Silica nanoparticles reduce egg laying by fall armyworm

Foliar application of silicon dioxide nanoparticles generated a residual effect in the soil capable of reducing fall armyworm egg laying in corn plants grown in the next generation. The mechanism involved soil microorganisms and changes in the emission of volatile compounds by the crop, according to a study by Chinese researchers (doi 10.1002/ps.71169).

Corn grown in soil treated with nanoparticles received fewer Spodoptera frugiperda eggs in field and laboratory tests. Choice assays also indicated less preference for the plants by adults and larvae. The treatment did not cause significant changes in initial growth or silicon accumulation.

Soil sterilization eliminated the response. Reintroduction of the microbial community restored the effect, a result associated with the participation of microorganisms in the process.

Analysis of volatiles identified increased emissions of hexanal, (Z)-β-ionone, dihydroactinidiolide, 6,10,14-trimethyl-2-pentadecanone, and (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene.

Hexanal, dihydroactinidiolide, and the last compound showed concentration-dependent behavioral responses. At levels close to those observed in the control plants, they acted as attractants. At high concentrations, recorded in corn grown in conditioned soil, they began to repel the insect.

The results indicate a feedback mechanism between nanoparticles, soil, and plant. This strategy may support the development of methods aimed at reducing crop colonization by the pest.