Spores of Trichoderma Strains over P. vulgaris Beans: Direct Effect on Insect Attacks and Indirect Effect on Agronomic Parameters

is an insect pest that attacks wild and cultivated common beans ( L). Four strains, the IBT 40837 wild-type strain (=Ta37), a producer of trichothecene harzianum A (HA), two transformants of strain, Ta37-17.139 (=Δ 17) and Ta37-23.74 (=Δ 23), and the IBT 40841 wild-type strain (=Tb41), which produces the trichothecene trichodermin, were assessed to establish their direct effect on insect attacks and their indirect effect on the plants grown from the beans treated with those fungal strains and exposed to insect attacks. Treatments of bean seeds with different strains led to different survival rates in the insects, and the Tb41 strain caused the lowest survival rate of all. An 86.10% of the insect cadavers (in contact with Δ 23) showed growth of this strain. This was the treatment that attracted the greatest number of insects. The daily emergence was reduced in beans treated with the Ta37, Tb41, and Δ 17 strains. The undamaged beans treated with Ta37 and Δ 23 showed a high capacity of germination (80.00% and 75.00%, respectively), whereas the Δ 17 and Tb41 treatments increased the capacity of germination in the damaged beans (66.67%). The undamaged beans treated with Δ 23 had the greatest dry weights for the aerial part (4.22 g) and root system in the plants (0.62 g). More studies on the mechanisms of insect control, plant growth promotion, and trichodermol and trichodermin production by Δ 23 and Tb41, respectively, should be explored in order to commercialize these fungal species on a large scale.