Inhibitory activity of Beauveria bassiana and Trichoderma spp. on the insect pests Xylotrechus arvicola (Coleoptera: Cerambycidae) and Acanthoscelides obtectus (Coleoptera: Chrisomelidae: Bruchinae).

Xylotrechus arvicola is an important pest in vineyards (Vitis vinifera) in the main Iberian wine-producing regions, and Acanthoscelides obtectus causes severe post-harvest losses in the common bean (Phaseolus vulgaris). Under laboratory conditions with a spray tower, the susceptibility of the immature stages of X. arvicola and A. obtectus against the entomopathogenic fungi Beauveria bassiana and four strains of Trichoderma spp. was evaluated. Both insect pests T. harzianum and B. bassiana showed a good inhibitory activity, accumulating an inhibition on the eggs of values above 85 and 82%, respectively. T. atroviride and T. citrinoviride had a lower inhibitory activity, with inhibition values of 74.1 and 73.3% respectively. These fungi can be considered a highly effective tool for the control during the immature stages of these species.

Genetic Response of Common Bean to the Inoculation with Indigenous Fusarium Isolates.

Fungal species from the genus Fusarium are important soil-borne pathogens worldwide, causing significant economic losses in diverse crops. The need to find sustainable solutions against this disease has led to the development of new strategies-for instance, the use of biocontrol agents. In this regard, non-pathogenic Fusarium isolates have demonstrated their ability to help other plants withstand subsequent pathogen attacks. In the present work, several Fusarium isolates were evaluated in climatic chambers to identify those presenting low or non-pathogenic behavior. The inoculation with a low-pathogenic isolate of the fungus did not affect the development of the plant, contrary to the results observed in plants inoculated with pathogenic isolates. The expression of defense-related genes was evaluated and compared between plants inoculated with pathogenic and low-pathogenic Fusarium isolates. Low-pathogenic isolates caused a general downregulation of several plant defense-related genes, while pathogenic ones produced an upregulation of these genes. This kind of response to low-pathogenic fungal isolates has been already described for other plant species and fungal pathogens, being related to enhanced tolerance to later pathogen attacks. The results here presented suggest that low-pathogenic F. oxysporum and F. solani isolates may have potential biocontrol activity against bean pathogens via induced and systemic responses in the plant.