Tomato moth develops high resistance to bioinsecticide

A study by Chinese scientists has shown that tomato moth (Tuta absoluta) can develop high resistance to the bioinsecticide spinetoram when subjected to continuous use. After 20 generations of laboratory selection, the resistant strain (SPI-R) showed a 410-fold increase in tolerance to the product compared to susceptible populations.

Genetic analysis revealed that resistance follows a polygenic, autosomal, and incompletely recessive inheritance pattern, with high heritability. This indicates a strong potential for transmission of the resistance trait to future generations, increasing the risk of loss of field efficacy.

Biochemical tests showed that resistance is primarily related to increased activity of three detoxification enzymes: cytochrome P450 monooxygenases, glutathione transferases (GSTs), and carboxylesterases (CarEs). Among these, P450 played a predominant role, according to synergist assays.

Biological costs

Despite its resistance, the SPI-R lineage presented biological costs. Larval stages were prolonged, and adult longevity was reduced compared to the susceptible population. Intrinsic growth rate also decreased, reflecting the pest's lower fitness under conditions free from chemical pressure.

No mutations were detected in the insecticide target gene, suggesting that resistance arises primarily from metabolic mechanisms rather than changes in the site of action.

Further information at doi.org/10.1016/j.pestbp.2025.106659