Biocidal radiuses of abamectin, thiamethoxam and sulfoxaflor droplets controlling against wheat aphid (Sitobion avenae)

Abstract

Spraying insecticide is a common practice in the control against pest insects. However, little attention has been paid to the biocidal radius of droplets. Therefore, in this study, we investigated the biocidal radiuses of abamectin, thiamethoxam and sulfoxaflor droplets controlling against wheat aphid (Sitobion avenae). The mortality of S. avenae showed a droplet density dependent process that can be described by an exponential model. Calculated mortality limit (A2) varied with the concentration of insecticides. Although similar LD50 values were observed in abamectin (13.77 ng aphid−1) and sulfoxaflor (14.52 ng aphid−1) against S. avenae, sulfoxaflor had a larger biocidal radius (r50) than abamectin due to its translocation ability at the same concentration. And sulfoxaflor had a relatively larger biocidal radius than thiamethoxam (LD50 = 68.42 ng aphid−1) because it is more toxic to S. avenae. The ratio of r50/VMD was introduced to estimate the potential of droplets. Droplets generated by the air atomizing nozzle (VMD = 43 μm) had higher value of r50/VMD than the centrifugal atomizing nozzle (VMD = 153 μm). Our results indicated that the mortality limit can be reached at a concentration of an insecticide. The biocidal radius of a droplet is different from its actual size. The LD50 and translocation ability of insecticides contributed to their biocidal radius. Ratio of r50/VMD is an indicator of droplets’ insecticidal potential. Smaller droplets generated by the air atomizing nozzle have higher insecticidal potential.

Evaluation of insecticidal efficacy against maize leaf aphid [Rhopalosiphum maidis (Fitch)] under inner terai condition of Nepal

“…The result is in line with the findings of Aston et al (2022) who reported that sublethal concentrations of flonicamid and thiamethoxam increase fecundity and phloem-feeding behavior on Myzus persicae. Similar results of effectiveness of flonicamid and thiamethoxam have been earlier reported against wheat aphid (Cui et al, 2018), cowpea aphid (Bora et al, 2019), okra aphid (Kodandaram et al, 2017) and aphids in other crops (Morita et al, 2014). The findings are in line with the findings of Zhang et al (2021), who reported that the neonicotinoids, viz.…”

“…The main insecticidal mechanism of flonicamid is starvation due to the inhibition of stylet penetration into plant tissues (Morita et al, 2014). Thiamethoxam [(EZ)-3-(2-chloro-1,3-thiazol-5yl-methyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro)amine] is classified according to the pharmacophore as Nnitroguanidineneonicotinoid (Cui et al, 2018). Thiamethoxam is presently one of the most effective chemicals for the control of sucking pests such as aphids (Zhang et al, 2021), whiteflies (Kumar et al, 2019), thrips, some microlepidoptera, and a number of coleopteran species.…”

Biocidal radiuses of cycloxaprid, imidacloprid and lambda‐cyhalothrin droplets controlling against cotton aphid (Aphis gossypii) using an unmanned aerial vehicle

“…Droplet size is one of the most important factors for spray technology and researchers have established different theories about optimum biological droplet size . Himel et al .…”

“…48 Cui et al used the value of r 50 /Dv0.5 to indicate the insecticidal potential of different size of droplets. 45 A higher value of r 50 /Dv0.5 means the active ingredients can reach a relatively wider area and the biocide radiuses were larger than the actual droplet size. For example, when cycloxaprid was sprayed by the UAV (Dv0.5 = 185 ± 5 μm) at the concentration of 5 g L −1 , the r 50 /Dv0.5 was 4.86.…”

Detoxification enzyme activity, reproductive and developmental fitness of abamectin-resistant Bryobia praetiosa (Acari:Tetranychidae)

“…Abamectin is a 16-membered macrolide ring produced during the fermentation of Streptomyces avermitilis (Lasota & Dybas, 1991). It is the only highly effective and broad-spectrum bio-pesticide used in crop protection and medicine and is consequently widely used to control a variety of pest insects of crops, pest mites, and zoonotic parasites (Bhardwaj et al, 2020;Cui et al, 2018;Lloberas et al, 2013;Verdu et al, 2015). China is the primary abamectin manufacturer globally, and abamectin is also among the most commonly used bio-pesticides in China.…”