Emamectin benzoate (Emamectin benzoate)

Emamectin benzoate is a widely used agricultural insecticide, especially effective in controlling caterpillars (lepidoptera). It belongs to the avermectin class and is a semi-synthetic derivative of avermectin produced by... Streptomyces avermitilis.

Common name: emamectin benzoate

Number CAS: 155569-91-8 (benzoate salt). The base compound (emamectin) has CAS number 119791-41-2.

Gross chemical formula: C56H81NO15

Chemical class: Avermectins (IRAC Group 6 – glutamate-gated chloride channel activators). It is a semi-synthetic insecticide/acaricide from the macrocyclic lactone family, acting through ingestion and contact.

Main commercial product names in Brazil: Proclaim 50 WG

Development history: Derived from avermectin B1 (abamectin) through chemical modification at the 4″ position (deoxyepimethylamino). Developed by Merck Sharp & Dohme (compound MK-244) in the 1980s-1990s. Subsequently transferred to Novartis and then Syngenta. Initial registrations in the 1990s (e.g., Israel/Japan in 1997, USA in 1999). In Brazil, emergency use was authorized in 2014 against Helicoverpa armigera (due to strong pest pressure). After toxicological re-evaluation by Anvisa and a favorable opinion from Ibama, it obtained definitive registration (Proclaim 50).

Mechanism of action: It acts primarily on glutamate-gated chloride (GluCl) channels in the insect nervous system. Binding causes increased permeability to chloride ions, hyperpolarization of the membrane, interruption of nerve transmission, irreversible paralysis, and death (mainly by ingestion). It has a secondary action on GABA receptors. It is fast-acting (larvae stop feeding within hours) and has some translaminar action.

Control spectrum: It acts against lepidopteran larvae (mainly early to intermediate instars): Spodoptera frugiperda, S. littoralis, Helicoverpa spp., Plutella xylostella, Tuta absolute, Heliothis spp. etc. Also effective against some thrips, mites and leaf miners. Low efficacy against stink bugs, scale insects and adult lepidopterans. Low dose (generally 5–30 g ai/ha).

Compatibilities and interactions: Generally compatible with many fungicides and insecticides, but a jar test is always recommended before tank mixing. There may be physical and chemical incompatibility with some fertilizers (especially NPK) or fungicides such as propiconazole under certain conditions. Avoid extreme pH levels in the spray solution. Low phytotoxicity in most crops when used at recommended doses. Toxic to bees (avoid application during flowering); moderate impact on some natural enemies.

Agronomic positioning: Emamectin benzoate is agronomically positioned as a foliar insecticide applied by spraying, requiring good plant coverage, preferably targeting the lower parts of the leaves due to its limited translaminar action. It stands out for its use in low doses and for exhibiting moderate to good residual action, making it an excellent tool for controlling caterpillars in various crops such as soybeans, cotton, corn, beans, vegetables, and fruit trees. In Brazil, it has become especially strategic after the entry of... Helicoverpa armigera and remains relevant in the management of Spodoptera frugiperda and other caterpillars. Its use is recommended within Integrated Pest Management (IPM) programs, always with rotation of modes of action — alternating, for example, with insecticides from Groups 28 (diamides) and 5 (spinosyns) — to delay the development of resistance. Regarding safety, the product is relatively selective to some predators and parasitoids when compared to pyrethroids or organophosphates, although it is toxic to bees, and applications should be avoided during the flowering period; its impact on natural enemies is considered moderate.

