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Eisenia fetida (Annelida, Oligochaeta: Lumbricidae) is a biondicator of soil contamination and susceptible to the action of xenobiotics such as phytosanitary. The objective of this study was to determine the lethal and sublethal effect of three granulated baits based on Metaldehyde and / or Carbaryl on E. fetida. Three bioassays were carried out under a completely randomized design with 4 repetitions and under controlled conditions (20 ± 2°C and 14L: 10O). The experimental unit was a plastic container 11.5 cm in diameter and 11 cm in height, provided with a perforated lid, where 750 g of soil mixed with the doses of each bait and 10 clitellated adult individuals from 200 to 400 mg were placed. The treatments were: 0, 40, 80, 120, 160 and 200 g of Metaldehyde ha-1 (4% active ingredient (a.i.)); 0, 80, 160, 240, 320 and 400 g of Carbaryl ha-1 (8% of a.i.) and 0, 40 + 80, 80 + 160, 120 + 240, 160 + 320 and 200 + 400 g Metaldehyde + Carbaryl ha-1 (4% + 8% of a.i.). In the three bioassays, 100% survival of the individuals was obtained. Regarding the biomass of E. fetida, no changes were detected with the application of the baits at 7, 14, 21 and 28 days after application (DAA) (p> 0.05). On the other hand, there were no differences in the number of cocoons and juveniles at 56 DAA with all baits (p> 0.05). It is concluded that the baits based on Metaldehyde and / or Carbaryl did not cause adverse effects on survival, biomass and reproductive parameters of E. fetida. [ABSTRACT FROM AUTHOR]

Earthworms participate in soil ecosystem services and are considered potential indicators of soil health. The use of insecticides in agriculture may negatively affect the population of these earthworms. The aim of, this study was to evaluate: 1) the avoidance and / or attraction of Octolasion cyaneum (Oligochaeta, Lumbricidae) in the presence of Chlorpyrifos and 2) the lethal and sublethal effects of this insecticide on O. cyaneum. Avoidance, sublethal toxicity and reproduction bioassays were performed with 5 doses of Chlorpyrifos and a control with no chemical treatment. The proportion of individuals in the treated area, measured as the ratio of the weight of the treated area and the total weight of O. cyaneum did not differ among the different doses after 48 hours (p > 0.05). Therefore, there was no avoidance response of O. cyaneum to Chlorpyrifos. With different Chlorpyrifos doses, 238 individuals of O. cyaneum resulted alive and 2 dead, whereas 33% of the organisms presented morphological changes such as coiling and skin coloration. Twenty-eight days after application (DAA), damage percentage increased as the dose of Chlorpyrifos was higher (p = 0.051). Wet weight biomass (mg) of O. cyaneum did not differ between doses 7, 21 and 28 DAA, whereas it did vary 14 DAA (p = 0.004). Across all treatments including the controls, both O. cyaneum cocoons and juveniles numbers, were, on average, low. Therefore, Chlorpyrifos did not cause an avoidance behaviour response or a lethal effect on O. cyaneum. However, depending on the application rate, Chlorpyrifos produced morphological and biomass changes on these organisms. [ABSTRACT FROM AUTHOR]

