RELATIONSHIP BETWEN PESTS AND BENEFICIAL ORGANISMS DIVERSITY IN TOBACCO CROPS WITH VARIABLES OF CROP HETEROGENEITY AND WINDBREAKS BARRIER IN SALTA PROVINCE (ARGENTINA).

MIRAGLIO, R; OLIVO VERÓNICA,; CORRONCA, J. A.

San Miguel de Tucuman

Jornada; XXXI Jornadas Científicas de la Asociación de Biología de Tucumán; 2014

Sociedad de Biología de Tucumán

Tobacco is the main intensive crop of Valle de Lerma, and its agricultural pests are an economic, ecological and social problem that should to be considered to reduce crop losses. Therefore, in this paper we want to evaluate which is the relationship between variables of habitat heterogeneity with the arthropod guilds in tobacco crops and barriers surrounding the fields. We selected 22 tobacco farms implanted in different dates. We took at least 10 samples of arthropods on vegetation with a G-Vac in both sites, tobacco crop (T) and the herbaceous layer of windbreaks (B). The number of samples per farm was calculated in relation with the land size. Sampling was conducted in three stages of the phenological cycle of the crop from November (2013) to April (2014). Here, we considered the results of the first sampling date. At each farm variables of the habitat heterogeneity related with the height, canopy, percentage of tobacco coverture, of weeds in the herbaceous layer of the barrier and its stratification and composition (native vs introduced) was taken, among others. We related the environmental variables with the composition of guilds by a non-metric multidimensional scaling (NMS) to evaluate which of them explained the presence of natural enemies.We recorded 24,866 arthropods: 18,012 phytophagous (NT=7.059 y NB=10.953); 1,699 predators (NT=668 y NB=1.031), 1,530 parasitoids (NT=273 y NB=1.257) and 3,625 of ?others? guild (pollinators, detritivores and omnivores) (NT=2.052 y NB=1.537). The farms were divided into two groups according to the percentage of implanted tobacco and the composition of barrier vegetation. The NMS showed that a low percentage of weeds in the tobacco crop, in addition with a presence of a barrier represented by an herbaceous layer up to 5 meters surrounding the complete tobacco field increases the abundance of natural enemies. Furthermore, barriers with a percentage of non-native vegetation also increase the presence of predators, while phytophagous and parasitoids are favored by native vegetation on the barriers.