Effects of crude protein extract from Trichoderma longibrachiatum strain T6 on the behavior of Caenorhabditis elegans

Trichoderma longibrachiatum strain T6, as an important bacterium for the biocontrol of plant diseases, has been found to have strong toxic effects on plant nematodes. In this study, we evaluated the effects of different concentrations of a crude protein extract from the T6 strain on the behavior of Caenorhabditis elegans based on assessments of morphological and physiological parameters. The results revealed that a crude protein extract derived from the T6 strain (at concentrations of 50, 100, 150, 200, and 250 μg·mL⁻¹) had significant effects on nematodes, with the highest assessed concentration having the most pronounced effects. The body walls of nematodes treated with 250 μg·mL⁻¹ were found to be transparent and disrupted, leading to the leakage of the internal contents and subsequent fragmentation of the worm body. Nematodes that were exposed to the crude protein were characterized by significant reductions of 76.00%, 79.21%, 48.21%, 46.15%, 63.78%, and 30.47% in head thrashes, body bends, forward turns, backward turns, foraging behaviors, and reproduction (P < 0.05), respectively, whereas we detected no significant effects on the Omega/U-shaped swing frequency. Collectively, these findings revealed that a crude protein extract of the T6 strain of T. longibrachiatum has significant effects on the movement, foraging, and reproduction of C. elegans.