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In Costa Rica, the region of Río Macho is a highly fragmented landscape with imminent risk of landslides. This area, which provides important environmental services, has been partially recovered to its original forest through intentional reforestation with exotic species or natural regeneration after abandonment. The aim of this study was to evaluate the bioindicator potential of oligochaete presence as well as some litter and soil characteristics. The ecosystem recovery of the two common restoration modes was measured within three different forest covers. For this, some substrate characteristics were analyzed and compared in a 50 years old secondary forest, a 13 years tacotal, and a 35 years cypress (Cupressus lusitanica) plantation. The three sites studied differed in density, biomass and average mass of oligochaetes, and in some litter (depth, nitrogen, phosphorus and C/N ratio of litter), and soil variables (soil water content (CA), pH, phosphorus, cation exchange capacity, and magnesium). The forest registered the lowest density of earthworms and soil pH, and the highest soil CA and phosphorus. CA was inversely related to the oligochaete density across sites. Besides, there were positive correlations between C/N and C/P ratios from the litter and soil pH, and inverse correlations of litter depth, litter N and P concentrations with soil P. Discriminant Analysis (AD) performed with all soil and litter variables, produced a sharp classification of the three forest cover types. AD suggests that site differences were mostly determined by soil CA and litter nitrogen concentration. Considering all the evaluated parameters, our results suggest in the first place, that oligochaetes are sensitive to changes in some soil and litter characteristics. Secondly, aside from the striking oligochaete differences between the old secondary forest and the other two sites, some soil and litter traits resulted good indicators of the present recovery of the three forest covers. In addition, comparing soil nutrients content (organic carbon, nitrogen, calcium, potassium and sulfur) among the three sites, our findings indicate that the cypress plantation had reached soil nutrient conditions similar to the old secondary forest, presumably by the accumulation of nutrients, as a result of low nutrient recirculation. In conclusion, ecosystem level studies throughout simple evaluation criteria (soils, oligochaetes and ground litter) can be used as rapid indicators of the state of some of the many and complex forest ecosystem compartments. [ABSTRACT FROM AUTHOR]

In the present experiment, we evaluated the effect of three earthworm species on soil fertility and seedling growth of maize (Zea mays), a food plant of great importance in Mexico. One individual of each species (Balanteodrilus pearsei and Lavellodrilus bonampakensis, two native species and Pontoscolex corethrurus, an exotic), were used in the germination and initial maize growth experiment (vegetative phase v6), with four replicates per treatment and 9 seeds per pot, with 4 kg of soil each. Organic matter contents, total nitrogen and available phosphorus in the soil and in the maize leaves were determined at the end of the experiment. L. bonampakensis significantly increased foliar and root biomass, B. pearsei increased only shoot biomass and P. corethrurus decreased root biomass in relation to the control. Soil organic matter content increased significantly with earthworms, but for the remaining parameters, no significant differences were found between treatments with and without earthworms. Earthworm presence can affect soil fertility and initial maize growth positively, negatively or not at all, depending on the species involved. However, further research is necessary to better understand the relationships between native and exotic tropical earthworm species, plants and the soil. [ABSTRACT FROM AUTHOR]

En un diseño completamente aleatorizado con tres tratamientos (agroecosistemas): pastizal natural (PN), banco de proteína (BP) y caña de azúcar (caña) y en arreglo factorial 3 x 3 x 2 se estudió el efecto de los agroecosistemas PN, BP y caña en la dinámica de las poblaciones de L. terrestris. El experimento se condujo durante los años 1999, 2000 y 2001, al inicio del período lluvioso (IPLL) y al finalizar el mismo (FPLL). Los resultados mostraron interacciones significativas (P < 0.001) para los agroecosistemas con los años. Hubo estabilidad en la densidad de población (lombrices m² -1), con un promedio al tercer año de estudio de 128.75 y 86.25 en el PN y caña, respectivamente. En el BP se evidenciaron diferencias entre el primer y último año, con 98.75 individuos m² -1 al final de 2001. Con respecto a las interacciones de los agroecosistemas con la época, (P < 0.05) no se observaron diferencias entre el PN y el BP. Este último no difirió de la caña, cuando se compararon los muestreos al final del período lluvioso. Al inicio del mismo no hubo diferencias entre los agroecosistemas. Asimismo, no hubo diferencias entre las épocas para cada uno de los agroecosistemas. Las interacciones de los años con las épocas (P < 0.001) mostraron diferencias entre el primer y último año, dentro de cada época, con un promedio de 99.16 y 137.00 individuos al final del período lluvioso y en sus inicios, respectivamente. Se concluye que los agroecosistemas de PN y caña mantuvieron la densidad de lombrices y se incrementaron en el BP conforme a los principios agroecológicos. La supervivencia y densidad de estos individuos en las distintas épocas nos permiten confirmar su gran plasticidad ecológica, así como el manejo apropiado de los agroecosistemas estudiados. [ABSTRACT FROM AUTHOR]