emamectin-benzoate and spinetoram

Field control of pest thrips mainly relies on insecticides, but the toxicity of insecticides can vary among thrips species and populations. In this study, we examined the susceptibility of multiple field populations of two thrips pests, Frankliniella occidentalis, and Thrips palmi, that often co-occur on vegetables, to nine insecticides belonging to seven subgroups.. The highest level of variation in susceptibility among F. occidentalis populations was for spinetoram (73.92 fold difference between most resistant and most susceptible population), followed by three neonicotinoids (8.06-15.99 fold), while among T. palmi populations, it was also for spinetoram (257.19 fold), followed by emamectin benzoate, sulfoxaflor, and acetamiprid (23.64-45.50 fold). These findings suggest evolved resistance to these insecticides in some populations of the two thrips. One population of F. occidentalis had a particularly high level of resistance overall, being the most resistant for five of the nine insecticides tested. Likewise, a population of T. palmi had high resistance to all nine insecticides, again suggesting the evolution of resistance to multiple chemicals. For F. occidentalis, the LC. Our study found interspecific and intraspecific variations in the susceptibility of two thrips to nine insecticides and multiple resistance in some populations, highlighting the need for ongoing monitoring and resistance management. © 2023 Society of Chemical Industry.

Topics: Animals; Insecticides; Macrolides; Thysanoptera

Fall armyworm (FAW) Spodoptera frugiperda, is a serious invasive pest of many crops that causes huge economic losses to agricultural commodities. Insecticides are employed for the management of S. frugiperda. In this study, we investigated the impact of sublethal concentration (LC

Topics: Animals; Demography; Insecticides; Larva; Moths; Spodoptera

Spodoptera frugiperda (J.E. Smith) is a highly invasive noctuid pest first reported in northern Australia during early 2020. To document current status of resistance in S. frugiperda in Australia, insecticide toxicity was tested in field populations collected during the first year of establishment, between March 2020 and March 2021. Dose-response was measured by larval bioassay in 11 populations of S. frugiperda and a susceptible laboratory strain of Helicoverpa armigera. Emamectin benzoate was the most efficacious insecticide (LC50 0.023μg/ml) followed by chlorantraniliprole (LC50 0.055μg/ml), spinetoram (LC50 0.098μg/ml), spinosad (LC50 0.526μg/ml), and methoxyfenozide (1.413μg/ml). Indoxacarb was the least toxic selective insecticide on S. frugiperda (LC50 3.789μg/ml). Emamectin benzoate, chlorantraniliprole and methoxyfenozide were 2- to 7-fold less toxic on S. frugiperda compared with H. armigera while spinosyns were equally toxic on both species. Indoxacarb was 28-fold less toxic on S. frugiperda compared with H. armigera. There was decreased sensitivity to Group 1 insecticides and synthetic pyrethroids in S. frugiperda compared with H. armigera: toxicity was reduced up to 11-fold for methomyl, 56 to 199-fold for cyhalothrin, and 44 to 132-fold for alpha cypermethrin. Synergism bioassays with metabolic inhibitors suggest involvement of mixed function oxidase in pyrethroid resistance. Recommended diagnostic doses for emamectin benzoate, chlorantraniliprole, spinetoram, spinosad, methoxyfenozide and indoxacarb are 0.19, 1.0, 0.75, 6, 12 and 48μg/μl, respectively.

Topics: Animals; Australia; Drug Combinations; Gene Expression Regulation, Enzymologic; Hydrazines; Insect Proteins; Insecticide Resistance; Insecticides; Ivermectin; Juvenile Hormones; Larva; Lethal Dose 50; Macrolides; Mixed Function Oxygenases; ortho-Aminobenzoates; Oxazines; Population Surveillance; Spodoptera

Resistance management is very important for devising control strategies of polyphagous insect-pests like Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Considering the importance of resistance management, demographic features of selected and unselected populations of H. armigera were studied in 6 different treatments viz. emamectin benzoate, Helicoverpa armigera Nucleopolyhedrosis Virus (HaNPV), emamectin benzoate+HaNPV, spinetoram, spinetoram+HaNPV and control. Higher values for fecundity, intrinsic rate, the finite rate of increase (λ) were recorded in the control of selected as compared to the rest of treatment. Similarly, higher values for these population parameters viz. oviposition days, fecundity, intrinsic rate, the finite rate of increase were calculated in the unselected control. Similarly, net reproductive rate (R0) for selected and unselected control was higher as compared to the rest of the treatments. It may happen because these kinds of selection pressures can result in decreased fitness of the test insect thus decreased fitness of H. armigera in different treatments was observed as compared to the control. Additionally, quicker development of susceptible insects was observed because susceptible insects were growing without any stressor (xenobiotics) as compared to the rest which contributed to their faster development.

