Efecto del uso del suelo adyacente al cafetal sobre la dispersión y dinámica poblacional de la broca Hypothenemus hampei Ferrari y la abundancia de enemigos naturales en el cantón de Turrialba, Costa Rica

The fragmentation of natural ecosystems has generated landscapes where the matrix is mainly dominated by agricultural activities. The persistence of insect pests and beneficial insects in agro ecosystems is related to the spatial and temporary availability of habitats as well as the alternate hosts to crops. Both the dynamics of insect pests and natural enemies may be influenced by the landscape spatial arrangements which could have impacts on pest dispersal and colonization affecting the abundance of natural enemies. This study was conducted to investigate the effect of the land use adjacent to coffee plantations on short-distance dispersal and the coffee berry borer (Hypothenemus hamperi) population dynamics and the distribution of predatory ants. The study site was located in the canton of Turrialba, Costa Rica. Farms having different land use were selected. Four coffee plantations adjacent to sugar cane plantations were chosen, four coffee plantations adjacent to forests and four coffee plantations adjacent to pastures for a total of 12 coffee sites evaluated in six different coffee farms. In each of the land-use combinations (coffee- sugarcane, coffee- forest and coffee-forest-pasture) three transects were placed (180 m long each) and 18 Brocap® traps (4 inside the coffee plantations and 14 in the adjacent land use) using one of the most attractive mixtures for the coffee berry borer (methanol-ethanol, 3:1). Every 8 or 16 days bottles traps were withdrawn and counting was made in the laboratory. In addition, 1440 berries were monthly dissected per category (dry, green and ripe) and also monthly samplings were made to assess the levels of coffee berry borer infestation. Ant trapping using white cardboard traps impregnated with tuna bait was performed. The study was conducted between the months of February and July. The factors studied were: distance, land use and sampling time. The variables analyzed were: number of coffee berry borers per trap, number of alive females, number of killed females, number of eggs, number of larvae, number of pupae, average of infected berries per branch and the number of Solenopsis geminate and Pheidole radoszkowskii. The altitude of each of the coffee plots was used as covariate. To know the differences between the factors under study, generalized linear mixed models for dispersal data of coffee berry borer and ant abundance were used. An analysis of main components was performed to understand the relationship between ants, altitude, shade and coffee berry borer. The results indicated that there is land use effect on the dissemination of the coffee berry borer being the sugar cane use and pastures different from forests. Females were captured flying 140 m after the coffee plantation borderline. There were significant differences between the distances studied. There was no land use effect on the coffee berry borer populations caught in the traps inside coffee plantations, coffee borer populations in berries and infestation levels. Ant abundance was affected by the adjacent land use, being P. radoszkowskii more abundant in coffee plantations adjacent to sugar cane plantations and forests. S. geminate was present in a high proportion in coffee plantations adjacent to pastures. A positive relationship between the coffee berry borer and P. radoszkowskii was found as well as a negative relationship with S. geminate. (Résumé d'auteur)