## 3 Results and Discussion  
### Arthropods and Plants Diversity  
In this work, the diversity of arthropods from the soil and non-crop plants of a sisal agroecosystem was identified during the winter season, which is characterized by cold and dry conditions, in Bahia, Brazil. Regarding the arthropods, a total of 3259 specimens were captured in the pit-fall traps. They belonged to Araneae, Acari, Diptera, Hymenoptera, Collembola, Coleoptera, Orthoptera, Hemiptera, Blattodea, and Lepidoptera (Figure 2) and were separated into 153 morphospecies. Figure 2: Abundance (number) of the identified taxa in a sisal crop from June to September 2015. These taxa include several functional groups, such as predators, parasitoids, pollinators, or decomposers, that could play important roles in the sisal agroecosystem. Their abundance varied during the period of study. In June, the most abundant taxa were Diptera and Hymenoptera, with 38.4% and 35.5%, respectively, and the SiDI, ShDI, and E were 0.85, 2.43, and 0.66, respectively. The highest abundance of specimens occurred in July (1452) and August (975). During these months the SiDI, ShDI, and E decreased (July--SiDI = 0.53/ShDI = 1.46/E = 0.38; August--SiDI = 0.26/ShD = 0.77/E = 0.22), with Collembola being the dominant taxa and representing 78.6% and 91%, respectively. In September, the most abundant taxon was Hymenoptera, representing 58% of the total, and the SiDI, ShDI, and E increased (0.59, 1.65, and 0.50, respectively). To the best of our knowledge, there are no other studies that addressed arthropods diversity in a sisal crop. However, in _Agave tequilana_ Weber var. Azzul crops from Mexico, [PERSON] et al. [10] found ShDIs between 1.5 and 3.5, with higher richness and special relevance of Hemiptera, Coleoptera, Diptera, and Hymenoptera orders. Other studies evaluated the arthropods colonizing plants of _Agave palmeri_ [PERSON] [20]. Regarding the plants, in this study, a total of 21 species belonging to 8 families and 5 species in seedling stage were identified (Table 1). The richest families were _Asteraceae_, _Malvacae_, and _Fabaceae_, and the diversity varied during the period of study. In June, only the _Commelinaceae Commelina erecta_ L. was identified. In July, 13 species were identified. The highest IVI was presented by _Amaranthaceae Alternanthera tenella_ [PERSON] (IVI = 40.04), followed by species belonging to _Asteraceae_, _Malvacae_, and _Fabaceae_. In August, 15 species were identified. The most represented species belonged to _Asteraceae_ and were followed by _A. tenella_ (IVI = 22.54). Finally, in September, 10 species were identified, and the highest IVI was displayed by Fabaceae _Chmaecrista rotundifolia_ [PERSON] (IVI = 20.15), followed by Asteraceae _Lepidapola cotoneaster_ (Wild. ex Spreng.) (IVI = 18.09) and _Malvacae Pavonia cancellata_ ([PERSON]). [PERSON]. (IVI = 11.67) (Table 1). The plant diversity indexes decreased from July to September (July--SiDI = 0.50, ShDI = 0.78, E = 0.31; August--SiDI = 0.44, ShDI = 0.74, E = 0.29; September--SiDI = 0.29, ShDI = 0.47, E = 0.20). Thus, both plants and arthropods showed similar temporal patterns from June to July, whereas in September the biodiversity increased for arthropods and decreased for plants. Generally, the results agree with the seasonal patterns of tropical ecosystems such as the Caatinga, where soil arthropod abundance and richness occur following the dry and rainy seasons, being directly influenced by the weather conditions and food resources, such as non-crop plants [21]. The identified plants comprise multiple potential uses and may provide additional ecosystem services to the sisal crop. Among the agronomic potential uses, pest/diseases control, biostimulant properties, or the improvement of soil characteristics are included. In a study carried out in urban ecosystems, the increasing patch size and decreasing patch isolation of _C. erecta_ resulted in higher overall parasitism rates over the leaf miner, _Liriomyza commelina_ ([PERSON]) (Diptera: Agromyzidae) [22].