Other information:

Bioassay experiments were conducted to investigate the comparative efficacy of several new insecticides, including emamectin benzoate, lufenuron, and spinosad, against 3rd and 5th developmental instar larvae of Spodoptera littoralis. Time-mortality relationships, effects on larval weight gain, feeding damage, and larval development of S. littoralis were also determined. This study indicated that emamectin benzoate is the most potent among the insecticides tested against 3rd and 5th developmental instar larvae of S. littoralis, with chronic LC90 values ​​of 0,31 and 0,64 μg/ml, respectively. The combined effect of emamectin benzoate with lufenuron or spinosad was additive or antagonistic, suggesting that the isolated application of these insecticides is more effective than their combined application. Compared to lufenuron and spinosad, emamectin benzoate killed 3rd and 5th instar larvae of S. littoralis significantly faster, markedly reduced weight gain and feeding damage in 3rd instar larvae, and caused 100% mortality in 5th instar larvae during larval development. These results suggest that emamectin benzoate is an effective compound compared to lufenuron and spinosad for the control of S. littoralis. Field experiments with these insecticides may be useful to confirm the reduction of plant damage due to S. littoralis infestation. - DOI 10.1016/j.cropro.2014.10.022 -

The emamectin benzoate-resistant strain (Ben-R) was isolated via F2 screening in a field population collected in Lucas do Rio Verde, Mato Grosso state, Brazil. After ten generations of selective pressure with emamectin benzoate, the estimated LC50 of the Ben-R strain was 678,38 μg ai/mL, while that of the susceptible strain (Sus) was 0,29 μg ai/mL, resulting in a resistance ratio (RR) of 2340-fold. The LC50 values ​​of the progeny from reciprocal crosses of the Sus and Ben-R strains were 93,37 and 105,32 μg ai/mL, respectively, suggesting that resistance is an incompletely dominant autosomal trait. The high survival rate of heterozygous and emamectin benzoate-resistant (Ben-R) lines (>92%) in non-Bt maize sprayed with the field dose of emamectin benzoate confirmed that resistance is functionally dominant. The minimum number of segregations influencing resistance was 3,55, suggesting a polygenic effect. Low cross-resistance was detected between emamectin benzoate and the insecticides methomyl, chlorpyrifos, lambda-cyhalothrin, spinetoram, indoxacarb, and chlorantraniliprole (RR <5,75 times). There was no effect of the synergists piperonyl butoxide, diethyl maleate, and S,S,S-tributyl phosphorotrithiotate on the Ben-R line, suggesting a minor role for metabolic resistance. Our results showed a high risk of evolution of resistance in S. frugiperda to emamectin benzoate, based on incompletely dominant inheritance. Rotating insecticides with different modes of action may be one of the resistance management strategies to be implemented to delay the evolution of S. frugiperda resistance to emamectin benzoate in Brazil. DOI 10.1002/ps.6545

Emamectin benzoate is a crucial insecticide for the control of Spodoptera frugiperda. However, the emergence of resistance to emamectin benzoate represents a significant challenge for the effective management of the pest, and the underlying genetic mechanisms are still poorly understood. This study demonstrates that resistance levels in field populations of S. frugiperda have progressively increased, with ABCB1 expression positively associated with resistant phenotypes. Although microRNAs (miRNAs) are recognized as crucial regulators of gene expression at the post-transcriptional level, their specific involvement in modulating ABCB1 expression remains incompletely characterized. A total of 198 miRNAs were identified in S. frugiperda, of which 28 showed differential expression between resistant and susceptible strains to emamectin benzoate. Notably, miR-34-5p exhibited an inverse expression pattern relative to ABCB1 in both laboratory-selected resistant strains and field-derived resistant populations. Dual luciferase reporter assays confirmed that miR-34-5p directly targets the ABCB1 coding sequence, resulting in suppression of its expression. Functional studies demonstrated that both overexpression and silencing of miR-34-5p significantly alter the susceptibility of S. frugiperda to emamectin benzoate. Furthermore, bioinformatic analyses revealed that the miR-34-5p binding site within ABCB1 is highly conserved between S. frugiperda and Helicoverpa armigera. In vivo experiments showed that administration of miR-34-5p antagonists results in ABCB1 upregulation and decreased susceptibility to emamectin benzoate in H. armigera. These findings provide evidence that miR-34-5p participates in the post-transcriptional regulation of ABCB1 associated with susceptibility to emamectin benzoate in S. frugiperda and broaden the current understanding of miRNA-mediated detoxification regulation in lepidopteran insects. - DOI 10.1016/j.pestbp.2026.107169 -