Topics: Animals; Biological Control Agents; Female; Fertility; Insecticides; Ivermectin; Larva; Life Tables; Macrolides; Male; Moths; Nucleopolyhedroviruses; Oviposition

Selective insecticide application is one important strategy for more precisely targeting harmful insects while avoiding or mitigating collateral damage to beneficial insects like honey bees. Recently, macrocyclic lactone-class insecticides have been introduced into the market place as selective bio-insecticides for controlling many arthropod pests, but how to target this selectivity only to harmful insects has yet to be achieved. In this study, the authors investigated the acute toxicity of fourmacrocyclic lactone insecticides (commercialized as abamectin, emamectin benzoate, spinetoram, and spinosad) both topically and through feeding studies with adult forager honey bees. Results indicated emamectin benzoate as topically 133.3, 750.0, and 38.3-fold and orally 3.3, 7.6, and 31.7-fold more toxic, respectively than abamectin, spinetoram and spinosad. Using Hazard Quotients for estimates of field toxicity, abamectin was measured as the safest insecticide both topically and orally for honey bees. Moreover, a significant reduction of sugar solution consumption by treatment group honey bees for orally applied emamectin benzoate and spinetoram suggests that these insecticides may have repellent properties.

Topics: Animals; Bees; Drug Combinations; Insecticides; Ivermectin; Lactones; Macrolides; Toxicity Tests

Methomyl is currently used as a toxicant for the attracticide BioAttract in cotton and vegetables in China. However, methomyl is highly toxic to non-target organisms and a more environmental friendly acceptable alternative is required. Larvae of three lepidopteran insects Helicoverpa armigera, Agrotis ipsilon and Spodoptera litura are important pests of these crops in China. In the present study, the toxicity of 23 commonly used insecticides were tested on H. armigera, then tested the susceptibility of A. ipsilon and S. litura moths to the insecticides which were the most toxic to H. armigera, and the acute toxicity of the most efficacious insecticides were further investigated under laboratory conditions. Chlorantraniliprole, emamectin benzoate, spinetoram, spinosad and methomyl exhibited high levels of toxicity to H. armigera moths with a mortality of 86.67%, 91.11%, 73.33%, 57.78% and 80.00%, respectively, during 24 h period at the concentration of 1 mg a.i. L-1. Among these five insecticides, A. ipsilon and S. litura moths were more sensitive to chlorantraniliprole, emamectin benzoate and methomyl. The lethal time (LT50) values of chlorantraniliprole and methomyl were shorter than emamectin benzoate for all three lepidopteran moth species at 1000 mg a.i. L-1 compared to concentrations of 500, 100 and 1 mg a.i L-1. Chlorantraniliprole was found to have similar levels of toxicity and lethal time on the three lepidopteran moths tested to the standard methomyl, and therefore, can be used as an alternative insecticide to methomyl in the attracticide for controlling these pest species.

Topics: Animals; Biological Assay; Crop Protection; Drug Combinations; Female; Insect Control; Ivermectin; Larva; Macrolides; Male; Methomyl; Moths; ortho-Aminobenzoates; Pesticides

Studies were conducted to determine the residual toxicity of spinetoram, chlorantraniliprole, and emamectin benzoate to obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). Larvae were exposed to apple (Malus spp.) foliage collected at different intervals after an airblast sprayer application at the manufacturer-recommended field rate and half the field rate. A mortality of 100% was recorded at field rate applications of spinetoram, chlorantraniliprole, and emamectin benzoate through 59, 38, and 10 d after treatment (DAT), respectively. Significantly less foliage was consumed by C. rosaceana larvae surviving in the emamectin, chlorantraniliprole, and spinetoram treatments compared with those exposed to untreated foliage. Third-instar C. rosaceana exposed to fresh residues on terminal foliage showed 100% mortality after 5-d exposure to spinetoram residues and after 10-d exposure to chlorantraniliprole and emamectin benzoate. The effects of larval movement from foliage with fresh residues was examined by transferring neonate larvae from foliage treated with spinetoram, chlorantraniliprole, or emamectin benzoate to untreated foliage after various exposure intervals. An exposure of 1, 3, and 6 d was required for spinetoram, chlorantraniliprole, and emamectin benzoate to cause 100% mortality at the field rate, respectively. The higher the concentration of chlorantraniliprole and emamectin benzoate, the less exposure time was necessary to cause high levels of mortality in C. rosaceana neonates. Our results indicate that these novel insecticides are highly toxic to C. rosaceana larvae. Implications of these results for C. rosaceana management programs are discussed.

Topics: Animals; Disaccharides; Insecticides; Ivermectin; Larva; Macrolides; Malus; Moths; ortho-Aminobenzoates; Plant Leaves; Time Factors