Clemente Villanueva Verduzco

Respuesta Numérica de Chilocorus cacti Sobre Dactylopius opuntiae

Resumen. La respuesta numérica de Chilocorus cacti Linnaeus, 1767 (Coleoptera: Coccinellidae), como depredador de la cochinilla silvestre (Dactylopius opuntiae (Cockerell)), se determinó a través de estudios en laboratorio. Al cuantificar la dinámica de la respuesta numérica, se encontró que al aumentar la cantidad de presas ofrecidas, el depredador incrementó el número de huevos ovipositados y de presas depredadas. Según las regresiones lineales simples realizadas: por cada dos presas ofrecidas, se incrementó el número de huevos ovipositados en 1.238 y el número de presas depredadas en 0.554; y el número de huevos ovipositados se incrementó en 0.636 por cada dos presas depredadas.

Diagnosis and Integrated Management of Fruit Rot in Cucurbita argyrosperma , Caused by Sclerotium rolfsii

Fruit rot is the principal phytopathological problem of pipiana pumpkin (Cucurbita argyrosperma Huber) in the state of Guerrero. The aims of this research were to 1) identify the causal agent of southern blight on pumpkin fruits by morphological, pathogenic, and molecular analysis (ITS1, 5.8S, ITS2); 2) evaluate in vitro Trichoderma spp. strains and chemical fungicides; and 3) evaluate under rainfed field conditions, the strains that obtained the best results in vitro, combined with fungicides during two crop cycles. Number of commercial and non-commercial fruits at harvest, and seed yield (kg ha−1) were registered. Morphological, pathogenic and molecular characterization identified Sclerotium rolfsii as the causal agent of rot in pipiana pumpkin fruits. Now, in vitro conditions, the highest inhibition of S. rolfsii were obtained by Trichoderma virens strain G-41 (70.72%), T. asperellum strain CSAEGro-1 (69%), and the fungicides metalaxyl (100%), pyraclostrobin (100%), quintozene (100%), cyprodinil + fludioxonil (100%), and prochloraz (100%). Thiophanate-methyl only delayed growth (4.17%). In field conditions, during the spring-summer 2015 cycle, T. asperellum strain CSAEGro-1 + metalaxyl, and T. asperellum + cyprodinil + fludioxonil, favored the highest number of fruits and seed yield in the crop.