Effect of the cover crop ( Vicia faba L.) on the diversity , functional traits and activity of carabid beetles in citrus orchard (Guelma , Northeast of Algeria)

The effect of a cover crop (Vicia faba L.) in a citrus orchard on the diversity, functional traits, and activity of carabid beetles was investigated using pitfall traps over a two-year period. A total of 18 taxa were collected both inside the citrus orchard and at its edge. Species richness, estimated using the Chao-1 index, and the Shannon diversity index showed no significant difference between the two locations. The Jaccard index further confirmed a high similarity between the two communities. However, differences in beetle abundance were observed between the two sampling stations. Functional trait comparisons revealed that hygrophilous, zoophagous, and polyphagous beetles were more abundant inside the orchard compared to the edge. Both macropterous and smaller individuals dominated at both sites. Seasonal activity patterns showed more pronounced activity inside the orchard than at the edge. Our findings highlight the ecological benefits of cover cropping in citrus orchards, supporting carabid beetle diversity and abundance, and suggesting a potential role for cover crops in natural pest control.