Spodoptera litura develops high resistance to tetraniliprole in China.

The caterpillar Spodoptera lituraResearch conducted in China showed a high level of resistance to tetraniliprole, without compromising biological performance. Researchers from Yangtze University and the Beijing Academy of Agricultural and Forestry Sciences constructed a near-isogenic strain with 157 times greater resistance to the product and identified accelerated metabolism via cytochrome P450 as the main mechanism involved.

The work began with the crossing of a susceptible laboratory strain with a resistant field population collected in Nanchang. After five generations of backcrossing and selection with tetraniliprole, the authors isolated a strain genetically close to the susceptible strain, but highly resistant to the insecticide.

Toxicity tests confirmed high resistance to tetraniliprole and moderate cross-resistance to chlorantraniliprole. Other insecticides, such as indoxacarb, lambda-cyhalothrin, and emamectin, did not show relevant cross-resistance. The result indicates a risk associated with rotation between diamides and reinforces the need to alternate distinct modes of action.

Molecular analysis

Molecular analysis did not detect I4723M or I4723K mutations in the ryanodine receptor, a classic target of diamides. This data rules out resistance due to target site alteration in this case. Biochemical tests showed a 1,6-fold increase in cytochrome P450 activity in the resistant strain. The synergist piperonyl butoxide reduced the toxicity of tetraniliprole and chlorantraniliprole, confirming the involvement of oxidative metabolism.

Biological evaluation did not indicate an adaptive cost associated with resistance. The resistant strain showed a shorter mean generation time, a higher net reproductive rate, and a relative fitness of 1,13 compared to the susceptible strain. Females produced more eggs, despite a reduction in the hatching rate. The set of parameters resulted in equivalent or superior population performance.

More information at doi.org/10.1016/j.pestbp.2025.106834