium and four belonging to the genus Beauveria. One strain of the species Metarhizium robertsii with insecticidal activity was selected. By column fractionation, an active fraction was obtained, which caused mortalities higher than 90% after 48 h of exposure. Through HPLC it was determined that the active fraction is composed of more than 22 metabolites. Identification of the metabolites by UHPLC MS/MS revealed the presence of destruxin in E, D, A and B groups (destruxin E-diol, destruxin D, destruxin D1, destruxin D2, destruxin A2, destruxin A, destruxin A3, dihydrodestruxin A, desmB, destruxin B2, destruxin B and destruxin B1). The evaluation of the insecticidal capacity of the organic fractions obtained by HPLC indicated that the extract obtained from the isolate M. robertsii had a compound with high activity on adults of A. obliqua (destruxin A) causing massive mortality of up to 100%, after 48 h of the treatment administration. Furthermore, two other compounds with medium activity were found (destruxin A2 and destruxin B), showing mortalities between 60.0 and 81.3%, respectively. The extract of the isolate MT008 of M. robertsii showed higher insecticidal activity and a potential source for the control of A. obliqua.
Assuntos
Inseticidas , Mangifera , Tephritidae , Animais , Inseticidas/farmacologia , Colômbia , Espectrometria de Massas em Tandem , Extratos VegetaisRESUMO
BACKGROUND: Cacao is important for the economy of many countries in the humid tropics. Its quality is affected when fruits are not collected at the optimal harvest point. The aim of this study was to obtain maturity indices for producers to facilitate the timely harvest and improve the development of fermentation and the sensorial quality of cacao. The growth and respiration processes, and the physicochemical changes during the maturation of three cacao genotypes were determined. Physiological follow-ups measuring fruit length and diameter were performed from 30 days after anthesis to fruit deterioration in the tree. RESULTS: Growth equations were obtained, establishing four maturity stages based on days after anthesis, and fruit length and diameter. Nineteen descriptors were used for the characterization, and through Pearson's correlation and principal component analysis (PCA), five descriptors were identified as representative of the maturity stages of the cacao fruit. PCA results and respiration measurements established that stage 3 presented the highest substrate availability for obtaining good fermentation and quality cacao. This stage showed values between 124 and 197 days after anthesis with lengths between 167.7 and 249.73 mm, and diameters between 64.4 and 95.8 mm, according to the locality. CONCLUSION: Three growth phases of the cacao fruits were established considering days after anthesis. Both the edaphoclimatic conditions and the cacao genotype characteristics influenced this determination. Stage 3 of fruit maturation shows the best physicochemical conditions for good fermentation. © 2021 Society of Chemical Industry.