Development and evaluation of pymetrozine controlled-release formulation to control paddy planthopper

Abstract

Continuous outbreaks of rice planthoppers in rice-growing regions in China indicates the importance of redesigning several planthopper management programs. Chemical control remains the main strategy for planthopper control in China and other subtropical and temperate regions. Most common chemical insecticides are emulsifiable concentrates, suspension concentrates, soluble concentrates, and wettable powders. These insecticides are applied by dusting or spraying using simple equipment. The active ingredient, with short effectiveness time, is degraded rapidly in natural paddy ecosystems. Thus, repeated pesticide applications are required to control rice planthoppers. Altering the short-term effect formulation of pesticides to a long-acting formulation may be an alternative solution. A pymetrozine controlled-release granule (CRG; 1%) was developed by loading the pesticide on bentonite and coating the solid pesticide with resin. Analysis of pymetrozine release indicated that the 1% pymetrozine CRG release was more than 80% for 60 days. In the field trial screening, the 1% pymetrozine CRG showed a controlled effect of 61.96-78.87% at 48 days after CGR application. Application of 1% pymetrozine CRG at the recommended dosage and 1.5 times the recommended dosage resulted in terminal residues on brown rice below the maximum residue limit (0.1 mg kg À1 ) of China and Japan. Moreover, the pesticide granules showed low toxicity against all tested beneficial organisms in the environment.Pymetrozine CRG (1%) showed good controlled release and efficacy for controlling paddy planthoppers.The compound exhibited a low terminal residue and low toxicity against all tested beneficial organisms.Pymetrozine CRG (1%) showed great potential for field applications to control paddy planthoppers, because it overcame the rapid loss of biological function during treatment.

Controlled‐release granules for the delivery of pymetrozine to roots of transplanted rice seedlings with decreased phytotoxicity and enhanced control efficacy against paddy planthoppers

“…The controlled‐release granules can be applied through seedling boxes or paddy field treatment. A controlled‐release granule treatment suitable for paddy fields was demonstrated by the uniform broadcasting of urea fertilizer as granules on the field, to control paddy planthoppers 14 . In our study, seedling box treatment with granules controlled paddy planthoppers better than field treatment with the granules, which performed during the outbreak of rice planthopper 33 days after transplanting, at the same application rates (Table 7).…”

“…Xu et al . prepared a pymetrozine controlled‐release granule to control paddy planthopper by loading pymetrozine on bentonite and coating core particles with resin a pan granular 14 . This controlled‐release granule was applied to field surface by a urea fertilizer.…”

Novel comb‐like anion‐nonionic copolymer for improving the stability of pymetrozine suspension concentrate

“…Therefore, the SCs prepared by SA‐M and TERSPERSE® 2700 have little coalescence and flocculation. However, pymetrozine must stay in alkaline medium (pH > 8 in our cases) to avoid hydrolyses at low pH 34 . This means that the surface‐adsorbed carboxylate groups in SA‐M and TERSPERSE® 2700 dissociate, thus blocking the formulation of hydrogen bonds between COOH and the hydrogen atom in HCN of pymetrozine molecule.…”

“…However, pymetrozine must stay in alkaline medium (pH > 8 in our cases) to avoid hydrolyses at low pH. 34 This means that the surface-adsorbed carboxylate groups in SA-M and TERSPERSE ® 2700 dissociate, thus blocking the formulation of hydrogen bonds between COOH and the hydrogen atom in HC N of pymetrozine molecule. In comparison to TERSPERSE ® 2700, the existence of nonionic MPEG branches of SA-M makes it possible to form hydrogen bonds between EO and pymetrozine molecules ( Figure 5).…”

Development of ultra HPLC analytical method for pymetrozine residues in rice

“…P y m e t r o z i n e , 4 , 5 -d i h y d r o -6 -m e t h y l -4 -[ ( 3pyridylmethylene)-amino]-1,2,4-triazin-3(2H)-one (Figure 1), is a novel insecticide with effects on neuroregulation or nerve-muscle interaction against sucking insects by preventing these ones from inserting their stylus into the plant tissue, reduction in feeding and alteration in probing behaviors characterized by the prolonged non-probing, penetration initiation and extracellular activity and shortened salivation and phloem-related activities [1][2][3]. Pymetrozine has been widely used in rice against plant hoppers [4] as a substitution for highly toxic organophosphate pesticides and vegetables [5].…”