EDITORIAL

This special issue of Tropical and Subtropical Agroecosystems presents a selection of the scientific work conducted in recent years in the state of Veracruz, Mexico, associated with its agroecosystems, considering in a wide sense the term “ager†(field). Reviewing research carried out in a defined territory, such as a state, on its contrasting and sometimes complementary productive systems, allows us to visualize the topics on development by its scientific community frequently associated with the problems of a productive chain, the lack of sustainability, contamination affecting the regions and their living beings, the impacts of socioeconomic problems on food production and productivity. In this particular case livestock-related topics dealing with the yield of forages used for cattle grazing are revised, as well as epidemiological and animal-health aspects referring to the presence of paratuberculosis in goats and cryptosporidiosis in calves. As for agricultural aspects, biofertilization with rhizobacteria and mycorrhizal fungi in citrus is presented as an alternative to traditional fertilization; in the case of papaya, the integrated management of its pest mites as well as a participatory methodology to achieve its technological transfer are revised. In addition, the influence that human migration has on the change of land use in a mountain range community is presented, and the eating habits related with the potential practice of horticulture in peri-urban families from the subhumid tropics are revised. Some aquacultural elements are also included, such as the presence of parasitic microorganisms in the oyster depending on the season of the year, the cultivation of tilapia fry in water recirculation systems, basic studies on the genetic improvement of the crayfish, as well as the establishment of a hydroponic-aquaponic system where cultivation of basil and production of Malaysian prawn are combined. As for varied topics, the impact of oil contamination on forages and soil is reported, the use of edible insects in coffee agroecosystems is analyzed, and the distribution of Ceratozomia mexicana in preserved and disturbed environments is revised. This menu of topics represents the richness of our agroecosystems. They are also a chessboard of the variety of researchers from the central area of the Gulf of Mexico. We believe that the will the scientific community from Veracruz has put into the organization of their annual Forest and Agricultural and Livestock Scientific-Technological Meeting for the last 24 years, has allowed the consolidation of the effort, talent and collaboration of the researchers from the region. “Tropical and Subtropical Agroecosystems†has hosted the best works presented at the meeting celebrated in 2011, aiming to spread the diversity of topics and interactions that are given in food production and in the rural sphere in the tropics. We are very thankful for the kind sponsorship of this journal, which is a strong compromise we take very seriously in order to preserve the quality standards of this important electronic media for the diffusion of science. H. Veracruz, Veracruz, Mexico. November 13, 2012 Juan A. Villanueva-Jiménez and Concepción del Carmen Ahuja-Aguirre Section Editor

IMPACT OF MANGO MANILA MANAGEMENT SYSTEMS ON ARTHROPODS IN FOLIAGE AND WEEDS

In recent years, cultivation of mango Manila in the State of Veracruz, Mexico, has had a tendency of increased technification and continuous substitution by sugarcane. All this is causing a negative impact on the environment and biodiversity. Thus, the impact of mango Manila management systems on arthropods in foliage and weeds was evaluated. Arthropods associated with foliage and weeds were sampled during different seasons of the year on each management system: technified, transitional, minimum traditional, and substituted by sugarcane. Abundance, diversity and richness by substrate, system and season were calculated. Comparisons between the minimum traditional system and each one of the others were made with Student´s t-test (P ≤ 0.05). The system substituted by sugarcane had a negative impact on abundance, diversity and richness of arthropods in weeds and foliage during the dry season. The effect of management systems were significantly different after pooling seasons, with greater values during the rainy season, and similar in the dry and winter seasons. System substituted by sugarcane showed a negative impact on diversity during the dry and rainy seasons

BIOFERTILIZATION WITH RHIZOBACTERIA AND A CONSORTIUM OF ARBUSCULAR MYCORRHIZAL FUNGI IN CITRUS ROOTSTOCKS

Biofertilization of plants with rhizobacteria and vesicular arbuscular mycorrhizae (mycorrhizal consortium), potentially promotes plant growth and health, and reduces the use of agrochemicals. The effect of individual and combined biofertilization with three strains of rhizobacteria and the mycorrhizal consortium (MTZ-1) was evaluated under nursery conditions on the growth of rootstocks of Citrus volkameriana and Rangpur lime grafted with Tahiti lime. Plants were inoculated individually and combined with the rhizobacteria strains FCA-8, FCA-56 and FCA-60 of Pseudomonas putida, and with MTZ-1; 50 % fertilization also was applied (18-46-00 N-P-K) and compared with controls that received nursery management and 100 % fertilization. A split-plot experimental design with five replications per treatment was established. Individual and combined biofertilization with the three strains of bacteria and MTZ-1 positively promoted the growth of C. volkameriana, and Rangpur lime grafted with Tahiti lime, similar to the control with 100 % fertilization. The nutrient content of Tahiti lime leaves was similar to the control for both rootstocks. The presence of rhizobacterial and mycorrhizal populations in the combined biofertilization treatments demonstrated a positive synergism in the colonization of rootstock roots. Results demonstrate the potential of the three strains of P. putida and the MTZ-1 mycorrhizal consortium on the promotion of plant growth and assimilation of nutrients