Bottom-up effects of bamboo-charcoal soil amendment on the tomato insect pest Bemisia tabaci

Soil amendments can trigger bottom-up effects in crop-herbivorous pest interactions, thus impacting pest management and biochars may enhance plant growth and resistance to plant pests. We studied bottom-up effects of regenerative biochar bamboo charcoal on tomato (Solanum lycopersicum) and a major pest Bemisia tabaci, both under laboratory and field conditions. Plant height, stem diameter, and leaf dry-to-fresh weight ratio, as well as the content of free amino acids, starch, and soluble sugars, increased in the bamboo charcoal treatment compared with the control. Moreover, some plant-resistant substances or enzyme activities (e.g., flavonoids, phenylalanine ammonia lyase, and superoxide dismutase) were different among treatments. Applying bamboo charcoal reduced the survival rate and oviposition of B. tabaci. Y-tube olfactometer bioassay and volatilome analysis showed that the bamboo charcoal treatment reduced the attractiveness of tomato plants to B. tabaci by inducing the increasing release of the repellent volatile organic compound methyl salicylate. Field experiment showed that applying bamboo charcoal (5 L/m2) in the soil promoted the growth of tomato plants and suppressed the B. tabaci population. In conclusion, we demonstrate that applying bamboo charcoal could enhance the tomato plant growth and development and lower pest population by increasing the synthesis and accumulation of plant resistance substances. Therefore, it has the potential for large-scale field application to improve crop yield and significantly reduce B. tabaci occurrence.