Study finds limited impacts of spinosyn resistance

Field resistance to spinosyns remains restricted to a few species and specific regions, without significantly compromising the efficacy of the products. This was revealed by a study that reviewed more than 25 years of data. The research analyzed more than 1.100 cases of resistance documented in 400 studies.

Spinosyns include two main molecules: spinosad (spinisad, CAS 168316-95-8) and spinetoram (spinetoram, CAS 935545-74-7), introduced in 1997 and 2007, respectively. Both are used to combat pests such as Gut e caterpillars.

The study found that 52% of resistance cases were found in the field, with 46% involving thrips, 22% lepidopterans and 18% dipterans. However, only a small fraction of the populations analyzed presented high levels of resistance.

Resistance to spinosyns occurs due to three main mechanisms: changes in the site of action in the insect's nervous system, increased capacity to metabolize the insecticide and multifactorial factors.

The most common mechanism identified was the alteration in the nicotinic acetylcholine receptor gene (α6-nAChR), preventing the action of the insecticide. On a smaller scale, metabolic mechanisms were also recorded, such as the increased activity of enzymes that degrade spinosyns.

The study also assessed the possibility of cross-resistance with other insecticides, such as neonicotinoids, pyrethroids and diamides. The results showed that there is no significant correlation between resistance to spinosyns and other classes of insecticides. This indicates that the use of spinosyns can be combined with other products in resistance management.

More information can be found at doi.org/10.1016/j.pestbp.2025.106363

Learn more about spinosyns

Spinosyns are a group of natural compounds used as biological insecticides, derived from the bacteria Saccharopolyspora spinosa (click here for more information).

They act on the nervous system of insects, binding to nicotinic acetylcholine receptors, causing hyperexcitation, paralysis and death. They mainly affect insects in larval and adult stages, with a rapid effect (paralysis).

Saccharopolyspora spinosa was first isolated in 1982 by researchers at Eli Lilly and Company from soil samples in the Caribbean. The name "spinosa" refers to the spiny structures observed on its spores.

Classificação:

• Domain: Bacteria

• Phylum: Actinobacteria

• Genus: Saccharopolyspora

Features:

• Gram-positive, filamentous and spore-forming.

• It grows in aerobic conditions and is common in soils rich in organic matter.

• It forms colonies with branched structures (mycelium) and yellowish pigmentation.