Examinando por Autor "Koch Duarte, Christian"

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Ecological zone-based volume estimation of Calycophyllum spruceanum and Cedrelinga cateniformis in the Northeastern Peruvian Amazon
(Elsevier B.V., 2025-11-08) Koch Duarte, Christian; del Aguila Piña, Carlos Francisco; Fernández Sandoval, Andrés; Cárdenas Rengifo, Gloria Patricia; Santillán Gonzáles, Manuel Dante; Salazar Hinostroza, Evelin Judith; Castedo Dorado, Fernando; Álvarez Álvarez, Pedro; Goycochea Casas, Gianmarco; Baselly Villanueva, Juan Rodrigo
Forest volume modeling plays a fundamental role in forest inventory, biomass estimation, and the sustainable management of timber resources. In the Amazon region of Peru, native species such as Calycophyllum spruceanum and Cedrelinga cateniformis hold high ecological and commercial value, yet remain understudied in terms of volumetric estimation. This study aimed to develop and evaluate volumetric models for both species across three ecological zones—humid forest, very humid forest, and dry forest—representing the environmental diversity of the northeastern Peruvian Amazon. A total of 18 volumetric models were fitted for each species and site condition using linear regression techniques. Model performance was assessed through adjusted coefficient of determination (R²adj), root mean square error (RMSE), mean absolute error (MAE), Akaike Information Criterion (AIC), and diagnostic analyses including residual plots and relative error histograms. The results revealed that model performance varied by ecological zone, with the dry forest models showing the highest precision and lowest residual dispersion. Models M3 (Spurr), M4 (Schumacher & Hall), and M9 (Meyer) consistently achieved strong predictive accuracy. Prediction errors were higher in small-volume classes, suggesting the need for caution when applying models to young or small-diameter trees. The developed models are statistically reliable, requiring minimal input variables for the accurate estimation of the timber volume of the two species across various Amazonian environments. It is recommended to adopt zone-specific models for operational use and to continue expanding regional forest databases to improve future model calibration and validation.
Native entomopathogenic nematodes from Peru control Spodoptera frugiperda, a major pest of Zea mays in the Peruvian Amazon
(MDPI, 2026-03-09) Fachin Ruiz, Grecia; Córdova Sinarahua, Deyvis; Romero Chávez, Lorena Estefani; Alvarado Ramírez, Jaime; Quesquen Lopez, Cesar; Flores García, Eybis; Koch Duarte, Christian; Cerna Mendoza , Agustín; Vásquez Bardales, Joel; Corazon Guivin, Mike
This study evaluated entomopathogenic nematodes (EPNs) isolated from a cacao agroforestry system in the Peruvian Amazon, focusing on their molecular characterization and efficacy against Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae. Thirteen EPN isolates were obtained from 50 soil samples using the Galleria mellonella baiting technique. Mortality assays revealed significant differences among isolates at 24, 48, and 72 h, with isolates 11N-A4 and 8N-B1 being the most virulent, achieving maximum mortalities of 100% and 96.3% at 72 h, respectively. Median lethal time (LT50) values indicated rapid action of these isolates on G. mellonella larvae, with 33.3 h for 11N-A4 and 32.4 h for 8N-B1. Molecular identification using ITS, D2-D3 (LSU), and COI markers confirmed the isolates as Heterorhabditis sp. (11N-A4) and Heterorhabditis amazonensis (8N-B1). In bioassays with S. frugiperda larvae, both EPNs exhibited dose- and time-dependent mortality. H. amazonensis showed rapid action, reaching 100% mortality at the highest dose (60 IJs/larvae) within 48 h, whereas Heterorhabditis sp. displayed a gradual, sustained increase, attaining 91% mortality at 72 h. Median lethal dose (LD50) and LT50 values reflected the efficiency of both isolates, with Heterorhabditis sp. achieving lower LD50 at later stages and shorter LT50 at low-to-intermediate doses. These findings highlight the potential of Heterorhabditis sp. and H. amazonensis as effective biocontrol agents adapted to local conditions and represent the first report of H. amazonensis in Peru. Further studies under field conditions are required to confirm their suitability for incorporation into integrated pest management strategies in the Peruvian Amazon.